WO2014092539A1 - A system and method for balancing load in a network - Google Patents

A system and method for balancing load in a network Download PDF

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Publication number
WO2014092539A1
WO2014092539A1 PCT/MY2013/000239 MY2013000239W WO2014092539A1 WO 2014092539 A1 WO2014092539 A1 WO 2014092539A1 MY 2013000239 W MY2013000239 W MY 2013000239W WO 2014092539 A1 WO2014092539 A1 WO 2014092539A1
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WIPO (PCT)
Prior art keywords
network
message
load
access point
target load
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Application number
PCT/MY2013/000239
Other languages
French (fr)
Inventor
Kae Hsiang KWONG
Heng Tze Chieng
Kee Ngoh Ting
Peng Hou HO
Su Fong Chien
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Mimos Bhd.
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Publication of WO2014092539A1 publication Critical patent/WO2014092539A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/08—Load balancing or load distribution
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/0247—Traffic management, e.g. flow control or congestion control based on conditions of the access network or the infrastructure network

Definitions

  • the present invention generally relates to a system and method for balancing load in a network, more particularly the present invention relates to a system and method for balancing load in a wireless mesh network.
  • Wireless communication technology has never ceased evolving and has today arrived to provide a network capable of routing messages within devices in a network, or widely known as the wireless mesh network.
  • the concept of such wireless technology is beneficial due to the significant advantages in deploying low-cost, low power consumption, highly efficient, reconfigurable network over large areas, and moreover, messages are able to be delivered across a significant span of a physical area.
  • the technology is desirably beneficial to provide internet connectivity without proper network infrastructure, such as villages, or ad-hoc networks in a disaster area.
  • wireless mesh network is formed by at least an access point relaying packets from clients to a gateway, and more often than not, a single gateway can only be active in linking to an external network so as to prevent discontinuity in network connection caused by routing loop.
  • Such network structure fundamentally limits the amount of data traffic to the external network. It is therefore that the gateway experiences congestion due to the excessive data load relayed from the plurality of access points serving a plurality of clients, thus the phenomenon starts to deteriorate performance of the entire wireless mesh network, especially with respect to the end-to-end throughput, end-to-end latency, and possibly affecting packet loss rate when the aggregated data load exceed the link capacity.
  • US patent no. 7693051 discloses system and method for controlling congestion in a wireless multihopping communication network by controlling the use of nodes acting as bottleneck points.
  • US patent no. 7843817 discloses a congestion control system in a wireless mesh network, more particularly the prior art addresses congestion in a multi-hop wireless network.
  • mesh nodes typically monitor their own access class queues for congestion, sends congestion control messages to upstream nodes.
  • US patent no. 6765869 discloses a method and system for improving high speed data transmission efficiency between a packet data sending unit and a packet data receiving unit by dynamically controlling the passage data frames.
  • the prior arts lack an inventive solution to overcome load congestions in a network because the prior arts are mainly focused on sending messages to the nodes, instead of taking into consideration of load balancing in the transmission protocol, as well as monitoring network information in the nodes and gateway.
  • the present invention addresses the problem by introducing load balancing system and methods to effectively tackle load congestions in a network.
  • the present invention aims to introduce a load balancing system based on controlling load traffic in a network, so that time interval during packet transmissions can be effectively and efficiently regulated.
  • the present invention provides a system comprising a network balancer residing in a gateway, a load balancer residing in at least an access point, and a waiting slot controller residing in at least a client.
  • the present invention provides a system and method for balancing load in a network by monitoring the network traffic, identifying the network congestion, determining a waiting slot value for each client, and interrupts the packet transmission protocol so that the network load is appositely balanced.
  • Figure 1 illustrates the network architecture according to the present invention.
  • Figure 2 illustrates the network architecture showing load congestions.
  • FIG. 3 illustrates schematic representation of the system architecture for the gateway according to the present invention.
  • Figure 4 illustrates schematic representation of the system architecture for the access point according to the present invention.
  • Figure 5 illustrates schematic representation of the radio modules in the access point according to the present invention.
  • Figure 6 illustrates schematic representation of the system architecture for the client according to the present invention.
  • Figure 7 illustrates a schematic representation of the overall system architecture and relationship for balancing load according to the present invention.
  • Figure 8 illustrates process flow for the overall method for balancing load according to the present invention.
  • Figure 9 illustrates process flow for the method of generating network information messages according to the present invention.
  • Figure 10 illustrates process flow for the method of generating acceptable target load message according to the present invention.
  • Figure 11 illustrates process flow for the method of determining acceptable target load according to the present invention.
  • Figure 12 illustrates process flow for the method of generating waiting slot message according to the present invention.
  • Figure 13 illustrates process flow for the method of determining waiting slot message according to the present invention.
  • Figure 14 illustrates two process flows in a client according to the present invention.
  • Figure 15 illustrates the message flow diagram according to the present invention.
  • Figure 16 illustrates the transmission protocol diagram according to the present invention.
  • Figure 17 illustrates the transmission protocol diagram according to the present invention.
  • Figure 18 illustrates the transmission protocol diagram according to the present invention.
  • Figure 19 illustrates an example schematic representation of the system architecture with load balancing implemented according to the present invention.
  • Figure 1 illustrates the network architecture according to the present invention, wherein the network shown is a typical system for balancing load comprising a gateway (11) for managing network load, at least an access point (12) in communication with the gateway (11) for managing network traffic and providing network access, and at least a client (13) in communication with at least an access point (12) for obtaining network connectivity to access the gateway (11).
  • Figure 2 however illustrates load congestions occurring between the gateway (11) and the first access point (12), and between the first access point (11) and the second access point (12). It is shown in Figure 2 that the uplink capacity, aggregate load and the load for the first access point (12) closer to the gateway (1 1) are 27 Mbps, 28 Mbps and 1 Mbps respectively. The uplink capacity, aggregate load and the load for the second access point (12) next to the first access point (12) are 27 Mbps, 28 Mbps and 14 Mbps respectively. The uplink capacity, aggregate load and the load for the third access point (12) next to the second access point (12) are 27 Mbps, 14 Mbps and 14 Mbps respectively.
  • the network implements a protocol, preferably but not limited to the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA).
  • CSMA/CA Carrier Sense Multiple Access/Collision Avoidance
  • the protocol only aims to avoid data collision in a wireless network, but the protocol has no support for congestion control and implementation of load balancing in a network described in the present invention.
  • the discussion in the present invention is that the CSMA/CA back-off time stays on minimum contention window (CWmin) for accessing network traffic because the transmission between at least a client (13) and at least an access point (12) is always successful.
  • CWmin minimum contention window
  • FIG. 3 illustrates the system architecture of the gateway (11) according to the present invention, wherein the gateway (11) fundamentally comprising a node processor, a memory system, an operating system, input and output buffers, mesh backhaul radio, network radio, and a module preferred in the present invention, a network balancer (14) for receiving network information messages, generating at least an acceptable target load message (21), and transmitting at least an acceptable target load message (21) to a corresponding access point (12).
  • the gateway (11) fundamentally comprising a node processor, a memory system, an operating system, input and output buffers, mesh backhaul radio, network radio, and a module preferred in the present invention
  • a network balancer (14) for receiving network information messages, generating at least an acceptable target load message (21), and transmitting at least an acceptable target load message (21) to a corresponding access point (12).
  • the network balancer (14) further comprises at least a network information manager (31) for receiving and updating network information messages from at least an access point (12), at least a congestion detector (32) for determining network congestion, at least a target load generator (33) for determining and generating an acceptable target load message (21) for each access point (12), and at least a target load communicator (34) for transmitting the acceptable target load message (21) to each access point (12).
  • a network information manager (31) for receiving and updating network information messages from at least an access point (12)
  • at least a congestion detector (32) for determining network congestion
  • at least a target load generator (33) for determining and generating an acceptable target load message (21) for each access point (12)
  • at least a target load communicator (34) for transmitting the acceptable target load message (21) to each access point (12).
