KR101482565B1 - Wireless communication method and wlan for signaling deferral management messages - Google Patents

Abstract

A grace management method is implemented in a wireless local area network (WLAN) that includes an access point (AP) and a plurality of wireless transmit / receive units (WTRUs). The AP sends a request message of deferral management capabilities to the WTRUs to determine the deferral management capabilities of the WTRUs. In response, each of the WTRUs sends an indicator message of deferral management capabilities to the AP. The AP may also send a grace management parameter setting message to the WTRUs to indicate values for setting the grace management parameters. In response, each of the WTRUs may optionally send a grace management parameter establishment confirm message to the AP. In addition, the WTRUs may set values of various grace management parameters according to a predetermined rule specified in the grace period management rule message transmitted by the AP. Optionally, the WTRUs may respond to the AP as a grace management rule execution acknowledgment message.

Description

WLAN COMMUNICATION METHOD AND WLAN FOR SIGNALING DEFERRAL MANAGEMENT MESSAGES < RTI ID = 0.0 > (WLAN) < / RTI >

 The present invention relates to a wireless local area network (WLAN). More particularly, the present invention relates to implementing deferral management strategies in a WLAN.

WLANs, such as, but not limited to, IEEE 802.11 wireless local area networks (WLANs), use a carrier-sense multiple access / collision avoidance (CSMA / CA) (I.e., mobile stations (STAs)). This scheme forces the WTRUs to detect whether the WM is idle or busy before sending the packet. This is done using the clear channel assessment (CCA) function. If the WTRU detects that the channel is busy (the WTRU is listening to another transmission in the following), the WTRU can not transmit the WTRU's packet and must wait until the channel is idle before attempting to win the channel competition . This is called a deferred stage. By preventing two WTRUs listening to each other from simultaneously transmitting, the CSMA / CA scheme controls the level of interference of the system.

The low interference level in the WLAN improves the system capacity indirectly because the throughput realized in each radio link increases as the interference decreases. On the other hand, two nodes listening to each other in the sense that a number of base station systems (BSSs) cause capacity limitations in systems using the same channel since insufficient spectrum channel resources can not be reused can be transmitted simultaneously The costs associated with preventing the < / RTI >

In CSMA / CA systems, a determination as to whether a first WTRU will defer to a second WTRU (where the second WTRU is located at a given path loss from the first WTRU) (1) the transmit power used by the first WTRU; And (2) the receive / deferral thresholds used by the second WTRU. Thus, by controlling one or both of these factors, it is possible to control the grace level in the WLAN and the capacity accordingly. In CCA functions of WTRUs operating in the CSMA / CA scheme, two basic receive / defer thresholds are: (1) an energy detect threshold (EDT) representing the minimum received signal power at which reception of a packet is attempted; And (2) a defer threshold (DT) representing the minimum received signal power at which packet transmission by the WTRU is to be suspended may be used.

Briefly, the transmit power for WTRUs of the same-channel BSSs, in terms of capacity, is set such that the WTRUs from one of the BSSs do not defer to the WTRUs from the other one of the BSSs and vice versa And / or to increase the DT / EDT for them. However, problems may arise if coordination of deferral parameters is performed separately in each WTRU, with no consideration of the effect of such an adjustment on other WTRUs. For example, if the WTRU excessively reduces its transmit power, it may become impossible for other WTRUs of the same BSS to detect signals exceeding EDT or DT from such WTRUs, Node condition will occur. The phenomena of hidden nodes across BSSs can also occur. In order for the optimization to work properly, coordination between the WTRUs is needed to allow all necessary information to be collected at the node making the determination of the setting of the delay parameters. The node may be the WTRU itself or an access point (AP) to which the WTRU is associated. In the latter case, coordination is also necessary to allow the AP to communicate the values of the optimal grace parameters to the associated WTRU (s).

