METHOD FOR TRANSMIT AND RECEIVE POWER CONTROL IN MESH SYSTEMS

Abstract

A method and apparatus are disclosed herein for controlling transmit power in a station (STA) of a wireless local area network (WLAN). A STA may transmit, to another STA, transmit power step size information that indicates a maximum transmission power for an operational bandwidth that the STA supports. The STA may receive, from another STA, a signal in one of the plurality of operational bandwidths that the STA supports. The received signal may include a transmission power based on the transmitted adjustment step size setting.

Claims

1. A method for controlling transmit power in a station (STA) of a wireless local area network (WLAN), the method comprising: transmitting, from the STA, transmit power step size information that indicates an adjustment step size setting for at least one of a plurality of operational bandwidths that the STA supports; and receiving a signal, in one of the plurality of operational bandwidths that the STA supports, having a transmission power based on the transmitted adjustment step size setting.

2. The method of claim 1, wherein the transmit power step size information is transmitted in one of a broadcast message, a multicast message, or a unicast message.

3. The method of claim 1, wherein the transmit power step size information is transmitted in a control frame.

4. The method of claim 1, wherein the transmit power step size information includes at least one of minimum transmit power information, maximum transmit power information, or a transmit power adjustment step size setting.

5. A station (STA) comprising: a transmitter configured to transmit, to another STA, transmit power step size information that indicates an adjustment step size setting for at least one of a plurality of operational bandwidths that the STA supports; and a receiver configured to receive a signal, in one of the plurality of operational bandwidths that the STA supports, having a transmission power based on the transmitted adjustment step size setting.

6. The STA of claim 5, wherein the transmitter is further configured to transmit the transmit power step size information in one of a broadcast message, a multicast message, or a unicast message.

7. The STA of claim 5, wherein the transmitter is further configured to transmit the transmit power step size information in a control frame.

8. The STA of claim 5, wherein the transmit power step size information includes at least one of minimum transmit power information, maximum transmit power information, or a transmit power adjustment step size setting.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 shows block diagram of a conventional wireless LAN.

[0029] FIG. 2A shows a block diagram of a simple Mesh infrastructure and FIG. 2B is a legend of elements illustrated in FIG. 2A.

[0030] FIG. 3A shows a signaling diagram of a power capability information exchange between a Mesh point and a power master Mesh point and FIG. 3B shows another signaling diagram of a power capability information exchange between a Mesh point and a power master Mesh point.

[0031] FIG. 3C shows a signaling diagram of a distributed power capability information exchange between Mesh points and FIG. 3D shows another signaling diagram of a distributed power capability information exchange between Mesh points.

[0032] FIG. 4A shows a signaling diagram of Mesh allowed power settings information retrieval from a power master Mesh point and FIG. 4B shows another signaling diagram of Mesh allowed power settings information retrieval from a power master Mesh point.

[0033] FIG. 4C shows a signaling diagram of Mesh allowed power settings information retrieval from other Mesh points and FIG. 4D shows another signaling diagram of Mesh allowed power settings information retrieval from other Mesh points.

[0034] FIG. 5 shows a signal diagram for transmit power control according to the present invention.

[0035] FIG. 6 shows a signal diagram for adjustment of MP transmit power settings in response to received allowed power setting information.

[0036] FIG. 7 shows a signal diagram of a power master selection procedure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Although the features and elements of the present invention are described in the preferred embodiments in particular combinations, each feature or element can be used alone (without the other features and elements of the preferred embodiments) or in various combinations with or without other features and elements of the present invention.

[0038] Hereafter, a mesh point includes but is not limited to a wireless transmit/receive unit (WTRU), user equipment, mobile station, fixed or mobile subscriber unit, pager, or any other type of device capable of operating in a wireless environment. When referred to hereafter, an access point includes but is not limited to a base station, Node-B, site controller, access point or any other type of interfacing device in a wireless environment.

[0039] The term “Mesh neighbor” herein refers to the immediate neighbors of a particular Mesh point, (i.e., the ones in radio range). It also refers to other Mesh nodes that the MP can reach when its signaling messages are forwarded through the Mesh over multiple hops by other MPs. It can also include network entities beyond the immediate reach of the wireless Mesh, such as nodes residing in the wired backhaul network connected with the Mesh.

