HK1133755B - Message exchange scheme for asynchronous wireless communication - Google Patents

Description

Message exchange scheme for asynchronous wireless communications

Claiming priority in accordance with 35 U.S.C. § 119

This application claims benefit and priority to commonly owned U.S. provisional application serial No.60/836,179, filed on 7/8/2006 and assigned attorney docket No.061675P1, the disclosure of which is incorporated herein by reference.

Technical Field

The present application relates generally to wireless communications and more particularly, but not exclusively, to medium access control for asynchronous wireless systems.

Background

Wireless communications may be established using various network topologies. For example, a wide area network, a local area network, or some other type of network may be deployed depending on the particular wireless communication capabilities required for a given application.

Wireless wide area networks are typically planned deployments within licensed frequency bands. Such networks may be used to optimize spectral efficiency and quality of service to support a large number of users. A cellular network is an example of a wireless wide area network.

Wireless local area networks are often not uniformly planned for deployment. For example, such networks may be deployed in an unlicensed spectrum in a temporary manner. Thus, a single user or a small number of users may be supported using this type of network. Wi-Fi networks (i.e., IEEE 802.11-based networks) are an example of a wireless local area network.

In practice, each of the above networks has various drawbacks due to the need to compromise the provision of a given type of service. For example, establishing a wireless wide area network may be relatively expensive and time consuming due to the complexity of the unified planning. Thus, such a scheme may not be suitable for "hot spot" deployments. On the other hand, a temporary network, such as Wi-Fi, may not achieve the same level of spatial efficiency (bits/unit area) as the planned network. Furthermore, to compensate for potential interference between network nodes, Wi-Fi networks may employ interference mitigation techniques, such as carrier sense multiple access. However, such interference mitigation techniques may result in poor utilization and provide limited fairness control, and may be sensitive to hidden and exposed nodes.

Disclosure of Invention

An outline of an example scheme of the present disclosure is as follows. It should be appreciated that any reference herein to an aspect may refer to one or more aspects of the present disclosure.

In certain aspects, the present disclosure relates to wireless medium access control supporting asynchronous communications. Here, nodes of different groups (e.g., a transmitting node and a receiving node associated with each other to communicate with each other) may communicate with other group nodes in an asynchronous manner. Thus, for a given set of nodes, the transmission time and duration may be defined independently of the transmission time and duration of the different sets of nodes.

In certain aspects, the disclosure also relates to wireless medium access control to support overlapping wireless transmissions. Here, a group of nodes may schedule a transmission based on consideration of current or future transmissions by one or more neighboring nodes. This consideration may include, for example, defining appropriate transmission parameters, such as transmission rate, code rate, and transmission time, to ensure that transmissions do not unduly interfere with other nodes and can be reliably received at the relevant receiving node.

In certain aspects, a node analyzes a control message sent by another node to determine whether to request or schedule a transmission. For example, the first node may transmit a control message (e.g., grant or acknowledgement) indicating the time at which the transmission is scheduled and the relative transmit power of the first node. Thus, a second node receiving the control message may determine whether and to what extent the second node's transmission is affected, or whether the second node's reception is affected by the first node's scheduled transmission, based on the power level of the received message and the rate and duration of the scheduled transmission. For example, a sending node may determine whether to initiate a request for transmission to a receiving node based on whether the desired transmission will interfere with reception by its neighboring nodes. Likewise, the receiving node may determine whether to issue a grant message to schedule the requested transmission based on whether the transmission may be reliably received based on any transmissions scheduled by one or more nodes in the vicinity of the receiving node.

In some aspects, a scheduled transmission may be divided into several segments, with a time period defined between each segment for the reception and transmission of control messages. In case the condition of the transmission channel or the interference condition changes in some way, the transmitting node may receive control information indicating this so that the transmitting node may adapt the transmission parameters for one or more subsequent segments. In addition, the transmitting node may receive control information indicating that the current transmission opportunity may terminate without transmitting data during one or more previously scheduled segments. Also at this point, the sending node may send control messages to the neighboring nodes to inform them whether there are any subsequent segments and, if so, for subsequent segments.

In certain aspects, a monitoring period is defined after a scheduled transmission period to enable a transmitting node to acquire control information that may otherwise have been transmitted during the scheduled transmission period. For example, the neighboring node may delay transmission of the control message until after the scheduled transmission time period has expired to ensure that the transmitting node receives the message. This stems from the fact that in a time division duplex ("TDD") system, a node transmitting data on a data channel may not be able to receive data on either the data channel or a control channel at the same time. Alternatively, the neighboring node may transmit a control message after the scheduled transmission period ends, the control message including information that has been previously transmitted during the scheduled transmission period.

In certain aspects, data and control information are transmitted on different frequency division multiplexed ("FDM") channels such that the data and control information can be transmitted simultaneously. In some implementations, the data and control channels are associated with contiguous frequency bands, whereby portions of the control channels are interspersed among portions of the data channels within a common frequency band. In this way, frequency diversity and rate prediction of the system may be improved.

Drawings

Example features, aspects, and advantages of the disclosure will become apparent from the following detailed description and the appended claims, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a simplified block diagram of several embodiments of a communication system;

fig. 2 is a flow diagram of several embodiments of communication operations that may be performed by a node in an asynchronous wireless system;

FIG. 3 is a diagram of several embodiments of a frequency division multiplexed channel;

FIG. 4 is a simplified timing diagram of several embodiments of a message exchange scheme;

FIG. 5 is a simplified block diagram of several embodiments of a sending node;

FIG. 6 is a simplified block diagram of several embodiments of a receiving node;

figure 7 (including figures 7A and 7B) is a flow diagram of several embodiments of operations that may be performed by a sending node;

FIG. 8 (including FIGS. 8A and 8B) is a flow diagram of several embodiments of operations that may be performed by a receiving node;

FIG. 9 (including FIGS. 9A and 9B) is a flow diagram of several embodiments of operations that may be performed in connection with a resource utilization message based fairness scheme;

FIG. 10 is a flow diagram of several embodiments of operations that may be performed in connection with determining whether to transmit over a control channel;

FIG. 11 is a simplified timing diagram of several embodiments of a message exchange scheme showing an example of where nodes are sent at different times;

FIG. 12 is a simplified timing diagram of several embodiments of a message exchange scheme showing an example of where nodes are sent at the same time;

FIG. 13 (including FIGS. 13A and 13B) is a flow diagram of several embodiments of operations that may be performed in connection with the transmission of scheduling control information;

FIG. 14 is a simplified block diagram of several embodiments of a communications component; and

fig. 15-19 are simplified block diagrams of several embodiments of apparatuses for supporting asynchronous wireless communication.

In accordance with common practice, the various features shown in the drawings may not be drawn to scale. Accordingly, the dimensions of the various features may be arbitrarily expanded or reduced for clarity. Furthermore, some of the figures may be simplified for clarity. Accordingly, not all components of a given apparatus (e.g., device) or method may be depicted in a diagram. Finally, like reference numerals are used to indicate like features throughout the specification and drawings.

Detailed Description

Aspects of the disclosure are described below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative. Based on the teachings described herein, one skilled in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be implemented using any of the schemes presented herein. Further, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. For example, in some aspects, a transmitting node determines whether to issue a request to transmit based on a reception that the node has received that is scheduled with respect to a neighboring node. Further, in some aspects, the receiving node determines whether to schedule a transmission based on transmissions that the node has received that have been scheduled with respect to neighboring nodes.

Fig. 1 illustrates several embodiments of a wireless communication system 100. The system 100 includes a number of wireless nodes, generally designated as nodes 102 and 104. A given node may receive one or more traffic flows, transmit one or more traffic flows, or both. For example, each node may include at least one antenna and associated receiver and transmitter components. In the discussion that follows, the term receiving node may be used to refer to a node that receives, while the term transmitting node may be used to refer to a node that transmits. This does not mean that the node is not capable of transmitting and receiving simultaneously.

In some implementations, a node may comprise an access terminal, relay point, or access point. For example, node 102 may comprise an access point or relay and node 104 may comprise an access terminal. In a typical implementation, the access point 102 provides connectivity for a network (e.g., a Wi-Fi network, a cellular network, a WiMAX network, a wide area network such as the internet, etc.). A relay 102 may provide a connection to another relay or access point. For example, when an access terminal (e.g., access terminal 104A) is within the coverage of a relay (e.g., relay 102A) or an access point (e.g., access point 102B), the access terminal 104A may communicate with another device connected to the system 100 or some other network.

In some aspects, different node groups in system 100 may communicate with other node groups in an asynchronous manner. For example, each group of associated nodes (e.g., a group of nodes including nodes 104A and 104B), may independently select when and how long one node in the group sends data to the other nodes in the group. In such systems, various techniques may be deployed to reduce inter-node interference and ensure that access to the communication medium is provided to all nodes in a fair manner while maximizing the utilization of the available bandwidth of the communication medium.

The following discussion describes various medium access control and related techniques that may be employed to, for example, reduce interference, facilitate fair sharing of resources, and achieve relatively high spectral efficiency. Referring first to fig. 2, this figure illustrates an overview of operations that may be performed by a wireless node to determine whether and how to transmit simultaneously and on the same channel as a neighboring wireless node.

In certain aspects, wireless nodes may communicate over respective control channels and data channels. Further, in some implementations, a relatively short control message may be transmitted using a control channel. In this way, the control channel can be easily utilized, which in turn can reduce the delay on the control channel and also reduce collisions if that control channel supports random access.

As shown in block 202, in some aspects, a wireless node may communicate over frequency division multiplexed control and data channels. By using the frequency-divided channel, different groups of wireless nodes can simultaneously transmit and receive data and control information, thereby improving the utilization rate of the data channel. For example, while data is being transmitted from a first wireless node to a second wireless node using a data channel, other wireless nodes not participating in this data exchange may exchange control messages on a control channel to establish the data channel in a manner that overlaps with or after completion of the current data exchange. Thus, the other wireless nodes do not have to wait until the end of the current data transmission for contending for the data channel.

Fig. 3 shows in a simplified manner an example of how the data channels and the control channels are frequency division multiplexed. In this example, control channel 304, represented by sub-channels 304A-304D, and data channel, represented by sub-channels 306A-306D, are defined contiguously within common frequency band 302. Here, band 302 is defined as being from a lower frequency f₁To a higher frequency f₂The frequency range of (c). However, it should be appreciated that the common frequency band 302 may be in some other manner (e.g., substantially continuous or discontinuous)) Is defined.

In fig. 3, control channel 304 and data channel 306 are tone interleaved. In other words, the control channel is associated with a plurality of sub-bands interspersed within the common frequency band 302. The use of such tone-interleaved control channels may provide frequency diversity and improved rate prediction. For example, in accordance with some aspects of the present disclosure, control channel RSSI measurements may be used for signal and interference estimation and to predict an appropriate rate for transmission on a data channel. Thus, by interspersing portions of the control channel throughout the data channel, these measurements may more accurately reflect the conditions throughout the data channel. Given that interference can be estimated more accurately in this way, the system can better select an acceptable transmission and code rate for any data transmission that suffers from such interference.