  • the methods that are executed in the network balancer (14) starts by extracting network information messages, updating records of the extracted network information messages, determining congestions from the network information messages, determining an acceptable target load for each access point (12), updating records of the determined acceptable target load value, generating at least an acceptable target load message (21), and transmitting a corresponding acceptable target load message (21) to a corresponding access point (12).
  • the acceptable target load value is essentially for ensuring network is balanced.
  • the acceptable target load value is determined by first obtaining network information of traffic load of at least an access point (12), status of uplink and downlink channels, input and output buffer information of at least an access point (12), information on data packets from the network balancer (14) records, or in a combination thereof.
  • Congestions are identified by determining buffer size in comparison to a predetermined threshold value, network channel capacity associated with packet arrival rate, network load associated with packet drop rate, load values requested by at least an access point (12), or in combination thereof.
  • the an acceptable target load is determined as and when aggregation value of a backhaul load and the network load is lower than the network channel capacity, characterized by reducing backhaul load and updating the network balancer (14) records, and reducing network load and transmitting an acceptable target load message (21) to at least an access point (12).
  • the acceptable target load message (21) most importantly contains information of the target load value so that the access point (12) is informed of the new target value for effective packet transmission, and to avoid load congestion.
  • Figure 4 illustrates the system architecture of the access point (12) according to the present invention, wherein the access point (12) fundamentally comprising a node processor, a memory system, an operating system, input and output buffers, mesh backhaul uplink radio, mesh backhaul downlink radio, access network radio, and a module preferred in the present invention, a load balancer (15) for monitoring the network, generating and transmitting network information messages to the gateway (11), receiving a corresponding acceptable target load message (21) from the gateway (11), and generating and transmitting waiting slot message (22) to at least an associated client (13).
  • the access point (12) fundamentally comprising a node processor, a memory system, an operating system, input and output buffers, mesh backhaul uplink radio, mesh backhaul downlink radio, access network radio, and a module preferred in the present invention
  • a load balancer (15) for monitoring the network, generating and transmitting network information messages to the gateway (11), receiving a corresponding acceptable target load message (21) from the gateway (11), and generating and
  • the load balancer (15) further comprising at least a network traffic monitor (41) for monitoring and obtaining network information from at least an access point (12), at least a network information communicator (42) for generating and transmitting network information messages to the gateway (11), at least a target load manager (43) for receiving, extracting and managing acceptable target load message (21) from the gateway (11), at least a slot calculator (44) for determining a waiting slot value, and at least a slot communicator (45) for generating and transmitting waiting slot message (22) to an associated client (13).
  • a network traffic monitor (41) for monitoring and obtaining network information from at least an access point (12)
  • at least a network information communicator (42) for generating and transmitting network information messages to the gateway (11)
  • at least a target load manager (43) for receiving, extracting and managing acceptable target load message (21) from the gateway (11)
  • at least a slot calculator (44) for determining a waiting slot value
  • at least a slot communicator (45) for generating and transmitting waiting
  • the acceptable target load message (21) most importantly contains information of the target load value so that the access point (12) is informed of the new target value for effective packet transmission.
  • the methods that are executed in the network balancer (14) starts by monitoring and collecting network information, updating records of the collected network information, generating network information messages, transmitting the network information messages to the gateway (11), receiving a corresponding acceptable target load message (21) from the gateway (11) and extracting acceptable target load value, updating records with the acceptable target load value, determining a waiting slot value and updating records, generating at least a waiting slot message (22), and transmitting at least a corresponding waiting slot message (22) to an associated client (13).
  • the waiting slot value is determined by obtaining network information, determining total value for each waiting slot, and determining number waiting slots for insertion into a transmission protocol of the network, and distributing the waiting slot values.
  • Each access point (12) thus comprises at least three radio modules (101).
  • each access point (12) there is at least dual radio modules (101) equipped in each access point (12) so that different channels can be assigned to communicate with the forward and backward nodes in order to improve performance of the wireless network.
  • This channel segregation allows an access point (12) to transmit packets to forward hop and receives packets from backward hop simultaneously. This approach doubles the utilization of an access point (12) in relaying packets.
  • a third radio module interface is considered to be embedded in the access point (12).
  • This module is preferably used for connectivity to at least a client (13). Therefore, a two-tier mesh network is established in which two of the radio interfaces are applied for packet relay (commonly defined as mesh backhaul) and the third radio interface is only used for the purpose of allowing at least a client (13) connecting to an access point (12).
  • Figure 6 illustrates the system architecture of the client (13) according to the present invention, wherein the client (12) fundamentally comprising a microprocessor, a memory system, an operating system, input and output buffers, a wireless radio, and a module preferred in the present invention, a waiting slot controller (16) for receiving and extracting waiting slot message (22) from an associated access point (12), and regulating time interval during packet transmission.
  • the client (12) fundamentally comprising a microprocessor, a memory system, an operating system, input and output buffers, a wireless radio, and a module preferred in the present invention
  • a waiting slot controller (16) for receiving and extracting waiting slot message (22) from an associated access point (12), and regulating time interval during packet transmission.
  • the waiting slot controller (16) further comprising at least a slot manager (51) for receiving and extracting waiting slot message (22) from an associated access point (12), and at least a slot provider (52) for implementing the received waiting slot message (22) to regulate time interval during packet transmissions.
  • the methods that are executed in the waiting slot controller (16) starts by receiving waiting slot message (22), extracting waiting slot message (22), and interrupting packet transmission process performing in a predetermined protocol by implementing the received waiting slot message (22) to regulate time interval during packet transmissions.
  • the packet transmission is interrupted by determining whether network channel is idle, interrupting transmission protocol when the network channel is idle, pausing packet transmission for non-zero waiting slot value, and resuming packet transmission for zero waiting slot value.
  • the waiting slot message (22) fundamentally contains a waiting slot value, to be inserted into the packet transmission protocol, so that load balancing is achieved.
  • the gateway (11) is shown having a network balancer (14) with at least a network information manager (31), at least a congestion detector (32), at least a target load generator (33), and at least a target load communicator (34).
  • the network information manager (31) communicates with the network information records, whilst the congestion detector (32), the target load generator (33), and the target load communicator (34) receive communication from the network information records.
  • the access point (12) is shown having a load balancer (15) with at least a network traffic monitor (41), at least a network information communicator (42), at least a target load manager (43), at least a slot calculator (44), and at least a slot communicator (45). It is shown that the network traffic monitor (41) and the target load manager (43) communicates with the access point information records, and the network information communicator (42) and the slot calculator (44) receive communication from the access point information records.
  • the client (13) is shown having a waiting slot controller (16) with at least a slot manager (51), and at least a slot provider (52).
  • the procedure of the preferred embodiment in the present invention begins with the network traffic monitor (41) in the load balancer (15) monitoring and obtaining network information from at least an access point (12), and updates records of the collected network information with the access point information records. Then, the network information communicator (42) receives the updates from the records for generating and transmitting network information messages to the gateway (11).
  • the network information manager (31) receives and updates network information messages from the access point (12) with the network information records. Then, the congestion detector (32) will determine network congestion using the updated network information messages. The target load generator (33) subsequently determines and generates an acceptable target load message (21) for the access point (12). The target load communicator (34) then transmits the acceptable target load message (21) to the access point (12).
  • the target load manager (43) for receives, extracts and manages the acceptable target load message (21) from the gateway (11).
  • the slot calculator (44) determines a waiting slot value, and the slot communicator (45) generates and transmits waiting slot message (22) to an associated client (13).
  • the slot manager (51) receives and extracts waiting slot message (22) from an associated access point (12), and the slot provider (52) implements the received waiting slot message (22) to regulate time interval during packet transmissions via interrupting the transmission protocol.
  • FIG 8 there is illustrated the process flow for the overall method for balancing load according to the present invention, wherein the process starts in the access point (12).