[0040] The present invention provides signaling procedures and mechanisms that will provide the means by which Mesh systems can adjust Tx and Rx power levels for regulatory and radio management purposes at system start-up, when an MP joins the Mesh network and during the lifetime of the Mesh network. The invention addresses a distributed scenario (i.e., the MPs are engaged in “peer-to-peer” signaling), as well as a master-slave scenario, in which the relationship between MPs is one of master and slave. In the latter scenario, a Power Master (PM) is a master MP that is responsible for dictating the power settings in the Mesh, both the overall regulatory settings and the individual power settings per Mesh Point and per link.

[0041] The present invention includes methods and apparatus with means for: [0042] a) Signaling by which MPs exchange power-setting relevant capability information such as maximum and minimum power settings; [0043] b) Signaling by which MPs learn about allowed power settings in the Mesh; [0044] c) An MP reacting to different or conflicting allowed power setting information messages and configuration parameters; [0045] d) Power adjustments in the Mesh to meet regulatory requirements and to dynamically adjust power settings; and [0046] e) Electing a given Mesh node as PM.

[0047] FIGS. 3A and 3B show signaling diagrams of a power capability information exchange between an MP 101 and a PM in a master-slave arrangement. The power capability information preferably includes, but is not limited to any of the items as shown in Table 1, including any combination thereof.

TABLE-US-00001 TABLE 1 Power Capability Information Type Description Tx power step Minimum and maximum Tx power and adjustment sizes step size settings that the MP supports Rx power step Minimum and maximum Rx power and adjustment sizes step size settings, sensitivity levels and CCA thresholds settings that the MP supports Mode The operational modes (e.g., 802.11a, b, g, n, j, etc.) the MP is able to support Bandwidth The operational bandwidth that the MP is able to support (e.g., 802.11n supports bandwidths of 10/20/40 MHz and 802.11j supports 10 or 20 MHz bandwidths) Freq. Bands The number of bands and sub-bands on which the MP is capable of simultaneous operation (e.g., 2.4 GHz, 5 GHz, 5 GHz Lower U-NII, 5 GHZ Middle U- NII)

[0048] In FIG. 3A, an MP 101 reports its power capability information 301 to the PM in an un-solicited manner, such as part of a broadcast/multicast-type frame for example. In FIG. 3B, MP1 reports its power capability information 303 in a solicited manner as a response-type frame in response to a power capability request 302 (e.g., the exchanged signals 302, 303 may be in the form of a directed unicast request/response-type frame exchange between the MP 101 and the PM. Although FIGS. 3A and 3B show power capability information signaling between the MP 101 and the PM, such signaling may also be exchanged between MP 101 and other neighboring MPs. FIGS. 3C and 3D show such a distributed scenario of power capability information exchanged between the MP 101 and an MP 102 similar to that shown in FIGS. 3A and 3B.

[0049] According to the present invention, solicited (request/report-type) reporting and un-solicited reporting of power capability information 301, 303 by MPs can be sent as a piggy-backed IE on top of a Mesh unicast, multicast or broadcast management or control frame. Alternatively, the reporting of power capabilities can be sent as a separate Mesh unicast, multicast or broadcast management or control frame.

[0050] As an example of a Mesh management frame embodiment, the MP power capability information 301, 303 may be included as an additional IE in a Mesh ASSOCIATION frame or a Mesh AUTHENTICATION frame (e.g., frame exchanges with other MPs for the purpose of becoming part of the Mesh network). Alternatively, the power capability signaling information 301, 303 is included as an additional IE within a Mesh BEACON frame or a Mesh PROBE RESPONSE frame, which may also be used in exchanges for the purpose of discovering the presence of a Mesh network or synchronizing general Mesh parameters such as timer values. Another alternative is to include the power capability information 301, 303 as an IE in an Association or Re-Association Response frame. Another alternative is to include the power capability information 301, 303 as part of a directed special purpose per-link or multi-hop Mesh POWER CAPABILITY frame.

[0051] FIGS. 4A and 4B show a signaling diagram by which an MP learns of allowed power settings for the Mesh, which is useful for dealing with the regulatory need for MPs not to exceed certain maximum admissible power settings during communication. The allowed power setting information preferably includes (but is not limited to) any of the items as shown in Table 2, including any combination thereof.

