KR101331720B1 - Wireless communication method and wlan for signaling deferral management messages - Google Patents

Abstract

The 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 the grace management capabilities to the WTRUs to determine the grace management capabilities of the WTRUs. In response, each of the WTRUs sends an indicator message of grace management capabilities to the AP. The AP may also send a grace management parameter configuration message to the WTRUs to indicate values for setting grace management parameters. In response, each of the WTRUs may optionally send a grace management parameter setting execution confirmation message to the AP. In addition, WTRUs may set values of various grace management parameters according to a predetermined rule specified in a grace management rule message sent by an AP. Optionally, the WTRUs may respond to the AP with a grace management rule execution confirm message.

Grace management methods, grace management messages, AP, WTRU, WLAN,

Description

WIRELESS COMMUNICATION METHOD AND WLAN FOR SIGNALING DEFERRAL MANAGEMENT MESSAGES

A more detailed understanding of the invention may be obtained from the following description, which is presented by way of example and is to be understood in connection with the accompanying drawings.

1 is a signal flow diagram of a grace management signaling procedure in which an AP defines grace parameters to be used by a plurality of WTRUs.

2 is a signal flow diagram of a grace management signaling procedure used during WTRU measurements, in accordance with the present invention.

3 is a signal flow diagram of a grace 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.

<Explanation of symbols for the main parts of the drawings>

100, 200, 300: WLAN

105, 205, 305: AP

110, 210, 310: WTRU

115: Request message of grace management capabilities

120: indicator of grace management abilities

125: grace management parameter setting message

130: confirmation message for execution of grace management parameter setting

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

WLANs, such as but not limited to, for example, IEEE 802.11 wireless local area network (WLAN), use carrier-sense multiple access / collision avoidance (CSMA / CA) schemes to enable multiple WTRUs (wireless transmit / receive units). That is, share a wireless medium (WM) between mobile stations (STAs). This approach 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 (in the following it is said that the WTRU is listening to another transmission), the WTRU cannot transmit the packet of the WTRU and must wait until the channel is idle before attempting to win the channel competition. . This is called the grace phase. By preventing two WTRUs listening to each other from transmitting at the same time, the CSMA / CA scheme controls the interference level of the system.

Low interference levels in the WLAN indirectly improves system capacity because the throughput realized on each radio link increases as interference decreases. On the other hand, two nodes listening to each other simultaneously transmit on the same channel in that insufficient spectral channel resources cannot be reused, resulting in capacity limitations in systems where multiple base station systems use the same channel. The costs associated with preventing them are realized.

In CSMA / CA systems, the determination of whether or not the first WTRU will be suspended to the second WTRU (where the second WTRU is placed at a predetermined path loss from the first WTRU) has two factors: (1) transmit power used by the first WTRU; And (2) reception / delay thresholds used by the second WTRU. Thus, by controlling one or both of these factors, it is possible to control the level of grace and thus capacity in the WLAN. In the CCA functions of WTRUs operating in the CSMA / CA scheme, there are two basic receive / delay thresholds: (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) that represents the minimum received signal power at which packet transmission by the WTRU will be suspended.

In summary, the transmit power for WTRUs of co-channel BSSs in terms of capacity so that WTRUs from one of the BSSs are not suspended to WTRUs from the other of the BSSs and vice versa. It is generally desirable to reduce and / or increase DT / EDT for them. However, problems may arise if the adjustment of the grace parameters is performed separately at each WTRU without taking into account the impact of this adjustment on other WTRUs. For example, if a 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, resulting in degraded capacity, The node situation will occur. Symptoms of hidden nodes across BSSs may also occur. In order for the optimization to work properly, coordination between WTRUs is required to allow all the necessary information to be collected at the node making the decision on the setting of the grace parameters. This node may be the WTRU itself or an access point (AP) with which the WTRU is associated. In the latter case, adjustment is also necessary to enable the AP to pass the values of the best grace parameters to the associated WTRU (s).

The present invention relates to a grace management method implemented in a WLAN including an AP and a plurality of WTRUs. The AP sends a request message of the graceful management capabilities to the WTRUs to determine graceful management capabilities of the WTRUs, such as maximum transmit power, minimum transmit and / or dynamic range, minimum and maximum DT / EDT, and different CCA modes. Send. In response, each of the WTRUs sends an indicator message of grace management capabilities to the AP. The AP may also send a deferral management parameter set message to the WTRUs to indicate values for setting grace management parameters including message destination identification information, configuration time limit, and transmit power settings. I can send it. In response, each of the WTRUs may optionally send a grace management parameter setting execution confirmation message to the AP. In another embodiment, the WTRUs may set values of various grace management parameters according to a predetermined rule specified in a grace management rule message sent by the AP. Optionally, the WTRUs may respond to the AP with a grace management rule enforcement confirmation message that includes actual values of grace management parameters resulting from the execution of the rule.

