CN101185295A - Methods of channel access in a meshed network - Google Patents

Abstract

Methods for providing a client access to a channel in a meshed wireless local area network are disclosed. The methods comprise that a client in the meshed wireless local area network implement a polling based channel access methodology. The client determines that the channel is available by sensing that the channel is not busy and sends a request for access to the channel to an access point, wherein the request specifies a priority of data that is to be transmitted when the client is granted access to the channel. The client waits a time period before receiving at least one of a) a rejection of the request for access to the channel, b) access to the channel, c) modification of the request for access to the channel, and d) delay access to the channel.

Description

Channel access method in the mesh network

Invention field

The present invention relates generally to wireless communication system, and the channel that is particularly related in the meshed wireless local area network inserts the field.

Background of invention

In meshed wireless local area network (WLAN), there is the air station (client or access point (AP)) of carrying out radio communication each other.Usually, when first air station wished to communicate by letter with second air station, this first air station must at first be linked into radio frequency (RF) channel, thereby sent communication to second air station.(Institute of Electrical and Electronics Engineers) (electronics and The Institution of Electrical Engineers) be the 802.11 channel access procedures that mix synergistic function controlled channel access (HCCA) that are called as of having specified based on poll (IEEE).Use this HCCA process, the first air station exploitable channel is communicated by letter with second air station.Yet, because the air station in the mesh WLAN is a power constrained devices, and will support bursty data traffic, therefore, usefully, make HCCA that electricity-saving mechanism is provided and support the business of bursting simultaneously, thus the polled time of air station wake-up waiting be minimized, and do not need to predict the professional traffic performance of bursting.

Therefore, existence is for the needs of improved channel access method in the mesh network.

Brief description of drawings

Now will be by only describing the preferred embodiments of the present invention with reference to the accompanying drawings as an example, wherein:

Fig. 1 is exemplary block diagram, and typical according to an embodiment of the invention meshed wireless local area network system has been described.

Fig. 2 is a message diagram, has illustrated to be used for the method that the meshed wireless local area network channel inserts according to an embodiment of the invention.

Fig. 3 is a message diagram, has illustrated to be used for the other method that the meshed wireless local area network channel inserts according to an embodiment of the invention.

Fig. 4 is that channel inserts the frame format of asking according to an embodiment of the invention.

Fig. 5 is the frame format for Fig. 4 request responding according to an embodiment of the invention.

Fig. 6 is the frame format of quality of service information element as shown in Figures 4 and 5 according to an embodiment of the invention.

Fig. 7 is the frame format of " request delay information element " according to an embodiment of the invention.

Will be appreciated that,, be not necessarily to scale the element shown in the accompanying drawing for the simplification that illustrates and clear.For example, the size of some element is exaggerated with respect to other element.Further, it is suitable to consider here, and the reference number of Chong Fuing is represented identity element in the accompanying drawings.

Embodiment

With reference to figure 1 one embodiment of the present of invention are described.Shown in Fig. 1 is meshed wireless local area network (WLAN) 100, and it has single access point (AP) 102 and a plurality of client 104,106,108.AP 102 provides the access of arriving cable network network (not shown) directly or indirectly, for example passes through the hierarchical network of a plurality of more AP.All communications in the mesh WLAN are sent out on single frequency (i.e. channel 110).AP and all clients are utilized this channel 110 mutual communication.Therefore, each in the client 104,106,108 and AP102 communicate with one another on this channel 110.

Although show the client of mesh WLAN 100 randomly, the client of this mesh WLAN 100 and/or AP can be considered to layering.That is, the client of level 1, for example client 104, directly communicate by letter with AP, to be linked into the cable network (not shown) or to be linked into the remainder of WLAN communication level.In level 2, the client of level 2, for example client 108, communicate by letter with AP indirectly, to be linked into the cable network (not shown) or to be linked into the remainder of wireless WLAN communication level, here " indirectly " mean level 2 client directly and the client communication of level 1, and the client of level 1 is transmitted to AP with the communication of level 2 clients.

