HK1152191A - Method and apparatus for frequency reuse in a multi-carrier communications system - Google Patents

Abstract

Systems and methods are described that facilitate evaluating conditions of nodes (e.g., access points, access terminals, etc.) in a wireless communication environment having a plurality of carriers to determine a level of disadvantage for a given node relative to other nodes. The node may transmit a resource utilization message (RUM) that represents the level of disadvantage for the node and request other interference nodes to back off on one or more carriers. This would allow frequency reuse if nodes vary the power of transmission for particular carriers, in conjunction with neighboring nodes.

Description

Method and apparatus for frequency reuse in a multi-carrier communication system

Technical Field

The following description relates generally to wireless communications, and more particularly to reducing interference and improving throughput and channel quality in a wireless communication environment.

Background

Wireless communication systems have become a prevalent means by which a majority of people worldwide have come to communicate. Wireless communication devices have become smaller and more powerful to meet consumer needs and to improve portability and convenience. The increase in processing power in mobile devices, such as cellular telephones, has led to an increase in demand for wireless network transmission systems. Such systems are typically not as easily updated as the cellular devices that communicate thereon. As mobile device capabilities expand, maintaining older wireless network systems in a manner that facilitates fully exploiting new and improved wireless device capabilities can be difficult.

A typical wireless communication network (e.g., employing frequency, time, and code division techniques) includes one or more base stations that provide a coverage area and one or more mobile (e.g., wireless) terminals that can transmit and receive data within the coverage area. A typical base station can simultaneously transmit multiple data streams for broadcast, multicast, and/or unicast services, wherein a data stream is a stream of data that can be of independent reception interest to a mobile device. A mobile terminal within the coverage area of that base station can be interested in receiving one, more than one, or all the data streams carried by the composite stream. Likewise, a mobile terminal may transmit data to the base station or another mobile terminal. This communication between the base station and the mobile terminal or between the mobile terminals may be degraded due to channel variations and/or interference power variations. Accordingly, there is a need in the art for systems and/or methods that facilitate reducing interference and improving throughput in a wireless communication environment.

Disclosure of Invention

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

According to various aspects, the present innovation relates to providing unified techniques for wide and local area wireless communication networks in order to facilitate achieving the benefits associated with cellular and Wi-Fi technologies while mitigating disadvantages associated therewith. For example, cellular networks may be arranged according to a planned deployment, which may increase efficiency when designing or building the network, while Wi-Fi networks are typically deployed in a more convenient, dedicated manner. Wi-Fi networks may additionally facilitate providing symmetric Media Access Control (MAC) channels for access points and access terminals, as well as backhaul support with in-band wireless capabilities, which are not provided by cellular systems.

The unified techniques described herein facilitate deploying a network in a flexible manner. The approach described in this disclosure allows adapting performance according to the deployment, thus providing good efficiency if the deployment is planned or semi-planned, and sufficient robustness if the network is unplanned. That is, the various aspects described herein permit a network to be deployed using planned deployments (e.g., as in a cellular deployment scenario), dedicated deployments (e.g., such as may be used for Wi-Fi network deployments), or a combination of both. Still further, other aspects relate to supporting nodes with varying transmit power levels and enabling inter-cell fairness with respect to resource allocation, which are not adequately supported by Wi-Fi or cellular systems.

For example, according to some aspects, weighted fair sharing of a set of wireless carriers may be facilitated by joint scheduling of transmissions by both a transmitter and a receiver using Resource Utilization Messages (RUMs), whereby the transmitter requests a set of resources based on knowledge of availability in its neighborhood, and the receiver grants a subset of the requested carriers based on knowledge of availability in its neighborhood. The transmitter learns of availability based on listening to the receivers in its vicinity, and the receiver learns of potential interference by listening to the transmitters in its vicinity. According to related aspects, RUMs may be weighted to indicate not only that the node receiving the data transmission is faulty (due to the interference it experiences when receiving) and requires a collision avoidance transmission mode, but also the extent to which the node is faulty. The RUM-receiving node may utilize the fact that it has received a RUM and its weight to determine an appropriate response. As an example, this announcement of weights makes collision avoidance possible in a fair manner. The present invention describes this method.

According to related aspects, a RUM-sending node may indicate its degree of disadvantage by indicating the number of carriers to which the RUM applies, such that the number of carriers (which may be resources, channels, frequency carriers/subcarriers, and/or time slots, in general) indicates the degree of disadvantage. If the level of disadvantage is reduced in response to a RUM, the number of carriers used for RUM transmission may be reduced for subsequent RUM transmissions. If the level of the disadvantage is not reduced, the number of carriers to which the RUM applies may be increased for subsequent RUM transmissions.

The RUM may be sent at a constant Power Spectral Density (PSD), and the receiving node may estimate the Radio Frequency (RF) channel gain between itself and the RUM sending node using the received power spectral density and/or the received power of the RUM to determine whether interference at the sending node will result (e.g., above a predetermined acceptable threshold level) if it transmits. Thus, there may be situations where a RUM receiving node is able to decode a RUM from a RUM sending node, but determines that the RUM receiving node will not cause interference. When a RUM-receiving node determines that it should obey a RUM, it may do so by choosing to either completely yield from that resource or by choosing to use a sufficiently reduced transmit power (such that its estimated potential interference level is below a predetermined acceptable threshold level). Thus, both "hard" interference avoidance (full yielding) and "soft" interference avoidance (power control) are supported in a unified manner. According to related aspects, a RUM may be used by a receiving node to determine a channel gain between the receiving node and a RUM sending node in order to facilitate determining whether to transmit based on estimated interference caused at the sending node.

In a power control interference avoidance approach, nodes, such as access points, may be organized in a manner to serve associated nodes (e.g., access terminals) that are close to them with low transmit power using the same set of carriers. The remainder of the carrier is used with higher transmit power and may be used by both distant and close associated nodes. To minimize interference of high power carriers by clients, such as neighboring nodes of an access point, the cell containing a node and its associated node is further organized in such a way that two neighboring cells do not use the same high power carrier. Thus, a remote associated terminal of the node will not experience the high power carrier as an interfering neighbor node. This approach is also referred to as a flexible bandwidth or flexible band approach.