  • the process illustrates that the access point (12) initially collects network information and transmits network information messages to the gateway (1 1).
  • the network information manager (31) updates records of the network information messages received from the access point (12), and using the updated network information messages, the gateway (11) identifies if network congestion has occurred. If there is no network congestion, the process flow ends. If network congestion is identified, the process flow continues by determining an acceptable target load, thereby generating target load message (21).
  • the target load message (21) will be transmitted to the access point (12), where the target load manager (43) updates records using the target load message (21) received from the gateway (11). Once the records in the access point (12) are updated, a waiting slot value will be determined, thereby generating waiting slot message (22), and the waiting slot message (22) will be transmitted to the client (13).
  • waiting slot message (22) received from the access point (12) are extracted and used to interrupt the transmission protocol, and ending the process flow.
  • FIG 9 there is illustrated the process flow for the method of generating network information messages according to the present invention, wherein the process is initiated by collecting network information. This is done by the load balancer (15) introduced in the previous figures.
  • the network traffic monitor (41) then updates records of the network information, and the updated network information is obtained from the records for generating network information messages.
  • the generated network information messages are then transmitted to the gateway (11).
  • FIG 10 there is illustrated the process flow for the method of generating acceptable target load message (21) according to the present invention, wherein the process is initiated by receiving network information messages. This is performed by the network balancer (14) introduced in the preceding description.
  • the process flow restarts until the network information messages are received. Once received, the network information manager (31) then updates records the messages and identifies for network congestion. If there is no network congestion, the process flow ends. If network congestion is identified, the process flow continues by determining an acceptable target load, thereby generating target load message (21).
  • Information records in the network balancer (14) will be updated with the acceptable target load message (21), and further transmitting the message to a corresponding load balancer (15) in an access point (12) as introduced in the preceding description.
  • the target load generator (33) identifies congestions by determining buffer size in comparison to a predetermined threshold value, network channel capacity associated with packet arrival rate, network load associated with packet drop rate, load values requested by at least an access point (12) introduced in the preceding description, or in combination thereof.
  • the target load generator (33) finally determines an acceptable target load as and when aggregation value of a backhaul load and the network load is lower than the network channel capacity, characterized by reducing backhaul load and updating the network balancer (14) records, and reducing network load.
  • An acceptable target load message (21) is generated and transmitted to at least an access point (12).
  • FIG 12 there is illustrated the process flow for the method of generating waiting slot message according to the present invention, wherein the process is initiated by receiving target load message (21). This is performed by the load balancer (15) introduced in the preceding description.
  • the process flow restarts until the target load message (21) is received. Once received, the acceptable target load value will be extracted from the target load message (21), and a waiting slot value will be calculated therefrom.
  • the load balancer (15) then updates its records with the determined waiting slot value, and thereby generating waiting slot message (22).
  • the waiting slot message (22) will be transmitted for the next process in the present invention.
  • FIG. 13 there is illustrated the process flow for the method of determining waiting slot message (22) according to the present invention, wherein the process is initiated by the slot calculator (11) obtaining network information such as packet arrival from the access point (12) records introduced earlier. This is performed by the waiting slot controller (16) also described earlier.
  • the slot calculator (44) determines the value of the total waiting slots by dividing an acceptable target load value by a waiting slot value.
  • the slot calculator (44) determines the number of total waiting slots to be inserted into the transmission protocol, and distributing the total waiting slots in each packet transmission.
  • FIG 14 there is illustrated two process flows in a client (13) according to the present invention, wherein the first process flow is for updating the client (13) with a waiting slot value, and the second process flow is for interrupting the transmission protocol by inserting the waiting slot value.
  • the first process flow is initiated by determining whether waiting slot message (22) have been received. If the waiting slot message (22) is not received, the process flow restarts until the waiting slot message (22) are received. Once received, the waiting slot message (22) is updated in the records with the waiting slot value.
  • FIG. 15 there is illustrated the message flow diagram according to the present invention, wherein the diagram shows message communication flow between the gateway (11), at least an access point (12), and at least a client (13).
  • the diagram shows that network information messages are initially transmitted from at least an access point (12) to the gateway (11). Then, the network information records will be updated based on the received network information messages, and an acceptable target load will be determined based on the updated records.
  • the gateway (11) then transmits an acceptable target load message (21) to each access point (12).
  • Waiting slot message (22) is subsequently generated based on the target load value, and shown transmitted from an access point (12) to an associated client (13).
  • the client (13) then interrupts the transmission protocol to insert the waiting slot values.
  • the records are updated and maintained in the gateway (11) are in the form following table.
  • the table represents records from three access points, MAP 1, MAP 2 and MAP 3, comprising their individual network information. This information is obtained from each access point (12), which is updated by the network traffic monitor (41) in the access point (12).
  • the target load value however will be determined by the target load generator (33) in the gateway (11).
  • the records are updated and maintained in the access point (12) are in the form following table.
  • the table represents records of network information that are collected in the access point (12), which are the values of Access Load, Mesh Backhaul Load, Uplink Capacity and Packet Per Second (PktPSec) in Access Network, Target Load extracted from the acceptable target load message (21) and a waiting slot (WS) calculated by the slot calculator (44).
  • Network information messages are generated and transmitted from a network information communicator (42) to the gateway (11) is in the form of the following table format.
  • the network information communicator (42) in an at least an access point (12) generates network information messages to inform the gateway (11) about the network information collected by the network traffic monitor (41).
  • the Message ID shown in the table represents the identification of the message, which is the network information message in this case.
  • the Source MAP address represents Internet Protocol address or Media Access Control address that belongs to the transmitter access point (12).
  • GW address represents the Internet Protocol address or Media Access Control of the receiving gateway (11).
  • MAP Network Info represents values of Access Load, Mesh Backhaul Load and Uplink Capacity collected by the network traffic monitor (41) of the corresponding access point (12).
  • Target load message (21) which is generated from the gateway (11) is in the form of the following table format.
  • the target load communicator (34) in the gateway (11) generates the above target load message (21) to inform each access point (12) according to acceptable target load value.
  • the Message ID shown in the table represents the identification of the message, which is in this case the target load message (21).
  • the Destination MAP address represents Internet Protocol address or Media Access Control address that belongs to the receiving access point (12).
  • Target Load represents the acceptable target load value generated by the target load generator (33), and the value is measured by Mbit/s. Waiting Slot Message
  • Waiting slot message (22) are generated and transmitted from an access point (12) to an associating client (13) in the form of the following table format.
  • Message ID shown in the table represents the identification of the message, which is the waiting slot message (22) in this case.
  • the Source MAP address represents Internet Protocol address or Media Access Control address that belongs to the transmitter access point (12).
  • Waiting Slot represents the waiting slot value determined by the slot calculator (44) in the access point and, which is an integer value.
  • CSMA/CA Carrier sense multiple access with collision avoidance
  • STA station
  • MMPDUs Media Access Control Management Protocol Data Units
  • DIFS Distributed Interframe Space
  • EIFS Extended Interframe Space
  • the STA shall then generate a random backoff period for an additional deferral time before transmitting data, unless the backoff timer already contains a nonzero value, in which case the selection of a random number is not needed and not performed. This process minimizes collisions during contention between multiple STAs that have been deferring to the same event.
  • the backoff time is calsulated as follows.
  • Random() Pseudo-random integer drawn from a uniform distribution over the interval [0,CW], where CW (contention window) is an integer within the range of values of the PHY (physical) characteristics of aCWmin and aCWmax, aCWmin ⁇ CW and ⁇ aCWmax.
  • aSlotTime The value of the correspondingly named PHY characteristic.
  • the contention window (CW) parameter shall take an initial value of aCWmin. Every STA shall maintain a STA short retry count (SSRC) as well as a STA long retry count (SLRC), both of which shall take an initial value of zero.