It should be understood that one or more control channels and one or more data channels may be defined in the manner described above. For example, subchannels 304A-304D may represent a single control channel or multiple control channels. Likewise, subchannels 306A-306D may represent a single data channel or multiple data channels.

Fig. 3 also illustrates that, in some implementations, guard bands 308 may be defined between adjacent control subchannels and data subchannels. In other words, a subset of the frequency band 302 located between the sub-channels may be allocated to neither the data channel nor the control channel. In this way, interference between adjacent data subchannels and control subchannels may be reduced to mitigate, for example, near-far problems to some extent.

It should be appreciated that the above describes merely one example of how wireless nodes may communicate. Thus, in other implementations, data and control information may be sent on a common channel or in some other manner. For example, the data and control channels may be time division multiplexed rather than frequency division multiplexed.

In addition, other forms of multiplexing may be employed for the control channels. For example, if there are a plurality of OFDM symbols at the same time, the control channel can hop between symbols to effectively achieve the same effect as that of the example shown in fig. 3. This scheme may be used as an alternative to using only a few selected frequencies (e.g., the four bands shown in fig. 3) across all OFDM symbols.

Referring again to fig. 2, the node as shown at block 202 may monitor the communication medium for control information from one or more other nodes to support interference management and fairness. Here, it may be assumed that any transmitting node that does not receive a control message from another node (e.g., due to the distance between the nodes) does not interfere with the node that transmits the control message. Rather, it is desirable that any node that receives a control message take appropriate action to ensure that it does not interfere with the node that sent the control message.

For example, each node in the system may transmit control information that provides certain details regarding scheduled transmissions (e.g., current or upcoming). Any nearby nodes that receive this control information may then analyze this information to determine whether they can fully or partially overlap their data transmissions with the scheduled transmission without unduly interfering with the scheduled transmission. Fairness can be achieved through the use of resource utilization messages that indicate whether a given receiving node has not received data at an expected quality of service level. Here, any transmitting node that receives a resource utilization message may limit its transmission to improve reception by disadvantaged receiving nodes.

Fig. 4 is a simplified timing diagram illustrating an example of receiving and transmitting information (e.g., messages) at a pair of associated wireless nodes a and B. The upper waveform 402 represents the control channel information transmitted and received by node a. The intermediate waveform 404 represents control channel information transmitted and received by the node B. The lower waveform 406 represents data being sent from node a to node B over the data channel. For each control channel, the transmission of information is represented by a box above the horizontal line (e.g., box 408), and the reception of information is represented by a box below the horizontal line (e.g., box 410). Furthermore, the dashed boxes represent the respective reception at one node of information transmitted by other nodes.

In some implementations, a pair of associated nodes may utilize a request-grant-acknowledgement scheme to manage interference and maximize reuse of system resources. Briefly, a node (e.g., a sending node) that wishes to send data to another node (e.g., a receiving node) initiates an exchange by sending a send request. The associated receiving node then schedules the transmission by granting the request, which grant may also determine when and how to transmit. The sending node informs of the receipt of the grant by sending an acknowledgement.

In some implementations, this grant and acknowledgement may include information describing one or more parameters of the scheduled transmission. For example, this information may indicate when transmission is to occur, the transmit power to be used, and other parameters to be discussed below. A node may thus monitor the control channel to regularly obtain this information from its neighboring nodes and use the obtained information to determine whether or how to schedule its own transmission (corresponding to the receiving node being receiving).

Fig. 4 shows an example where node a observes a series of grants from neighboring nodes over a period of time, and node B observes a series of acknowledgements from neighboring nodes over a period of time represented by line 412. It should be noted that these grants (414A-C) and acknowledgements (416A-C) observed on the control channel are independent of any transmission or reception by node A or node B. Here, permissions are represented by permission blocks ("G") 414A-414C, and acknowledgements are represented by acknowledgement blocks ("C") 416A-416C. It should be appreciated that other types of control messages may be received by the node during time period 412. However, the receipt of the grant by the sending node (e.g., node a) and the acknowledgement by the receiving node (e.g., node B) is a focus of the immediate discussion below regarding the operation in block 204.

In certain aspects, node a generates a transmit constraint state based on the received grant. For example, the transmit constraint status may include a record of information provided by each grant. In this way, node a will have information about the transmissions that are scheduled by any receiving node in the proximity of node a. Thus, the transmit constraint state provides a mechanism by which node a can determine whether any receiving node that node a may potentially interfere with is receiving data or is about to receive data.

In a similar manner, the node B generates a rate prediction state based on the received acknowledgement. In some implementations, the rate prediction state may include a record of information provided by each acknowledgment. Thus, the node B will have information about transmissions scheduled by any transmitting node in the proximity of the node B. In this way, the rate prediction state provides a mechanism by which the node B can determine whether any transmitting node that may be interfering at the node B is transmitting or is about to transmit data.

Here, it should be appreciated that the neighbor nodes of node B may differ from the neighbor nodes of node a. For example, neighboring nodes are defined based on whether a node can receive a control message from another node, and if node a and node B are separated by an appropriate distance, some nodes that can communicate with node B may not be able to communicate with node a, and vice versa. Thus, node a and node B, in conjunction with the interference avoidance and fairness operations described herein, may independently identify their neighboring nodes.

Referring again to the flow diagram of fig. 2, an exemplary request-grant-acknowledgement message exchange is described. A sending node wishing to send data to a receiving node may send a send request, block 206. Here, whether to issue a request, as determined by the sending node, may be based on its sending constraint status (e.g., based on received control information). For example, node a may determine whether its scheduled transmission would interfere with any scheduled reception at a receiving node of neighboring node a. Based on this determination, node a may decide to transmit, defer transmission, or alter one or more parameters related to its transmission, as will be discussed in more detail below.

If the sending node determines that a transmission can be scheduled, a request message is sent to the receiving node. In the example of FIG. 4, this is represented by request block ("R") 408.

Upon receiving the request, the associated receiving node determines whether to schedule the requested transmission, as shown in block 208. Here, the receiving node determines whether to schedule the requested transmission may be based on its rate prediction state (e.g., based on received control information). For example, the node B may determine whether it can reliably receive the requested transmission based on any transmissions scheduled by transmitting nodes of neighboring node bs. As will be discussed in more detail below, based on this determination, the node B may decide to schedule the requested transmission, not schedule the requested transmission, or adjust one or more parameters (e.g., transmission timing, transmission power, transmission rate, code rate) related to this requested transmission so that the transmission can be continuously received.

If the receiving node chooses to schedule the transmission, a grant is sent back to the transmitting node. In the example of fig. 4, grant block ("G") 418 represents grant messages sent and received by node B and node a, respectively. As described above, the grant may include information related to the scheduled transmission. Thus, any sending node that receives this grant 418 may define (e.g., update or create) its sending constraint status based on this information.

As shown at block 210 in fig. 2, upon receiving a grant message from an associated node, the transmitting node broadcasts an acknowledgement message to acknowledge the grant by the associated receiving node and notifies the neighboring nodes of the scheduled transmission. In the example of fig. 4, an acknowledgement block ("C") 420 represents grant messages sent and received by node a and node B, respectively. As described above, the acknowledgement may include information related to the scheduled transmission. Thus, any receiving node that receives this acknowledgement 420 may define (e.g., update or create) its rate prediction state based on this information.

The transmitting node, after transmitting the acknowledgement, transmits the data for a scheduled transmit time period, as represented by a transmit opportunity ("TXOP") interval 422 in fig. 4, as shown at block 212. In some implementations, a single transmission opportunity (e.g., associated with a relatively long TXOP time period) may be divided into smaller segments to allow better interference management and rate selection for ongoing transmissions. In the example of fig. 4, scheduled transmissions are defined as a series of transmission periods 424A and 424B separated by time intervals 426 designated for receiving or transmitting control information. For example, node a may transmit data during time period 424A, then monitor for and/or transmit control messages during time interval 426, and then retransmit the data during time period 424B. It will be appreciated that the relative lengths of the time periods in fig. 4 need not be the same as those used in an actual system.

Subdividing the transmissions in this manner, if it is determined that conditions on the communication medium have changed since the initial grant 418, node a may adjust its transmission of data during a subsequent time period (e.g., time period 424B). For example, during period 424A, node B may receive additional control information (e.g., acknowledgement 416D) from one neighboring node. Based on this information (e.g., which indicates a scheduled transmission during time period 424B), the node B may adjust its rate prediction state. If any change in the rate prediction state correlates with channel conditions during period 424B, node B may adjust transmission parameters (e.g., transmission rate, number of redundant bits included, etc.) for subsequent node a transmissions.

In some implementations, a receiving node may send such transmission parameters to its associated sending node in conjunction with an acknowledgement of a given transmission segment. In the example of fig. 4, node B sends an acknowledgement 428 to node a to acknowledge receipt of segment 424A. Acknowledgement 428 may also include information similar to that sent in grant 418, or sent in conjunction with information similar to that sent in grant 418. Thus, this information may define or relate to the transmission time period, transmission power information, and other information to be used by node a for the transmission of a subsequent segment (e.g., segment 424B). The acknowledgement 428 may also be used to provide this information to the sending nodes of the neighboring node bs so that these nodes can update their respective sending constraint states.

In some implementations, node a may monitor for control information from other nodes during interval 426. For example, node a may receive a grant or resource utilization message, whereby node a may choose to adjust its current transmission or subsequent transmissions based on the received information.

In some implementations, node a may send an acknowledgement 430 during interval 426. The acknowledgement 430 may include, for example, information similar to that provided by the acknowledgement 420. Thus, the acknowledgement 430 may define or relate to a transmission time period, transmission power information, and other information to be used by node a for transmission of a subsequent segment (e.g., segment 424B). In some cases, the acknowledgement 430 may be generated in response to the acknowledgement 428. In particular, where the acknowledgement 428 requests parameter adjustments for a subsequent period, the acknowledgement 430 may be used to provide this information to those receiving nodes that are adjacent to node a so that these nodes may update their respective rate prediction states.

Referring again to fig. 2, as shown at block 214, in some implementations, the transmitting node may monitor the control channel for a defined period of time after completing its transmission. For example, as shown in fig. 4, a post TXOP monitoring period 432, which may directly (or, substantially directly) follow the TXOP period 422. Using this monitoring period, a node may define (e.g., update or reacquire) its transmit constraint status and rate prediction status information to enable the node to subsequently initiate a request to transmit data and generate a grant to schedule data for receipt at this node. Here, it should be appreciated that during the time periods in which the nodes are transmitting (e.g., period 424A and period 424B), the nodes may not receive the control messages. For example, node a does not receive the grant 410 and the acknowledgement 434 that may be sent by the receiving node and the sending node, respectively, of the neighboring node a. Thus, in some implementations, these neighboring nodes may be used to transmit this information during the post TXOP time period 432 so that node a may determine its state based on this information.

In some implementations, a node may be configured to delay sending its control information to ensure that its neighboring nodes (e.g., node a) receive this information. Here, a node may monitor control information sent by its neighboring nodes (e.g., acknowledgements 420 sent from node a) to determine when those nodes transmit. The node may then delay transmitting its control information until the end of its neighboring node's transmission time period (e.g., time period 422). This is illustrated in fig. 4, for example, by the grant 436 and acknowledgement 438 received by node a during the post TXOP time period 432.