Those skilled in the art will recognize that, these clients can be can be in the Wireless Telecom Equipment of any adequate types of ad-hoc intra network communication, for example computer, PDA(Personal Digital Assistant), hard-wired equipment, the equipment that is placed in the vehicles or handheld device etc.If desired, some client also can be connected to fixed communication infrastructure.

The method of access channel in the mesh WLAN 100 is according to an embodiment of the invention described referring now to the message flow chart of Fig. 2 and 3.As an example, Fig. 2 has illustrated the message flow between client (for example client 104) and the AP (for example AP 102), and client-requested is linked into channel here, and the AP refusal is linked into this channel.Similarly, Fig. 3 has illustrated the message flow between client (for example client 104) and the AP (for example AP 102), and client-requested is linked into channel here, and client is authorized to be linked into this channel.In one embodiment, AP inserts to client authorization with explicit way, and in another embodiment, is authorized to be linked into this channel in AP client when client sends data.Under any circumstance, client has the access right to this channel.As used herein, in one embodiment, Reference News 202 and 302, Reference News 204 and 304 and Reference News 206 and 306 exchange because these message have identical message format.In one embodiment, these message are non-interchangeable.For example, message 206 and 306 has been passed on different information as described below.

With reference to figure 2, in operation,, client is used for when AP launch when having upstream data, perhaps, it is used for when AP retrieves when having down stream data transfer, and client is launched the request 202 to transmission opportunity (TxOP).As shown in Figure 2, request 202 is called message A.In one embodiment, be that effectively beacon interval is defined as the time between the continuous beacon here in the request 202 times (for example one or more beacon interval), and beacon is defined as the message in predetermined moment periodic transmission by AP in appointment.Client-requested 202 is requests of the polled transmission opportunity (TxOP) for given priority.In one embodiment, this priority is based on the request 202 associated upstreams and/or the priority of downstream traffic.For example, be used to be transmitted to AP, then ask 202 to comprise the information that relates to high priority if client has the upstream data of high priority.

In one embodiment, use based on the technology based on contention known in the IEEE802.11 standard and launch request 202, " based on contention " means that client and AP (based on priority) keep out of the way (back off) and contention channel randomly here.By the characteristic based on the contention scheme of describing in IEEE 802.11 standards, the request of higher priority is launched than the request of lower priority is more Zao.In one embodiment, before the lower priority request, handle higher priority request at AP.

In a further embodiment, request 202 also can comprise the duration, and the duration of client-requested is based on its data that need launch, for example upstream data that it cushioned here.In another embodiment, the duration of client-requested be static configuration and be not suitable for data in the mesh WLAN 100.In another embodiment, there is not the duration of given client end request, because client is not known the required duration, for example, if to be passed without any down stream data transfer.In this embodiment, send the unappropriated duration and further do not have armed upstream data to AP notice client, and request transmitting downstream flow data.In another embodiment, this request comprises queue size.

After the request of receiving 202, AP confirms 204 these requests and will ask to line up with received request, determines to accept which request and refuse which request.As shown in Figure 2, confirm that 204 are called as message B.AP handles request 202 and determines whether to accept or to refuse this request.Time between transmitting acknowledgement 204 and the transmitting response 206,306 comprises one or more in the following delay: queueing delay (for example, wait in line the delay that request caused handled by AP at the AP place), request processing time (for example AP estimate this and ask to determine whether should accept/refuse/revise the required time of this request), channel access delay (for example, the AP use is based on the required time of the method access channel of contention) and random wait time.In one embodiment, random wait time-dependent one or more in following content: a) priority, the b of the request 202,302 of Jie Shouing) number of queuing request, and c) be the up duration of all accepted request distribution T xOP at the AP place.For example, if received low priority request 202,302, then the random wait time may be sufficiently long, to adapt to the channel access delay of higher priority request.Further, when the up duration that is used for distribution T xOP at the number increase and/or the AP place of queuing request descended, the random wait time also descended.