The invention relates to a graceful management method implemented in a WLAN comprising an AP and a plurality of WTRUs. The AP sends request messages of deferral management capabilities to the WTRUs to determine the grace management capabilities of the WTRUs, such as maximum transmit power, minimum transmission and / or dynamic range, minimum and maximum DT / EDT, and different CCA modes . In response, each of the WTRUs sends an indicator message of deferral management capabilities to the AP. The AP also sends a deferral management parameter set message to the WTRUs to indicate values for setting the deferred management parameters, including message destination identification information, configuration time limit, and transmission power settings. Can be transmitted. In response, each of the WTRUs may optionally send a grace management parameter establishment confirm message to the AP. In another embodiment, the WTRUs may set values of various grace management parameters, according to a predetermined rule specified in the grace period management rule message sent by the AP. Optionally, the WTRUs may respond to the AP with a Deferred Management Rule Execution Confirmation message that contains the actual values of the deferred management parameters resulting from the execution of the rule.

The present invention relates to wireless systems using the CSMA / CA scheme, for example, but not limited to, the IEEE 802.11 family of standards. Deferral management strategies are implemented in a coordinated manner among all WTRUs. In medium and relatively large wireless systems, deferral management strategies can increase system capacity by more than 500% of the factors. Certain examples to which the invention applies are within the scope of the IEEE 802.11v standard.

The present invention allows WTRUs of the BSS to set their grace management parameters in a coordinated manner that will ultimately enable the grace management policies to make full use of the potential increase in capacity that grace management policies can provide .

Thus, according to the present invention, a method of deferral management in a wireless local area network (WLAN) comprising an access point (AP) and a plurality of wireless transmit / receive units (WTRUs) is implemented.

A more detailed understanding of the present invention can be obtained from the following description, which is presented by way of example and which should be understood in conjunction with the accompanying drawings.
1 is a signal flow diagram of a deferred management signaling procedure in which an AP defines deferred parameters to be used by a plurality of WTRUs, in accordance with the present invention.
2 is a signal flow diagram of a graceful management signaling procedure used during WTRU measurements, in accordance with the present invention.
3 is a signal flow diagram of a graceful management signaling procedure in which grace management rules used by one or more WTRUs are defined by an AP, in accordance with the present invention.
Description of the Related Art
100, 200, 300: WLAN
105, 205, 305: AP
110, 210, 310: WTRU
115: Request message of deferred management capabilities
120: Indicators of deferred management abilities
125: Deferred management parameter setting message
130: Deferred management parameter setting execution confirmation message

Although the specification and elements of the present invention are described in terms of certain combinations of preferred embodiments, each feature or element (without the remainder of the specification and elements of the preferred embodiments) alone or in combination with other features and elements of the present invention May be used in various combinations with or without.

The term "WTRU" includes, but is not limited to, a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, or any other type of device capable of operating in a wireless environment no. The term "AP" includes, but is not limited to, a base station, a Node-B, a site controller, or any other type of interfacing device in a wireless environment.

The present invention provides two preferred embodiments for implementing grace management. In the first embodiment, the AP directly communicates, with one or more of the WTRUs associated with it, the values for which these WTRUs should set their deferred management parameters. In the second embodiment, the AP forwards rules for calculating and setting its own deferred management parameters to one or more of the WTRUs associated with it.

There are two desirable signaling procedures that allow the WTRUs' grace management parameters to be controlled by the AP on an individual basis. The first signaling procedure allows the AP to indicate to one or more WTRUs the deferral parameters that one or more WTRUs should use. The second signaling procedure allows the AP to collect important measurements from one or more WTRUs for the determination of the grace parameters that one or more WTRUs should use.

1 is a flow diagram of a first signaling procedure implemented in a wireless communication system (e.g., a WLAN) that includes an AP 105 and a plurality of WTRUs 110 ₁ -110 _N. The AP 105 sends a request message 115 of deferral management capabilities to one WTRU or multiple WTRUs to report its deferral management capabilities. The request message 115 of deferral management capabilities may be transmitted as a broadcast, multicast or unicast signal. Deferral management capabilities include the following parameters:

1) maximum transmit power, minimum transmit power and / or dynamic range of the WTRU;

2) the minimum DT / EDT and maximum DT / EDT that the WTRU can use; And

3) Different Clear Channel Assessment (CCA) modes supported by the WTRU.