  • the SSRC shall be incremented when any short retry count (SRC) associated with any MPDU of type Data is incremented.
  • the SLRC shall be incremented when any long retry count (LRC) associated with any MPDU of type Data is incremented.
  • the CW shall take the next value in the series every time an unsuccessful attempt to transmit an MPDU causes either STA retry counter to increment, until the CW reaches the value of aCWmax.
  • a retry is defined as the entire sequence of frames sent, separated by SIFS intervals, in an attempt to deliver an MPDU. Once it reaches aCWmax, the CW shall remain at the value of aCWmax until the CW is reset.
  • the CW shall be reset to aCWmin after every successful attempt to transmit an MPDU or MMPDU, when SLRC reaches dot 1 lLongRetry Limit, or when SSRC reaches dot l l ShortRetry Limit.
  • the SSRC shall be reset to 0 when a CTS frame is received in response to Request to Send (RTS) frame, when an Acknowledge (ACK) frame is received in response to an MPDU or MMPDU transmission, or when a frame with a group address in the Addressl field is transmitted.
  • RTS Request to Send
  • ACK Acknowledge
  • the SLRC shall be reset to 0 when an ACK frame is received in response to transmission of an MPDU or MMPDU of length greater than dotl IRTSThreshold, or when a frame with a group address in the Addressl field is transmitted.
  • the set of CW values shall be sequentially ascending integer powers of 2, minus 1, beginning with a PHY-specific aCWmin value, and continuing up to and including a PHY-specific aCWmax value.
  • Original CSMA/CA is shown in Figure 16.
  • the network information message table that is generated by the first access point (12) is:
  • the network information message table that is generated by the second access point (12) is: etwork I o I MAP 2
  • the acceptable target load for each access point 120 in determined by the target load generator (33) in the gateway (11) after receiving the network messages from each access point (12) by the implementation of the foregoing description of the present invention, and updated in the records of the gateway (11) using the Network Info Table.
  • the Network Info Table for the present case scenario is represented as follows.
  • the target load communicator (34) generates an acceptable corresponding target load message (21) to each access point (12), such that tables are represented as follows.
  • the first access point (12) After each access point (12) has received their respective target load message (21), the first access point (12) has 0 (zero) waiting slot value because the target load value is the same as the access load value and the Access Info Table therefore as follows.
  • the transmission protocol diagram preferably the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol as preferred in the present invention for the first access point (12) is shown in Figure 16. The diagram has no changes.
  • CSMA/CA Carrier Sense Multiple Access/Collision Avoidance
  • the Access Info Table for the second access point (12) is therefore as follows.
  • the transmission protocol diagram preferably the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol as preferred in the present invention for the second access point (12) is shown in Figure 17.
  • the diagram is shown inserted with the number of waiting slot values.
  • CSMA/CA Carrier Sense Multiple Access/Collision Avoidance
  • Access Info Table for the third access point (12) is therefore as follows.
  • the transmission protocol diagram preferably the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol as preferred in the present invention for the third access point (12) is shown in Figure 18.
  • the diagram is shown inserted with the number of waiting slot values.
  • CSMA/CA Carrier Sense Multiple Access/Collision Avoidance
  • FIG 19 the figure shows the network architecture being achieved with the load balancing as preferred in the present invention.

Abstract

The present invention generally relates to a system and method for balancing load in a network, more particularly the present invention relates to a system and method for balancing load in a wireless mesh network, wherein the system comprising a gateway (11), at least an access point (12), and at least a client (13). The gateway (11) characterized by a network balancer (14), the access point (12) characterized by a load balancer (15), and the client (13) characterized by a waiting slot controller (16).

Description

A SYSTEM AND METHOD FOR BALANCING LOAD IN A NETWORK
TECHNICAL FIELD
The present invention generally relates to a system and method for balancing load in a network, more particularly the present invention relates to a system and method for balancing load in a wireless mesh network.
BACKGROUND OF INVENTION
Wireless communication technology has never ceased evolving and has today arrived to provide a network capable of routing messages within devices in a network, or widely known as the wireless mesh network.
The concept of such wireless technology is beneficial due to the significant advantages in deploying low-cost, low power consumption, highly efficient, reconfigurable network over large areas, and moreover, messages are able to be delivered across a significant span of a physical area. The technology is desirably beneficial to provide internet connectivity without proper network infrastructure, such as villages, or ad-hoc networks in a disaster area.
Essentially, wireless mesh network is formed by at least an access point relaying packets from clients to a gateway, and more often than not, a single gateway can only be active in linking to an external network so as to prevent discontinuity in network connection caused by routing loop. Such network structure fundamentally limits the amount of data traffic to the external network. It is therefore that the gateway experiences congestion due to the excessive data load relayed from the plurality of access points serving a plurality of clients, thus the phenomenon starts to deteriorate performance of the entire wireless mesh network, especially with respect to the end-to-end throughput, end-to-end latency, and possibly affecting packet loss rate when the aggregated data load exceed the link capacity. There are several prior arts divulged system and method for balancing load in a network to address the discussed problems. US patent no. 7693051 discloses system and method for controlling congestion in a wireless multihopping communication network by controlling the use of nodes acting as bottleneck points.
US patent no. 7843817 discloses a congestion control system in a wireless mesh network, more particularly the prior art addresses congestion in a multi-hop wireless network. In the prior art, mesh nodes typically monitor their own access class queues for congestion, sends congestion control messages to upstream nodes.
US patent no. 6765869 discloses a method and system for improving high speed data transmission efficiency between a packet data sending unit and a packet data receiving unit by dynamically controlling the passage data frames. The prior arts however lack an inventive solution to overcome load congestions in a network because the prior arts are mainly focused on sending messages to the nodes, instead of taking into consideration of load balancing in the transmission protocol, as well as monitoring network information in the nodes and gateway. The present invention addresses the problem by introducing load balancing system and methods to effectively tackle load congestions in a network.
SUMMARY OF INVENTION
The present invention aims to introduce a load balancing system based on controlling load traffic in a network, so that time interval during packet transmissions can be effectively and efficiently regulated. Fundamentally, the present invention provides a system comprising a network balancer residing in a gateway, a load balancer residing in at least an access point, and a waiting slot controller residing in at least a client.
It is an object of the present invention to provide a system for balancing load in a network, wherein the gateway comprises at least a network balancer for receiving network information messages, generating at least an acceptable target load message, and transmitting at least an acceptable target load message to an access point.
It is another object of the present invention to provide a system for balancing load in a network, wherein the access point comprises at least a load balancer for monitoring the network, generating and transmitting network information messages to the gateway, receiving a corresponding acceptable target load message from the gateway, and generating and transmitting waiting slot message to at least an associated client. It is yet another object of the present invention to provide a system for balancing load in a network, wherein the client comprises at least a waiting slot controller for receiving and extracting waiting slot message from an associated access point, and effectively and efficiently regulating time interval during packet transmission. It is a further object of the present invention to provide a method for balancing load in a network, wherein the network balancer extracts network information messages, updates records, determines congestion from the network information messages, determines an acceptable target load for each access point, updates records of the determined acceptable target load, generates at least an acceptable target load message, and transmits a corresponding acceptable target load message.
It is another further object of the present invention to provide a method for balancing load in a network, wherein the load balancer monitors and collects network information, updates records of the collected network information, generates network information messages, transmits the network information messages to the gateway, receives a corresponding acceptable target load message from the gateway and extracts acceptable target load value, updates records with the acceptable target load value, determines a waiting slot value and updates records, generates at least a waiting slot message, and transmits at least a corresponding waiting slot message to a client.
It is yet another further object of the present invention to provide a method for balancing load in a network, wherein the waiting slot controller receives waiting slot message, extracts waiting slot message, and interrupts packet transmission process performing in a predetermined protocol by implementing the received waiting slot message to regulate time interval during packet transmissions.