According to an aspect, a method for transmitting data may include receiving at least one RUM associated with a plurality of resources; determining a transmission profile for at least one resource of the plurality of resources based on the at least one RUM; and scheduling a transmission on the at least one resource based on the transmission profile.

Another aspect relates to an apparatus for transmitting data, comprising: means for receiving at least one RUM associated with a plurality of resources; means for determining a transmission profile for at least one resource of the plurality of resources based on the at least one RUM; and means for scheduling a transmission on the at least one resource based on the transmission profile.

Another aspect relates to an access point having an antenna and a processing system coupled to the antenna. The processing system is configured to receive, via the antenna, at least one RUM associated with a plurality of resources; determining a transmission profile for at least one resource of the plurality of resources based on the at least one RUM; and scheduling a transmission on the at least one resource based on the transmission profile.

Another aspect relates to an access terminal having a transducer and a processing system coupled to the transducer. The processing system is configured to receive at least one RUM for a plurality of resources available to communicate data usable with the transformer; determining a transmission profile for at least one resource of the plurality of resources based on the at least one RUM; and scheduling a transmission on the at least one resource based on the transmission profile.

Another aspect relates to a computer program product for communicating data having a computer-readable medium with code executable to: receiving at least one RUM associated with a plurality of resources; determining a transmission profile for at least one resource of the plurality of resources based on the at least one RUM; and scheduling a transmission on the at least one resource based on the transmission profile.

Another aspect relates to an apparatus for communicating data having a processing system. The processing system is configured to receive at least one RUM associated with a plurality of resources; determining a transmission profile for at least one resource of the plurality of resources based on the at least one RUM; and scheduling a transmission on the at least one resource based on the transmission profile.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects of the one or more aspects. These aspects are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed and the described aspects are intended to include all such aspects and their equivalents.

Drawings

Fig. 1 is a network diagram of an exemplary wireless communication system with multiple access points and multiple access terminals, e.g., a communication system that can be utilized in connection with one or more aspects of a method for managing interference through the use of Resource Utilization Messages (RUMs).

Fig. 2 is a process diagram of a series of request-grant events that may facilitate resource allocation in accordance with one or more aspects described herein.

FIG. 3 is a flow chart of an exemplary method for generating a RUM.

Fig. 4 is a diagram of a carrier mask-to-carrier mapping scheme for use in a RUM in a multi-carrier system, in accordance with one or more aspects.

Fig. 5 is an illustration of a methodology for implementing a flexible band system using a pseudo-random carrier mask, in accordance with one or more aspects.

Fig. 6 is an illustration of a methodology for creating dynamic learning/adjustment of neighboring base station carrier masks, in accordance with one or more aspects.

Fig. 7 is an illustration of a method for an access terminal to request bandwidth from an access point based on a received RUM, in accordance with one or more aspects.

Fig. 8 is an illustration of a series of carrier masks created based on one or more received RUMs, in accordance with one or more aspects.

Fig. 9 is an illustration of a method for determining the number and selection of carriers to be requested as part of a request transmitted by an access terminal to an access point and determining the number and selection of carriers to be granted as part of a request grant by the access terminal to the access terminal.

Fig. 10 is a flow chart illustrating a carrier mask creation process based on a pseudo-random carrier mask priority list.

Fig. 11 is a diagram for explaining an operation of the pseudo random carrier selection process of fig. 10.

Fig. 12 is a flow chart illustrating a carrier mask creation process based on a prioritized list of carrier mask priorities using interfering thermal measurements.

Fig. 13 is a flow diagram illustrating a power adjustment process based on an estimate made by a node of a carrier on which an interfering node will cause least/most interference.

Fig. 14 is a block diagram illustrating the creation of a carrier mask based on the carrier selection process of fig. 13.

Fig. 15 is an illustration of a method for generating a grant of a request to transmit, in accordance with one or more aspects.

Fig. 16 is an illustration of a wireless network environment that can be employed in conjunction with the various systems and methods described herein.

Fig. 17 is an illustration of an apparatus that facilitates wireless data communication in accordance with various aspects.

Fig. 18 is an illustration of an apparatus that facilitates wireless communication using a RUM, in accordance with one or more aspects.

Fig. 19 is an illustration of an apparatus that facilitates scheduling transmissions based on a transmission profile.

Detailed Description

Various aspects of the invention 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 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 practiced using any number of the aspects set forth 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. Furthermore, an aspect may comprise at least one element of a claim.

The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects. Further, references to a list of elements including "at least one of A, B and C" should be interpreted as referring individually to each of elements A, B and C and any combination of elements A, B and C. Additionally, the description also utilizes networks involving the IEEE 802.11 standard, networks utilizing other protocols may benefit from the various techniques and systems disclosed herein.

It should be understood that a "node" as used herein may be an access terminal or access point, and each node may be a receiving node as well as a transmitting node. For example, each node may include at least one receive antenna and associated receiver chain, and at least one transmit antenna and associated transmit chain. Further, each node may include one or more processors that execute software code for performing any and all of the methods and/or protocols described herein, as well as memory for storing data and/or computer-executable instructions associated with the various methods and/or protocols described herein.

Fig. 1 illustrates several sample aspects of a wireless communication system 100. System 100 includes several wireless nodes, generally designated as nodes 102 and 104. A given node may receive and/or transmit one or more traffic flows (e.g., data flows). For example, each node may include at least one antenna and associated receiver and transmitter components. In the following discussion, the term receiving node may be used to refer to a node that is receiving and the term transmitting node may be used to refer to a node that is transmitting. This reference does not imply that the node is not capable of performing both transmit and receive operations.

The nodes may be implemented in various ways. For example, in some implementations, a node may comprise an access terminal, relay point, or access point. Referring to fig. 1, node 102 may comprise an access point or relay point and node 104 may comprise an access terminal. In some embodiments, node 102 facilitates communication between nodes of a network (e.g., a Wi-Fi network, a cellular network, or a WiMAX network). For example, when an access terminal (e.g., access terminal 104A) is within the coverage area of an access point (e.g., access point 102A) or a relay point, the access terminal 104A may thereby communicate with another device of the system 100 or some other network coupled to communicate with the system 100. Here, one or more of the nodes (e.g., nodes 102B and 102D) may include a wired access point that provides connectivity to another or more networks (e.g., wide area network 108, such as the internet).