As a response to the request message 115 of deferral management capabilities sent by the AP 105, an indicator message 120 of deferral management capabilities may be sent by the WTRUs 110 or as a standalone message . Indicator messages 120 of deferral management capabilities may be attached to such an association request message that manages the grant of WTRU 110 in WLAN 100 or other message related to the association / admission control procedure.

A grace management parameter set message 125 indicating which values are to be set for the graceful management parameters of the WTRU 110 is sent from the AP 105 to one or more of the WTRUs 110. [ The deferral management parameter setting message 125 may be transmitted as a broadcast, multicast or unicast signal, and preferably includes the following information.

1) Identification information of the WTRU destination for the message is provided. Although the identification information may be a medium access cintrol (MAC) address, any other type of WTRU destination identifier may be used.

2) The time at which the configuration of the WTRU's grace management parameter according to the grace management parameter setting message should occur. Alternatively, the grace period management parameter setting message 125 may indicate a time limit during which the configuration should have occurred. The temporal information may be expressed as a time offset or as an absolute condition.

3) Deferred management parameters and values that the WTRU should use. Examples of these parameters are as follows.

a) Transmit power settings in normal operations.

b) Transmit power settings in special operations. Examples of special operations include, but are not limited to, scanning operations and measurement acquisition steps.

c) DT / EDT settings in regular operations.

d) DT / EDT settings in special operations. Examples of special operations include, but are not limited to, scanning operations and measurement acquisition steps.

e) CCA mode (s).

1, the WTRU (s) 110 sends a graceful management parameter setting execution confirmation message 130 to the AP 110 to confirm whether the configuration indicated in the predetermined grace period parameter setting message 125 has occurred. (105). ≪ / RTI > The optional grace period management parameter setting execution period message 130 may include any of the parameters specified in the above-mentioned grace period management parameter setting message or may set the grace period management parameter setting execution confirmation message 130 to the corresponding grace period management parameter setting May refer to the transaction identifier to be associated with the message 125. The reason for specifying the grace period management with the grace period management parameter setting execution confirmation message 130 is to allow the AP 105 to report the actual parameters set according to the grace period management parameter setting message 125. [ For example, if the AP 105 instructs the WRTU 110 to set its transmit power to 0 dBm and its EDT to -75 dBm, then the WRTU 110 will lower its EDT to -75 dBm It is possible and it is possible to lower its power, but it can not be lowered to less than 13 dBm. In that case, the WRTU 110 sends a graceful management parameter setting execution confirmation message indicating the actual settings of the configuration that can be realized by providing the same type of information that can be found in the grace management parameter setting message 125 Lt; RTI ID = 0.0 > 130 < / RTI >

2 is a flow diagram of a second signaling procedure implemented in a wireless communication system 200 including an AP 205 and a plurality of WTRUs 210 ₁ -210 _N. The second signaling procedure allows the AP 205 to collect important measurements from the WTRU (s) 210 for determining the grace parameters that the WTRU (s) 210 should use. Related measurements include, but are not limited to:

1) The signal strength (or average thereof) of packets that the WTRU receives from other specific WTRUs.

2) the number and total duration of packets received by the WTRU, resulting from other specific WTRUs.

This signaling procedure compensates for the possibility that optimal graceful management parameters in terms of provisioning capacity during regular operations may not be optimal when the WTRU 210 must perform measurements, such as during a scanning period. For example, in certain situations where it is desirable for a given WTRU 210 to increase its DT / EDT in regular operations, a high DT / EDT may be used by the WTRU 210 to accurately measure certain metrics such as channel occupancy ) May be weakened. To prevent such failures, the AP 205 indicates which grace management parameters the WTRU should use when collecting measurements, as part of the measurement request.