In some implementations, a node may be configured to retransmit its control information to ensure that its neighboring nodes (e.g., node a) receive this information. In this case, the node may first send its control information (e.g., grant 410 or acknowledgement 434) at normal times (e.g., without delay). However, a node may also monitor control information transmitted by its neighboring nodes (e.g., node a) to determine whether any of those nodes are transmitting at the time the node transmits its control information. If so, the node may transmit additional control information that repeats information that has been previously transmitted. In this case, the grant 436 and acknowledgement 438 received by node a during the post TXOP time period 432 may correspond to "retransmitted" control information.

In some implementations, in a wireless communication system, the length of the post TXOP time period 432 is determined to be at least as long as the maximum length of the time period (e.g., time period 424A) plus the maximum length of the interval 426. In this case, the node monitoring the control channel during time period 432 may ensure that any transmitted acknowledgements or acknowledgements are received during interval 426, where interval 426 is defined for any other group of associated nodes in the system. Further, a disadvantaged receiving node may broadcast a resource utilization message ("RUM") using time period 432 or send a directed RUM to a particular node (e.g., a node associated with a TXOP that is unfair to the receiving node) in an attempt to improve the quality of service of the disadvantaged receiving node. As will be discussed in more detail below, a RUM may provide a mechanism by which a node may cause its neighboring nodes to compensate for its transmissions, thus causing the node to gain access to the channel in an efficient manner. Various details regarding the implementation of several examples and the application of RUMs have been discussed in U.S. patent application publication No.2007/0105574, the disclosure of which is incorporated herein by reference.

With the above in mind, examples of additional implementation and operational details that may be employed based on the teachings herein are discussed in conjunction with FIGS. 5-8. Fig. 5 illustrates several example functional components associated with a transmitting node 500 (e.g., a wireless node performing a transmit operation). Fig. 6 illustrates several example functional components of a receiving node 600 (e.g., a wireless node performing a receiving operation). Fig. 7 illustrates several example operations that may be performed by a sending node. Fig. 8 illustrates several example operations that may be performed by a receiving node.

Referring first to fig. 5 and 6, a transmitting node 500 and a receiving node 600 include various means for communicating with each other or other wireless nodes. E.g., nodes 500 and 600, include transceivers 502 and 602, respectively, for transmitting information (e.g., data and control information) and receiving information over a wireless medium. In addition, the nodes 500 and 600 include control message generators 506 and 606, respectively, for generating control messages and control message processors 504 and 604 for processing received control messages. Channel definer 508 and 608 can cooperate to define, select, or otherwise implement data and control channels used by node 500 and node 600 to communicate with each other or with some other node. For example, channel definers 508 and 608 may cooperate with transceivers 502 and 602, respectively, to transmit and receive data and control information over the appropriate frequency bands (e.g., as shown in fig. 3). Nodes 500 and 600 also include respective data stores for storing, for example, transmission parameters 510 and 610 and status records 512 and 612, respectively. Further, the transmitting node 500 includes a transmission controller 514 for controlling various transmission-related operations of the node 500; and receiving node 600 includes a receive controller 614 for controlling various receive-related receive operations of node 600. The receiving node 600 further comprises a resource utilization message "RUM" generator 616 for generating resource utilization messages, and the sending node 500 comprises a "RUM" processor 532 for processing received RUMs.

Example operations of the sending node 500 and the receiving node 600 will be discussed in more detail in conjunction with the flowcharts of fig. 7 and 8, respectively. For convenience, the operations of fig. 7 and 8 (or any other operations discussed or taught herein) may be described as being performed by specific components (e.g., components of node 500 or 600). However, it should be appreciated that these operations may be performed by other types of components, and may be performed by a different number of components. It should also be appreciated that one or more of the operations described herein may not be employed in a given implementation.

As shown in blocks 702 and 802, the nodes 500 and 600 regularly monitor the control channel for control messages. For example, in a typical configuration, receiver 518 of node 500 and receiver 618 of node 600 each monitor the control channel whenever the respective transmitter 520 and 620 of each node is not transmitting. In other words, a node may obtain control messages when it is receiving or idle. In this case, each of nodes 500 and 600 may obtain control information regarding scheduled transmissions associated with neighboring nodes, thereby maintaining the state as discussed below.

The control message processors 504 and 604 of each node process each received control message and extract the transmission schedule and other information from the message. As discussed above, the received control message may include a grant, an acknowledgement, or some other suitable control information. The grants and acknowledgements generated by its neighboring receiving nodes are of particular interest to a node that wishes to transmit (e.g., a transmitting node) because the transmitting node will use the information provided by these control messages to determine whether it will interfere with the reception that its neighboring node has scheduled. Conversely, acknowledgements generated by its neighboring transmitting nodes are of particular interest to a node that wishes to receive (e.g., a receiving node), because the receiving node will use the information provided by the control messages to determine whether it can sustainably receive data based on the scheduled transmissions of those nodes.

As described above, a grant or acknowledgement may include information regarding the granted resources and the timing and duration of the corresponding granted TXOP. These timing parameters may include, for example, the start time of the TXOP, the end time of the TXOP, and the duration of the TXOP. In some implementations, these timing parameters may be related to the transmission time of the message or some other timing reference.

The grant or acknowledgement may also include transmission parameters defined at the receiving node to facilitate reliable reception of the transmission at the receiving node. As described above, the receiving node may define these parameters based on transmissions (ongoing or future) scheduled by nodes in the vicinity of the receiving node. The information may include, for example, recommended or specified transmission parameters such as transmission power, transmission rate, number of redundant bits to be transmitted, and code rate used by the associated transmitting node during the scheduled transmission.

In some implementations, the grant or acknowledgement may indicate a desired channel-to-interference ratio ("C/I") at the receiving node. In this case, the associated sending node may use this information to define the appropriate sending parameters.

In some implementations, the grant or acknowledgement may indicate a reception margin at the receiving node. This reception margin may indicate, for example, how much margin (e.g., defined in decibels) the transmission parameters provided by the control message can include. This reception margin information may then be used by the transmitting node to ensure that any interference caused by overlapping transmissions falls sufficiently low for an error correction mechanism (e.g., HARQ) at the receiving node to be able to recover the associated data packet.

In some implementations, the grant or acknowledgement may include or be associated with a pilot signal that may be used by neighboring nodes to determine how much a particular transmit power value will affect (e.g., interfere with) the receiving node. For example, the pilot signal may be associated with a fixed and known power spectral density or transmit power, whereby the transmitting node may use this known information to determine the path loss to the adjacent receiving node. To this end, the receiver 518 may include a received signal strength indication ("RSSI") measurer 524 that may be used to measure the signal strength of a received signal (e.g., a pilot). In some implementations, this pilot signal may be transmitted over one or more control subchannels so that one instance of the overall channel may be reliably obtained (e.g., advantageous for frequency-selectively depleted channels).

In some implementations, the acknowledgement may include information similar to that described in connection with the grants and acknowledgements above, except that in this case the information is from a neighboring node that transmits during the scheduled transmission time period. For example, the acknowledgement may include a start time of the TXOP, an end time of the TXOP, a duration of the TXOP, a transmit power, a transmit rate, an amount of redundancy bits to be transmitted, and a code rate.

The acknowledgement may also include or be associated with a pilot signal. Furthermore, the pilot signal may be associated with a fixed and known power spectral density or transmit power, whereby the receiving node may determine the path loss to the transmitting node. Thus, the receiver 618 may also include an RSSI measurer 624 that may be used to measure the signal strength of the received acknowledgement signal (e.g., pilot).

In some implementations, the acknowledgement may indicate a transmit power delta used by the transmitting node for its scheduled transmission. This power increment may indicate, for example, a difference (e.g., an increase or decrease) between a power level of a message to be transmitted and an acknowledged power level (e.g., an associated pilot signal) during a scheduled transmission. By utilizing the measured power levels of the transmit power delta and the received acknowledgement, the receiving node can determine how much interference it can expect from neighboring transmitting nodes. For example, based on the received acknowledgements of previously scheduled transmissions, the receiving node may establish a received interference level versus time graph (e.g., a status record).

As shown in blocks 704 and 804, state controllers 522 and 622 define a state record for each node based on the received control information. Here, when new control information is received, it is added to the appropriate state record. Instead, upon completion of a given TXOP (e.g., as indicated by comparing the end time of the TXOP to the current time), the associated record is deleted from the state record.

Fig. 5 shows the sending constraint status records 512, which are of particular interest to the sending node 500. As described above, the transmit restriction state includes a record of the received grant and, in some implementations, an acknowledgement of the receipt. Thus, for a given received message, the entry 526 of the status record 512 may include the start time of the scheduled transmission (or the current time when the transmission is in progress), the corresponding end time, the transmission time period, the reception margin, the RSSI associated with the received message, the C/I, and the reception margin of the node that transmitted the message (e.g., the node that transmitted the grant or acknowledgement).

Fig. 6 shows rate prediction state records 612 that are of particular interest to the receiving node 600. The rate prediction state includes a record of the received acknowledgements. Thus, for a given received message, entry 626 of status record 612 may include the start time of the scheduled transmission (or the current time when the transmission is in progress), the corresponding end time, the transmission time period, the RSSI associated with the received message, and the transmit power increment of the node transmitting the message.

Referring now to blocks 806 and 706 in fig. 8 and 7, in some implementations, nodes in a system may implement a resource utilization message ("RUM") scheme to attempt to ensure that resources of the system are shared among the nodes in a fair manner. Generally, the operations of block 806 include sending a message over a control channel to indicate that the receiving node is disadvantaged (e.g., due to interference that the node "sees" upon reception), and that the node wishes to preferentially access the shared communication medium (e.g., a given data channel). In block 706 of fig. 7, the transmitting node monitors upcoming traffic on the control channel to determine if any of its neighboring nodes have transmitted RUMs. This information is taken into account whenever the sending node wishes to invoke a send request. Example operations associated with the RUM-based scheme will be discussed in more detail in conjunction with fig. 9.

As shown in block 902 in fig. 9A, at some point in time (e.g., regularly), the receiving node determines whether it is receiving data according to an expected quality of service level (e.g., an expected data transmission rate or delay). In some cases, the quality of service may be lower than expected due to interference from neighboring transmitting nodes. For example, a receiving node may not be able to grant a request to transmit from an associated transmitting node due to a transmission that is scheduled by a neighboring node. In the event that the receiving node determines that it is disadvantaged, it will generate a RUM in an attempt to cause neighboring nodes to reduce interference thereto. The neighboring nodes may respond by contending for less transmission on the data channel over a period of time, by a less frequent request or reduced power or other suitable means, to satisfy the node that sent the RUM.

As shown at block 904, in some implementations, the RUM may be weighted (e.g., include a weight) to indicate a degree to which reception at the wireless receiving node fails to achieve a desired level of quality of service (e.g., a degree to which the receiving node is disadvantaged). For example, a disadvantaged receiving node may calculate a weight for the RUM that indicates how different the expected received data rate differs from the actual data received rate (e.g., the ratio of the two values).

