CN101951658A - Mobile self-networking Internet gateway routing selection method based on path quality perception - Google Patents

Abstract

The invention relates to a mobile self-networking Internet gateway routing selection method based on path quality perception. A 802.11 MAC layer carrier monitoring mechanism estimates the residual available bandwidth of a link, path quality information is integrated into a multiple-target routing selection criterion in a weighting mode, namely Metric=alpha.MBR+beta.PDR+gamma.NQR. A node required to carry out gateway discovery initiates a gateway routing request, and the routing request calculates the path quality information of each path on the way; after receiving the gateway routing request, the gateway calculates a path Metric according to the routing selection criterion, a unicast gateway routing reply is returned to a resource node, and the resource node selects a route with the maximum Metric as a default route to the gateway and is maintained. A simulation result shows that the invention can provide the optimal Internet interconnection performance for the mobile node, satisfies the QoS requirements of interconnection service and keeps reasonable control expenditure.

Description

A kind of mobile ad hoc network Internet gateway route selection method based on the path quality perception

Technical field

The invention belongs to the Internet gateway route selection method in a kind of wireless network communication technique field, particularly a kind of mobile ad hoc network (Mobile Ad Hoc Network based on the path quality perception, MANET) Internet gateway route selection method, utilization is striden layer design philosophy and is estimated the link residual available bandwidth, and chooses to the method for Internet gateway route by calculating gateway Route Selection criterion.

Background technology

In recent years, the high speed development of the communications field has been brought people into a unprecedented information age.Earth-shaking variation has taken place in the life that makes people especially that develops rapidly of mobile communication, becomes a spotlight of network service.As several key areas of modern communication technology, WLAN (wireless local area network) WLAN, wireless MAN Wimax, and traditional GSM, CDMA telephone network have satisfied people's demand from different angles.Yet on network configuration, above-mentioned network also only is that single star network connects, and the communication between the mobile node all will be passed through stationary nodes, and this model needs nonvolatil fixation means, and for some special area, as sea, desert, and by the city of eaerthquake damage, battlefield etc., above-mentioned mobile radio communication just can not meet the demands, this just needs a kind of ad hoc network, can interim fast automatic networking, can directly carry out information interaction by Radio Link between mobile node.A kind of brand-new mobile multi-hop network---the appearance of mobile ad hoc network has solved this problem.

Mobile ad hoc network is made up of one group of mobile terminal node that has a radio communication R-T unit, has self-organizing, recovers certainly, the provisional no central site network of adaptive multi-hop.This network does not rely on the infrastructure of base station and so on, the distributed operation of all nodes, and at any one time, node forms a network topology structure arbitrarily by wireless channel.In the MANET network, each node is born main frame and two kinds of roles of router simultaneously, and the control of whole network is by carrying out distributed control between each node.Node need move relevant Routing Protocol as router, carries out common routing operations such as route discovery, route maintenance, is not that oneself grouping need be carried out packet forward to the stay of two nights that receives.MANET can not have or the situation of the existing network infrastructure of not convenient usefulness under a kind of communication supporting environment is provided, thereby widened the applied environment of mobile communications network.

The characteristics of mobile ad hoc network can reduce following some:

(1) multi-hop route.Because the scope of the restriction node of node transmitting power is limited, in the time will communicating with the node outside its coverage, needs the forwarding of intermediate node, promptly will pass through multi-hop.Multi-hop route in the MANET network is finished jointly by ordinary node, rather than is finished by the routing device (as router) of special use.

(2) dynamic network topology structure.Be connected to form a fully connected topology arbitrarily by wireless channel between node, connection between the node since node leave arrival with new node, and node is mobile arbitrarily, composite factors such as variation, the wireless channel dynamic characteristic influence that adds the wireless base station apparatus transmitted power down, may cause network topology structure that violent dynamic change takes place, and this variation is uncertain.

(3) portability of portable terminal.Portable terminal has characteristics such as easy to carry, portable and smart, and network replacement is convenient unusually, but also has inherent shortcoming, and is limited as the energy, internal memory is less, the CUP disposal ability is lower and cost is more high.Mobile node generally all relies on the battery of finite energy to power, and therefore how to use the energy content of battery of node and the life span of prolongation node and the life span of whole network just to become very distinct issues efficiently.