As shown in FIG. 2, the WTRUs 210 determine what type of measurement to perform and what grace management parameters (e.g., DT / EDT, CCA mode, etc.) should be used when collecting the requested measurements A measurement request message 215 is sent by the AP 205 to the WTRUs (210). A measurement report message 220 indicating the results of the measurement and indicating whether any deferred management parameters (e.g., DT / EDT, CCA mode, etc.) were actually used to collect the reported measurements are provided to the WTRUs 210 To the AP 205 via the network. Messages 215 and 220 may be used separately or together. The grace management parameters used during the measurement may be different from the parameters requested in the measurement request message 215 by the AP 205. Using measurements collected from its associated WTRUs 210, the AP 205 can perform calculations and determine optimal grace parameters to use for each WTRU 210. [ For example, a possible strategy is to set the EDT of a given WTRU 210 to the minimum signal strength (minus) of the packets it receives from other WTRUs 210 of the same BSS.

As discussed above, in order for the system to be able to take full advantage of the capacity gains that can be realized by deferral management, deferral management must be performed in a manner that is coordinated across all WTRUs. Previously, signaling mechanisms have been proposed that allow the AP to actively determine values and to set the grace management parameters of each of its associated WTRUs in a direct manner. This strategy ensures that the deferred management parameter settings for each WTRU are calculated at the central location (i.e., the AP), so that they are coherent. On the other hand, this centralized approach relies on the fact that the AP collects significant amounts of measurements and signaling from the WTRUs. To allow the AP to determine the DT / EDT value that the WTRU should use, for example, so that the WTRU is not deferred to a given co-channel extras-BSS WTRU, To determine the signal strength of the signals.

Another way to reduce the amount of signaling required in the system is to allow the AP to set guidelines or rules that the WTRUs should follow when determining the values and setting their deferral management parameters, To be responsible for determining and setting the values of the parameters. This approach provides consistency between the deferred management strategies used by each WTRU, while freeing the system from some signaling between the WTRU and the AP.

3 shows a signaling procedure implemented in a wireless communication system 300 that includes an AP 305 and a plurality of WTRUs 310 ₁ -310 _N. The AP 305 sends a grace period rule message 315 to the one or more WTRUs 310 that specifies a predetermined rule that the WTRU 310 should follow in order to determine the values to use for its grace management parameters. Optionally, after calculating the appropriate setting of the grace management parameters according to the rules sent by the AP 305, the WTRU 310 may include the actual value (s) of the grace management parameter (s) It may respond to the AP 305 with the grace period management rule execution confirmation message 320. [ This information may subsequently be used by the AP 305 in transmitting the deferral management rules messages 315 to other WTRUs 310. [

The information that is to be communicated to the WTRU 310 by the AP 305 depends to some degree on the rules that the AP 305 wishes to be implemented. The following are examples of input parameters that AP 305 should typically provide to enable WTRU 310 to implement rules, as well as general but novel rules that may be used.

The first rule specifies which WTRUs are to be deferred by WTRU (s) 310. This rule instructs the WTRU (s) 310 to set its DT / EDT to the highest possible value to allow it to listen to a given set of WTRUs. In one embodiment, the AP 305 may select that the set of WTRUs are all WTRUs of the BSS. It would imply that the WTRUs 310 set their DT / EDT parameters as high as possible, while still ensuring that they listen to all the WTRUs in their BSS.

In the preferred embodiment, the rules that the WTRU 310 should follow and the list of WTRUs to which the WTRU 310 should suspend may be included in a single message, but in other embodiments may be delivered in two different messages. The message can also measure the margin (M) that the WTRU 310 should use when determining the value of the parameter. For example, if the WTRU 310 determines that the maximum value for which it will listen to all its neighbors is a DT / EDT of -85 dBm, a margin of 3 dB indicates that the WTRU 310 has set its DT / 85dBm - margin = -88dBm.