After determining to refuse this request, AP emission refusal response 206, thus client can be transferred to battery saving mode.For example, if AP will launch without any down stream data transfer, then AP will send refusal response 206.As shown in Figure 2, this refusal response 206 is called as message C.Client is confirmed 208 determined responses and is transferred to battery saving mode then.As shown in Figure 2, this affirmation 208 is called as message B, and with confirm that 204 is same types.

Similarly, begin mandate in an identical manner and be linked into channel.At first, client is asked the polled transmission opportunity (TxOP) (being also referred to as message A) of 302 given priority to AP.In one embodiment, this request also comprises the duration.After receiving this request, AP confirms 304 (being also referred to as message B) this request, and will ask to line up with other request that receives, to determine to accept and refuse which request.After determining to authorize this request, AP launches authorization response 306 (being also referred to as message C).In one embodiment, this authorization response 306 is different message with refusal response 206.As above mentioned, message 206 and message 306 are similar message in one embodiment, when for example explicit request grant takes place, and are different in one embodiment, when for example implicit expression mandate as shown in Figure 3 takes place.Like this, in one embodiment, authorize (306) not need by signaling with explicit way in the following manner: promptly, the TxOP that asks to given client authorization by the concurrent family end data 308 of seing a visitor out of poll client by AP.As shown in Figure 3, this poll and data communication are represented as a series of exchanges data and confirm 308.After receiving and having confirmed data 308, client is transferred to battery saving mode.

In one embodiment, if client receives explicit rejection response, 206 (being also referred to as message C) for example, then client still keeps waking up, till receiving the refusal response or receiving direct poll.For example, if client receives direct polling message, then client can be transferred to battery saving mode after poll.Further, in one embodiment, the TxOP that is asked also can be used to transmit downstream traffic to client.In other cases, client can send new request 202 to AP.

In one embodiment, may there be proprietary signaling, the message that between AP and client, sends for example, it is used for the assistant client terminal access channel.For example, message A, B and C can be IEEE 802.11 expansion and not as the message of this standard part.In another embodiment, some or all message among message A, B and the C can be followed IEEE 802.11 standards, and other message can be proprietary.In any situation, in client is not mesh WLAN 100 communication a part of the time allow this client power saving and allow this client dormancy aspect, comprise that message A, B and C are useful.

In the exemplary embodiment, Fig. 4 has represented that channel inserts request 202,302 (being also referred to as message A), and in following description.As mentioned above, the function of request 202,302 is the TxOP that allow the client-requested assigned priority, thereby client can be launched upstream traffic.In one embodiment, 202,302 duration that also can specify TxOP of request.In alternative embodiment, client can be asked the TxOP (replace or remove the appointment duration) of 202,302 specified queue size.In this embodiment, client needn't be determined the duration, and AP is based on the queue size calculating prolongeding time of appointment.

In any situation, in one embodiment, request 202,302 can be followed among the IEEE802.11 frame format for the appointment of " Action " management frames.So, claim frame 202,302 comprises mac header 402, its have according to appointment in the standard and for the known MAC Address of those of ordinary skills.Further, request 202,302 points out to relate to the frame of service quality (QoS or QOS) by setting classification field 404QoS.In one embodiment, classification field 404 is set to " 1 " and is used to point out the QoS classification.Further, behavior field (action field) 406 is pointed out frame type, i.e. TxOP request.Therefore, in one embodiment, the behavior field is set to " 254 ", is used to point out the TxOP request.

Further, request 202,302 comprises QoS control information element (IE) field 408, and it points out the information that QoS is relevant.This QoS control IE field 408 is as described below; Yet for request 202,302, what client specified that it is asking is to specify the TxOP of duration or the TxOP of specified queue size.Further, client is also specified the priority of this request, as further describing with reference to figure 6.Alternatively, request 202,302 go back portability " request postpone IE " field (not shown), client therein the given client end before the TxOP request that retry is confirmed with the duration of waiting for.