In practice, the RUM may include various types of information, as shown in block 906. For example, in some implementations, a RUM may indicate a desired level of interference reduction. Further, in some implementations, a RUM may indicate a particular resource that a disadvantaged receiving node wishes to clean up.

The receiving node then transmits the RUM over the control channel, as shown in block 908. In the example of FIG. 6, RUM generator 616 may generate information related to the RUMs described above. The control message generator 606 may then cooperate with the transmitter 620 to transmit the RUM over the control channel.

As shown in block 708 of fig. 7, based on the transmit constraint state and, optionally, any received RUMs, the transmitting node determines whether or how to issue a transmit request. In some aspects, the request indicates that the sending node has data to send to its associated receiving node. Further, the request may be for indicating that no ongoing transmission is preventing the transmitting node from transmitting data.

If it is determined at block 706 that a neighboring node has sent a RUM, the transmitting node may utilize the received RUM, its weight, and any other information included in the RUM to determine an appropriate response. For example, a transmitting node may limit its future transmissions, or it may ignore a RUM, e.g., if the node has received a RUM from an associated receiving node indicating that the relevant receiving node is at a lesser disadvantage than any other neighboring receiving node.

Referring to fig. 9B, at block 910, the RUM processor 532 of the sending node 500 determines whether the received RUM indicates that a neighboring receiving node is more disadvantaged than the receiving node associated with the sending node. As a preliminary measure, at block 912, the interference determiner 528 may determine whether the transmitting node's transmission would further interfere with an disadvantaged receiving node (e.g., as discussed above). This may include, for example, comparing received power information associated with the received RUM (e.g., RSSI of the pilot signal) to an appropriate threshold level. A transmitting node may ignore a received RUM if it is determined that the transmit power to be used in the transmission is low enough or other parameters of the intended transmission (e.g., transmit time) do not cause excessive interference at an unfavorably receiving node.

In block 914, where the transmitting node determines that the intended transmission may interfere with reception by the disadvantaged receiving node, the transmitting node 500 may take appropriate action (e.g., define different transmission parameters) to avoid such interference. For example, the sending node 500 (e.g., sending node controller 514) may perform one or more of the following steps: the method may include delaying sending a request for transmission, forgoing sending the request message until a resource utilization message of an associated receiving node indicates a higher degree of disadvantage than the received resource utilization message, sending a request for a later transmission, changing (e.g., reducing) a rate at which the node sends the request message, changing (e.g., reducing) a length of a transmission time period (e.g., TXOP), sending a request for transmission at a different (e.g., reduced) power level, changing (e.g., reducing) a transmission power increment, modifying a set of rules (e.g., one or more rules 530) related to how well the node sends may interfere with reception by neighboring nodes (e.g., changing a safety margin), or performing some other suitable step.

When the received RUM indicates that the receiving node associated with the sending node is less favorable than other nodes, the sending node may perform the opposite operation. For example, in this case, the transmitting node may increase the rate at which requests are transmitted, increase the length of the TXOP, and so on.

As described above, the sending node may also limit the request based on the current state. In the example of fig. 5, the interference determiner 528 may utilize the transmission constraint status record 512 to determine whether an expected transmission would interfere with any scheduled data reception at a node that is relatively close to the transmitting node. This determination may also be based on one or more interference rules 530, which may define, for example, a margin, coding scheme, or other condition associated with an acceptable interference level for a given transmission rate. As an example, based on the RSSI of any received grant and the reception margin information, a node may determine whether it should request an overlapping transmission and, if so, how to select a transmission power to limit potential interference to any scheduled transmission. If the interference determiner 528 determines that the expected transmission may excessively interfere with reception by one or more neighboring nodes, the transmitting node 500 may select, for example: for example, the method may include forgoing sending a send request, delaying sending a send request message, sending a request to request a later send, sending a request to send at a reduced power level, adjusting a send time period (e.g., TXOP), or taking some other appropriate action. For example, if the transmitting node chooses to transmit at a lower power level, it may want to transmit as many bits per packet as it does. In this case, the transmitting node may specify a longer TXOP.

The techniques discussed above with respect to whether to issue a request to transmit data may also be used to determine whether to transmit over the control channel. For example, if a node uses relatively excessive power to transmit over a control channel, the transmission of control messages by the node may interfere with the data reception by neighboring nodes. This may occur, in particular, when a data transmitting node associated with a data receiving node is further away from the data receiving node than a node transmitting on the control channel. Such interference may also occur when the frequency associated with the transmission of control information is relatively close to the data reception frequency. As an example of the latter, referring to fig. 3, the frequency band of the data channel portion being used (e.g., sub-channel 306D) may be relatively close in frequency to the frequency band of the control channel portion being used (e.g., sub-channel 304D). The operations associated with handling the above near-far problem will be discussed in detail in connection with fig. 10. In some cases, a node's transmission may be insensitive to the receiver of its immediate neighbors, causing saturation at the receiver and packet loss (also referred to as receiver interference). This may occur even when the transmit frequency is separated from the receive frequency. Determining whether to transmit on the control channel based on the likelihood of making neighboring receivers insensitive is also part of the transmit constraint state processing.

A node wishing to transmit over a control channel will monitor the control channel for information indicating whether any neighboring receiving nodes have scheduled (e.g., granted) any requested transmissions, as shown at block 1002. At block 1004, the node thus defines its state record (e.g., transmit constraint state) as discussed herein.

At some point in time, the node may determine that it wishes to transmit over the control channel, block 1006. In this case, the node may utilize the transmission constraint state information along with transmission parameters related to the expected control channel transmission to determine whether the expected transmission would interfere with or would desensitize the adjacent receiver. This may include determining whether and how to schedule the desired transmission in a manner similar to that discussed herein and with other similar operations. For example, in some implementations, a decision may be made to proceed with the transmission, delay the transmission, or change some parameter associated with the transmission (block 1008).

In some implementations, the transmit power used to transmit the control message may not be adjusted when attempting to avoid interference. For example, in some cases, it may be desirable to ensure that a control message is transmitted at a power level such that a node receiving the control message makes a decision to avoid interference (e.g., those discussed herein) based on the power level of the received control message. Thus, in these cases, avoiding interference may include adjusting the timing of the transmission or some other parameter that does not affect the transmission power. In the event that interference is unavoidable by re-scheduling the transmission of control channel messages (e.g., subsequent transmissions), interference between the control and data channels can be handled by using the guard bands and/or adding margin as discussed above.

Once a node determines that it can transmit over a control channel and does not cause excessive interference with the reception of data by neighboring nodes, the node may invoke an access scheme assigned to the control channel, block 1010. For example, to avoid latency on the control channel, nodes may transmit on the control channel one at a time. Some implementations may use interference avoidance schemes such as carrier sense multiple access with collision detection ("CSMA/CA"). In this manner, operation on the FDM control channel may be limited substantially only by the signal-to-noise ratio of the channel. In some implementations, reservation or NAV setting is not allowed because a node transmitting on the data channel may not be able to listen to the control channel to maintain the NAV setting. Once a node has access to the control channel, the node may send its control messages over the control channel, as discussed herein (block 1012).

At block 710 in fig. 7, where a decision is made to issue a request to send, control message generator 506 generates an appropriate request message 534 including, for example, the requested start and end times or some other parameter discussed herein associated with the desired transmission. The transmitter 520 then sends the request over the control channel.

Referring again to fig. 8, at block 808, the receiving node receives a send request. At block 810, the receiving node determines whether to schedule the requested transmission and, if so, how the transmission should be scheduled. As described above, this decision may be based on the requested parameters and the rate prediction state.

In the example of fig. 6, the sustainable reception determiner 632 uses the rate prediction state record 612 to determine whether sustainable data reception may be maintained at the receiving node 600 according to any transmissions scheduled by nodes neighboring the receiving node (e.g., by selecting different parameters). For example, a node may determine an expected interference level based on RSSI and transmit power delta information for any received acknowledgement messages, thereby determining a sustainable rate for scheduled transmissions. In case the expected interference is excessive, the receiving node may not respond to the send request at all. In this case, the sending node may back off and attempt the request later.

Various factors may be considered when deciding whether to schedule overlapping transmissions. For example, a determination of the signal strength of the most recent grant may be considered. It may additionally be considered whether the grant transmitter has recently transmitted a RUM indicating a relatively high degree of disadvantaged. Further, the amount of data that needs to be transmitted may become a factor in making a decision whether to schedule overlapping transmissions. For example, if the amount of data that needs to be transmitted is relatively small, the data may be transmitted at low power and for a relatively long period of time to facilitate overlapping transmissions.

In the event that the receiving node elects to schedule a transmission, the transmission parameter definer component 634 can define one or more transmission parameters 610 to facilitate efficient reception of the scheduled transmission (e.g., selection of different parameters). For example, transmit parameters 610 may include one or more of the following parameters: a transmission start time, a transmission end time, a transmission time period, a time period definition, a transmission power, an amount of redundant bits to be transmitted, a reception headroom, a C/I, or a code rate that may be used during transmission or that may be used to define one or more transmission parameters.

At block 812, control message generator 606 generates grant message 636 including pertinent information such as the allocated TXOP time period, the specified transmission bandwidth, the allocation of the rate, and any other grant related parameters discussed herein. The transmitter 620 then transmits the grant over the control channel.

At block 712 in fig. 7, the receiver 518 (fig. 5) receives the grant over the control channel. As discussed above, RSSI measurer 524 may measure a signal strength or some other power related parameter associated with the received grant message.

At block 714, the control message processor 504 extracts information related to the transmit parameters from the grant message. Further, the transmission parameter definer 536 may determine any transmission parameters that are not directly provided by the grant, if necessary. As discussed above, transmitting node 500 may maintain its transmit parameters 510 in data storage for subsequent use by transmit controller 514 and control message generator 506.

At block 716, control message generator 506 generates acknowledgement 538 (e.g., in response to the received grant). Generally, the transmission of the acknowledgement 538 immediately precedes the transmission of the data on the data channel.

In some implementations, the acknowledgement may include information related to the scheduled transmission discussed herein. For example, the acknowledgement 538 may include a transmission start time, a transmission end time, packet format and sequence number information provided by, for example, the packet formatter 540, and transmit power delta information 542. The transmitter 520 sends an acknowledgement message (e.g., in conjunction with a pilot signal) over the control channel.

As shown in block 814 of fig. 8, the nodes of the receiving node and any other neighboring sending nodes receive the acknowledgements. Here, the other nodes may thus update their state information based on the acknowledgement. The acknowledgement indicates the selected transmission mode and packet format (e.g., for HARQ) for the associated receiving node. In some implementations, the indication of the packet format may be provided in-band (or implicitly) rather than explicitly in the acknowledgement message.

In a typical implementation, the grant issued at block 812 indicates that the sending node may start its TXOP immediately after receiving the grant. However, in some cases, the grant may indicate a later start time for the TXOP. In the case where the TXOP starts at a later point in time, the sending node and receiving node may start the actual data exchange by invoking an acknowledgement/confirmation exchange (not shown in fig. 7 and 8) to provide updated status messages to the nodes.