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

The present invention enables the WTRUs of the BSS to set their grace management parameters in a coordinated manner that will ultimately enable the grace management policies to make the most of the potential increase in capacity that the grace management policies can provide. Provide mechanisms to do this.

Although the specifications and elements of the invention are described in the preferred embodiments of specific combinations, each specification or element may be used alone (without the remaining specifications and elements of the preferred embodiments) or as other specifications and elements of the invention. It may be used in various combinations with or without them.

With reference to the following, 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 device type that may operate in a wireless environment. no. Referring to the following, the term "AP" includes, but is not limited to, a base station, Node-B, 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 delivers directly to one or more of the WTRUs associated with it, values that these WTRUs must set their grace management parameters to. In a second embodiment, the AP carries rules for calculating and setting its own grace management parameters to one or more of the WTRUs associated with it.

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

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

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

2) minimum DT / EDT and maximum DT / EDT available to the WTRU; And

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

In response to the request message 115 of grace management capabilities transmitted by the AP 105, the indicator message 120 of grace management capabilities may be sent by the WTRU (s) 110 or as a standalone message. . The indicator message 120 of grace management capabilities may be attached to such an association request message or other message related to an association / authorization control procedure that manages the granting of the WTRU 110 in the WLAN 100.

A grace management parameter setting message 125 is sent from the AP 105 to one or more of the WTRUs 110 indicating which values will be set for the grace management parameters of the WTRU 110. The grace 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 is preferably 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 parameters according to the grace management parameter setting message should occur. Alternatively, the grace management parameter setting message 125 may indicate a time limit at which the configuration should have occurred. The time information may be expressed in time offset or in absolute condition.

3) Grace management parameters and values that the WTRU should use. Examples of such parameters include the following.

a) transmit power settings in regular operations.

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

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 collection.

e) CCA mode (s).

As shown in FIG. 1, in order to confirm whether the configuration indicated in the predetermined grace management parameter setting message 125 has occurred, a grace management parameter setting execution confirmation message 130 is sent by the WTRU (s) 110 to the AP. Selectively sent to 105. The optional grace management parameter setting execution message 130 may include any of the parameters specified in the above-described grace management parameter setting message or sets the grace management parameter setting execution confirmation message 130 to the corresponding grace management parameter setting. Reference may also be made to the transaction identifier associated with message 125. The reason for specifying grace management with the grace management parameter setting execution confirmation message 130 is to enable the AP 105 to report actual parameters set according to the grace 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, the WRTU 110 lowers its EDT to -75 dBm. It is possible and possible to lower its power, but it will not be possible to lower it below 13 dBm. In that case, the WRTU 110 sends a grace management parameter setting execution confirmation message indicating 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. 130 may be transmitted.

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

1) 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 counters the possibility that the best grace management parameters in terms of capacity provisioning 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 can accurately measure certain metrics such as channel occupancy. May weaken the ability of). To prevent this defect, the AP 205 indicates, as part of the measurement request, which grace management parameter the WTRU should use when collecting measurements.

As shown in FIG. 2, what type of measurements the WTRUs 210 should perform and what grace management parameters (eg, DT / EDT, CCA mode, etc.) should be used when collecting the requested measurements. An indication measurement request message 215 is sent by the AP 205 to the WTRU (s) 210. A WTRU (s) 210 is a measurement report message 220 indicating the results of the measurements and indicating which grace management parameters (eg, DT / EDT, CCA mode, etc.) were actually used to collect the reported measurements. ) To the AP 205. The messages 215 and 220 can be used individually 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 the measurements collected from its associated WTRUs 210, the AP 205 may perform the calculations and determine the optimal grace parameters to use for each WTRU 210. For example, one possible strategy is to set the EDT of a given WTRU 210 to the minimum signal strength (-margin) of packets that the WTRU 210 receives from other WTRUs 210 of the same BSS.

As described above, in order for the system to make full use of the capacity gains that can be realized by grace management, grace management must be performed in a coordinated manner across all WTRUs. Previously, signaling mechanisms have been proposed that allow an AP to actively determine values and to set grace management parameters of each of its associated WTRUs in a direct manner. This strategy ensures that they are coherent because the grace management parameter settings for each WTRU are calculated at a central location (ie AP). On the other hand, this centralized approach relies on the fact that the AP collects a significant amount of measurements and signaling from the WTRUs. For example, in order for the AP to be able to determine the DT / EDT value that the WTRU should use, such that the WTRU does not defer to any co-channel extra-BSS WTRU, the AP may request that the WTRU receive packets from the extra-BSS WTRU. Should be able to determine their signal strength.

Another way to reduce the amount of signaling required in the system is not to allow the AP to set guidelines or rules that the WTRUs should follow when determining values and setting their grace management parameters, but each WTRU is responsible for their grace management parameters. Is responsible for determining and setting their values. This approach provides consistency between the grace management strategies used by each WTRU, while releasing the system from some signaling between the WTRU and the AP.