Essentially, the present invention provides a system and method for balancing load in a network by monitoring the network traffic, identifying the network congestion, determining a waiting slot value for each client, and interrupts the packet transmission protocol so that the network load is appositely balanced.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 illustrates the network architecture according to the present invention. Figure 2 illustrates the network architecture showing load congestions.
Figure 3 illustrates schematic representation of the system architecture for the gateway according to the present invention.
Figure 4 illustrates schematic representation of the system architecture for the access point according to the present invention.
Figure 5 illustrates schematic representation of the radio modules in the access point according to the present invention. Figure 6 illustrates schematic representation of the system architecture for the client according to the present invention.
Figure 7 illustrates a schematic representation of the overall system architecture and relationship for balancing load according to the present invention.
Figure 8 illustrates process flow for the overall method for balancing load according to the present invention. Figure 9 illustrates process flow for the method of generating network information messages according to the present invention.
Figure 10 illustrates process flow for the method of generating acceptable target load message according to the present invention.
Figure 11 illustrates process flow for the method of determining acceptable target load according to the present invention. Figure 12 illustrates process flow for the method of generating waiting slot message according to the present invention.
Figure 13 illustrates process flow for the method of determining waiting slot message according to the present invention.
Figure 14 illustrates two process flows in a client according to the present invention. Figure 15 illustrates the message flow diagram according to the present invention. Figure 16 illustrates the transmission protocol diagram according to the present invention. Figure 17 illustrates the transmission protocol diagram according to the present invention. Figure 18 illustrates the transmission protocol diagram according to the present invention.
Figure 19 illustrates an example schematic representation of the system architecture with load balancing implemented according to the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
Described below are preferred embodiments of the present invention with reference to the accompanying drawings. Each of the following preferred embodiments describes an example not limiting in any aspect. It will be appreciated that the reference signs for an acceptable target load message (21) and a waiting slot message (22), indicated in Figures 12 and 14 are used throughout the entire description, without showing reference to a particular figure. Referring to Figure 1 and 2, Figure 1 illustrates the network architecture according to the present invention, wherein the network shown is a typical system for balancing load comprising a gateway (11) for managing network load, at least an access point (12) in communication with the gateway (11) for managing network traffic and providing network access, and at least a client (13) in communication with at least an access point (12) for obtaining network connectivity to access the gateway (11).
Figure 2 however illustrates load congestions occurring between the gateway (11) and the first access point (12), and between the first access point (11) and the second access point (12). It is shown in Figure 2 that the uplink capacity, aggregate load and the load for the first access point (12) closer to the gateway (1 1) are 27 Mbps, 28 Mbps and 1 Mbps respectively. The uplink capacity, aggregate load and the load for the second access point (12) next to the first access point (12) are 27 Mbps, 28 Mbps and 14 Mbps respectively. The uplink capacity, aggregate load and the load for the third access point (12) next to the second access point (12) are 27 Mbps, 14 Mbps and 14 Mbps respectively.
By way of example in the preferred embodiment, it will be discussed that the network implements a protocol, preferably but not limited to the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA). The protocol only aims to avoid data collision in a wireless network, but the protocol has no support for congestion control and implementation of load balancing in a network described in the present invention.
Elaborating further, the discussion in the present invention is that the CSMA/CA back-off time stays on minimum contention window (CWmin) for accessing network traffic because the transmission between at least a client (13) and at least an access point (12) is always successful.
However, when the congestion links exists due to aggregated load (sum of access load and mesh backhaul load) being greater than uplink capacity, the CSMA/CA procedure does not provide congestion control and load balancing in the wireless mesh network. Referring now to Figure 1 and Figure 3, Figure 3 illustrates the system architecture of the gateway (11) according to the present invention, wherein the gateway (11) fundamentally comprising a node processor, a memory system, an operating system, input and output buffers, mesh backhaul radio, network radio, and a module preferred in the present invention, a network balancer (14) for receiving network information messages, generating at least an acceptable target load message (21), and transmitting at least an acceptable target load message (21) to a corresponding access point (12).
The network balancer (14) further comprises at least a network information manager (31) for receiving and updating network information messages from at least an access point (12), at least a congestion detector (32) for determining network congestion, at least a target load generator (33) for determining and generating an acceptable target load message (21) for each access point (12), and at least a target load communicator (34) for transmitting the acceptable target load message (21) to each access point (12).
Essentially, the methods that are executed in the network balancer (14) starts by extracting network information messages, updating records of the extracted network information messages, determining congestions from the network information messages, determining an acceptable target load for each access point (12), updating records of the determined acceptable target load value, generating at least an acceptable target load message (21), and transmitting a corresponding acceptable target load message (21) to a corresponding access point (12).
The acceptable target load value is essentially for ensuring network is balanced.
The acceptable target load value is determined by first obtaining network information of traffic load of at least an access point (12), status of uplink and downlink channels, input and output buffer information of at least an access point (12), information on data packets from the network balancer (14) records, or in a combination thereof.
Congestions are identified by determining buffer size in comparison to a predetermined threshold value, network channel capacity associated with packet arrival rate, network load associated with packet drop rate, load values requested by at least an access point (12), or in combination thereof. The an acceptable target load is determined as and when aggregation value of a backhaul load and the network load is lower than the network channel capacity, characterized by reducing backhaul load and updating the network balancer (14) records, and reducing network load and transmitting an acceptable target load message (21) to at least an access point (12).
The acceptable target load message (21) most importantly contains information of the target load value so that the access point (12) is informed of the new target value for effective packet transmission, and to avoid load congestion.
Referring now to Figure 1 and Figure 4, Figure 4 illustrates the system architecture of the access point (12) according to the present invention, wherein the access point (12) fundamentally comprising a node processor, a memory system, an operating system, input and output buffers, mesh backhaul uplink radio, mesh backhaul downlink radio, access network radio, and a module preferred in the present invention, a load balancer (15) for monitoring the network, generating and transmitting network information messages to the gateway (11), receiving a corresponding acceptable target load message (21) from the gateway (11), and generating and transmitting waiting slot message (22) to at least an associated client (13).
The load balancer (15) further comprising at least a network traffic monitor (41) for monitoring and obtaining network information from at least an access point (12), at least a network information communicator (42) for generating and transmitting network information messages to the gateway (11), at least a target load manager (43) for receiving, extracting and managing acceptable target load message (21) from the gateway (11), at least a slot calculator (44) for determining a waiting slot value, and at least a slot communicator (45) for generating and transmitting waiting slot message (22) to an associated client (13).
As mentioned earlier, the acceptable target load message (21) most importantly contains information of the target load value so that the access point (12) is informed of the new target value for effective packet transmission. Essentially, the methods that are executed in the network balancer (14) starts by monitoring and collecting network information, updating records of the collected network information, generating network information messages, transmitting the network information messages to the gateway (11), receiving a corresponding acceptable target load message (21) from the gateway (11) and extracting acceptable target load value, updating records with the acceptable target load value, determining a waiting slot value and updating records, generating at least a waiting slot message (22), and transmitting at least a corresponding waiting slot message (22) to an associated client (13).
The waiting slot value is determined by obtaining network information, determining total value for each waiting slot, and determining number waiting slots for insertion into a transmission protocol of the network, and distributing the waiting slot values.
Referring now to Figure 5, there is illustrated simple system architecture as preferred in the present invention showing contributing radio modules in each access point (12).
It is shown that there are a gateway (11), a first access point (12) connected to the gateway (11), a second access point (12) connected to the first access point (12), and at least a client (13) connected to each of the first access point (12) and second access point (12). Each access point (12) thus comprises at least three radio modules (101).
Typically, there is at least dual radio modules (101) equipped in each access point (12) so that different channels can be assigned to communicate with the forward and backward nodes in order to improve performance of the wireless network. This channel segregation allows an access point (12) to transmit packets to forward hop and receives packets from backward hop simultaneously. This approach doubles the utilization of an access point (12) in relaying packets.