(4) limited wireless transmission bandwidth.Because the physical characteristic of wireless channel itself, the relative wire message way of the network bandwidth that it can provide is much lower.In addition, consider that the competition sharing wireless channel produces factors such as collision, signal attenuation, noise jamming, interchannel interference, the available actual bandwidth of node is far smaller than theoretic bandwidth value.

(5) distributed control.All network behavior in the MANET network comprises the discovery of topological structure and the transmission of message, all must be finished by node oneself.That is to say that routing function must be integrated in the mobile node, do not have the control point, on-line file center of similar base station, thereby be a kind of distributed control network.

(6) may there be the uni-directional wireless channel.Because each node transmitting power difference, signal spread scope are also different, may have A and can hear B, and B can't hear the situation of A.

(7) limited bandwidth.The capacity of Radio Link is significantly less than the capacity of wire link, and because of being subjected to noise, decline, interference to influence actual capacity lower.

These characteristics make and are fixed with the shortest path of spider lines from the source to the destination node by generally being difficult to directly apply in the MANET network, at this moment, the quality of variable Radio Link is the key factor that must consider, the influence that network should be able to the adaptively modifying route alleviates these factors.

Along with mobile ad hoc network increases and the continuous development of portable terminal technology the interconnected focus that becomes industry research gradually of mobile ad hoc network and Internet day by day to Internet real time business demand.The carrier Internet business more need be paid attention to Network Load Balance and QoS and ensure, and the Internet gateway that is positioned at the mobile ad hoc network edge also becomes potential load bottleneck when connecting bridge as heterogeneous network.Therefore, find and select then to become the emphasis problem that mobile ad hoc network access Internet need consider than the available gateway of low load.Because special Access Network attribute, it is particularly outstanding that congested control problem seems, and existing access mechanism is mostly based on the minimum hop count criterion, can't QoS demand and the transmission fairness of perception path quality to satisfy the user, and the interconnection performance is unsatisfactory.

Summary of the invention

The purpose of this invention is to provide a kind of quality condition and gateway Route Selection and combine, be intended to that (MobileAd hoc Network, MANET) the Internet gateway discovery provides the route selection method that QoS ensures for mobile ad hoc network link.

To achieve these goals, the present invention estimates the link residual available bandwidth according to striding layer design philosophy, and introduce gateway Route Selection criterion function source node in the mobile ad hoc network to the route of Internet gateway is selected, many-sided factors such as residual available bandwidth, delivery rate and formation load of link have been taken all factors into consideration, a kind of feasible path quality state model has been discussed, promptly based on a gateway Route Selection criterion of striding layer design, and proposed a kind of based on the path quality perception with stride the mobile ad hoc network Internet gateway route selection method that layer designs.

Concrete steps of the present invention are:

First step: select gateway Route Selection criterion based on the path quality perception:

Metric＝α·MBR+β·PDR+γ·NQR (1)

Definition path minimum bandwidth availability factor MBR:

$\mathrm{MBR}=\frac{\min ({\mathrm{Bw}}_1,{\mathrm{Bw}}_2,\·\·\·{,\mathrm{Bw}}_i,\·\·\·,{\mathrm{Bw}}_n)}{B}---\left(2\right)$

Definition path accumulation delivery rate PDR:

$\mathrm{PDR}=\underset{i=1}{\overset{n-1}{\mathrm{\Π}}}\mathrm{pdr}(i,i+1)---\left(3\right)$

Definition path minimum formation residue load availability factor NQR:

$\mathrm{NQR}=\min (\frac{Q_1-q_1}{Q_1},\·\·\·,\frac{Q_i-q_i}{Q_i},\·\·\·,\frac{Q_n-q_n}{Q_n})---\left(4\right)$

Wherein n is a path, Bw _iBe the residual available bandwidth of node i, B is the master data bandwidth; Pdr (i, i+1) the expression node i is to the delivery rate of node i+1; q _iThe load queue length of expression node i, Q _iCache size for node i; α, beta, gamma are weighted factor, and α, beta, gamma 〉=0, alpha+beta+γ=1.