In some aspects, two or more nodes (e.g., nodes of a common independent service group) in system 100 are associated with each other to establish traffic flows between the nodes via one or more communication links. For example, nodes 104A and 104B may associate with each other via corresponding access points 102A and 102C. Thus, one or more traffic flows may be established to and from access terminal 104A via access point 102A, and one or more traffic flows may be established to and from access terminal 104B via access point 102C.

In some cases, several nodes in system 100 may attempt to transmit simultaneously (e.g., during the same time slot). Depending on the relative positions of the transmitting and receiving nodes and the transmit power of the transmitting node, such simultaneous communication may not be reliably possible. In these cases, the wireless resources of system 100 may be well utilized as compared to, for example, a system that uses only a carrier sense multiple access ("CSMA") mode of operation.

In these cases, however, wireless transmissions from nodes in system 100 may interfere with reception at non-associated nodes in system 100. For example, node 104B may receive from node 102C (as represented by wireless communication symbol 106A) while node 102D is transmitting to node 104C (as represented by symbol 106B). Depending on the distance between nodes 104B and 102D and the transmit power of node 102D, transmissions from node 102D (as represented by dashed symbol 106C) may interfere with reception at node 104B. In a similar manner, depending on the transmit power of the node 104B, transmissions from the node 104B may interfere with reception at the node 102D.

To mitigate such interference, for example, nodes of a wireless communication system may employ an inter-node messaging scheme. For example, a receiving node that is experiencing interference may transmit a Resource Utilization Message (RUM) in some manner that indicates that the node has a drawback. Neighboring nodes that receive RUMs, which may be potential interferers, may choose to limit their future transmissions in some manner to avoid interfering with the node that sent the RUM-i.e., the receiving node that sent the RUM. Further, the decision by the receiving node to transmit a RUM may be based, at least in part, on the quality of service associated with the data received at that node.

The request message, grant message, and data transmissions may be power controlled: however, the node may still experience excessive interference that results in unacceptable levels of its signal to interference noise (SINR). To mitigate undesirably low SINR, RUM may be utilized. A RUM may be broadcast by a receiver when an interference level on a desired carrier of the receiver exceeds a predetermined threshold level. As discussed herein, in an aspect of the deployment of RUMs, a receiving node sends out a RUM when the receiving node is unable to meet its quality of service (QoS) requirements. The QoS requirements may be predetermined and may be expressed in terms of throughput (e.g., for full buffer traffic), latency (e.g., for voice traffic), average spectral efficiency, minimum carrier-to-interference (C/I) ratio, or other suitable metric. The RUM encapsulates a weight that represents the degree of disadvantage faced by the node that is transmitting the RUM. In other words, the degree of disadvantage in using weights varies with the QoS of the node and its desired QoS. This RUM weight may be quantized using a predetermined number of bits.

A "shortcoming" as used herein may be determined, for example, as a function of a ratio of a target value to an actual value for a given node. For example, when a drawback is measured as a function of throughput, spectral efficiency, data rate, or some other parameter if a higher value is desirable, then when a node has a drawback, the actual value will be relatively lower than the target value. In these cases, the weighted value indicative of the level of the disadvantage of the node may be a function of the ratio of the target value to the actual value. In cases where the parameter on which the flaw is required to be based is low (e.g., latency), the inverse of the ratio of the target value to the actual value may be used to generate the weight. As used herein, a node described as having a "better" condition relative to another node may be understood as having a lesser level of disadvantage (e.g., a node having a better condition has less interference, less latency, a higher data rate, a higher throughput, a higher spectral efficiency, etc. than another node to which it is compared).

By using RUMs, a receiving node (e.g., an access point) may block interfering nodes that cause too much interference to it. In other words, the receiving node may request other nodes to transmit on the carrier. In a network design where the bandwidth contains only one carrier, when a RUM is sent by a receiving node, the entire bandwidth is blocked for its intended access terminal. Through a multi-carrier communication system (where the available bandwidth is divided into separate portions-each of which is referred to as a carrier or channel); only certain carriers may be blocked so that the receiving node may still achieve its desired throughput while limiting the impact on the rest of the system.

For example, the available bandwidth in a multi-carrier communication system may be divided into four (4) carriers. Each transmitting node may then be scheduled to transmit on one (1) or more carriers, thereby allowing better sharing of resources. To ensure interference avoidance in a fair manner-i.e., to ensure that all nodes get a fair transmitter encounter, the RUM may contain a list of carriers on which the receiving node needs reduced interference, as described herein, along with the aforementioned weight information. The weight of a given receiving node may be used to compute a fair share of the resources for allocation to the node.

Fig. 2 illustrates an exemplary request-grant event sequence 200 that involves the use of RUMs to facilitate resource allocation, in accordance with one or more aspects described herein. In the example shown in the figure, the associated node pair 290 includes an access terminal 292 and a first access point 1294, and a second access point 2296 that is not associated with the associated node pair 290.

Sequence 200 begins at 204 and 206 during which access point 1294 and access point 2296 each generate a RUM to be broadcast to other nodes, including access terminal 292. The RUM includes a weight that indicates how faulty the access point is and on which carriers the access point wishes to block other nodes from transmitting, as further described herein with reference to fig. 3.

In 212, access point 1294 and access point 2296 broadcast their respective RUMs to a node, e.g., access terminal 292.

In 222, the access terminal 292 processes all RUMs received in 212. RUM processing performed by the access terminal 292 is described herein with reference to fig. 7.

If, in 232, the access terminal 292 determines that there are available carriers after processing the received RUM, then, in 242, the access terminal 292 will determine the carrier on which the access terminal 292 wishes to send a request to transmit from the access point 1294.