In the present invention however a third radio module interface is considered to be embedded in the access point (12). This module is preferably used for connectivity to at least a client (13). Therefore, a two-tier mesh network is established in which two of the radio interfaces are applied for packet relay (commonly defined as mesh backhaul) and the third radio interface is only used for the purpose of allowing at least a client (13) connecting to an access point (12). Referring now to Figure 1 and Figure 6, Figure 6 illustrates the system architecture of the client (13) according to the present invention, wherein the client (12) fundamentally comprising a microprocessor, a memory system, an operating system, input and output buffers, a wireless radio, and a module preferred in the present invention, a waiting slot controller (16) for receiving and extracting waiting slot message (22) from an associated access point (12), and regulating time interval during packet transmission.
The waiting slot controller (16) further comprising at least a slot manager (51) for receiving and extracting waiting slot message (22) from an associated access point (12), and at least a slot provider (52) for implementing the received waiting slot message (22) to regulate time interval during packet transmissions.
Essentially, the methods that are executed in the waiting slot controller (16) starts by receiving waiting slot message (22), extracting waiting slot message (22), and interrupting packet transmission process performing in a predetermined protocol by implementing the received waiting slot message (22) to regulate time interval during packet transmissions. The packet transmission is interrupted by determining whether network channel is idle, interrupting transmission protocol when the network channel is idle, pausing packet transmission for non-zero waiting slot value, and resuming packet transmission for zero waiting slot value.
The waiting slot message (22) fundamentally contains a waiting slot value, to be inserted into the packet transmission protocol, so that load balancing is achieved. Referring now to Figure 7, there is illustrated the overall system architecture on the surface for balancing load according to the present invention, wherein the gateway (11) is shown having a network balancer (14) with at least a network information manager (31), at least a congestion detector (32), at least a target load generator (33), and at least a target load communicator (34).
It is shown that the network information manager (31) communicates with the network information records, whilst the congestion detector (32), the target load generator (33), and the target load communicator (34) receive communication from the network information records. The access point (12) is shown having a load balancer (15) with at least a network traffic monitor (41), at least a network information communicator (42), at least a target load manager (43), at least a slot calculator (44), and at least a slot communicator (45). It is shown that the network traffic monitor (41) and the target load manager (43) communicates with the access point information records, and the network information communicator (42) and the slot calculator (44) receive communication from the access point information records.
The client (13) is shown having a waiting slot controller (16) with at least a slot manager (51), and at least a slot provider (52).
The procedure of the preferred embodiment in the present invention begins with the network traffic monitor (41) in the load balancer (15) monitoring and obtaining network information from at least an access point (12), and updates records of the collected network information with the access point information records. Then, the network information communicator (42) receives the updates from the records for generating and transmitting network information messages to the gateway (11).
At the network balancer (14), the network information manager (31) receives and updates network information messages from the access point (12) with the network information records. Then, the congestion detector (32) will determine network congestion using the updated network information messages. The target load generator (33) subsequently determines and generates an acceptable target load message (21) for the access point (12). The target load communicator (34) then transmits the acceptable target load message (21) to the access point (12).
Back to the access point (12), the target load manager (43) for receives, extracts and manages the acceptable target load message (21) from the gateway (11). The slot calculator (44) then determines a waiting slot value, and the slot communicator (45) generates and transmits waiting slot message (22) to an associated client (13).
At the waiting slot controller (16), the slot manager (51) receives and extracts waiting slot message (22) from an associated access point (12), and the slot provider (52) implements the received waiting slot message (22) to regulate time interval during packet transmissions via interrupting the transmission protocol.
Referring now to Figure 8, there is illustrated the process flow for the overall method for balancing load according to the present invention, wherein the process starts in the access point (12). The process illustrates that the access point (12) initially collects network information and transmits network information messages to the gateway (1 1).
At the gateway (11), the network information manager (31) updates records of the network information messages received from the access point (12), and using the updated network information messages, the gateway (11) identifies if network congestion has occurred. If there is no network congestion, the process flow ends. If network congestion is identified, the process flow continues by determining an acceptable target load, thereby generating target load message (21).
Then, the target load message (21) will be transmitted to the access point (12), where the target load manager (43) updates records using the target load message (21) received from the gateway (11). Once the records in the access point (12) are updated, a waiting slot value will be determined, thereby generating waiting slot message (22), and the waiting slot message (22) will be transmitted to the client (13).
At the client (13), waiting slot message (22) received from the access point (12) are extracted and used to interrupt the transmission protocol, and ending the process flow. Referring now to Figure 9, there is illustrated the process flow for the method of generating network information messages according to the present invention, wherein the process is initiated by collecting network information. This is done by the load balancer (15) introduced in the previous figures. The network traffic monitor (41) then updates records of the network information, and the updated network information is obtained from the records for generating network information messages. The generated network information messages are then transmitted to the gateway (11). Referring now to Figure 10, there is illustrated the process flow for the method of generating acceptable target load message (21) according to the present invention, wherein the process is initiated by receiving network information messages. This is performed by the network balancer (14) introduced in the preceding description.
If the network information messages are not received, the process flow restarts until the network information messages are received. Once received, the network information manager (31) then updates records the messages and identifies for network congestion. If there is no network congestion, the process flow ends. If network congestion is identified, the process flow continues by determining an acceptable target load, thereby generating target load message (21).
Information records in the network balancer (14) will be updated with the acceptable target load message (21), and further transmitting the message to a corresponding load balancer (15) in an access point (12) as introduced in the preceding description.
Referring now to Figure 11, there is illustrated the process flow for the method of determining acceptable target load according to the present invention, wherein process is initiated by obtaining network information messages using the target load generator (33). The network information messages comprises at least information of traffic load, status of uplink and downlink channels, input and output buffer information, information on data packets from the network balancer (14) records discussed earlier in the foregoing description, or in a combination thereof. The target load generator (33) then identifies congestions by determining buffer size in comparison to a predetermined threshold value, network channel capacity associated with packet arrival rate, network load associated with packet drop rate, load values requested by at least an access point (12) introduced in the preceding description, or in combination thereof.
The target load generator (33) finally determines an acceptable target load as and when aggregation value of a backhaul load and the network load is lower than the network channel capacity, characterized by reducing backhaul load and updating the network balancer (14) records, and reducing network load. An acceptable target load message (21) is generated and transmitted to at least an access point (12).
Referring now to Figure 12, there is illustrated the process flow for the method of generating waiting slot message according to the present invention, wherein the process is initiated by receiving target load message (21). This is performed by the load balancer (15) introduced in the preceding description.
If the target load message (21) is not received, the process flow restarts until the target load message (21) is received. Once received, the acceptable target load value will be extracted from the target load message (21), and a waiting slot value will be calculated therefrom.
The load balancer (15) then updates its records with the determined waiting slot value, and thereby generating waiting slot message (22). The waiting slot message (22) will be transmitted for the next process in the present invention.
Referring now to Figure 13, there is illustrated the process flow for the method of determining waiting slot message (22) according to the present invention, wherein the process is initiated by the slot calculator (11) obtaining network information such as packet arrival from the access point (12) records introduced earlier. This is performed by the waiting slot controller (16) also described earlier.
The slot calculator (44) then determines the value of the total waiting slots by dividing an acceptable target load value by a waiting slot value. The slot calculator (44) then determines the number of total waiting slots to be inserted into the transmission protocol, and distributing the total waiting slots in each packet transmission.
Referring now to Figure 14, there is illustrated two process flows in a client (13) according to the present invention, wherein the first process flow is for updating the client (13) with a waiting slot value, and the second process flow is for interrupting the transmission protocol by inserting the waiting slot value. The first process flow is initiated by determining whether waiting slot message (22) have been received. If the waiting slot message (22) is not received, the process flow restarts until the waiting slot message (22) are received. Once received, the waiting slot message (22) is updated in the records with the waiting slot value.
