CN1857016B - Wireless communication method and apparatus for performing access point start and primary channel selection - Google Patents

Abstract

A startup process of an access point (AP) includes a discovery phase and an announcement phase. During the discovery phase, the AP detects neighboring APs from its own extended service set (ESS), neighboring APs from different ESSs, and external sources of interference. During the announcement phase, the AP transmits its beacon signals at maximum power in order to accelerate recognition by neighboring AP running the discovery phase. An automatic initialization channel selection process of an AP scans channels the AP will use to communicate. Information of each scanned channel is recorded and a best performance channel is determined for use by the AP.

Description

Carry out the wireless communications method and the device of access point starting and preliminary channel selection procedure

Technical field

The present invention is about a kind of wireless communication system.Particular more, the present invention is about being an access point (AP) initialization operation parameter and selecting the most appropriate channel of operation.

Background technology

The condition of one radio link at one wireless communication system running place possibly change at any time.Because a wireless transmission/receive unit (WTRU) takes action, this WTRU looks its position and possibly break away from surely or in the scope of one or more AP.When an AP just has been established or because start shooting once more after some former thereby shutdown, the starting process of this AP must be assessed its radio resource environment.Generally speaking, starting process also provides one to be used for announcing the mechanism that oneself occurs to other AP of its own extension services set (ESS), makes that other AP can the own operating parameter of self-in view of the above adjustment.

There are several frameworks to be used to improve the capacity of wireless communication system now.It is that these frameworks are wherein a kind of that channel (that is frequency) is selected, and uses to let one or more interior AP of a network select the relevant WTRU contact with other of one or more channel.The coordination that the AP channel is selected generally is to carry out with manual mode.But it is very unpractical coordinating the channel selection with manual mode in response to each the little variation in the network configuration, because this possibly cause the design and configuration again again of all AP.The problem that unauthorized frequency spectrum and external interference source also can cause manual coordination fully to solve.In addition, be difficult to make the news affair load of adjacent AP share in available channel Channel Assignment one-tenth with the mode of a maximize overall system capacity through manual channel selective mode.

The convention framework have that a plurality of AP attempt to start shooting simultaneously the time can meet with another problem.This situation takes place in a network, and all AP attempt making a channel in the identical time and select.Therefore, it can not be best that the channel of AP is selected, and does not select to include in to consider because each AP will be close to the channel of AP.

The method and system that overcome foregoing problems can be very favourable.

Summary of the invention

The present invention proposes the starting of a kind of implementation one AP and the method and the device of preliminary channel selection procedure.

The starting process of this AP comprises path forfeiture and finds a step and an announcement phase.During step was found in the forfeiture of this path, this AP detected from the contiguous AP of its own ESS, from the contiguous AP of different ESSs, reaches external interference source.During this announcement phase, this AP launches a beacon signal and is just found that in the operating path forfeiture the contiguous AP of step recognizes so that quicken.This starting process provides monitoring to this AP and assesses the ability of its radio environment, thereby allows the preliminary operating parameter of this AP oneself decision.

A kind of AP Initial Channel Assignment selection course is carried out when the starting process of this AP begins automatically.

Description of drawings

We can be from proposing with way of example and should more understand for the present invention together with the appended graphic following detailed description of understanding, graphic in:

Fig. 1 is a calcspar according to a wireless communication system of the present invention;

Fig. 2 is a flow chart according to the AP starting process of one embodiment of the invention;

Fig. 3 is a flow chart according to the automatic channel selection course of another embodiment of the present invention; And

Fig. 4 is a flow chart according to the Initial Channel Assignment selection course of another embodiment of the present invention.

Embodiment

Hereinafter, the non-limitation of term " WTRU " comprises the device of user's equipment (UE), an action station, fixing or mobile subscriber unit, calling set or any type that other can operate in a wireless environment.

Hereinafter, the tipping that is situated between of the non-limitation of term " AP " wireless environment that comprises an access point, a base station, B node, site controller or any other type is put.

Characteristic of the present invention can be merged in the IC or be configured in one and comprise in the circuit of a plurality of interconnecting assemblies.

Be described below; The present invention can be applicable to WLAN (WLAN) technology substantially; For example be applied to IEEE 802.11 and ETSI HyperLAN specification substantially, so can infer it is applied in other limit interferences wireless system such as IEEE 802.15 and IEEE 802.16.