At 252, a transmission request is sent from the access terminal 292 to the access point 1294. The request may include a list of carriers on which the access terminal 292 is willing to transmit data. The sequence of events 200 may be performed in view of a number of constraints that may be enforced during the communication event. For example, the access terminal 292 may request any carrier(s) that have not been blocked by a RUM in a previous slot. The requested carriers may be prioritized by biasing the successful carriers in the most recent transmission cycle.

In 264, the access point 1294 determines, based on the request received from the access terminal 292, the carrier on which the access terminal 292 will be granted to transmit. The grant may include all or a subset of the requested carriers. Thus, the grant from the access point 1294 may be a subset of the carriers listed in the request sent by the access terminal 292. Access point 1294 may be granted the authority to avoid carriers that exhibit high interference levels during the most recent transmission.

In 272, the access point 1294 may then send a grant message to the access terminal 292 indicating that all or a subset of the requested carriers have been granted.

In 282, the access terminal 292 can then transmit a pilot message to the access point 1294, upon receipt of which the access point 1294 can transmit rate information back to the access terminal 292 to facilitate mitigating the undesirably low SINR. Upon receiving the rate information, the access terminal 292 may continue with data transmission on the granted carrier and at the indicated transmission rate. Additionally, when transmitting, the access terminal 292 may send data on all or a subset of the carriers granted in the grant message. Access terminal 292 may reduce transmit power on some or all carriers during its data transmission.

Fig. 3 is an illustration of a methodology 300 for generating a RUM in a multi-carrier system, in accordance with various aspects described above. In accordance with one or more aspects, a method for achieving fairness among competing nodes is performed by adjusting a number of carriers for which RUMs are transmitted according to a level of disadvantage associated with a given mode. As described herein, a RUM is sent out by a receiving node, such as an access point, to indicate that it is experiencing poor communication conditions and wants to reduce the interference it faces. The RUM includes a weight that quantifies the degree of disadvantage that the node is experiencing. According to an aspect, the weight may be set as a function of a threshold referred to as a RUM transmission threshold (RST). In another aspect, the weight may be set to an average throughput. Furthermore, RST is the average throughput required by the node. When a transmitting node, e.g., an access terminal, hears multiple RUMs, it may utilize respective weights to resolve contention among the RUMs. For example, if an access terminal receives multiple RUMs and the RUM with the highest weight originates from the access point of the access terminal itself, it may decide to transmit a request to send data to its access point. If not, the access terminal may refrain from transmitting.

RUMs allow an access point to clear interference in its immediate neighborhood because the node receiving the RUM may be induced to refrain from transmitting. While the weights allow for fair contention (e.g., the access point with the greatest disadvantage wins), having a multi-carrier MAC may provide another degree of freedom. In particular, when the system supports multiple carriers, the RUM may carry CM (i.e., bit mask) in addition to the weights. The CM indicates the carrier where this RUM is applicable. The number of carriers for which an access point may send a RUM may be based on its degree of disadvantage to allow nodes with very poor history to keep up faster. When a RUM is successful and the transmission rate received by the access point in response to it improves its conditions, the access point may reduce the number of carriers for which it sends RUMs. If the RUM is initially unsuccessful due to severe congestion and the throughput is not improved, the access point may increase the number of carriers for which it sends the RUM. In very congested situations, the access point may become highly disadvantaged and may send RUMs for all carriers, thereby degrading to a single carrier case.

At 302, a defect level of an access point may be determined, and a RUM may be generated that indicates the defect level to other nodes within "listening" range (i.e., whether they sent data to the access point), wherein the RUM includes information indicating that a first predetermined threshold has been met or exceeded. For example, the first predetermined threshold may represent, for example, a level of interference over thermal noise (IOT), a data rate, a C/I ratio, a throughput level, a spectral efficiency level, a latency level, or any other suitable measure by which service at the first node may be measured.

At 304, the RUM may be weighted so as to indicate the extent to which a second predetermined threshold has been exceeded. For example, the second predetermined threshold may represent a level of IOT noise, a data rate, a C/I ratio, a throughput level, a spectral efficiency level, a latency level, or any other suitable measure by which a level of service at the first node may be measured. According to some aspects, the weighting value may be a quantized value. Although the first and second predetermined thresholds may be substantially equal, they need not be.

The weight information carried in each RUM is intended to communicate to all nodes within listening range to the extent that the access point lacks bandwidth due to interference from other transmissions. The weight may represent the degree of the disadvantage, and may be larger when the access point has more disadvantages and smaller when there are fewer disadvantages. Various factors may be used to derive the degree of disadvantage. As an example, if throughput is used to measure the degree of shortcoming, one possible relationship may be expressed as:

wherein R is_targetIndicating the desired throughput, R_actualIs the actual throughput being achieved, and q (x) represents the quantization value x. When there is a single flow at the access point, then R_targetMay represent the minimum desired throughput for that flow, and R_actualMay represent the average throughput that has been achieved for that flow. Note that higher value weights indicate a greater degree of disadvantage as a matter of habit. As an example, assume that the desired throughput for a node is 500 kbps. However, the node only achieves a practical throughput of 250 kbps. In this case, it may be based on the need to double the current throughput (500kbps/250kbps ═ c)2) The weights are calculated by the nodes that achieve the desired throughput.

In a similar manner, the convention of representing a lower degree of disadvantage with a higher value weight may be utilized, so long as the weight resolution logic is appropriately modified. For example, the weights may be calculated using the ratio of actual throughput to target throughput (the inverse of the example shown above). Thus, using the above values, the ratio would be 250kbps/500kbps, which would be 1/2 or 50% of the target throughput.

When there is a potentially different R at the access point_targetMultiple streams of values, the access point may choose to set the weights based on the most imperfect streams. For example:

where j is the flow index at the access point. Other options may also be performed, such as basing the weights on the sum of the stream throughputs. Note that the functional form used for the weights in the above description is purely illustrative. The weights may be calculated in a number of different ways and using different metrics than throughput. According to related aspects, an access point may determine whether it has unprocessed data from a sender (e.g., a transmitter). If it has received a request, or if it has received a previous request that it has not granted, then there is unprocessed data. In this case, when R_actualLower than R_targetThe access point may send out a RUM.