Referring now to Figure 15, there is illustrated the message flow diagram according to the present invention, wherein the diagram shows message communication flow between the gateway (11), at least an access point (12), and at least a client (13). The diagram shows that network information messages are initially transmitted from at least an access point (12) to the gateway (11). Then, the network information records will be updated based on the received network information messages, and an acceptable target load will be determined based on the updated records. The gateway (11) then transmits an acceptable target load message (21) to each access point (12).
Waiting slot message (22) is subsequently generated based on the target load value, and shown transmitted from an access point (12) to an associated client (13). The client (13) then interrupts the transmission protocol to insert the waiting slot values.
For the purpose of further elaboration, the aforementioned records in the gateway (11) and access point (12), network information messages, target load message (21), and waiting slot message (22) are represented and described as follows for a better understanding.
Network Info Table
The records are updated and maintained in the gateway (11) are in the form following table.
Table 1 : Example of Network Info Table
Figure imgf000017_0001
Typically the table represents records from three access points, MAP 1, MAP 2 and MAP 3, comprising their individual network information. This information is obtained from each access point (12), which is updated by the network traffic monitor (41) in the access point (12).
The target load value however will be determined by the target load generator (33) in the gateway (11).
Access Point Info Table
The records are updated and maintained in the access point (12) are in the form following table.
Table 2 : Example of Access Point Info Table
Figure imgf000018_0001
Typically the table represents records of network information that are collected in the access point (12), which are the values of Access Load, Mesh Backhaul Load, Uplink Capacity and Packet Per Second (PktPSec) in Access Network, Target Load extracted from the acceptable target load message (21) and a waiting slot (WS) calculated by the slot calculator (44).
Network Information Messages
Network information messages are generated and transmitted from a network information communicator (42) to the gateway (11) is in the form of the following table format.
Table 3 : Network Information Messages Format
Source MAP MA Network
es a e D 6 address
info The network information communicator (42) in an at least an access point (12) generates network information messages to inform the gateway (11) about the network information collected by the network traffic monitor (41). The Message ID shown in the table represents the identification of the message, which is the network information message in this case. The Source MAP address represents Internet Protocol address or Media Access Control address that belongs to the transmitter access point (12).
GW address represents the Internet Protocol address or Media Access Control of the receiving gateway (11). MAP Network Info represents values of Access Load, Mesh Backhaul Load and Uplink Capacity collected by the network traffic monitor (41) of the corresponding access point (12). Target Load Message (21)
Target load message (21) which is generated from the gateway (11) is in the form of the following table format.
Table 4 : Target Load Message Format
Destination
essage ID Target Load
MAP Address
The target load communicator (34) in the gateway (11) generates the above target load message (21) to inform each access point (12) according to acceptable target load value. The Message ID shown in the table represents the identification of the message, which is in this case the target load message (21).
The Destination MAP address represents Internet Protocol address or Media Access Control address that belongs to the receiving access point (12). Target Load represents the acceptable target load value generated by the target load generator (33), and the value is measured by Mbit/s. Waiting Slot Message
Waiting slot message (22) are generated and transmitted from an access point (12) to an associating client (13) in the form of the following table format.
Table 5 : Waiting slot message Format
Source MAP
Message SO Waiting Slot
Address
Slot Communicator (45) in an access point (120 generates the waiting slot message (22) to inform new waiting slot value to at least an associating client (13).
Message ID shown in the table represents the identification of the message, which is the waiting slot message (22) in this case. The Source MAP address represents Internet Protocol address or Media Access Control address that belongs to the transmitter access point (12). Waiting Slot represents the waiting slot value determined by the slot calculator (44) in the access point and, which is an integer value.
Carrier sense multiple access with collision avoidance (CSMA/CA)
In a nutshell, whenever a station (STA) is inclined to initiate a transfer of data of Media Access Control Protocol Data Units (MPDUs) and/or Media Access Control Management Protocol Data Units (MMPDUs) shall invoke the Carrier Sense mechanism to determine the busy/idle state of the medium. If the medium is busy, the STA shall defer operation until the medium is determined to be idle without interruption for a period of time equal to Distributed Interframe Space (DIFS) when the last frame detected on the medium was correctly received, or after the medium is determined to be idle without interruption for a period of time equal to Extended Interframe Space (EIFS) when the last frame detected on the medium was not correctly received. Once the DIFS or EIFS medium time is idle, the STA shall then generate a random backoff period for an additional deferral time before transmitting data, unless the backoff timer already contains a nonzero value, in which case the selection of a random number is not needed and not performed. This process minimizes collisions during contention between multiple STAs that have been deferring to the same event.
The backoff time is calsulated as follows.
Backoff Time = Random() xaSlotTime where
Random() = Pseudo-random integer drawn from a uniform distribution over the interval [0,CW], where CW (contention window) is an integer within the range of values of the PHY (physical) characteristics of aCWmin and aCWmax, aCWmin <CW and <aCWmax. aSlotTime = The value of the correspondingly named PHY characteristic.
The contention window (CW) parameter shall take an initial value of aCWmin. Every STA shall maintain a STA short retry count (SSRC) as well as a STA long retry count (SLRC), both of which shall take an initial value of zero. The SSRC shall be incremented when any short retry count (SRC) associated with any MPDU of type Data is incremented. The SLRC shall be incremented when any long retry count (LRC) associated with any MPDU of type Data is incremented.
The CW shall take the next value in the series every time an unsuccessful attempt to transmit an MPDU causes either STA retry counter to increment, until the CW reaches the value of aCWmax. A retry is defined as the entire sequence of frames sent, separated by SIFS intervals, in an attempt to deliver an MPDU. Once it reaches aCWmax, the CW shall remain at the value of aCWmax until the CW is reset.
The CW shall be reset to aCWmin after every successful attempt to transmit an MPDU or MMPDU, when SLRC reaches dot 1 lLongRetry Limit, or when SSRC reaches dot l l ShortRetry Limit. The SSRC shall be reset to 0 when a CTS frame is received in response to Request to Send (RTS) frame, when an Acknowledge (ACK) frame is received in response to an MPDU or MMPDU transmission, or when a frame with a group address in the Addressl field is transmitted. The SLRC shall be reset to 0 when an ACK frame is received in response to transmission of an MPDU or MMPDU of length greater than dotl IRTSThreshold, or when a frame with a group address in the Addressl field is transmitted.
The set of CW values shall be sequentially ascending integer powers of 2, minus 1, beginning with a PHY-specific aCWmin value, and continuing up to and including a PHY-specific aCWmax value. Original CSMA/CA is shown in Figure 16.
EXAMPLE CASE SCENARIO For the purpose of explaining the invention further, the inventors would like to consider the following example of a network condition that poses network congestion, and the condition can be referred to the conditions as in Figure 2.
Figure imgf000022_0001
Ensuing that, the network information message table that is generated by the first access point (12) is:
Figure imgf000022_0002
The initial conditions in the second access point (12) in the Figure 2
Figure imgf000022_0003
Ensuing that, the network information message table that is generated by the second access point (12) is: etwork I o I MAP 2
GW address I 14 I 1 27
¾s«»se iD I Address
Figure imgf000023_0001
Ensuing that, the network information message table that is generated by the third access point (12) is
Figure imgf000023_0002
Subsequently, the acceptable target load for each access point (120 in determined by the target load generator (33) in the gateway (11) after receiving the network messages from each access point (12) by the implementation of the foregoing description of the present invention, and updated in the records of the gateway (11) using the Network Info Table. The Network Info Table for the present case scenario is represented as follows.
Figure imgf000023_0003
Then, the target load communicator (34) generates an acceptable corresponding target load message (21) to each access point (12), such that tables are represented as follows.
Target load message (21) to the first access point (12):
Target load j MAP 1 I 1
J.