Fig. 1 is a calcspar according to wireless communication system 100 of the present invention.Wireless communication system 100 comprises an AP 105 and a plurality of WTRU 110a-110n.AP 105 sees through a wireless link 115 and WTRU110a-110n contact via an antenna 120.AP 105 comprises a transceiver 125, a channel selector 130, a measuring unit 135, a power controller 140, a timer 145 and an internal memory 150.Transceiver 125 sends signal 115a-115n and receives signal 115a-115n from said WTRU via 120 couples of WTRU110a-110n of antenna.

Channel selector 130 is selected the channel that is used for each WTRU 110a-110n contact.Measuring unit 135 is measured the operating parameter of supporting AP 105.Measuring unit 135 is responsible for collecting, handling and the memory channel measuring value; The non-limitation of these measuring values comprises: channel utilization rate (that is time percentage of channel busy); The level that disturb outside (non-802.11) from receiving the reception signal strength signal intensity that package records, reaches the similar quantity measured value.The through-put power of power controller 140 control AP 105.Timer 145 is set one or more predetermined period that AP 105 carries out some operation.Internal memory 150 provides storage capacity for AP 105, comprises the data of record such as measurement result.

Fig. 2 is the flow chart of the starting process 200 of an AP 105, and this process comprises one and finds a step 210 and an announcement phase 220.In finding step 210, its measurement parameters of AP 105 initialization and numerical value (step 211).Measurement parameters that is initialised and numerical example can comprise parameter and the numerical value that is listed in the table below in 1.As have the knack of this art and can understand, can more use other parameter and numerical value or replace at these parameters and numerical value outer with other parameter and numerical value.

Symbol	Describe	Type	Default value
				ACS	The tolerable channel set	Configuration parameters	{1，6，11 }
T mpp_fix Discov	Produce the discovery step value of fixed component at interval quiet measuring period	Configuration parameters	1000 milliseconds
				T mpp_va Discov	Produce the discovery step value of the amplitude of variable componenent at interval quiet measuring period	Configuration parameters	0 millisecond
T mpp_du Discov	The discovery step value of the duration of one quiet measuring period	Configuration parameters	1000 milliseconds
				N MIN_ Discov	The minimum number of the measuring assembly during the discovery step	Configuration parameters	4
N MAX_ Discov	The maximum quantity of the measuring assembly during the discovery step	Configuration parameters	15
				T dur Announ	The announcement phase duration	Configuration parameters	10 seconds
T beacon Announ	The beacon transmissions cycle during the announcement phase	Configuration parameters						100 milliseconds
				P max	Maximum AP through-put power	Configuration parameters	20dBm

Table 1

In the step 212 of finding step 210, measuring unit 135 is to carry out N _{Meas_sets} ^DiscoverThe mode measuring operation parameter of measuring assembly obtains the measuring value in a period of time that each channel is made up of the complete cycle of the measuring period of implementing all channels in this ACS in the tolerable channel set (ACS) by this in regular turn during a measuring assembly.For instance, operating parameter can be through-put power and the channel setting value of AP 105.Preferable, the measurement duration of the integral body on each channel (is equivalent to T _{Mpp_fix} ^Discover* N ^Discover) set for and can receive enough strong package from contiguous AP.Strong package is sent to improve it by the package of the detected possibility of contiguous AP with maximum power by an AP.

T _{Mpp_fix} ^DiscoverDuration be configured to be long enough to the Restricted edge edge effect, this edge effect system occurs in a package and is between the tour between measuring period (MPs) in the transmission in the state.Again, preferable with T _{Mpp_fix} ^DiscoverSet for to be short to and be enough to allow that rotating continuously of interchannel makes AP 105 can detect a contiguous AP channel variation of one wherein.This duration and said periodic system are by timer 145 decisions.The duration of finding step 210 is by being evenly distributed on N _{MIN_MS} ^DiscoverWith N _{MAX_MS} ^DiscoverBetween any a plurality of measuring assemblies form.The duration of finding step 210 is arbitrarily, uses and considers the situation that two or more AP start shooting simultaneously, avoids these AP to carry out preliminary channel in the identical time and selects.

Because these measurements, AP 105 is able to judge its radio environment, for example from the detection of the contiguous AP of its own ESS, from the detection of the contiguous AP of different ESSs, reach the detection of external interference source.