As shown in block 718 of fig. 7, transmitting node 500 transmits its data during a scheduled TXOP time period over a data channel. Here, if the TXOP is not fragmented, transmitting node 500 will transmit data throughout the TXOP (block 720). Otherwise, the transmitting node transmits the data within a time period, as discussed below. Transmitting node 500 uses current transmit parameters 510 and transmit power delta 542 to determine the appropriate transmit time, transmit rate, code rate, etc. to transmit data. The transmitted data is then received by the receiving node 600 as indicated by block 816 of fig. 8 via the data channel. If the TXOP is not fragmented, receiving node 600 receives the data for the entire TXOP (blocks 818 and 820). Otherwise, the receiving node receives the data within the time period, as discussed below.

Fig. 11 and 12 show two examples of how transmissions may be scheduled for transmission based on neighboring nodes having been scheduled for transmission. In fig. 11, node A issues A request granted by node B (REQ- A). The grant from node B (GNT-B) defines the start time and end time of the TXOP as shown by lines 1102 and 1104, respectively. Once the acknowledgement message (CNF-a) is sent, node a starts sending its data, as shown by the shaded portion associated with the data channel used by node a in fig. 11.

At a later point in time, node C issues a request granted by node D (REQ-C). In this case, node D chooses to avoid any overlap with the transmissions that node a has scheduled. As discussed herein, this selection may be made based on the transmission from node a unduly interfering with the reception of data at node D. Thus, the grant from node D (GNT-D) defines the start time and end time of the TXOP as shown by lines 1106 and 1108, respectively. Once the transmission of the acknowledgement message (CNF-C) is complete, node C starts transmitting its data at the specified time, as shown by the shaded portion associated with the data channel used by node C in fig. 11.

In fig. 12, node A again issues A request granted by node B (REQ- A). The grant from node B (GNT-B) defines the start time and end time of the TXOP as shown by lines 1202 and 1204, respectively. When the acknowledgement message (CNF-a) is sent, node a starts sending its data, as shown by the shaded portion associated with the data channel used by node a in fig. 11.

Node C again issues a request granted by node D (REQ-C). In this case, however, node D chooses to overlap the transmission to node D with the transmission that node a has scheduled. Here, the grant from node D (GNT-D) defines the start time and end time of the TXOP as shown by lines 1206 and 1208, respectively. Therefore, as shown by the cross-hatched portion in fig. 11, nodes a and C can simultaneously use the data channel. Here, it should be appreciated that such techniques may help provide greater spatial reuse efficiency as compared to medium access control schemes in which a transmitter can only use the communication medium (e.g., channel) when it is idle for any other transmission.

Referring again to blocks 720 and 818 in fig. 7 and 8, respectively, in some implementations, a given TXOP may define several transmit periods (e.g., periods 424A and 424B in fig. 4). In some cases, bi-directional exchanges using acknowledgement messages and acknowledgement messages may be utilized to maintain state and update transmission parameters, if necessary, throughout the TXOP.

After a transmitting node transmits a given segment, the node monitors the control channel at least during a portion of the defined segment-to-segment time interval, blocks 722 and 724. For example, during this interval (e.g., interval 426 in fig. 4), the transmitting node may receive an acknowledgement from the associated receiving node acknowledging receipt of the most recently transmitted segment. Further, during this interval the sending node may receive other control information that may be used to update the state record (e.g., the sending constraint state and the rate prediction state) for this node as discussed herein. Also, the sending node may receive an indication from the receiving node that the transmission may be terminated.

As shown in block 822 of fig. 8, the receiving node receives each segment and decodes the corresponding data, if necessary. In block 824, in the event that the receiving node has successfully decoded all data to be transmitted (e.g., a complete data packet) during the TXOP, the receiving node may define control information to be transmitted to the transmitting node that indicates that the transmission has ended. In the event that a packet is successfully decoded even though there are one or more segments that have been scheduled to be transmitted, the control information may indicate, for example, that the duration of the TXOP is to be adjusted (e.g., reduced), or that one or more upcoming time periods are to be eliminated (e.g., adjusting the number of time periods in the TXOP).

As shown at block 826, the receive controller 614 of the sending node 600 may determine whether to adjust one or more transmit parameters for the subsequent segment (e.g., based on the current rate prediction state) based on the control information received from the grant time at block 812. Here, the receive controller 614 may choose to adjust one or more transmission parameters if another wireless node has recently scheduled a transmission that will be made at the same time as one or more subsequent segments. Such adjustments may include, for example, reducing the transmission rate, changing the code rate, adjusting the transmission time, or modifying some other parameter for one or more of the remaining segments.

It should be appreciated that due to the interference avoidance techniques described herein, the received C/I associated with an ongoing scheduled Transmission (TXOP) may not change significantly during the TXOP. For example, if it has been determined that a requested transmission will excessively interfere with a previously scheduled transmission, the transmission request cannot be scheduled at the same time as another scheduled transmission (e.g., a grant). Thus, since a node may assume that the conditions of the communication channel do not change substantially during a given TXOP time period, the receiving node may actively select a transmission rate and a code rate for its scheduled transmission.

As shown in block 830, the control message generator 606 may then generate an acknowledgement 638 acknowledging receipt of the segment (e.g., segment 424A). Here, different acknowledgements may be used to provide feedback for each segment being transmitted. Further, the acknowledgement 638 may include or be associated with information similar to that sent by or in conjunction with the grant 636 in block 812, and may be modified to include information regarding one or more adjusted transmission parameters from block 826, as necessary. In other words, the acknowledgement may act as an intermediate "reserved grant" that provides updated resource allocation and rate feedback information and may be used by the neighboring node to update the state related to scheduled receptions in the vicinity of the neighboring node. Thus, the acknowledgement 638 may include one or more of the following: the method comprises the steps of starting transmission of at least one time period, ending transmission of at least one time period, transmitting time period of at least one time period, transmitting power of at least one time period, amount of redundant bits to be transmitted of at least one time period, code rate of at least one time period, expected channel interference ratio of at least one time period, receiving margin and pilot signals.

Referring again to fig. 7, at block 726, based on the control information received during the segment-to-segment interval, the transmit controller 514 adjusts its transmit parameters as necessary. As described above, such adjustments may be based on information received via acknowledgements from associated receiving nodes, or based on information received from other neighboring nodes (e.g., grants or other acknowledgements).

As shown at block 728, in some implementations, the control message generator 506 generates another form of acknowledgement message (e.g., similar to the acknowledgement message sent at block 716) to notify the neighboring node of the transmission parameters to be used for transmission during a subsequent time period (e.g., time period 424B), or to notify the neighboring node of the completion of the transmission. This acknowledgement message may therefore include information similar to that included in acknowledgement 538. In this case, however, the acknowledgement information may include appropriate adjustments based on any changed transmission parameters and include appropriate time parameters relating to the remaining segments to be transmitted. Thus, the acknowledgment sent at block 728 may include, for example, a transmission start time for the at least one period, a transmission end time for the at least one period, a transmission time period for the at least one period, a transmission power increment, a packet format, and a pilot signal.

Referring back to fig. 8, as shown at block 832, during the segment-to-segment intervals and while monitoring the data channel within the segment that the receiving node is transmitting, the receiving node continues to monitor the control channel for control information. Thus, the receiving node will continue to update its state, if necessary, so that it can continue to adjust the transmit parameters for the current TXOP.

The above operations are repeated for each subsequent transmit segment, as shown at block 730 in fig. 7 and at block 826 in fig. 8. After all segments have been transmitted (e.g., at the end of the TXOP time period), the node, including receiving node 600, continues to monitor the control channel, if necessary, to update its transmit constraint state and rate prediction state and to process or initiate a transmit request, as shown at block 836 in fig. 8.

Referring again to fig. 7, at the end of the TXOP time period, the transmitting node monitors the control channel for a defined period of time so that it can update or retrieve its state record based on received control messages such as grants, acknowledgements, and RUMs (block 732). Fig. 11 and 12 show examples of such a status update period (i.e., post-TXOP monitoring period) defined immediately after a scheduled transmission. Here, the state update of node a (STU-a) may directly follow the end of node a's tmutexop, as shown by lines 1104 and 1204. Similarly, the state update of node C (STU-C) may directly follow the end of node C's TXOP, as lines 1108 and 1208 do not.

As described above in connection with fig. 4, the control information (e.g., message exchange message and RUM) received at this time may include information that has been scheduled to be transmitted, with or without consideration of the TXOP period of the transmitting node 500. Two examples of the former will be discussed in connection with fig. 13. Fig. 13A relates to a case in which, at the end of the TXOP period, when a neighboring node is transmitting data, the node retransmits information that has been previously transmitted. Fig. 13B relates to a case where a node intentionally delays sending its control information until the end of the TXOP time period of a neighboring node to ensure that the information can be received by the neighboring node.

Referring first to fig. 13A, as shown in block 1302, a given node maintains its state by monitoring control channels for information transmitted by other nodes, as discussed herein. In this manner, a node may obtain information regarding the TXOP time period that its neighboring transmitting nodes schedule.

At some point in time (e.g., as discussed herein), the node may send control information over a control channel, as shown at block 1304. In conjunction with this operation, the node may determine whether any neighboring transmitting nodes are transmitting over the data channel while it is transmitting control information over the control channel (block 1306). In this manner, a node may determine that one or more neighboring nodes may not have received its control information.

Thus, at block 1308, the node may send another control message at the end of the TXOP time period for each neighboring node that did not receive the original control message. Here, the "retransmitted" control message may repeat information previously transmitted in the original control message. In this manner, when those nodes determine whether to issue a request to transmit or whether to grant the requested transmission, the node may ensure that its neighboring nodes consider its scheduled transmissions.

Referring now to fig. 13B, the node maintains its state by monitoring the control channel for information sent by other nodes, as shown at block 1312. The node may thus obtain information about the scheduled TXOP time periods of its neighboring transmitting nodes.

At some point in time (e.g., as discussed herein), the node may determine that control information needs to be sent over the control channel, as shown at block 1314. However, before a node transmits control information, the node may determine whether any of its neighboring transmitting nodes are scheduled to transmit over the data channel while the node attempts to transmit its control information over the control channel. In this case, a node (e.g., transmit controller 514 or receive controller 614) may schedule (e.g., delay) the transmission of its control information so that its neighboring nodes may receive the control information to be transmitted (block 1316).

As shown in block 1318, after the TXOP time period for each neighboring node is over, the node sends delayed control information. Thus, when those nodes determine whether to issue a request to transmit or grant a requested transmission, the node may thus ensure that its neighbors consider its scheduled transmissions.

Referring again to fig. 7, once the node, including sending node 500, receives the control information, it updates or retrieves its state record for use in invoking future send requests or granting send requests from other nodes (block 734). The node may then continue to monitor the control channel to update its status or send a request service, or it may invoke additional requests to send any other backlogged data, as shown in block 736.

The control message exchange scheme described herein may be implemented in various ways. For example, in some implementations, different types of messages may be given higher or lower priority over the control channel. For example, acknowledgement messages may be given priority over request messages (using a shorter IFS) because the exchange related to acknowledgement occurs in the middle of an ongoing TXOP. This prioritization scheme may avoid unnecessary waste of data bandwidth during a TXOP.