In alternative embodiment, the frame format into the empty frame appointment of the QoS among the IEEE 802.11 is followed in request 202,302.So, claim frame 202,302 is used to specify the QoS control son field in the mac header of this request.What client specified that it is asking is to specify the TxOP of duration or the TxOP of specified queue size.Further, client is also specified as further with reference to the priority of figure 6 described these requests.

In the exemplary embodiment, insert request responding 206,306 (being also referred to as message C) as shown in Figure 5 for channel, and in following description.As mentioned above, the function of response 206,306 is will be to client notice refusal, the modification that inserts, inserts and/or the delay that is linked into channel.In the exemplary embodiment, this response is mainly used in the refusal channel and inserts request.

In one embodiment, response 206,306 frame formats of following " Action " management frames appointment among the IEEE802.11.So, response frame 206,306 comprises mac header 502, and it has according to MAC Address appointment in this standard and known to a person of ordinary skill in the art.Further, response 206,306 points out that by setting classification field 504QoS this frame relates to service quality (QoS).In one embodiment, classification field 504 is set to " 1 ", is used to point out the QoS classification.Further, behavior field 506 is pointed out frame type, i.e. TxOP response.Therefore, in one embodiment, the behavior field is set to " 255 " and points out this TxOP response.

Further, response 206,306 comprises conditional code 508, is used to point out whether this request is rejected, accepts, revises or postpones.For example, this field can be set to " 255 ", is used to point out that this request is rejected.Further, response 206,306 comprises that request postpones IE 510, but is used in reference to out the time of client retry request.For example, request delay IE 510 can point out sending the time that will wait for before the request once more.In example, AP can be set at this field " 0 ", is used in reference to out client and can waits for uncertain time quantum before sending request once more.Further, response 206,306 comprises QoS control information element (IE) field 512, and it points out the information that QoS is relevant.This QoS control IE field 512 is in following description; Yet for response 206,306, this QoS control IE field 512 portabilities relate to the information requested that is accepted or revises.

In one embodiment, confirm that 204,208,304 (being also referred to as message B) follow " ACK " frame format of appointment among the IEEE802.11, and be the frame that comprises the FCS of the mac header of 10 length in octets and 4 length in octets.In alternative embodiment, confirm that 204,208,304 also can follow the frame format to " QoS CF ACK " appointment of appointment among the IEEE 802.11.This alternative embodiment is not expectation, because it is bigger frame, and the bigger frame of needs can be wasted the capacity on the channel.

Do not signaling among the embodiment of the mandate that is linked into channel with explicit way, client can receive the indication of access channel by the mac header of decoding institute switching frame (for example 308).For example, in one embodiment, the QoS of mac header control TxOP limited field to the client notice for treating that switching frame (for example 308) is used for the remaining time that channel inserts.Further again, if the appointment of time insert to(for) channel is inadequate for client, then AP can specify it that time of further access will be provided in the time after a while.Provide after a while time by the intention to client notice AP, the client decidable keeps waking up next chance that inserts up to channel.

In another embodiment, AP keeps about giving each client authorization knowledge how long.For example, AP can not allow first client than second client access channel more.By following the tracks of the access of channel, AP has prevented the resource shortage in the client.For example, ask up duration to separate to second of channel, processed before second request with first request that allows equal priority.In this embodiment, each client only just needs to launch new request 202,302 in the following cases: if a) previous request 202,302 is rejected, b) previous request 202,302 is not enough to handle the upstream and the downstream traffic of client, perhaps c) arrive from previous request 202,302 processed new back business.Because AP keeps about giving each client authorization knowledge how long, if thereby previous request 202,302 partly finished, then each client does not propose new request 202,302.

Further, AP can use and be the frame format of " QoS CF Poll " appointment among the IEEE802.11, exchange the poll of being carried out client before at frame (for example 308).