Later with reference to figure 2, in case accomplish N _{Meas_sets} ^DiscoverUsefulness measuring assembly (step 212), the power control (step 213) of power controller 140 priming AP 105.A baseline scope and the dependency basis linear heat generation rate set point of power control decision AP 105.In the control of the power of AP 105 after step 213 priming, the channel of channel selector 130 primings one channel optimization procedures (step 214) to select a specific AP or AP network to use.The preliminary channel setting value system of AP 105 serves as the basis decision with the parameter by power controller 140 decisions.

During finding step 210, AP 105 keeps quiet (that is AP 105 does not send any package).After finding that step 210 is accomplished, AP 105 has collected enough information and has decided an optimum operation channel and select a through-put power set point.

Finding that step 210 is an announcement phase 220 after finishing.During announcement phase 220, AP becomes its channel of operation configuration the optimum channel of decision when finding that step 210 finishes.It will be appreciated that and optionally during transition to carry out other process.The purpose of announcement phase 220 is to quicken AP to be detected by its contiguous AP.When announcement phase 220 beginning, each parameter (T for example _Dur ^Announce, T _Beacon ^Announce, P _MAX) (step 221) is initialised.In the announcement phase duration T _Dur ^AnnounceDuring this time, AP 105 is only with cycle T _Beacon ^AnnounceSend and have a maximum transmission power P _MAXBeacon frame

(step 222).This quickens AP 105 and is detected by other AP, because only send the maximum power package.During announcement phase 220, the covering the extraneous WTRU of ripple and possibly attempt getting in touch of AP 105, because AP 105 is just with its maximum power P with AP 105 _MaxEmission.Therefore event, can refusal during announcement phase 220 from all association request of WTRU to avoid relating to the WTRU of disengaging scope during normal running for a moment.

In case announcement phase 220 finishes, the starting of AP 105 is promptly accomplished.AP 105 is with himself its normal running use (step 223) of configuration one-tenth confession and beginning normal running (step 230) then.AP 105 sets its through-put power for by power controller 140 decisions set point, and AP 105 begins normal runnings and begins to accept the association request from WTRU 110 after this.

Fig. 3 is a flow chart according to the auto-initiation channel selection procedure 300 of one embodiment of the invention.In this preferred embodiment, this channel selection procedure by priming, has been obtained the measuring value on each channel this moment when finding that step 210 finishes.Select to supply a specific AP or the channel of AP network use.Channel is selected to such an extent that be to accomplish with manual mode or automated manner, and must be for when disposing, just beginning to carry out or dynamically carry out in operation.The present invention's WLAN (WLAN) of can arranging in pairs or groups is used (for example according to IEEE 802.11) and is carried out.

Initial Channel Assignment selection course 300 ties up to carries out during the starting process 200 and determines the optimum operation channel.In preferred embodiment, channel is scanned during finding step 210.When finding that step 210 finishes, channel selection procedure in step 214 by priming with according to during finding step 210 with regard to each channel observation to measuring value serve as that optimum channel is selected on the basis.In all situations, the Initial Channel Assignment selection course 300 a plurality of channels of scanning (for example channel 1-11) are to detect available optimum channel.Can be according to a predefined procedure by the sequence of scanning channel, perhaps it can be at random.Channel sequence not necessarily will comprise all available channels.For each by scanning channel, this process judgment: 1) have which other AP on this channel, to operate; 2) whether said AP is the part (that is according to ESS) of same system; 3) signal strength signal intensity of said AP; 4) the news affair amount on this channel; And 5) whether any other interference source (for example non-802.11 disturb) is arranged on this channel, and the non-WLAN interference power level of receiving.After scanning was accomplished, which channel AP can calculate can obtain best efficiency (channel that for example has minimum interference).AP is with oneself retuning into this channel then.Look detected said other AP and whether be the part of same system and decide, AP can determine for the selection of using channel more actively or more not positive.

In an alternate embodiment, coordinate frequency is selected and can be accomplished in the following manner: 1) make AP exchange the information of relevant its speciality (for example load, capacity or position) each other; Or 2) have one can obtain the channel of all AP in information and the setting network from each AP centralized architecture.With regard to first kind of situation, each AP still can independently make decision, but the exchange information can allow one better the decision (for example its can comprise be difficult to by another AP from external observation to statistics).With regard to second kind of situation, notify a centralized unit or device from different AP acquisition of informations and with these information, this centralized unit is made a decision and is later notified different AP with this decision after receiving information.