In some implementations, the RUM may be a broadcast transmission that is not acknowledged. Furthermore, the RUM may be assigned the lowest access priority as compared to the request and acknowledgement. Further, in some implementations, the RUM may not terminate an ongoing TXOP.

In some implementations, fairness can be achieved on a time scale that corresponds to the maximum length of a TXOP in some other amount of time. For example, a disadvantaged node may specify that its RUM is valid for a defined period of time (e.g., a significant amount of time sufficient to schedule its own TXOP). In some implementations, the defined time period may be included in the RUM. Conversely, in some implementations, a node receiving a RUM may indicate that any RUM it receives will be considered within a defined time period. For example, such a node may define a time window within which it will limit its transmission or requests for transmission if it has received a RUM from a particular node. It will be appreciated that the time period defined above may be dynamically changed depending on the current conditions of the system.

In some implementations, if a sending node with backlog data is unable to send a request due to the current transmit constraint status, the sending node may send an indication of its backlog status to its associated receiving node (e.g., using a request message with the transmit constraint bit set). In this case, the receiving node may use the RUM mechanism to indicate to neighboring transmitting nodes that they should compensate for the transmission.

In some implementations, the overhead associated with the message exchange scheme may be reduced by eliminating requests and grants. For example, for the transmission of relatively short data packets, the transmitter may initiate a message exchange by simply sending an acknowledgement on the control channel and then sending data on the data channel, assuming that the current transmission constraint state allows such transmission. Here, the acknowledgement informs the neighboring nodes of the upcoming transmission. Generally, the length of such a packet may be relatively short. For example, in some embodiments, the length of such a packet is shorter than the length of a given time period (e.g., time period 424A). Here, because the C/I of the receiving node may not be known, the transmitting node may select a reserved value for one or more of: transmit power, transmit rate, or code rate.

After transmitting the data, the transmitting node will wait for an acknowledgement from the relevant receiving node. In the event that no acknowledgement is received, the sending node will fall back and retry the transmission using a brief acknowledgement-acknowledgement exchange. Alternatively, the sending node may fall back and retry sending using a full request-grant-acknowledge exchange.

Alternatively, an unsolicited grant scheme may be used by which the receiving node sends a grant at any time when its current interference situation indicates that data can be reliably received. In this case, the transmitting node receiving the unsolicited grant may select a transmit power based on any constraints that may be imposed by the current transmit constraint state.

It should be appreciated that the operation and content of control messages, such as those described herein, may depend on the type of device sending the request. For example, in an implementation in which a pair of associated nodes, including an access point and an access terminal, have established a forward link (i.e., data flows from the access point to the access terminal), the request generated by the access point may include one or more parameters, which have been described above in connection with the grant. For example, the request may include information related to: what the access point wants to send, how the access point wants to send it, for example, it may include a specified TXOP time period, an amount of data to send, frequency resources to use, e.g., a specified bandwidth, and so on. In this case, in response to the request, the access terminal may simply send a message that accepts the request (e.g., "grant") and includes information relating to, for example, the transmission rate supportable by the access point, whereupon the access point acknowledges receipt of the response. In this case, the response generated by the access terminal may not actually "grant" the request of the access point in a general sense.

Various measures may also be taken to address the "near-far" problem. As described above, the near-far problem may involve inter-node interference (e.g., when a transmitting node is interfering with a receiving node, the transmitting node associated with the receiving node is farther away than the transmitting node that is implementing the interference). An example of a solution to the near-far problem caused by transmission on the control channel has been discussed above in connection with fig. 10.

The mutual near-far problem relates to a data transmitting node interfering with the reception of a control message of another node. In other words, if there is a strong data transmitting node in the vicinity, the node is rejected for the control channel. It should be appreciated, however, that this problem is similar to the case where the affected node itself is transmitting and therefore does not receive the control channel message. Thus, during the idle post TXOP monitoring period of the transmitting node implementing the interference, the affected node is able to update its state.

Near-far problems on data channels may be handled using techniques similar to those described herein. For example, when the data channel uses OFDMA, there may be other data transmissions that result in leakage interference that affects data reception at the receiving node. The interference management methods described herein, which involve request-grant-acknowledgement exchanges and acknowledgement-acknowledgement exchanges, may also be used to handle near-far issues with data reception of overlapping OFDMA transmissions. These thresholds may be expanded for inter-hop port (inter-hop-port) interference for OFDMA, similar to the interference management thresholds applied to the transmit constraint state and the rate prediction state. Further, when a node (e.g., access point) schedules multiple simultaneous receptions, the access point can manage the near-far problem by power controlling the receptions.

Various techniques may be used to determine whether to issue or grant a request, as taught herein. For example, some implementations may utilize one or more thresholds that are compared to one or more of the parameters described above. As a particular example, determining whether to schedule a transmission may be based on a comparison of a threshold value to a value based on an estimated channel gain associated with at least one node and an expected transmit power for the scheduled transmission. Finally, it should be noted that some control information between the transmitter and receiver that is not pertinent to interference management may be sent with the data on a data channel instead of a control channel. This ensures that the control channel is used as little as possible, since due to the nature of random access it is important to maintain a low utilization of the control channel. As an example, certain parameters of the acknowledgement message, such as the modulation method used, the number of bits of data transmitted, the remaining data in the buffer, the stream identifier (in case multiple streams from the transmitter are multiplexed), and in some cases even the code rate, may be transmitted with the data as in-band control.

The teachings herein may be incorporated into a device that uses various components for communicating with at least one other wireless device. FIG. 14 depicts several example components that facilitate communication between devices. Here, a first device 1402 (e.g., an access terminal) and a second device 1404 (e.g., an access point) are adapted to communicate over a suitable medium via a wireless communication link 1406.

First, components that participate in sending information from device 1402 to device 1404 (e.g., a reverse link) are discussed. A transmit ("TX") data processor 1408 receives traffic data (e.g., data packets) from a data buffer 1410 or some other suitable component. A tx data processor 1408 processes (e.g., encodes, interleaves, and symbol maps) each data packet based on a selected coding and modulation scheme and provides data symbols. Typically, the data symbols are modulation symbols for data and the pilot symbols are modulation symbols for pilot (previously known). A modulator 1412 receives the data symbols, pilot symbols, and possibly signaling for the reverse link and performs modulation (e.g., OFDM or some other suitable modulation) and/or other processing as specified by the system and provides a stream of output chips. A transmitter ("TMTR") 1414 processes (e.g., converts to analog, filters, amplifies, and frequency upconverts) the output chip stream and generates a modulated signal, which is then transmitted from an antenna 1416.

The modulated signals transmitted by device 1402 (along with signals from other devices in communication with device 1404) are received by antennas 1418 of device 1404. A receiver ("RCVR") 1420 processes (e.g., conditions and digitizes) the received signal from antenna 1418 and provides received samples. A demodulator ("DEMOD") 1422 processes (e.g., demodulates and detects) the received samples and provides detected data symbols, which may be a noisy estimate of the data symbols sent by the other devices to the device 1404. A receive ("RX") data processor 1424 processes (e.g., symbol demaps, deinterleaves, and decodes) the detected data symbols and provides decoded data associated with each transmitting device (e.g., device 1402).

Components that participate in sending information from device 1404 to device 1402 (e.g., a forward link) are now discussed. At device 1404, a transmit ("TX") data processor 1426 processes traffic data to generate data symbols. A modulator 1428 receives the data symbols, pilot signals, and signaling for the forward link, performs modulation (e.g., OFDM or some other suitable modulation) and/or other related processing, and provides an output chip stream, which is further conditioned by a transmitter ("TMTR") 1430 and transmitted from an antenna 1418. In some implementations, the signaling for the forward link may include power control commands and other information (e.g., relating to a communication channel) generated by controller 1432 for all devices (e.g., terminals) transmitting on the reverse link to device 1404.

At the device 1402, the modulated signal transmitted by the device 1404 is received by an antenna 1416, conditioned and digitized by a receiver ("RCVR") 1434, and processed by a demodulator ("DEMOD") 1436 to obtain detected data symbols. A receive ("RX") data processor 1438 processes the detected data symbols and provides the decoded data and forward link signaling to device 1402. A controller 1440 receives power control commands and other information for controlling data transmission and for controlling transmit power on the reverse link to device 1404.

Controllers 1440 and 1432 direct the various operations of device 1402 and device 1404, respectively. For example, the controller may determine the appropriate filter, report information about the filter, and decode the information using the filter. Data memories 1442 and 1444 may store program codes and data used by controllers 1440 and 1432, respectively.

Fig. 14 also illustrates that the communication components may include one or more components that perform one or more operations taught herein. For example, a media access control ("MAC") component 1446 can cooperate with the controller 1440 and/or other components of the device 1402 to transmit data and control information and to receive data and control information from another device (e.g., device 1404) according to the asynchronous techniques taught herein. Also, the MAC component 1448 can cooperate with the controller 1432 and/or other components of the device 1404 to transmit data and control information and to receive data and control information from another device (e.g., the device 1402) in accordance with asynchronous techniques described herein.

The teachings herein may be incorporated into (e.g., implemented in or performed by) a variety of apparatuses (e.g., devices). For example, each node may be configured or referred to as an access point ("AP"), NodeB, radio network controller ("RNC"), eNodeB, base station controller ("BSC"), base transceiver station ("BTS"), base station ("BS"), transceiver function ("TF"), radio router, radio transceiver, basic service set ("BSs"), extended service set ("ESS"), radio base station ("RBS"), or some other terminology. Some nodes may also be referred to as subscriber stations. A subscriber station can also be known as a subscriber unit, mobile station, remote terminal, access terminal, user agent, user device, or user equipment. In some implementations, a subscriber station may include a cellular telephone, a cordless telephone, a session initiation protocol ("SIP") phone, a wireless local loop ("WALL") station, a personal digital assistant ("PDA"), a handheld device having wireless connection capability, or some other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a phone (e.g., a cellular phone or smart phone), a computer (e.g., a laptop), a portable communication device, a portable computing device (e.g., a personal digital assistant), an entertainment device (e.g., a music or video device or a satellite radio), a global positioning system device, or any other suitable device configured to communicate over a wireless medium.

As described above, in certain aspects, a wireless node may comprise an access device (e.g., a cellular telephone or Wi-Fi access point) of a communication system. Such an access device may provide a connection to or to a network (e.g., a wide area network such as the internet or a cellular network), for example, through a wired or wireless communication link. Thus, the access device may enable other devices (e.g., Wi-Fi stations) to access the network or some other functionality.

The wireless node may thus include various components that perform functions based on data transmitted or received by the wireless node. For example, an access point and an access terminal may include antennas to transmit and receive signals (e.g., control and data). The access point may also include a traffic manager for managing data traffic flows received by a receiver of the access point from a plurality of wireless nodes or transmitted by a transmitter of the access point to the plurality of wireless nodes. In addition, the access terminal can include a user interface for outputting an indication based upon data received by the receiver (e.g., based upon scheduled reception of data) or providing data for transmission by the transmitter.