TABLE-US-00002 TABLE 2 Allowed Power Setting Information Type Description PM Info PM address or PM identifier Mode Regulatory domain within which the Mesh network currently operates (e.g., 802.11b, g, n, j, etc.) Freq. Bands frequency bands and sub-bands within which the Mesh network currently operates Tx Power minimum, instantaneous, and maximum allowed Tx power settings Rx Power minimum, instantaneous, and maximum allowed Rx power settings CCA minimum, instantaneous, and maximum allowed CCA threshold settings Timing validity timers or time-out values Measurement measurement intervals and configuration Timing validity timers or time-out values Silence silence periods Offset temporary offset values for any of the above plus associated life-time values

[0052] A master-slave scenario is depicted in FIGS. 4A and 4B, in which a slave MP 101 obtains this information from the master PM. In FIG. 4A, MP 101 obtains its allowed power setting information 401 from the PM in an un-solicited manner, such as part of a broadcast/multicast-type frame for example. In FIG. 4B, MP1 obtains its allowed power setting information 403 in a solicited manner as a response-type frame in response to a power capability request 402 (e.g., the exchanged signals 402, 403 may be in the form of a directed unicast request/response-type frame exchange between the MP 101 and the PM. Although FIGS. 4A and 4B show allowed power setting information signaling between MP101 and the PM, such signaling may also be exchanged similarly in a distributed scenario between the MP 101 and other neighboring MPs. FIGS. 4C and 4D show such a distributed scenario of power capability information exchanged between the MP 101 and an MP 102 similar to that shown in FIGS. 4A and 4B.

[0053] According to the present invention, solicited (request/report-type) and un-solicited receiving of allowed power setting information 401, 403 can be sent as a piggy-backed IE on top of a Mesh unicast, multicast or broadcast management or control frame. Alternatively, the allowed power setting information 401, 403 can be sent as a separate Mesh unicast, multicast or broadcast management or control frame.

[0054] As an example of a Mesh management frame embodiment, the signaling of allowed power setting information 401, 403 in the Mesh may be included as part of a Mesh BEACON frame or a Mesh PROBE RESPONSE frames (e.g. signaling frames and exchanges for the purpose of discovering the presence of a Mesh network or synchronizing general Mesh parameters such as timer values). Alternatively, the MP power allowed power setting information 401, 403 is part of Mesh ASSOCIATION or Mesh AUTHENTICATION frames (e.g. frame exchanges with other MPs for the purpose of becoming part of the Mesh network). In another alternative, the allowed power setting information is part of a directed special purpose per-link or multi-hop Mesh ALLOWED POWER SETTING frame.

[0055] Allowed power setting information 401, 403 can be signaled for any of the following, either alone or in combination: the entire Mesh (e.g. valid for all nodes in the Mesh); a particular Mesh link or path (e.g. valid for a set of Mesh nodes); a particular Mesh node (e.g. valid for all radio channels of a MP); a particular radio interface of a Mesh node (e.g. settable per-link and per-neighbor of a MP).

[0056] Allowed power setting information 401, 403 can be signaled as absolute values, relative values relating to some pre-determined absolute value, or a combination of absolute and relative values (e.g. max admissible Tx power=regulatory max−temporary offset).

[0057] Turning to FIG. 5, a distributed scenario is now described in reference to an MP 501, in which there is no PM and it is possible that the MP 501 receives different allowed power setting information from two or more MPs, shown as an MP 502 and an MP 503. With no PM in the distributed scenario, the MP 501 needs to determine which allowed power setting information it will use when setting its own Tx power settings and when signaling its allowed power setting information to the other MPs, MP 502 and MP 503. The signaling procedure shown in FIG. 5 resolves a situation in which the MP 501 determines which allowed power setting information to use while resolving a conflict with mismatched allowed power setting information received from other MPs.

[0058] The MP 501 configures its own allowed power setting information APSI_own, while receiving APSI_i which represents the allowed power setting information signaled from MP_i with index i=2 and 3 for the example shown in FIG. 5. The APSI_i values can be further represented by a vector APSI_vector, which represents the ensemble of the APSI_i values MP 501 receives from the other MPs.

[0059] An example of an allowed power setting information IE includes a Maximum Allowed Tx Power Setting (MATPS). For the sake of simplicity, the following method illustration includes only the MATPS IE. From a set of inputs MATPS_own 504 and MATPS_vector values 505, 506, the MP 501 needs to determine which MATPS will be used when setting its own Tx Power settings and when signaling allowed power setting information to other MPs. This can be achieved by implementing a decision-making function F in MP 501.