In addition, the weights may be normalized with respect to maximum and minimum values. For example, the weights may be normalized to a value between 0 and 1. A normalized value may be determined based on the received RUM weights, with the highest received RUM weight set to a value of 1 and the lowest received RUM weight set to a value of 0.

An additional dimension for collision avoidance may be achieved if the list of carriers in the RUM that the node wants to reduce interference is included with weights in the RUM, which may be useful when a receiving node, such as an access point, needs to schedule reception of a small amount of data on a portion of the channel and does not want other nodes to yield from the entire channel. The carrier list may be implemented with a bit mask that contains information about which carriers the access point wishes to reduce interference. When each RUM is augmented with a bit mask, also referred to herein as a Carrier Mask (CM), a node may reduce interference from its neighboring nodes (e.g., access points or access terminals) on a subset of carriers, rather than all carriers. This aspect may provide finer granularity of collision avoidance mechanisms, which may be important for bursty traffic. In addition, the CM may also be used to generate requests transmitted by the access terminal in requesting a portion of the channel, and to generate grants for the requests by the access point in response to the requests (e.g., the response may be a grant for a portion of the channel).

Referring to fig. 4, in the case of dividing the bandwidth into 4 carriers, the CM 400 contained in the RUM will have a form XXXX, where each X is a bitmap, which may be: a "1" indicating that the carrier it refers to is to be blocked (i.e., the interference above will be reduced); or "0" indicating that the carrier it refers to is not blocked. Additionally, in the described exemplary implementation, where the carriers are numbered "0", "1", "2", "3", the leftmost bit 402 in the CM 400 is the bit mask for carrier "3", the second bit 404 to the right of the leftmost bit 402 is the bit mask for carrier "2", the third bit 406 to the right of the second bit 404 is the bit mask for carrier "1", and the fourth bit 408 to the right of the third bit 406 is the bit mask for carrier "0". For aspects in which the entire bandwidth may be blocked by a RUM, the RUM will contain a CM with a full "1" indicating that the access point wants to block each carrier in the bandwidth. Other aspects provide for using the CM to indicate a number of carriers allocated to the access point. For example, a 6-bit mask may be utilized to indicate that a RUM may be sent for up to six carriers. The access point may additionally request that the interfering node refrain from transmitting on all or a subset of the allocated subcarriers.

At 306 and 308, during the creation of a CM to implement fractional bandwidth interference management, both of the variables that need to be determined are the number of carriers that should be blocked by the access point and the specific identity of the carriers that should be subject to blocking.

At 310, the weighted and masked RUM may be transmitted to one or more other nodes. As discussed herein, when a node hears a RUM, it needs only the carriers specified in the carrier mask to obey the RUM. For example, when an access terminal needs to obey multiple RUMs from different access points, it must perform an or operation on the carriers in all the RUM carrier masks-the complement of this mask indicates the carriers that the access terminal is able to request from the access point.

In an aspect of a system, a node, such as an access point, is organized in a manner to serve associated access terminals proximate thereto using a first set of carriers at a first transmit power level. The remaining portion of the carrier is used with the second transmit power level and may be used by both distant and close associated access terminals. The first transmit power level is lower than the second transmit power level. The carriers assigned to the first transmit power level are referred to as low power carriers and the carriers assigned to the second transmit power level are referred to as high power, respectively. To minimize interference of high power carriers of clients of neighboring access terminals, the cells are further organized in such a way that two neighboring cells do not use the same high power carrier. Thus, close and distant subscribers of the access point will not be affected by the high power carrier of the neighboring access point as interference.

In one exemplary implementation, a dynamic bandwidth sharing flexible band system is created in the forward link using a multi-carrier RUM, following the process 500 illustrated in fig. 5. In step 502, each base station generates a dynamic carrier mask. In an aspect, a dynamic carrier mask is generated based on a pseudo-random sequence, as further described herein. In each time slot, the node generates a new carrier mask and uses this to select the blocked carrier.

In step 504, each access terminal associated with the access point is provided with a common carrier mask. In an aspect, this may be ensured by providing the associated access terminal with the same key that the access point used to generate the pseudorandom sequence.

In step 506, when one or more of the associated access terminals need to perform interference management, they send out RUMs following a common carrier mask (such as in 222 of fig. 2). In fact, all access terminals associated with an access point will send out RUMs using the same carrier mask as that generated by the access point. Different access terminals associated with the same access point may send out RUMs for different numbers of carriers, but will use the same carrier mask priority sequence.

In step 508, neighboring access points may hear one or more of these RUMs sent from the access terminal, e.g., in 224 and 226 of fig. 2. It will then obey these RUMs and reduce its power on these carriers. In one aspect, the associated access terminal may also be required to reduce power on these carriers, thereby ensuring that all relevant nodes have the same transmission profile.

In an aspect, preplanning may be used to ensure that neighboring base stations have complementary carrier masks. Thus, in a time slot when a particular carrier (e.g., carrier 1) appears in front of the carrier mask in the first access point, its neighboring access points will have that same carrier (e.g., carrier 1) appearing at the end of its carrier mask.

In another aspect, dynamic learning/adjustment of the neighboring base station carrier mask may also be used. An exemplary process 600 of operation of this method on the forward link is illustrated in fig. 6, where an access terminal associated with a particular access point listens for superframe preambles or beacons from interfering access points in 602. These beacons (or superframe preambles) carry information about the carrier masks used by interfering access points. This information is relayed 604 to the access point associated with the access terminal, which may adjust its shielding accordingly 606.

Consider an example. The carrier mask priority sequence for access point a is "4231" and the sequence for neighboring access point B is "1324". When an access terminal belonging to two neighboring access points sends out a RUM, it will do so on different carriers. Assume that the access terminal of access point a transmits a RUM with carrier mask "1010" (2 blocked carriers), while the access terminal of access point B transmits a RUM with carrier mask "0001" (1 blocked carrier). Access point B will then obey the RUM of access point a and reduce its power on carriers 4 and 2, while access point a will reduce its power on carrier 1. This enables flexible band behavior in a dynamic manner.