The wireless devices may communicate via one or more wireless communication links based on or supporting any suitable wireless communication technology. For example, in certain aspects, a wireless device may be associated with a network, or two or more wireless devices may constitute a network. In certain aspects, the network may comprise a local area network or a wide area network. The wireless device may support or use one or more of a variety of wireless communication technologies, protocols, or standards, such as CDMA, TDMA, OFDM, OFDMA, WiMAX, and Wi-Fi. Likewise, the wireless device may support or use one or more of a variety of corresponding modulation or multiplexing schemes. The wireless node may thus include appropriate components (e.g., air interfaces) to establish and communicate using the above or other wireless communication techniques over one or more wireless communication links. For example, a wireless device may include a wireless transceiver with associated transmitter and receiver components (e.g., transmitters 520 and 620 and receivers 518 and 618) that may include various components (e.g., signal generators and signal processors) that facilitate communication over a wireless medium.

The components described herein may be implemented in various ways. Referring to fig. 15-19, several means 1502, 1504, 1602, 1604, 1702, 1704, 1802, 1804, and 1902 are represented as a series of interrelated functional blocks, which represent functions implemented by, for example, one or more integrated circuits (e.g., an ASIC), or which may be implemented in some other manner as taught herein. As discussed herein, an integrated circuit may include a processor, software, other components, or some combination thereof.

The apparatus 1502, 1504, 1602, 1604, 1702, 1704, 1802, 1804, and 1902 may include one or more modules that may perform one or more of the functions described above with reference to the different figures. For example, the ASIC 1506, 1524, 1618, 1716, 1806, 1904, or 1908 used for transmission may, for example, correspond to the transmitter discussed herein. ASICs 1522, 1606, 1620, 1706, 1820, 1906, 1914, or 1918 for receiving, ASICs 1508 or 1808 for monitoring, or ASICs 1622 or 1718 for obtaining information may, for example, correspond to receivers discussed herein. The ASICs 1512, 1528, 1610, 1712, 1810, or 1916 for defining the states may, for example, correspond to the state controllers discussed herein. ASIC 1510 for adjusting transmission parameters, ASIC 1530 or 1922 for determining transmission parameters, ASIC 1526 or 1824 for defining control information, ASIC 1616 or 1714 for defining information may for example correspond to the transmission parameter definer discussed herein. The ASIC 1516 or 1534 for defining the time period may, for example, correspond to the transmit parameter definer discussed herein. The ASIC 1514 or 1912 for issuing the request, the ASIC 1518 for determining whether to issue the request, the ASIC 1536 for adjusting, the ASIC 1612 for determining whether to restrict transmission, the ASIC 1814 for determining whether to abort the request for transmission, the ASIC 1608, 1624, or 1910 for determining whether to restrict transmission, or the ASIC 1920 for determining whether to restrict the request may correspond, for example, to the transmission controller discussed herein. The ASICs 1520, 1614, or 1812 for determining interference may, for example, correspond to the interference determiner discussed herein. The ASIC for scheduling 1532, 1816, or 1822, or the ASIC for determining scheduling 1708, may correspond, for example, to a transmit controller or a receive controller as discussed herein. The ASIC 1624 or 1710 for determining sustainable reception, or the ASIC 1818 for determining whether to forgo sending a grant may, for example, correspond to the reception controller discussed herein.

As mentioned above, in some aspects these components may be implemented by appropriate processor components. In certain aspects, these processor components may be implemented, at least in part, using the structures taught herein. In some aspects, a processor may be adapted to implement some or all of the functionality of one or more of these components. In certain aspects, one or more components represented by dashed boxes are optional.

As described above, the apparatuses 1502, 1504, 1602, 1604, 1702, 1704, 1802, 1804, and 1902 may include one or more integrated circuits. For example, in some aspects a single integrated circuit may implement the functionality of one or more of the components shown, while in other aspects more than one integrated circuit may implement the functionality of one or more of the components shown.

Further, the components and functions illustrated in FIGS. 15-19, as well as other components and functions described herein, may be implemented using any suitable modules. Such a module may be implemented, at least in part, using corresponding structure as taught herein. For example, the components described above in connection with the "ASIC" components of FIGS. 15-19 may also correspond to similarly designated "module" functionality. Thus, in some aspects, one or more such modules may be implemented using one or more processor components, integrated circuits, or other suitable structures as taught herein.

Further, it will be appreciated that any reference to elements herein using a name such as "first," "second," etc., does not generally limit the number or order of such elements. Rather, these names are used herein as a convenient way to distinguish between two or more different nodes. Thus, reference to first and second nodes does not mean that only two nodes are employed, nor does it mean that the first node must somehow precede the second node.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, processors, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware (e.g., a digital implementation, an analog implementation, or combinations of the two, which may be designed using source code or some other technique), various forms of program or design code incorporating instructions (which are referred to herein, for convenience, as "software" or a "software module"), or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

The various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented within or performed by an integrated circuit ("IC"), an access terminal, or an access point. The IC may include a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, electrical components, optical components, mechanical components, or any combination thereof designed to perform the functions described herein, and may execute code or instructions that reside within the IC, outside of the IC, or both. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

It should be understood that any particular order or hierarchy of steps in any disclosed process is an example of exemplary approaches. It should be understood that the specific order or hierarchy of steps in the processes may be rearranged based on design preferences, while remaining within the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The steps of a method or algorithm described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module (e.g., including executable instructions and related data) and other data may reside in a data memory such as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of computer-readable storage medium known in the art. An example storage medium may be coupled to a machine such as a computer/processor (which may be referred to herein, for convenience, as a "processor") such that the processor can read information (e.g., code) from, and write information to, the storage medium. An exemplary storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in user equipment. In the alternative, the processor and the storage medium may reside as discrete components in user equipment. Further, in certain aspects, any suitable computer-program product may comprise a computer-readable medium comprising code (e.g., executable by at least one computer) relating to one or more embodiments of the present disclosure. In certain aspects, a computer program product may include packaging materials.

The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the disclosure. Thus, the present disclosure is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (57)

1. A method at a first wireless node for wireless communication, comprising:

transmitting a request to transmit data to a third wireless node;

receiving a grant from the third wireless node for scheduling the requested data transmission; and is

Transmitting an acknowledgement to the third wireless node in response to the grant, the acknowledgement including information related to the scheduled data transmission,

wherein the method further comprises:

issuing the request to transmit data based on whether transmission of the data interferes with reception at a second wireless node, wherein the second wireless node is a neighboring wireless node to the first wireless node.

2. The method of claim 1, further comprising:

determining whether to transmit the request based on the determination of whether transmission of the data during the scheduled transmission time period would interfere with reception at the second wireless node.

3. The method of claim 2, further comprising:

receiving information indicative of scheduled data reception at the second wireless node; and is

Defining a transmission constraint state based on the received information;

wherein the request to send data is issued based on the send constraint state.

4. The method of claim 3, wherein the transmit constraint state comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission time period, a reception margin, and a received signal strength indication related to a grant or acknowledgement.

5. The method of claim 3, wherein the transmit constraint state is used to determine whether to abstain from transmitting a request for transmission, delay transmission of a request for transmission, adjust a transmission time period, or request to transmit at a reduced power level.

6. The method of claim 3, wherein:

the received information comprises a grant generated by the second wireless node in response to another pair of transmitted requests; and is

The grant comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission period, transmission power, an amount of redundant bits to be transmitted, a code rate, a desired channel-to-interference ratio, a reception margin, and a pilot signal.

7. The method of claim 3, wherein:

the received information comprises an acknowledgement generated by the second wireless node to acknowledge receipt of the transmitted data; and is

The acknowledgement comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission period, transmission power, an amount of redundant bits to be transmitted, a code rate, a desired channel-to-interference ratio, a reception margin, and a pilot signal.

8. The method of claim 1, further comprising:

receiving a resource utilization message comprising at least one of the group consisting of: an indication of a desired level of interference reduction, resources to be cleared, and a degree to which reception at the wireless receiving node does not reach a desired level of quality of service; and is

Determining whether to limit the request to send data based on the resource utilization message.

9. The method of claim 8, wherein the determining whether to limit the request to transmit data comprises at least one of the group consisting of: the method may include the steps of forgoing transmission of a request to transmit, requesting a later transmission, delaying a request to transmit, determining a transmission time period, and requesting transmission at a reduced power level.

10. The method of claim 8, further comprising: performing, in response to the received resource utilization message, at least one of the group consisting of: changing a rate of transmission requests, forgoing transmission of a request message until a resource utilization message of an associated receiver indicates a higher level of disadvantage than a received resource utilization message, changing a length of a scheduled transmission time period, changing a transmit power delta, and modifying a set of rules related to a degree of transmission interference with reception by the second wireless node.

11. The method of claim 1, further comprising:

at least one transmission parameter is defined based on the grant.

12. The method of claim 11, wherein the grant comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission period, transmission power, an amount of redundant bits to be transmitted, a code rate, a desired channel-to-interference ratio, a reception margin, and a pilot signal.

13. The method of claim 1, wherein the scheduling the requested data transmission is based on a determination of whether the second wireless node can sustainably receive the transmitted data while accounting for potential transmissions by other wireless nodes.

14. The method of claim 1, wherein the acknowledgement comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission period, a transmission power increment, a packet format, and a pilot signal.

15. The method of claim 1, wherein:

transmitting data during a plurality of time periods defined within a scheduled transmission time period in accordance with a scheduled data transmission; and is

At least one time interval for transmitting or receiving control information is temporally located between the time periods.

16. The method of claim 15, wherein:

the control information comprises at least one acknowledgement transmitted during the time period for acknowledging receipt of the transmitted data; and is

The at least one acknowledgement comprises at least one of the group consisting of: a transmission start time of at least one of the periods, a transmission end time of at least one of the periods, a transmission time period of at least one of the periods, a transmission power of at least one of the periods, an amount of redundant bits to be transmitted of at least one of the periods, a code rate of at least one of the periods, a desired channel-to-interference ratio of at least one of the periods, a reception margin, and a pilot signal.

17. The method of claim 15, wherein:

the control information comprises at least one acknowledgement sent during the at least one time interval; and is

The at least one acknowledgement comprises at least one of the group consisting of: a transmission start time of at least one of the periods, a transmission end time of at least one of the periods, a transmission time period of at least one of the periods, a transmission power increment, a packet format, and a pilot signal.

18. The method of claim 1, wherein:

the request and the acknowledgement are sent over a control channel and the grant is received over a control channel;

the data is sent through a data channel;

the control channel and the data channel are frequency division multiplexed within a common frequency band; and is

The control channel is associated with a plurality of sub-bands interspersed within the common frequency band.

19. An apparatus for wireless communication, comprising:

a transmitter for transmitting a request to transmit data to a third wireless node; and

a receiver for receiving a grant from the third wireless node for scheduling the requested data transmission;

wherein the transmitter is further configured to transmit an acknowledgement to the third wireless node in response to the grant, the acknowledgement including information related to the scheduled data transmission,

wherein the apparatus further comprises:

a transmission controller to issue the request to transmit data based on whether transmission of the data interferes with reception at a second wireless node, wherein the second wireless node is a neighboring wireless node of the apparatus.