[0060] For example, assume MP 501 receives MATPS_vector which comprises two vector value settings 505, 506: MATPS_1=20 dBM from MP 502 and MATPS_2 =10 dBm from MP 503. Also assume that MP 501's own MATPS setting is configured to be MATPS_own=15 dBm. In the preferred implementation, the function F will determine the minimum MATPS value from all its inputs (i.e., min(10,20,15)=10 dBM) and the MP 501 will use an operational MATPS value when setting its Tx Power and it will signal it as part of the allowed power setting information that the MP 501 signals to other MPs, including MP1 and MP2. Accordingly, the operational MATPS 507 in terms of function F can be expressed as follows:

MATPS_operational=F(MATPS_own, MATPS_vector)=min(MATPS_own, MATPS_vector).   Equation (1)

Similarly, other operational power settings can be selected using a suitable function F.

[0061] In an alternative embodiment, the MP 501 uses the value MATPS_operational determined by Equation(1) while determining its Tx Power, but MP 501 signals the MATPS_own value as its allowed power setting information to the other MPs, MP502 and MP503.

[0062] FIG. 6 shows a signaling method for an MP 601 entering a Mesh 600 in which the Tx Power is adjusted to meet regulatory requirements. While the Tx Power setting adjustment is described in reference to MP601, the same Tx Power setting adjustment procedure applies to each MP in the Mesh 600. The Tx power can be similarly controlled for a subset of MPs. The Mesh 600 comprises MP602-MPN at the time that the MP601 seeks entry. One or more of the MPs MP602-MPN may be a PM. At initial joining 610, at switch-on, MP601 sends its Tx Power capability information 611 to MP602-MPN as described above for FIGS. 3A-3D. As aforementioned, a preferred way to send the Tx power capability information is as part of ASSOCIATION or AUTHENTICATION (or Re-ASSOCIATION or Re-AUTHENTICATION) frames. The Tx Power Capability information 611 may be performed periodically or in a solicited or in an un-solicited manner. At step 612, the MP601 becomes part of the Mesh. The MP601 receives allowed power settings information 613 which is sent periodically in the Mesh or in an un-solicited manner or in a solicited manner by the Mesh neighbors MP602-MPN, during the process of discovery or joining the Mesh network. The allowed power setting information is exchanged as described above for FIGS. 4A-4D. As aforementioned, a preferred way of such signaling is to use Mesh BEACON or Mesh PROBE RESPONSE frames. At step 614, the MP601 reads the received allowed power settings information 613 and adjusts its Tx power settings. The MP601 may or may not acknowledge its Tx power setting adjustment to the other MPs MP602-MPN.

[0063] The MP601 sends its own allowed power setting information 615 to MP602-MPN. Likewise, the MP601 receives Tx Power setting changes from MP602-MPN, triggered by changes in their Tx Power settings. Several optional and complementary signaling extensions are possible (not shown in FIG. 6) to support adjustment of power settings in the Mesh. For example, the MP601 can request reporting of measurements from its MP neighbors MP602-MPN regarding power settings, perceived SNR and link margin values, perceived interference power and channel busy times.

[0064] According to the present invention, a selection procedure is performed by the Mesh MPs for negotiating and selecting a Mesh PM. The preferred PM selection and re-selection procedure includes one or more of the following: [0065] a) The first MP to belong in the Mesh automatically becomes PM. [0066] b) An MP at switch-on determines if one of its neighbors is a PM. The PM can be identified by means of L2 or L3 broadcast, multicast or dedicated signaling received by the MP as part of the set-up procedures, (e.g. authentication, Mesh BEACON reception, capability exchanges and so on). [0067] c) The PM can be pre-set, (i.e. fixed for the lifetime of the Mesh) or time-limited, (i.e., after a certain pre-determined amount of time or tied to the occurrence of certain conditions, the PM selection procedure is re-initiated) [0068] d) In one advantageous realization, the PM coincides with the Mesh Portal and Mesh Portal identifiers therefore automatically point to the PM. [0069] e) The MPs with the most links to neighbors becomes the PM. [0070] f) The MPs determine the PM by means of a random number draw. [0071] g) The MPs determine the PM as a function of the number of hops from the Mesh Portal or from a certain agreed-upon MP. [0072] h) Any combination of the above.