Second step: based on the residual available bandwidth method of estimation of striding layer design

Utilize the carrier sense mechanism of 802.11MAC layer to estimate residual available bandwidth in conjunction with network allocation vector (NAV) field of mac frame frame head.The not busy ratio of node channel busy, promptly channel idle degree and channel can get the average residual bandwidth and be approximated to direct ratio.The definition remaining bandwidth is estimated expression formula:

${\mathrm{Bw}}_i=\mathrm{kB}\frac{\mathrm{\Δ}-\underset{j}{\mathrm{\Σ}}({\mathrm{NAV}}_j+\mathrm{DIFS})-\mathrm{Backo}{\mathrm{ff}}_i}{\mathrm{\Δ}}---\left(5\right)$

Wherein, B represents the link average bandwidth; Δ is represented measuring period; NAV _jThe NAV value of neighbors in Δ for node i; DIFS is the DCF interFrameGap; Backoff _iKeep away the value of moving back counter for node i.Because the IEEE802.11 characteristic, can not reach theory and reach the standard grade keeping away the available bandwidth that moves back strategy and influence lower node, so setting modifying factor k, value is 0.89.

Third step: the method for choosing Internet gateway route

Inner all nodes of mobile ad hoc network carry out the on-demand route discovery, and its route to gateway is kept as default route.There is not the node of default route if there is the Internet business demand need initiate the gateway route requests.Expand the path quality information field in the gateway routing request packet, comprised path minimum bandwidth availability factor MBR, path accumulation delivery rate PDR, the minimum formation residue load availability factor NQR in path and gateway selection criterion Metric.The gateway route requests is noted the path quality information of every link on the way, gateway is after receiving the gateway route requests, calculate gateway according to path quality according to (1) and select criterion Metric, and add Metric to the gateway route and answer in the bag, and this gateway route is answered the bag clean culture return source node.Source node is answered the record from the route of identical or different gateway from the L bar that receives, and the route of selecting to have maximum Metric value is preserved remaining gateway route simultaneously and answered record as the default route to gateway.

The 4th step: the method for safeguarding default route

The default route of safeguarding when source node to gateway node lost efficacy or communication path when fracture takes place, and source node is from remaining acknowledges requests record, and the route of selecting to have maximum Metric value needs to carry out the gateway switching in case of necessity as default route.If this time selection still can not proper communication, then source node is initiated the gateway route requests again.

Simulation result shows that the present invention can effectively improve the delivery of packets rate for setting up an optimal communication path between nodes in MANET and Internet gateway, reduces mean transit delay, improves the interconnected performance in networking, and reduces routing cost.

Description of drawings

Accompanying drawing 1 is gateway route finding process flow chart of the present invention, and accompanying drawing 2 is gateway route requests packet format of the present invention, and accompanying drawing 3 is answered packet format for gateway route of the present invention.

Embodiment

Below in conjunction with accompanying drawing and have a try that the invention will be further described for example, but this embodiment should not be construed as limitation of the present invention.

1. based on the gateway Route Selection criterion of path quality perception

Suppose that path is n, the residual available bandwidth of node i is Bw _i, the master data bandwidth is B; Pdr (i, i+1) the expression node i is to the delivery rate of node i+1; q _iThe load queue length of expression node i, Q _iBe the cache size of node i, define following three kinds of path quality information indexs simultaneously:

Definition path minimum bandwidth availability factor MBR:

$\mathrm{MBR}=\frac{\min ({\mathrm{Bw}}_1,{\mathrm{Bw}}_2,\·\·\·{,\mathrm{Bw}}_i,\·\·\·,{\mathrm{Bw}}_n)}{B}$

Definition path accumulation delivery rate PDR:

$\mathrm{PDR}=\underset{i=1}{\overset{n-1}{\mathrm{\Π}}}\mathrm{pdr}(i,i+1)$

Definition path minimum formation residue load availability factor NQR:

$\mathrm{NQR}=\min (\frac{Q_1-q_1}{Q_1},\·\·\·,\frac{Q_i-q_i}{Q_i},\·\·\·,\frac{Q_n-q_n}{Q_n})$

Then the gateway Route Selection criterion based on the path quality perception is:

Metric＝α·MBR+β·PDR+γ·NQR

α, beta, gamma are weighted factor, and α, beta, gamma 〉=0, alpha+beta+γ=1.Node can be estimated the remaining bandwidth availability factor according to the information that the MAC layer provides, and remains the load availability factor in network layer statistics delivery rate and formation, and it is integrated into gateway Route Selection criterion by weighting, better the response path quality condition.