This rule can be summarized by the following equation (1)

Where max DT / EDT _n is the largest DT / EDT required to listen to WTRU _n , n is the WTRU identifier, M represents the margin, and all of these values are provided by the AP 305.

Other preferred rules specify for the WTRU 310 the set of WTRUs it should listen to. This rule instructs the WTRU 310 that the WTRU 310 should set its transmit power to a possible low value that ensures that it is listened to by a given set of WTRUs.

In one embodiment, the AP 305 selects a set of WTRUs to include all the WTRUs of the BSS. It would imply that the WTRUs 310 set their transmit power to a possible low value that ensures that it is listened to by all WTRUs at their BSS.

In a preferred embodiment, the list of WTRUs that the WTRUs 310 should follow and the WTRUs 310 that the WTRU 310 should ensure it will be included in a single message, but in another embodiment, It is possible. The message may also specify a DT / EDT value used by each of the WTRUs that need to listen to the WTRU 310. [ The message may also include a margin that the WTRU 310 should use when determining the value of the transmission power parameter. For example, if the WTRU 310 determines that 8 dBm power will cause the WTRU 310 to be listened to by all of the WTRUs specified in the list provided from the AP 305, (310) will set the transmit power of the WTRU 310 to 8 dBm + margin = 11 dBm. The message may also specify a minimum transmission rate that the WTRU 310 should not exceed while reducing its transmission power.

This rule can be summarized by the following equation (2)

Here, the min Tx_Power _i = DT / EDT value + WTRU _i and the path loss between the WTRU of the WTRU _i, min Tx_Power _RATE is the minimum transmission power for realizing the desired transmission speed, it is min Tx_Power _n is listening by the WTRU _n N is the WRTU identifier.

Although the features and elements of the present invention are described in terms of preferred embodiments of particular combinations, each feature or element may be used alone or in various combinations with or without other features and elements of the invention.

Claims (10)

1. A deferral management method for use at an access point (AP)
Sending a deferred management capability request to the wireless transmit / receive unit (WTRU) indicating deferred parameters supported by the AP;
Receiving a deferred management capability response from the WTRU in response to the deferred management capability request indicating deferral management capabilities of the WTRU and deferred parameters supported by the WTRU; And
And in response to receiving the deferral management capability response, sending to the WTRU a deferral parameter message indicating at least one additional deferral parameter. The method according to claim 1,
Responsive to sending the grace parameter message, receiving a response message indicating an acceptance of the at least one additional grace parameter. The method according to claim 1,
Wherein the grace parameter message indicates at least one of a maximum transmit power, a minimum transmit power, or a dynamic range. The method according to claim 1,
Wherein the grace parameter message indicates at least one of a minimum DT (deferreseshold) / EDT (energy detect threshold) for the WTRU and a maximum DT / EDT for the WTRU. . The method according to claim 1,
Comparing grace management capabilities of a plurality of WTRUs associated with the AP; And
Further comprising determining an optimal energy detect threshold (EDT) for the plurality of WTRUs associated with the AP. The method according to claim 1,
Wherein the grace parameter message transmitted to the WTRU is transmitted as a unicast signal. A graceful management method for use in a wireless transmit / receive unit (WTRU)
Receiving a deferred management capability request indicating a deferred management capability supported by an access point (AP);
Sending a graceful management capability response to the AP indicating grace management capabilities of the WTRU and grace management parameters supported by the WTRU in response to the grace management capability request; And
And receiving from the AP a grace parameter message indicating at least one additional grace parameter. 8. The method of claim 7,
And in response to receiving the grace parameter message, sending a response message indicating acceptance of the at least one additional grace parameter. 8. The method of claim 7,
Wherein the deferral parameter message indicates at least one of a maximum transmit power, a minimum transmit power, or a dynamic range. 8. The method of claim 7,
Wherein the deferral parameter message indicates at least one of a minimum DT (deferreseshold) / EDT (energy detect threshold) for the WTRU and a maximum DT / EDT for the WTRU. .

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