In the exemplary embodiment, QoS control IE 408,512 is as providing QoS information in " Action " management frames, and " Action " management frames is specified in IEEE 802.11 here.With reference to figure 6, QoS control IE 408,512 comprises element ID 602, length 604, TID (task identifier) 606, EOSP (service period ending) 608, confirms the TxOP duration/queue size 612 of strategy 610, TxOP restriction/QAP PS (QOS AP power saving) buffer status/request.In the exemplary embodiment, element ID 602 is set to " 254 " and is used to point out TxOP, and length field is set to 2 bytes, is used to point out the length of QoS control IE 408,512.In the exemplary embodiment, TID 606 is set to the User Priority of the TxOP duration/queue size 612 of TxOP restriction/QAPPS buffer status/request of being reported.In the exemplary embodiment, the EOSP 608 usefulness factor in the information that TxOP duration/queue size 612 by TxOP restriction/QAP PS buffer status/request transmits that elects.In the exemplary embodiment, this TxOP restriction/QAP PS buffer status/TxOP duration/queue size 612 of request is used for signaling at least one of above-mentioned four information.The combination of carrying the frame type/subtype of this IE and EOSP value is used for determining these four options, and which is signaled, and is as follows.In the exemplary embodiment, client can be set at 0 with the value of signaling, and being used in reference to out does not have upstream traffic to be cushioned but this client keeps waking up to retrieve the not downstream traffic of specified amount.

Frame	EOSP	TxOP duration/the queue size of TxOP restriction/QAP PS buffer status/request
			Request	0	The TxOP duration of request
Request
		1	Queue size
Response				0	The TxOP restriction
	Response
		1	QAP PS buffer status

In the exemplary embodiment, request postpones IE 700 as the information that relates to the retry time is provided.For example, AP can postpone IE 700 and points out how long client should be waited for before in retry request (for example 202,302) by sending request.Another example, client can point out how long it will wait for before in retry request (for example 202,302).In the exemplary embodiment, this request postpones IE 700 and comprises that element ID 702, length 704 and request postpone 706.In the exemplary embodiment, element ID 702 is set to " 255 ", is used to point out TxOP, and length field is set to 4 bytes, is used to point out to ask to postpone the length of IE 700.In the exemplary embodiment, this request postpones 706 and points out to recommend the amount that postpones, but recommends to postpone back its request of client retry (for example 202,302) at this.

As mentioned above, the embodiment that utilizes channel described here to insert is for the client in the mesh WLAN 100 provides power saving.In addition, the embodiment that utilizes channel described here to insert has alleviated " concealed terminal " known to a person of ordinary skill in the art problem.By using request and the response that reaches as mentioned above in the accompanying drawing, because request described herein and response message are short messages, thereby exist less conflict possibility in the mesh WLAN 100, its short-and-medium length that is defined as is less than Frame.In one embodiment, request (for example 202,302) only has 34 byte longs, and typical packet is between the 130-1500 byte.Under any circumstance, because request and response message are short messages, therefore the possibility of request of receiving under the situation of not makeing mistakes and response message is higher.Further, be by starting (for example message C) by AP owing to be linked into the channel that is used for exchanges data, so the data in the mesh WLAN 100 are protected and do not have " concealed terminal " (hidden terminal) problem.

Though described the present invention in conjunction with specific embodiment, other advantage and modification can easily take place for those skilled in the art.The present invention therefore aspect its broad, be not limited to specific details, representative device and shown in and the illustrative example described.For example, subscriber unit and/or base radio equipment can comprise storage medium, have stored instruction set on it, but when this instruction is loaded in the hardware device (for example microprocessor), causes hardware device and carry out following function of the present invention.Can be in hardware, firmware and/or software at least a in realize the present invention.According to above stated specification, various replacements, modification and variation are conspicuous for those skilled in the art.Therefore, should be appreciated that the present invention is not limited to above-mentioned explanation, and comprise all these replacements, modification and variation according to the spirit and scope of claims.