2. based on the residual available bandwidth method of estimation of striding layer design

Utilize the carrier sense mechanism of 802.11MAC layer to estimate residual available bandwidth in conjunction with network allocation vector (NAV) field of mac frame frame head.The not busy ratio of node channel busy, promptly channel idle degree and channel can get the average residual bandwidth and be approximated to direct ratio.Suppose that the link average bandwidth is B, be Δ measuring period, and the NAV value of the neighbors of node i in Δ is NAV _j, the DCF interFrameGap is DIFS, it is Backoff that node i is kept away the value of moving back counter _i, then remaining bandwidth estimates that expression formula is:

${\mathrm{Bw}}_i=\mathrm{kB}\frac{\mathrm{\Δ}-\underset{j}{\mathrm{\Σ}}({\mathrm{NAV}}_j+\mathrm{DIFS})-\mathrm{Backo}{\mathrm{ff}}_i}{\mathrm{\Δ}}$

Because the IEEE802.11 characteristic, can not reach theory and reach the standard grade keeping away the available bandwidth that moves back strategy and influence lower node, so setting modifying factor k, value is 0.89.

3. choose the method for Internet gateway route

After introducing gateway Route Selection criterion, this method require in each mobile ad hoc network source node can be in suitable packet format territory (as Fig. 2, Fig. 3) the record path quality information, when one of source node needs lead to the route of gateway node, this method starts the gateway route finding process, when node receives the gateway route requests, as Fig. 1, this method is according to the steps of processing route requests:

A. start the gateway route finding process;

B. broadcasting comprises the gateway routing request packet of path quality information;

When C. intermediate node is received this request package,, then destroy request package, no longer transmit if this bag was once handled by this node;

D. otherwise, if intermediate node is in overload, then destroy request package, will not transmit;

E. otherwise, provide the information of the path quality in the information updating request package according to this node MAC layer and network layer, be established to the reverse route of a hop node, and continue transmit this request package;

If F. node is a gateway node, the path quality information in the update request bag is calculated Metric according to (1), and path quality information and Metric are added in the gateway route answer bag;

G. the gateway route is answered the bag clean culture and return source node;

If H. source node does not receive the answer of L bar route, then continue to receive, answer until receiving L bar route;

I. after source node received that L bar route is answered, the route of selecting to have maximum Metric was as the default route to gateway, and this gateway is its default gateway, preserved remaining gateway route simultaneously and answered record;

J. finish the gateway route finding process.

Unique ID number the gateway route requests wraps in the network and constantly is forwarded up to being received by destination node in order to determine each gateway routing request packet.If this gateway discovery failure then the gateway routing request packet is added 1 for ID number continue to initiate gateway discovery next time behind the certain number of times of accumulative total as still be not found to the route of gateway, thinks that then this node can't set up Internet and connect.

4. safeguard the method for default route

Compare with cable network, wireless network is because of its inherent feature, and stability is relatively low.802.11 utilize the affirmation one by one of MAC (MediumAccess Control) layer that early stage detection and retransmission of lost and ruined packet is provided.If MAC layer reflection transmission problem can not be repaired, node is to source node transmit path erroneous packets, and source node is attempted from remaining acknowledges requests record, and the route of selecting to have maximum Metric value needs to carry out gateway in case of necessity and switches as default route.If this time selection still can not proper communication, then source node is initiated the gateway route requests again.

The content term this area professional and technical personnel's known prior art that is not described in detail in this specification.

Claims (2)

1. mobile ad hoc network Internet gateway route selection method based on the path quality perception, its concrete steps are: first step: select the gateway Route Selection criterion based on the path quality perception:

Metric＝α·MBR+β·PDR+γ·NQR (1)

Definition path minimum bandwidth availability factor MBR:

$\mathrm{MBR}=\frac{\min ({\mathrm{Bw}}_1,{\mathrm{Bw}}_2,\·\·\·,{\mathrm{Bw}}_i,\·\·\·,{\mathrm{Bw}}_n)}{B}---\left(2\right)$

Definition path accumulation delivery rate PDR:

$\mathrm{PDR}=\underset{i=1}{\overset{n-1}{\mathrm{\Π}}}\mathrm{pdr}(i,i+1)---\left(3\right)$

Definition path minimum formation residue load availability factor NQR:

$\mathrm{NQR}=\min (\frac{Q_1-q_1}{Q_1},\·\·\·,\frac{Q_i-q_i}{Q_i},\·\·\·,\frac{Q_n{-q}_n}{Q_n})---\left(4\right)$

Wherein n is a path, Bw _iBe the residual available bandwidth of node i, B is the master data bandwidth; Pdr (i, i+1) the expression node i is to the delivery rate of node i+1; q _iThe load queue length of expression node i, Q _iCache size for node i; α, beta, gamma are weighted factor, and α, beta, gamma 〉=0, alpha+beta+γ=1.