In one aspect, unlike static flexible band systems, multi-carrier RUM systems impose constraints as needed. For example, a power constraint for a particular carrier is only imposed when some nodes do not meet their QoS requirements.

Referring again to fig. 2, referring now to fig. 7, the operation of an access terminal, such as access terminal 292, in requesting bandwidth at 222, 232, and 242 is described with reference also to fig. 8. In 702, the access terminal 292 receives and collects RUMs sent by any access points, including its associated access point 1294.

In 704, in an aspect of operation of the access terminal 292, the access terminal 292 only considers those RUMs from the received RUMs that have a higher weight than the weight of the access point associated with the access terminal 292 (i.e., access point 1294). Consider an example in which the access terminal 292 has received RUMs from three access points in addition to the RUM from access point 1294 (its associated access point); each of the three other RUMs has a higher weight than the RUM from access point 1294. The three RUMs have CMs of CM 802 ("1001"), CM 804 ("1000"), and CM 806 ("0010"), which follow the exemplary CM form as described in fig. 4. Additionally, assume that the access terminal 292 must consider three RUMs based on their weights. Therefore, the access terminal 292 must process CMs contained in three RUMs.

In 706, assuming the access terminal 292 has to consider and process three received RUMs, the access terminal 292 will perform an or operation on the CMs of these RUMs to create a composite CM 812 (i.e., a composite carrier mask). Continuing with the above example, composite CM 812 is "1011". In one aspect, the CM from the associated access point of the access terminal 292 is not utilized.

In 708, to determine if there are any carriers on which the access terminal 292 may request bandwidth, the access terminal 292 performs a "no" operation on the composite CM 812 to create an opposite composite CM (I-CM)822, which will indicate which carriers are available. The I-CM 822 may be used by the access terminal 292 to request bandwidth from the access point 1294.

In 710, it is determined whether there are carriers on which the access terminal 292 may request bandwidth. In one aspect of exemplary operation of the access terminal 292, through the use of the I-CM 822, the access terminal 292 will determine whether there are any carriers that are not blocked. For example, if there is at least a single "1" in the I-CM 822, there is at least one available carrier.

At 712, the access terminal 292 will create a request CM (R-CM)832 if there are carriers available. In one aspect, R-CM832 is set to I-CM 822 created in 710. Continuing the example above of dividing the bandwidth among four (4) carriers, R-CM832 would also have the same form as CM 400, which is of the form "XXXX", where each "X" may be a "1" indicating that access terminal 292 is requesting to transmit on that carrier; or "0" indicating that access terminal 292 does not request transmission on that carrier. Thus, a CM with a value of "0100" may be sent to the access point 1294 in a request. In other words, access terminal 292 views carriers "3", "1", and "0" as blocked, with carrier "2" open. If the access terminal 292 decides to request bandwidth, the R-CM832 would be "0100".

In another aspect, R-CM832 is based on (but different from) I-CM 822, as illustrated by fig. 9, which illustrates a process 900 of determining how many carriers to set in a request transmitted by access terminal 292 to access point 1294. The figure may also be used to describe the number of carriers that the access point 1294 will grant the access terminal 292, as further explained herein.

In 902, the access terminal 292 will determine the number of carriers it will request. This determination may be based on the amount of traffic that access terminal 292 wishes to transmit. Such a determination may also be based on, for example, a need associated with interference experienced at the access terminal, or any other suitable parameter (e.g., latency, data rate, spectral efficiency, etc.).

According to other aspects, if a weight is associated with each node, the determination of the number of carriers needed for a given transmission may be a function of the weight associated with that node, a function of weights associated with other nodes requesting carriers, a function of the number of carriers available for transmission, or any combination of the foregoing factors. For example, the weights may be a function of the number of flows through the node, the level of interference experienced at the node, and so on. According to other aspects, carrier selection may include partitioning carriers into one or more sets, and may be based in part on a received RUM indicating that one or more carriers of the set of carriers are unavailable. The RUM may be evaluated to determine whether a given carrier is available (e.g., not identified by the RUM). For example, a given carrier may be determined to be available if it is not listed in the RUM. Another example is that a carrier is considered available even if a RUM for that carrier was received, but the advertised weight for that carrier is lower than the weight advertised in the RUM sent by the node's receiver.

In 904, the access terminal 292 will determine the particular carrier it will request in the R-CM, which may depend on the specific carrier designated for the particular traffic type or a predetermined selection criteria. In one aspect, the selected carriers are a function of (e.g., a subset of) the available carriers determined in step 710. Carrier selection may also be performed by biasing towards available carriers. For example, carriers known to be available in a previous transmission period may be selected prior to selecting carriers that have been occupied in the previous transmission period. It should be noted that the sequence of operations illustrated by 902 and 904 may be reversed or combined, as the total number of carriers that may be requested may be dictated by the carriers available. For example, if there is only one carrier available for selection, the sequence of operations illustrated by 902 and 904 may be combined.

At 906, after the R-CM has been constructed, a request will be sent. In the above example, the only possible configuration of the R-CM is "0100" because there is only one carrier available. In another example, if four carriers are available and the access terminal 292 wishes to transmit on carriers 0, 1, and 3, an R-CM of "1101" will be created.

In addition to determining the number of carriers that need to be listed in the CM, another consideration is the specific identity of the carriers that should be blocked by the node sending out the RUM. In one aspect, each node selects the particular carrier that it wishes to block using a pseudo-random carrier selection method in which a mask is created based on a CM priority list. In particular, carriers selected for inclusion in the CM are selected in the order specified in the CM priority list. A CM priority list is pseudo-randomly created for each time slot or communication cycle.

Fig. 10 illustrates the operation of an exemplary pseudo-random carrier selection process 1000, wherein a CM priority list is randomly created 1002. At 1004, a carrier is selected from the CM priority list. Next, it is determined whether there are any carriers remaining to be selected in 1006. For example, if more than one carrier needs to be selected, and only one carrier has been selected, the process returns to 1004 where another carrier is selected from the CM priority list in 1004. If all carriers that need to be selected have been identified, operation continues with 1008 in which a CM is created based on carriers selected from the CM priority list. With respect to 1002, in another aspect of the pseudo random carrier selection process 1000, the CM priority list is generated only if it is determined that at least one carrier is to be blocked.