20. The apparatus of claim 19, wherein the transmit controller is further configured to:

determining whether to transmit the request based on the determination of whether transmission of the data during the scheduled transmission time period would interfere with reception at the second wireless node.

21. The apparatus of claim 20, wherein:

the receiver is further for receiving information indicative of scheduled data reception at the second wireless node;

the apparatus further comprises a state controller for defining a transmission constraint state based on the received information; and is

The request to send data is issued based on the send constraint state.

22. The apparatus of claim 21, wherein the transmit constraint state comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission time period, a reception margin, and a received signal strength indication related to a grant or acknowledgement.

23. The apparatus of claim 21, wherein the transmit constraint state is used to determine whether to abstain from transmitting a request for transmission, delay transmission of a request for transmission, adjust a transmission time period, or request to transmit at a reduced power level.

24. The apparatus of claim 21, wherein:

the received information comprises a grant generated by the second wireless node in response to another pair of transmitted requests; and is

The grant comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission period, transmission power, an amount of redundant bits to be transmitted, a code rate, a desired channel-to-interference ratio, a reception margin, and a pilot signal.

25. The apparatus of claim 21, wherein:

the received information comprises an acknowledgement generated by the second wireless node to acknowledge receipt of the transmitted data; and is

The acknowledgement comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission period, transmission power, an amount of redundant bits to be transmitted, a code rate, a desired channel-to-interference ratio, a reception margin, and a pilot signal.

26. The apparatus of claim 19, wherein:

the receiver is further configured to receive a resource utilization message comprising at least one of the group consisting of: an indication of a desired level of interference reduction, resources to be cleared, and a degree to which reception at the wireless receiving node does not reach a desired level of quality of service; and is

The apparatus also includes a transmit controller to determine whether to limit the request to transmit data based on the resource utilization message.

27. The apparatus of claim 26, wherein the determination of whether to limit the request to transmit data comprises at least one of the group consisting of: the method may include the steps of forgoing transmission of a request to transmit, requesting a later transmission, delaying a request to transmit, determining a transmission time period, and requesting transmission at a reduced power level.

28. The apparatus of claim 26, wherein the transmit controller is further for performing at least one of the group consisting of: changing a rate of transmission requests, forgoing transmission of a request message until a resource utilization message of an associated receiver indicates a higher level of disadvantage than a received resource utilization message, changing a length of a scheduled transmission time period, changing a transmit power delta, and modifying a set of rules related to a degree of transmission interference with reception by the second wireless node.

29. The apparatus of claim 19, further comprising:

a transmission parameter definer for defining at least one transmission parameter based on the grant.

30. The apparatus of claim 29, wherein the grant comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission period, transmission power, an amount of redundant bits to be transmitted, a code rate, a desired channel-to-interference ratio, a reception margin, and a pilot signal.

31. The apparatus of claim 19, wherein the scheduling the requested data transmission is based on a determination of whether the second wireless node can sustainably receive the transmitted data in view of potential transmissions by other wireless nodes.

32. The apparatus of claim 19, wherein the acknowledgement comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission period, a transmission power increment, a packet format, and a pilot signal.

33. The apparatus of claim 19, wherein:

transmitting data during a plurality of time periods defined within a scheduled transmission time period in accordance with a scheduled data transmission; and is

At least one time interval for transmitting or receiving control information is temporally located between the time periods.

34. The apparatus of claim 33, wherein:

the control information comprises at least one acknowledgement transmitted during the time period for acknowledging receipt of the transmitted data; and is

The at least one acknowledgement comprises at least one of the group consisting of: a transmission start time of at least one of the periods, a transmission end time of at least one of the periods, a transmission time period of at least one of the periods, a transmission power of at least one of the periods, an amount of redundant bits to be transmitted of at least one of the periods, a code rate of at least one of the periods, a desired channel-to-interference ratio of at least one of the periods, a reception margin, and a pilot signal.

35. The apparatus of claim 33, wherein:

the control information comprises at least one acknowledgement sent during the at least one time interval; and is

The at least one acknowledgement comprises at least one of the group consisting of: a transmission start time of at least one of the periods, a transmission end time of at least one of the periods, a transmission time period of at least one of the periods, a transmission power increment, a packet format, and a pilot signal.

36. The apparatus of claim 19, wherein:

the request and the acknowledgement are sent over a control channel and the grant is received over a control channel;

the data is sent through a data channel;

the control channel and the data channel are frequency division multiplexed within a common frequency band; and is

The control channel is associated with a plurality of sub-bands interspersed within the common frequency band.

37. An apparatus for wireless communication, comprising:

means for transmitting a request to transmit data to a third wireless node;

means for receiving a grant from the third wireless node for scheduling the requested data transmission; and

means for transmitting an acknowledgement to the third wireless node in response to the grant, the acknowledgement including information related to the scheduled data transmission,

wherein the apparatus further comprises:

means for issuing the request to transmit data based on whether transmission of the data interferes with reception at a second wireless node, wherein the second wireless node is a neighboring wireless node of the apparatus.

38. The apparatus of claim 37, further comprising:

means for determining whether to transmit the request based on the determination of whether transmission of the data during the scheduled transmission time period would interfere with reception at the second wireless node.

39. The apparatus of claim 38, wherein:

the means for receiving is further for receiving information indicative of scheduled data reception at the second wireless node;

the apparatus further comprises means for defining a transmit constraint state based on the received information; and is

The request to send data is issued based on the send constraint state.

40. The apparatus of claim 39, wherein the transmit constraint state comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission time period, a reception margin, and a received signal strength indication related to a grant or acknowledgement.

41. The apparatus of claim 39, wherein the transmit constraint state is used to determine whether to abstain from transmitting a request for transmission, delay transmission of a request for transmission, adjust a transmission time period, or request to transmit at a reduced power level.

42. The apparatus of claim 39, wherein:

the received information comprises a grant generated by the second wireless node in response to another pair of transmitted requests; and is

The grant comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission period, transmission power, an amount of redundant bits to be transmitted, a code rate, a desired channel-to-interference ratio, a reception margin, and a pilot signal.

43. The apparatus of claim 39, wherein:

the received information comprises an acknowledgement generated by the second wireless node to acknowledge receipt of the transmitted data; and is

The acknowledgement comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission period, transmission power, an amount of redundant bits to be transmitted, a code rate, a desired channel-to-interference ratio, a reception margin, and a pilot signal.

44. The apparatus of claim 37, wherein:

the means for receiving is further configured to receive a resource utilization message comprising at least one of the group consisting of: an indication of a desired level of interference reduction, resources to be cleared, and a degree to which reception at the wireless receiving node does not reach a desired level of quality of service; and is

The apparatus also includes means for determining whether to limit the request to send data based on the resource utilization message.

45. The apparatus of claim 44, wherein the determination of whether to limit the request to transmit data comprises at least one of the group consisting of: the method may include the steps of forgoing transmission of a request to transmit, requesting a later transmission, delaying a request to transmit, determining a transmission time period, and requesting transmission at a reduced power level.

46. The apparatus of claim 44, wherein the means for determining further performs at least one of the group consisting of, in response to the received resource utilization message: changing a rate of transmission requests, forgoing transmission of a request message until a resource utilization message of an associated receiver indicates a higher level of disadvantage than a received resource utilization message, changing a length of a scheduled transmission time period, changing a transmit power delta, and modifying a set of rules related to a degree of transmission interference with reception by the second wireless node.

47. The apparatus of claim 37, further comprising:

means for defining at least one transmission parameter based on the grant.

48. The apparatus of claim 47, wherein the grant comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission period, transmission power, an amount of redundant bits to be transmitted, a code rate, a desired channel-to-interference ratio, a reception margin, and a pilot signal.

49. The apparatus of claim 37, wherein the scheduling the requested data transmission is based on a determination of whether the second wireless node can sustainably receive the transmitted data in view of potential transmissions by other wireless nodes.

50. The apparatus of claim 37, wherein the acknowledgement comprises at least one of the group consisting of: a transmission start time, a transmission end time, a transmission period, a transmission power increment, a packet format, and a pilot signal.

51. The apparatus of claim 37, wherein:

transmitting data during a plurality of time periods defined within a scheduled transmission time period in accordance with a scheduled data transmission; and is

At least one time interval for transmitting or receiving control information is temporally located between the time periods.

52. The apparatus of claim 51, wherein:

the control information comprises at least one acknowledgement transmitted during the time period for acknowledging receipt of the transmitted data; and is

The at least one acknowledgement comprises at least one of the group consisting of: a transmission start time of at least one of the periods, a transmission end time of at least one of the periods, a transmission time period of at least one of the periods, a transmission power of at least one of the periods, an amount of redundant bits to be transmitted of at least one of the periods, a code rate of at least one of the periods, a desired channel-to-interference ratio of at least one of the periods, a reception margin, and a pilot signal.

53. The apparatus of claim 51, wherein:

the control information comprises at least one acknowledgement sent during the at least one time interval; and is

The at least one acknowledgement comprises at least one of the group consisting of: a transmission start time of at least one of the periods, a transmission end time of at least one of the periods, a transmission time period of at least one of the periods, a transmission power increment, a packet format, and a pilot signal.

54. The apparatus of claim 37, wherein:

the request and the acknowledgement are sent over a control channel and the grant is received over a control channel;

the data is sent through a data channel;

the control channel and the data channel are frequency division multiplexed within a common frequency band; and is

The control channel is associated with a plurality of sub-bands interspersed within the common frequency band.

55. An apparatus for wireless communication, comprising:

an ASIC for transmitting a request configured to transmit a request to transmit data to a third wireless node; and is

An ASIC for receiving a grant configured to receive a grant from the third wireless node for scheduling the requested data transmission;

an ASIC for transmitting an acknowledgement configured to transmit an acknowledgement to the third wireless node in response to the grant, the acknowledgement including information related to the scheduled data transmission

Wherein the apparatus further comprises:

an ASIC for issuing a request, configured to issue the request to transmit data based on whether transmission of the data interferes with reception at a second wireless node, wherein the second wireless node is a neighboring wireless node of the apparatus.

56. An access point for wireless communication, comprising:

an antenna;

a transmitter for transmitting a request to transmit data to a third wireless node through the antenna; and

a receiver for receiving a grant from the third wireless node for scheduling the requested data transmission;

wherein the transmitter is further configured to transmit an acknowledgement to the third wireless node in response to the grant, the acknowledgement including information related to the scheduled data transmission,

wherein the access point issues the request to transmit data based on whether transmission of the data interferes with reception at a second wireless node, wherein the second wireless node is a neighboring wireless node to the access point.

57. An access terminal for wireless communication, comprising:

a transmitter for transmitting a request to transmit data to a third wireless node;

a receiver for receiving a grant from the third wireless node for scheduling the requested data transmission; and

an interface for outputting an indication based on data received by the receiver;

wherein the transmitter is further configured to transmit an acknowledgement to the third wireless node in response to the grant, the acknowledgement including information related to the scheduled data transmission,

wherein the access terminal issues the request to transmit data based on whether transmission of the data interferes with reception at a second wireless node, wherein the second wireless node is a neighboring wireless node of the access terminal.