Message I D i Address i Target load message (21) to the second access point (12):
Target Load fV?AP 2
13
Message I D Address
Target load message (21) to the third access point (12):
Target Load MAP 3
13
Message ID Address
After each access point (12) has received their respective target load message (21), the first access point (12) has 0 (zero) waiting slot value because the target load value is the same as the access load value and the Access Info Table therefore as follows.
Figure imgf000024_0001
Thus, no waiting slot message (22) will be sent from the first access point (12). The transmission protocol diagram, preferably the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol as preferred in the present invention for the first access point (12) is shown in Figure 16. The diagram has no changes.
As for the second access point (12), the waiting slot value is calculated by the slot calculator (44) with a predetermined slot size of 80bit as follows: Δ = Access Load Value - Target Load Value
Hence,
Δ = 14Mbit/s - 13Mbit/s = IMbit/s Total Waiting Slot = (\Mbit/s) I {%0bif) = 13107.2 slot/s
Waiting Slot, WS = ((\4Mbit/s) x (13107.2 slot/s)) I ((UMbit/s) x (\249packet/s))
= 1 1.3 slot/packet Waiting Slot, WS = ceil (11.3) = 12 slot/packet
The Access Info Table for the second access point (12) is therefore as follows.
Figure imgf000025_0001
Thus, the following waitingslot message (22) from the second access point (12) indicating a waiting slot value of 12 will be sent to the associating client (13).
MAP 2
The transmission protocol diagram, preferably the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol as preferred in the present invention for the second access point (12) is shown in Figure 17. The diagram is shown inserted with the number of waiting slot values.
It should be noted since the values of Access Load and Target Load are the same for the second access point (12) and third access point (12), the waiting slot value is identical. The Access Info Table for the third access point (12) is therefore as follows.
Figure imgf000025_0002
Thus, the following waitingslot message (22) from the third access point (12) indicating a waiting slot value of 12 will be sent to the associating client (13).
Figure imgf000025_0003
The transmission protocol diagram, preferably the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol as preferred in the present invention for the third access point (12) is shown in Figure 18. The diagram is shown inserted with the number of waiting slot values.
Referring now to Figure 19, the figure shows the network architecture being achieved with the load balancing as preferred in the present invention.
In as much as the present invention is subject to many variations, modifications and changes in detail, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

1. A system for balancing load in a network comprising:
a gateway (11) for managing network load;
at least an access point (12) in communication with the gateway (11) for managing network traffic and providing network access; and
at least a client (13) in communication with at least an access point (12) for obtaining network connectivity to access the gateway (11);
characterized in that the gateway (11) further comprises at least a network balancer (14) for receiving network information messages, determining at least an acceptable target load value, generating at least an acceptable target load message (21), and transmitting at least an acceptable target load message (21) to a corresponding access point (12);
the access point (12) further comprises at least a load balancer (15) for monitoring the network, generating and transmitting network information messages to the gateway (11), receiving a corresponding acceptable target load message (21) from the gateway (11), and generating and transmitting waiting slot message (22) to at least an associated client (13);
the access point (12) comprises modules for communication between forward and backward nodes, and at least a client (12); and
the client (13) further comprises at least a waiting slot controller (16) with at least a slot manager (51) for receiving and extracting waiting slot message (22) from an associated access point (12), and at least a slot provider (52) for implementing the received waiting slot message (22) to regulate time interval during packet transmissions.
2. A system for balancing load in a network in accordance to claim 1, wherein the system is implemented in a wireless mesh network.
3. A system for balancing load in a network in accordance to claim 1, wherein the network balancer (14) comprising:
at least a network information manager (31) for receiving and updating network information messages from at least an access point (12);
at least a congestion detector (32) for determining network congestion; at least a target load generator (33) for determining and generating an acceptable target load message (21) for each access point (12); and
at least a target load communicator (34) for transmitting the acceptable target load message (21) to each access point (12).
4. A system for balancing load in a network in accordance to claim 1, wherein the acceptable target load value is determined by the following method:
obtaining network information of traffic load of at least an access point (12), status of uplink and downlink channels, input and output buffer information of at least an access point (12), information on data packets from the network balancer (14) records, or in a combination thereof;
identifying congestions by determining buffer size in comparison to a predetermined threshold value, network channel capacity associated with packet arrival rate, network load associated with packet drop rate, load values requested by at least an access point (12), or in combination thereof; and
determining an acceptable target load as and when aggregation value of a backhaul load and the network load is lower than the network channel capacity, characterized by reducing backhaul load and updating the network balancer (14) records, and reducing network load and transmitting an acceptable target load message (21) to at least an access point (12).
5. A system for balancing load in a network in accordance to claim 1, wherein the network balancer (14) transmits at least an acceptable target load message (21) to a corresponding access point (12) by the steps of:
extracting network information messages;
updating records of the extracted network information messages; determining congestions from the network information messages; determining an acceptable target load for each access point (12); updating records of the determined acceptable target load value; generating at least an acceptable target load message (21); and
transmitting a corresponding acceptable target load message (21) to a corresponding access point (12).
6. A system for balancing load in a network in accordance to claim 1, wherein the load balancer (15) comprising:
at least a network traffic monitor (41) for monitoring and obtaining network information from at least an access point (12);
at least a network information communicator (42) for generating and transmitting network information messages to the gateway (11);
at least a target load manager (43) for receiving, extracting and managing acceptable target load message (21) from the gateway (11);
at least a slot calculator (44) for determining a waiting slot value by obtaining network information, determining total value for each waiting slot and determining number of waiting slot values for insertion into a transmission protocol of the network and distributing the waiting slot value; and
at least a slot communicator (45) for generating and transmitting waiting slot message (22) to an associated client (13).
7. A system for balancing load in a network in accordance to claim 1, wherein the load balancer (15) transmits a waiting slot message (22) to at least an associated client (13) by the steps of:
monitoring and collecting network information;
updating records of the collected network information;
generating network information messages;
transmitting the network information messages to the gateway (11);
receiving a corresponding acceptable target load message (21) from the gateway (11), and extracting acceptable target load value;
updating records with the acceptable target load value;
determining a waiting slot value, and updating records;
generating at least a waiting slot message (22); and
transmitting at least a corresponding waiting slot message (22) to an associated client (13).
8. A system for balancing load in a network in accordance to claim 1, wherein the waiting slot controller (16) regulates time interval during packet transmission by the steps of:
receiving waiting slot message (22); extracting waiting slot message (22); and
interrupting packet transmission process performing in a predetermined protocol by implementing the received waiting slot message (22) to regulate time interval during packet transmission.
9. A system for balancing load in a network in accordance to claim 8, wherein the packet transmission is interrupted by the steps of:
determining whether network channel is idle;
interrupting transmission protocol when the network channel is idle;
pausing packet transmission for non-zero waiting slot value; and resuming packet transmission for zero waiting slot value.
10. A method for balancing load in a network executed by the system as claimed in claim 1, comprises the steps of:
monitoring and collecting network information;
updating records of the collected network information;
generating network information messages;
transmitting the network information messages to the gateway (11);
extracting network information messages;
updating records of the extracted network information messages; determining congestions from the network information messages; determining an acceptable target load for each access point (12); updating records of the determined acceptable target load value; generating at least an acceptable target load message (21);
transmitting a corresponding acceptable target load message (21) to at least a corresponding access point (12);
receiving a corresponding acceptable target load message (21) from the gateway (11), and extracting acceptable target load value;
updating records with the acceptable target load value;
determining a waiting slot value, and updating records;
generating at least a waiting slot message (22);
transmitting at least a corresponding waiting slot message (22) to an associated client (13);
receiving waiting slot message (22); extracting waiting slot message (22); and
interrupting packet transmission process performing in a predetermined protocol by implementing the received waiting slot message (22) to regulate time interval during packet transmission.
PCT/MY2013/000239 2012-12-13 2013-12-06 A system and method for balancing load in a network WO2014092539A1 (en)

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