Fig. 11 illustrates a table 1100 illustrating a mask created by the pseudo-random carrier selection process 1000, where a plurality of time slots 1110 are shown with: a multiple CM priority list 1120 that lists carriers to be priority-order masked; a list 1130 of several carriers to be blocked; and a list of resulting CMs 1140. Assume that four carriers are available in the exemplary system, with the carrier list in each CM having the most significant bit as the leftmost bit, so carrier "3" is indicated by the leftmost bit in the CM, carrier "2" is the second left bit, carrier "1" is the third left bit, and carrier "0" is the fourth left bit (or rightmost bit).

For example, during time slot 11112, a CM priority list 1122 of "3, 2, 1, 0" is listed, indicating that if only one carrier is to be blocked, only the first carrier in the list-i.e., carrier "3" will be included in the resulting CM. If both carriers are to be blocked, the first and second carriers in the list, i.e., carrier "3" and carrier "2", will be included in the resulting CM. If three carriers are to be blocked, then the first, second and third carriers-i.e., carrier "3", carrier "2" and carrier "1" will be included in the resulting CM. If all four carriers are to be blocked, carrier "3", carrier "2", carrier "1" and carrier "0" will be included in the resulting CM. As illustrated in fig. 11, when two carriers are to be blocked (as indicated by the number of carriers to be blocked indicator 1132), a resulting CM 1142 of "1100" is created.

In time slot 21114, three carriers will be blocked, as indicated by the number of carriers to be blocked indicator 1134. Given the CM priority list 1124 of "0, 2, 3, 1", a resulting CM 1144 of "1101" is created because carrier "0", carrier "2", and carrier "3" are selected for the CM. If only two carriers need to be selected, a resulting CM of "0101" will be created, since carrier "0" and carrier "2" will be selected. If only one carrier needs to be selected, a resulting CM of "0001" will be created, since carrier "0" will be selected.

In slot 31116, one carrier will be blocked, as indicated by the number of carriers to be blocked indicator 1136, and given the CM priority list 1126 of "2, 1, 0, 3", a resulting CM 1146 of "0100" is created because carrier "2" is selected for the CM.

In time slot 41118, the carrier is not blocked, as indicated by the number of carriers to be blocked indicator 1138, and a resulting CM 1148 of "0000" is created because carrier "2" is selected for the CM.

In another aspect, a pseudo-random CM priority list is generated for each slot instead of each node, each node configured with a fixed static CM priority list. By using the fixed static CM priority list, several carriers to be blocked will be selected in the order as specified in the CM priority list. Therefore, to block one carrier, the first carrier from the fixed CM priority list will be selected. To block both carriers, the first two carriers from the fixed CM priority list will be selected, and so on. In this scheme, frequency reuse may be incorporated by selecting the carriers to be listed in the resulting CM (i.e., the carriers to be blocked) in a predetermined manner. In a first example, a node will typically be able to use all frequencies. However, during the congestion time, the node will switch to selecting a number of carriers to be blocked in the order specified by the node's fixed CM priority list. In one approach, a fixed CM priority list may be transmitted to each node using a wireline connection (where the node is wired). For example, where the node is an AP wired to the network, a static CM priority list may be sent from the controller to the AP.

In another aspect of the dynamic flexible band system, the resulting carrier mask is created using a CM priority list based on measurements of the detected Interference Over Thermal (IOT) for each carrier, where a CM priority list is generated that includes each carrier along with the measured IOT for that carrier. The carriers listed in the CM priority list are then ordered in order from the highest measured IOT to the lowest measured IOT. In a method, carriers on which power is to be reduced are selected from a CM priority list in an ordered order, the carriers on which the node has experienced the most interference. In this approach, reducing the power on these carriers would give the other nodes the most benefit. However, these carriers are also carriers in which a node is likely to affect the maximum number of neighboring nodes. In another approach, the carriers are ordered in order from the minimum IOT to the maximum IOT. Thus, in this other approach, the node will set aside those carriers that are facing a large number of contends and, instead, focus on those carriers that will likely affect a minimum number of contenders.

Fig. 12 illustrates a CM creation process 1200 in which, in 1202, a CM priority list is generated that includes each carrier along with IOT measured for that carrier. Next, in 1204, carriers listed in the CM priority list are ordered in the order of the measured IOT. In one approach, as discussed above, the carriers listed higher in the list are the carriers on which the node estimates that the interfering node will cause the most interference. In another approach, the carriers listed higher in the list are the carriers on which the node estimates that the interfering node will cause the least interference. Carriers identified as to be included in a CM will be selected from the ordered CM priority list in a predetermined manner (e.g., top to bottom). For example, consider exemplary CM priority lists "3", "2", "0", and "1" of CM priority lists ordered from highest IOT to lowest IOT, meaning that the node has identified carrier "3" as having the highest IOT and carrier "1" as having the lowest IOT, where carrier "2" and carrier "0" are carriers having the second and third highest IOT, respectively. If interference is caused on only two of the four carriers, carrier "3" and carrier "2" will be selected in that order based on the instance of the node configured to limit interference on the carrier for which the node detected the highest IOT.

In 1206, it is determined whether there are any carriers that need to be identified for inclusion in the CM. In one aspect, this determination is made by determining whether there has been a sufficient number of carriers identified as being equal to the number of carriers over which power is to be reduced. Continuing with the previous example, if the power on both carriers needs to be reduced, but only one of those carriers has been identified (e.g., carrier "3"), a sufficient number of carriers on which the power is to be reduced has not been identified.

To continue identifying carriers on which power is to be reduced, operation continues to 1208, where a carrier is selected from the CM priority list. Continuing the example, where a carrier has been identified (i.e., carrier "3"), carrier "2," which is the next in the list under carrier "3," is identified for inclusion in the CM.