3 shows a signaling procedure which is implemented in a wireless communication system 300 that includes the AP (305) and a plurality of WTRU (310 ₁ -310 _N). The AP 305 sends a grace management rule message 315 to one or more WTRUs 310 specifying a certain rule that the WTRU 310 should follow for the determination of the values to use for its grace management parameters. Optionally, after calculating the appropriate setting of the grace management parameters in accordance with the rule sent by the AP 305, the WTRU 310 includes the actual value (s) of the grace management parameter (s) resulting from the execution of the rule. The AP 305 may be responded to with a grace management rule execution confirmation message 320. This information may be subsequently used by the AP 305 when sending grace management rule messages 315 to other WTRUs 310.

The information that should be conveyed by the AP 305 to the WTRU 310 depends to some extent on the rules that the AP 305 wants to be enforced. The following are examples of input parameters that the AP 305 would normally have to provide in order for the WTRU 310 to implement the rule, as well as general but novel rules that may be used.

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

In a preferred embodiment, the rules that the WTRU 310 should follow and the list of WTRUs that 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 may 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 at which it will listen to all its neighbors is a DT / EDT of -85 dBm, then the margin of 3 dB will cause the WTRU 310 to determine its DT / EDT parameter. This would imply that 85dBm-margin = -88dBm should be set.

This rule can be summarized as Equation 1 below.

여기에서, max DT/EDT_n은 WTRU_n을 청취하는데 필요한 최대의 DT/EDT이고, n은 WTRU 식별자이며, M은 마진을 표현하고, 이러한 값들 모두는 AP(305)에 의해 제공된다.

Where max DT / EDT _n is the maximum DT / EDT needed 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.

Another preferred rule specifies for the WTRU 310 the set of WTRUs it should listen to. This rule tells the WTRU 310 that the WTRU 310 should set its transmit power to the lowest possible value that ensures that it will be listened to by a given set of WTRUs.

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

In a preferred embodiment, the rules that the WTRUs 310 must follow and the list of WTRUs that the WTRU 310 must ensure that it is listened to will be included in a single message, but in another embodiment it will be delivered in two separate messages. It may be. The message may also specify the 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 transmit power parameter. For example, if the WTRU 310 determines that 8 dBm power will cause the WTRU 310 to be listened to by all WTRUs specified in the list provided from the AP 305, the margin of 3 dB is determined by the WTRU. It will imply that 310 sets the transmit power of WTRU 310 to 8 dBm + margin = 11 dBm. The message may also specify the minimum transmission rate that the WTRU 310 should not exceed while reducing its transmit 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.

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

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

Claims (67)

delete delete delete delete delete delete delete delete delete delete In an access point (AP) for deferral management, A transmitter configured to transmit a first message requesting a report of grace management capability of a wireless transmit / receive unit (WTRU), the first message indicating one or more values of grace parameters supported by the AP. To, the transmitter; And A receiver configured to receive a second message, the second message including a graceful management capability indicator and indicating one or more values of graceful parameters supported by the WTRU; The transmitter is further configured to transmit a third message in response to the second message, wherein the third message indicates one or more additional values of grace parameters. The method of claim 11, wherein the receiver, And receive a response message indicative of the acceptance of the one or more additional values of grace parameters in response to sending the third message. The method of claim 11, wherein the third message, And at least one of a maximum transmit power, a minimum transmit power, or a dynamic range. The method of claim 11, wherein the third message, Indicating at least one of a minimum defer theres / energy detect threshold (DTT) for the WTRU, and a maximum DT / EDT for the WTRU. 12. The method of claim 11, And a processor configured to compare grace management capabilities of a plurality of WTRUs associated with the AP and to determine an optimal energy detect threshold (EDT) for the plurality of WTRUs. 12. The access point of claim 11, wherein the transmitter is further configured to transmit the third message as a unicast signal. In the wireless transmit / receive unit (WTRU) for grace management, A receiver configured to receive a first message requesting reporting of the WTRU's grace management capability, the first message indicating one or more values of grace parameters supported by an access point (AP); The receiver; And A transmitter configured to transmit a second message, wherein the second message indicates one or more values of grace parameters and a grace management capability indicator supported by the WTRU; And the receiver is further configured to receive a third message in response to the second message, wherein the third message indicates one or more values of the graceful parameters. The method of claim 17, wherein the transmitter, And transmit a response message indicating acceptance of the one or more additional values of grace parameters in response to receiving the third message. The method of claim 17, wherein the third message, And at least one of a maximum transmit power, a minimum transmit power, or a dynamic range. The method of claim 17, wherein the third message, And at least one of a minimum defer theres / energy detect threshold (DTT) for the WTRU, and a maximum DT / EDT for the WTRU. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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