Second step: based on the residual available bandwidth method of estimation of striding layer design

Utilize the carrier sense mechanism of 802.11MAC layer to estimate residual available bandwidth in conjunction with network allocation vector (NAV) field of mac frame frame head.The not busy ratio of node channel busy, promptly channel idle degree and channel can get the average residual bandwidth and be approximated to direct ratio.The definition remaining bandwidth is estimated expression formula:

${\mathrm{Bw}}_i=\mathrm{kB}\frac{\mathrm{\Δ}-\underset{j}{\mathrm{\Σ}}(\mathrm{NA}{V}_j+\mathrm{DIFS})-\mathrm{Bac}{\mathrm{koff}}_i}{\mathrm{\Δ}}---\left(5\right)$

Wherein, B represents the link average bandwidth; Δ is represented measuring period; NAV _jThe NAV value of neighbors in Δ for node i; DIFS is the DCF interFrameGap; Backoff _iKeep away the value of moving back counter for node i.Because the IEEE802.11 characteristic, can not reach theory and reach the standard grade keeping away the available bandwidth that moves back strategy and influence lower node, so setting modifying factor k, value is 0.89.

Third step: the method for choosing Internet gateway route

Inner all nodes of mobile ad hoc network carry out the on-demand route discovery, and its route to gateway is kept as default route.There is not the node of default route if there is the Internet business demand need initiate the gateway route requests.Expand the path quality information field in the gateway routing request packet, comprised path minimum bandwidth availability factor MBR, path accumulation delivery rate PDR, the minimum formation residue load availability factor NQR in path and gateway selection criterion Metric.The gateway route requests is noted the path quality information of every link on the way, gateway is after receiving the gateway route requests, calculate gateway according to path quality according to (1) and select criterion Metric, and add Metric to the gateway route and answer in the bag, and this gateway route is answered the bag clean culture return source node.Source node is answered the record from the route of identical or different gateway from the L bar that receives, and the route of selecting to have maximum Metric value is preserved remaining gateway route simultaneously and answered record as the default route to gateway.

The 4th step: the method for safeguarding default route

The default route of safeguarding when source node to gateway node lost efficacy or communication path when fracture takes place, and source node is from remaining acknowledges requests record, and the route of selecting to have maximum Metric value needs to carry out the gateway switching in case of necessity as default route.If this time selection still can not proper communication, then source node is initiated the gateway route requests again.

2. as claimed in claim 1 a kind of based on the path quality perception with stride the mobile ad hoc network Internet gateway route selection method of layer design, it is characterized in that: after introducing gateway Route Selection criterion, this method require in each mobile ad hoc network source node can be in suitable packet format territory the record path quality information, when one of source node needs lead to the route of gateway node, this method starts the gateway route finding process, when node received the gateway route requests, this method was according to the steps of processing route requests:

A. start the gateway route finding process;

B. broadcasting comprises the gateway routing request packet of path quality information;

When C. intermediate node is received this request package,, then destroy request package, no longer transmit if this bag was once transmitted by this node;

D. otherwise, if intermediate node is in overload, then destroy request package, will not transmit;

E. otherwise, provide the information of the path quality in the information updating request package according to this node MAC layer and network layer, be established to the reverse route of a hop node, and continue transmit this request package;

If F. node is a gateway node, the path quality information in the update request bag is calculated Metric according to (1), and path quality information and Metric are added in the gateway route answer bag;

G. the gateway route is answered the bag clean culture and return source node;

If H. source node does not receive the answer of L bar route, then continue to receive, answer until receiving L bar route;

I. after source node received that L bar route is answered, the route of selecting to have maximum Metric was as the default route to gateway, and this gateway is its default gateway, preserved remaining gateway route simultaneously and answered record;

J. finish the gateway route finding process.

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