[0073] FIG. 7 shows a signaling diagram for identifying the Mesh PM according to the preferred methods described above. A PM Request Information Element (IE) is included as part of a broadcast/multicast/unicast signaling frame in signal 711 sent through the Mesh by MP 701 indicating to neighbor MPs MP702-MPN that a PM selection is required. This IE contains the address of the originating MP and other parameters, such as time-out values, selection criteria, default identifier for the proposed PM, reply-to address, and so on. A PM Response IE part of a broadcast/multicast/unicast signaling frame in signals 712 is sent through the Mesh containing the selection criteria response from the neighbor MPs MP702-MPN. A comparison procedure 713 is initiated in the MP701 where the selection criteria responses 712.sub.1 . . . 712.sub.N from the different neighbor MPs are evaluated. The PM selection decision is made based on which MP meets the requirements in terms of the chosen selection criteria, (e.g., highest random number draw or similar). The MP 701 broadcasts its final selection for PM to the Mesh in signal 713.

[0074] Alternatively, the MP 701 acts as the Mesh Portal and sets all of the Tx Power control settings for the Mesh and subsequently joining MPs are mandated to propagate these Tx Power control settings to other Mesh MPs.

[0075] The signaling messages and information exchanged between MPs or between MPs and the PM for the above described methods are preferably implemented as Layer L2 (e.g. MAC layer) signaling frames or IEs. As such, the physical implementation is a processor entity within each MP, such as MP101 MP102 and the PM shown in FIGS. 3A-3D, 4A-4D; MP 501, MP502, MP503 as shown in FIG. 5; MP601, MP602-MPN as shown in FIG. 6; and MP701, MP702-MPN as shown in FIG. 7. The processor entity may include for example, Layer L2 hardware or software in medium access control (MAC) or station management entity (SME). The layer L2 software, for example may be part of operation and maintenance (O&M) routines in MPs; or a combination thereof. Alternatively, the signaling is implemented as Layer L3 or above signaling packets or IEs, (e.g. encapsulated into IP packets, or into TCP/IP packets and so on). As such, the physical implementation would include Layer L3 hardware or software, such as IP or simple network management protocol (SNMP) entities. Another alternative includes a combination of Layer L2 and L3 signaling thereof.

[0076] All signaling messages and information exchanged as aforementioned can be either direct-link (e.g., MP-MP signaling frames) or multi-hop frame signaling (e.g., MP sending a message to another MP via intermediate forwarding MPs). Furthermore, signaling can take place between MPs and other nodes in the wired backhaul.

[0077] All methods described above can be subject to or are complemented by configuration settings in the individual MPs and can provide statistics and feedback to Mesh-internal or external network monitoring and control entities (e.g., using remote IT administrator network monitoring software) that can exercise control on MPs operational characteristics. These configuration settings and reportable statistics can be set in or reported from individual (or groups) of MPs by any of the following formats or a combination thereof: [0078] a) databases in the physical layer (PHY), medium access control (MAC) or system management entity (SME), advantageously realized (but not limited to) in the form of management information bases (MIBs); [0079] b) signaling messages between L2 MAC or SME to above protocol entities, advantageously realized in the form of APIs; or [0080] c) primitives exchanged between SME, MAC, PHY and other protocol entities in a MP implementation.

[0081] The above described configuration settings that can be used by external management entities on the MP (or groups of MPs) can contain any of the following: [0082] a) Admissible Tx, Rx and CCA value setting and ranges; [0083] b) Admissible mode settings (e.g. 11a,b,g,j,n and so on); [0084] c) Admissible band and sub-band settings (e.g. 2.4, 4.9, 5 GHz, U-NII lower, middle and upper band and so on); [0085] d) Mesh TPC feature on or off; [0086] e) Addresses and identifiers for PM; [0087] f) Timer values (e.g. channel dwell and measurement intervals) for TPC; [0088] g) Transmit Power change command for the MP; or [0089] h) Any combination thereof.

[0090] Reportable statistics in the MP that can be used by external management entities may include, but is not limited to any of the following, or a combination thereof: [0091] a) Current Tx power control settings, modes, bandwidth, number of simultaneous channels (or combination thereof) of MP and neighbor MPs (as far as known); or [0092] b) Channel statistics such as the value and type of measurements performed and so on.