Still,, allow AP 105 all channels of scanning to receive signal strength signal intensity indication (RSSI) (step 310) with the identity and of all AP detecting near when 300 beginnings (step 305) of initialization channel selection procedure with reference to Fig. 3.In preferred embodiment, step 310 can be during finding step 210 and carries out.In step 315, the scanning channel tabulation.All or part of of tabular channel can be according to a predetermined or random sequence and scanned in regular turn.The information (step 320) relevant that record arrives with regard to each Channel Detection with each AP.This information can comprise the identity of other AP that (but being not limited to) operate on by scanning channel, and whether other AP is the indication of the part of same ESS, the signal strength signal intensity of AP, and the news affair amount on the channel, and whether any other interference source is arranged on the channel.

After scanning was accomplished, AP 105 judged that which channel provides best efficiency (step 325).For instance, this possibly be that which channel has minimum interference or other AP is not that the mode of the part of same ESS is judged through measuring.In case judge the channel with best efficiency, AP 105 is with oneself being tuned to this optimum channel.

Fig. 4 one is used for the detail flowchart in the Initial Channel Assignment selection course 400 of AP starting back decision optimum channel according to another embodiment of the present invention.Initial Channel Assignment selection course 400 comprises a candidate channel decision process 405 and a channel selection procedure 450.

In candidate channel decision process 405, AP 105 retrieval maximums are allowed interference I _MAX(step 410), it serves as that the maximum that the basis determines is allowed interference for the baseline scope with an AP on any known channel.I _MAXCan obtain from power control process.Imax system utilizes equation (1) to calculate by Initial Channel Assignment selection course 400.The parameter some of them parameter of using in the equation (1) is to obtain from the power control process retrieval.In particular, power control can decision RNG _BaseOn the other hand, P _Max, (C/I) _{Req_hig}And M ₁It is the parameter that is predetermined.Preferable, be used for the I of candidate channel decision process 405 _MAXSystem calculates according to equation (1):

I _MAX=P _Max-RNG _Base-(C/I) _{Req_high}-M ₁Equation (1)

P wherein _MaxIt is the maximum transmission power of AP 105; RNG _BaseIt is the scope that AP 105 covers; And (C/I) _{Req_high}It is the necessary carrier power interference ratio of a two-forty package (for example 11Mbps).M _IBe that an elimination channel possesses the possible enough and to spare of too allowing the interference level of level near actual maximum.Another selects the predetermined I who is used to determine the candidate channel tabulation that is worthwhile for of Imax _MAX

Select one first channel (step 415) from an ACS.Measure the interference I of a channel and allow interference I with itself and maximum _MAXDo comparison (step 420).If allowing less than maximum, the interference I of this channel disturbs I _MAX, then AP 105 charges to a candidate list (step 425) in the internal memory 150 with this channel.If being not less than maximum, this channel disturbance I allows interference I _MAX, then whether also have any channel to have (step 430) in the AP 105 inspection ACS.If still there is channel to exist in the ACS, then AP 105 selects next channel (step 435) and candidate channel decision process 405 is got back to step 420 from ACS.

If no longer include channel in the ACS, then whether AP 105 inspections have any available candidate channel (step 440).If in step 440, judging does not have the available candidate channel, then AP 105 is with I _MAXIncrease Δ dB (step 445) and candidate channel decision process 405 and get back to step 415.If in step 440, judge to have at least a candidate channel to exist, then candidate channel decision process 405 is accomplished, and carries out channel selection procedure 450 then.

Channel selection procedure 450 used standards are quantity N of the contiguous BSSs that on each channel, records _B(k).In case select candidate channel, judge in the middle of all candidate channel the minimum number N that records beacon from different B SSs _B ^Min(step 455).The quantity of the contiguous BSSs that on channel k, records is N _B(k) and the minimum number that records BSSs be N _B ^MinCompare, from the candidate channel tabulation, remove $N_B\left(k\right)>N_B^{\mathrm{Min}}$ All channels (step 460).In other words, the channel that only possesses the minimum BSSs of recording is stayed.Another selection, in step 455 and 460, the quantity that records contiguous BSSs on each channel can be changed into the channel utilization rate on each channel.Channel utilization rate measuring value is equivalent to receiver by a WLAN signal carrier time of locking percentage.In this situation, channel selection procedure can preference have the channel that hangs down the channel utilization rate.