Should be noted that as used herein one of term " " or " one " definition for or a plurality of.Term " a plurality of " is defined as two or more than two as used herein.Term " another " is defined as at least the second or more a plurality of as used herein.Term " comprises " and/or " having " is defined as and comprises (that is open language) as used herein.

Claims (20)

1. one kind is used for providing client to be linked into the method for channel in meshed wireless local area network, comprising:

Client place in described meshed wireless local area network, wherein said meshed wireless local area network is carried out the channel access method based on poll:

Be not in a hurry to determine that by the described channel of sensing described channel can use;

To the request of access point transmission access channel, the priority of data has been specified in wherein said request, wherein launches described data when described client is authorized to be linked into described channel; And

Followingly every wait for a time period before one of them at least receiving: a) to refusal, the b of the request that inserts described channel) insert described channel, c) to the modification of the request that inserts described channel, and d) postpone to insert described channel.

2. the method for claim 1, wherein said request further comprises: at least one in duration and the queue size.

3. the method for claim 1, the wherein said time period relate to following every at least one of them: a) queueing delay, b) request processing time, c) the channel access delay, and d) the random wait time.

4. method as claimed in claim 3, wherein said random wait time-dependent in following every at least one of them: the number of the priority of data, the request that receives and access point distribute the up duration of launching opportunity for request.

5. method as claimed in claim 3, wherein said random wait temporal adaptation is in the channel access delay with the request that is higher than described request priority.

6. the method for claim 1 further comprises: dormancy when the refusal of the request that receives the described channel of butt joint.

7. the method for claim 1, wherein said request are short proprietary signaling messages.

8. the method for claim 1, wherein said IEEE 802.11 standards of determining to follow based on the access channel of contention.

9. the method for claim 1, wherein, following every one of them provides based on the described channel of the access of poll at least: a) to refusal, the b of the request that inserts described channel) insert described channel, c) to the modification of the request that inserts described channel, and d) postpone to insert described channel.

10. method that is used for providing in meshed wireless local area network the client access channel comprises:

Access point place in described meshed wireless local area network, wherein said meshed wireless local area network is carried out the channel access method based on poll;

From the request of described client reception for described channel, the priority of data has been specified in wherein said request, wherein launches described data when described client is authorized to insert described channel;

Confirm described request, and

Followingly every wait for a time period before one of them at least sending: a) to refusal, the b of the request that inserts described channel) insert described channel, c) to the modification of the request that inserts described channel, and d) postpone to insert described channel.

11. method as claimed in claim 10, wherein said request further comprises: at least one in duration and the queue size.

12. method as claimed in claim 10, the wherein said time period relate to following every at least one of them: a) queueing delay, b) request processing time, c) the channel access delay, and d) the random wait time.

13. method as claimed in claim 12, wherein said random wait time-dependent in following every at least one of them: the number of the priority of data, the request that receives and access point distribute the up duration of launching opportunity for request.

14. method as claimed in claim 12, wherein said random wait temporal adaptation is in the channel access delay with the request that is higher than described request priority.

15. method as claimed in claim 10, wherein said request are effective in the fixed time section.

16. method as claimed in claim 10, further comprise sending response, wherein said response be following every at least one of them: a) to refusal, the b of the request that inserts described channel) insert described channel, c) to the modification of the request that inserts described channel, and d) postpone to insert described channel.

17. method as claimed in claim 16, wherein said response comprises the request delay information element, but is used to point out the time of described client retry described request.

18. method as claimed in claim 10, wherein said request comprise service quality control information element.

19. method as claimed in claim 10, wherein said request are followed IEEE 802.11 " Action " management frame format.

20. method as claimed in claim 10, wherein by start based on the described access point of the cut-in method of poll point out following every at least one of them: a) to refusal, the b of the request that inserts described channel) insert described channel, c) to the modification of the request that inserts described channel, and d) postpone to insert described channel, the mixing synergistic function control channel that described cut-in method based on poll is followed IEEE 802. appointments inserts.

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