Another used standard of channel selection procedure is that minimum records interference level, and this is with all remaining candidate channel decisions (step 465).Record interference level I (k) and least interference level I with the minimum on the channel k _MINDo comparison, and from the candidate channel tabulation, remove I (k)＞I _MINAll channels (step 470).In other words, the channel that only possesses the least interference level is stayed.

If have the Minimum Power Level candidate channel more than to exist, then in the middle of remaining candidate channel, select a channel (step 475) at random.

The example parameter of Initial Channel Assignment selection course 400 is listed in the table below in 2.Haveing the knack of this art will appreciate that and can outside these parameters and numerical value, more use other parameter and numerical value or replace with other parameter and numerical value.

Symbol	Describe	Type	Default value
				ACS	The tolerable channel set	Configuration parameters	{1，6，11}
N B(k)	The quantity of the contiguous BSSs that on channel k, records.Utilize the minimum value of EDT to detect contiguous beacon frame.	Measuring value	Do not have
				I (k)	The interference that on channel k, records.I is measured as the average received signal power when not being received device " carrier lock " (that is receiver does not receive any package).	Measuring value	Do not have
RNG Base	The baseline scope (is established by path forfeiture discovery procedure	Inner parameter	Do not have
					Fixed)
(C/I) Req	Support the minimum necessary carrier power interference ratio of peak data transfer rate	Configuration parameters	10dB
				P Max	Maximum AP through-put power	Configuration parameters	20dBm
I MAX	Serve as that the maximum of basis decision is allowed interference with the baseline scope on any known channel	Inner parameter	Do not have
				M I	Be used to maximum permissible noise level I MAXThe interference enough and to spare of calculating	Configuration parameters	3dB
△	There is not I＜I MAXCandidate channel the time maximum is allowed disturb I MAXThe amount that increases, the dB of unit.	Configuration parameters	3dB

Table 2

Though in preferred embodiment, with regard to particular combination characteristic of the present invention and assembly are described, each characteristic or assembly must use by independent use or with the various combination that is with or without further feature of the present invention and assembly.

Claims (6)

1. the method selected of the employed channel of an optimization access point said method comprising the steps of:

Decision is the basis with the baseline scope of said access point on any known channel maximum is allowed and is disturbed I _MAX, I wherein _MAX=P _Max-RNG _Base-(C/I) _{Req_high}-M _I, P _MaxBe the maximum transmission power of said access point, RNG _BaseBe the scope that said access point covers, (C/I) _{Req_high}Be the necessary carrier power interference ratio of two-forty package, M _IBe to eliminate to possess too near I _MAXThe enough and to spare of channel of interference level, make the interference level and the I of channel _MAXBetween difference can be less than M _I

Select to supply the candidate channel of said access point use, wherein the interference of selected candidate channel is less than I _MAXAnd

In the middle of said candidate channel, select a channel based on the channel choice criteria, wherein select a channel to comprise:

The quantity of decision beacon of detecting on each said candidate channel and select at least one to possess the said candidate channel of the said detecting beacon of minimum number; Or

Determine the interference level of said candidate channel and select at least one to possess the said candidate channel of least interference level.

2. method according to claim 1 is characterized in that, said candidate channel is to be selected from the tolerable channel set.

3. method according to claim 1 is characterized in that, also comprises step:

When having two to select candidate channel, select a candidate channel at least randomly.

4. an access point comprises:

One measuring unit, the maximum that is the basis through the baseline scope that is configured to determine on any known channel with said access point are allowed and are disturbed I _MAX, I wherein _MAX=P _Max-RNG _Base-(C/I) _{Req_high}-M _I, P _MaxBe the maximum transmission power of said access point, RNG _BaseBe the scope that said access point covers, (C/I) _{Req_high}Be the necessary carrier power interference ratio of two-forty package, M _IBe to eliminate to possess too near I _MAXThe enough and to spare of channel of interference level, make the interference level and the I of channel _MAXBetween difference can be less than M _I

One channel selector, through being configured to select to supply the candidate channel of said access point use, wherein the interference of selected candidate channel is less than I _MAXAnd

Said channel selector, also through being configured in the middle of said candidate channel, to select a channel based on the channel choice criteria, said channel choice criteria comprises the detecting beacon or a least interference level of a minimum number.

5. method according to claim 4 is characterized in that, said channel selector is used for from the said candidate channel of the incompatible selection of tolerable channel set through configuration.

6. method according to claim 4 is characterized in that, said channel selector is selected said channel randomly through being configured to when existing at least two to select candidate channel in the middle of said candidate channel.

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