If all carriers on which power is to be reduced that need to be identified by the CM have been identified, the CM is created in 1210. Also, continuing with the given example, if two carriers ("3" and "2") in the CM priority list have been identified for inclusion in the CM based on their positions, no additional carriers need be identified, and a CM of "1100" is created (e.g., a CM in which carrier "3" and carrier "2" are indicated).

In another aspect, the carrier on which power is to be reduced is selected based on an amount of interference that the node estimates will encounter on the carrier. In one approach, the node will record the carrier it estimates will encounter the most interference. A consideration for this approach is that the node wants to reduce the interference on the carrier that it is experiencing the most interference as much as possible. In another approach, the node will increase its estimated power on the carrier that will experience the least interference. The consideration for this approach is that the node will use the carrier on which the fewest other nodes are transmitting, thereby causing the least amount of interference to other nodes using this carrier.

Fig. 13 illustrates a carrier selection process 1300 performed on an AP, where in 1302 the AP receives from each AT associated with the AP measurements of pilot signal strength from each of the APs in the active set of the particular AT by the particular AT. For example, where a network includes AP _0 associated with an AT, the AT will measure the strength of the pilot signals it receives from all APs in its active set and report those measurements to AP _ 0. In a method, each AT predicts its dominant interferer based on a series of interference measurements received over many previous time slots. In addition, each AT may identify its primary interferer because each AP sends its identification information in its RUM message.

In 1304, the strongest predicted interferer is identified by the AP based on measurements received from its associated ATs. For example, consider a scenario in which AP _0 is associated with a group of ATs, and some ATs in this group of ATs experience interference from AP _1 and AP _ 3. In this case, AP _0 will receive reports from its associated ATs that the APs causing the most interference to them are AP _1 and AP _3, and AP _0 will determine whether these APs are the strongest predicted interferers.

In 1306, the AP will create a CM to manage interference from those identified APs from which it has detected interference and predicted that interference will continue (i.e., predicted dominant interferers). In an aspect, the AP will maintain the transmit power of APs on carriers not listed in the carrier mask transmitted by the identified AP, while reducing the transmit power on carriers listed in the carrier mask of those interfering APs. In other words, the AP will utilize the AT's measurements to create a transmission profile for a set of carriers that is complementary to the set of carriers used by the predicted dominant interferer. In an aspect, a joint carrier mask (U-CM) may be created to list the carriers contained in the joint of carrier masks transmitted by each group of predicted dominant interferers. Additionally, to list carriers in a set of carriers complementary to carriers in the U-CM, a complementary carrier mask (C-CM) may be created, and this is the CM used as the resulting carrier mask (R-CM) for determining which carriers are to reduce interference. In the example, while multiple power transmission levels may be supported, the R-CM only indicates the carrier on which power is to be reduced. These are carriers with a "1" in the carrier position. Continuing with the present example, AP _0 will reduce the power on the carriers in the R-CM that are the carriers strongly interfered by { AP _1, AP _3} contained in the complement of the carrier-masked U-CM transmitted by AP _1 and AP _ 3.

It should be noted that not all carriers in the C-CM need to be listed in the R-CM. Rather, in another aspect, if the number of carriers on which the AP (e.g., AP _0) needs to adjust power is less than the number of carriers listed in the C-CM, the R-CM will list only the carriers that the AP needs to adjust. In this later aspect, C-CM may be used as a CM priority list from which the AP will first select the carrier on which to reduce power.

Fig. 14 illustrates a CM created based on the carrier selection process 1300 of fig. 13, with an AP _1CM 1402 from a RUM received from AP _1 shown as "1001" indicating that AP _1 wishes to minimize interference on carrier "3" and carrier "0". Also shown is the AP _3CM 1404 of the RUM received from AP _3 "1010," indicating that AP _3 is receiving interference on carriers "3" and "1. The combination of AP _1CM 1402 and AP _3CM 1404 produces a U-CM 1412 of "1011" where carriers "3", "1", and "0" are identified as being requested to reduce interference in the CM caused by the combination of AP _1 and AP _3, while the C-CM 1422 created by the complement of the U-CM results in the listing of carrier "2" as the only carrier that is not requested to reduce interference caused by the other of AP _1 and AP _ 3. The resulting RRR-CM 1432 is constructed from C-CM 1422, and in aspects disclosed herein, RRR-CM 1432 is set equal to C-CM 1422.

Referring back to fig. 7, in 714, the access terminal 292 sends a request to the access point 1294 that will carry the R-CM listing the carrier on which the access terminal 292 intends to transmit data. The request may be a request for a first plurality of carriers with power that has not been reduced in the most recent time slot affecting the access terminal 292. The request message sent at 714 may additionally be power controlled to ensure a desired level of reliability at access point 1294.

In 716, if there are no available carriers, the access terminal 292 will return to "dormant" mode to wait for the next RUM message broadcast or any message from the access point 1294.

Fig. 15 illustrates a methodology 1500 for processing a request and generating a grant for a transmit request, such as access point 1294 in 264, in accordance with one or more aspects. As discussed, each access terminal (e.g., access terminal 292) with traffic to send may send a request to its respective access point (e.g., access point 1294) unless it is blocked by a RUM from another access point. Based on the request received by access point 1294, access point 1294 may decide to grant a given request regarding one or more requested carriers.

In 1502, the access point 1294 evaluates the request. If a request has not been received, then access point 1294 will refrain from sending a grant message in 1504.

If at least one request has been received from the access terminal, the access point 1294 will determine the number and selection of carriers it will grant in response to the request, 1510. The process illustrated in fig. 9, described above with reference to the generation of a request for transmission by an access terminal (e.g., access terminal 292), may also be used to describe the selection of carriers granted in response to a request. In 902, access point 1294 will determine the number of carriers it will assign to each access terminal (e.g., access terminal 292) as part of its process of assigning bandwidth to all access terminals it serves (which have received requests from the access terminal). Then in 904, the access point 1294 will determine the particular carrier, if any, on which it will grant each access terminal (e.g., access terminal 292) permission to transmit.

In an aspect, the access point's ability to assign carriers in a grant in response to each request from an access terminal is limited. For example, the access point 1294 may be restricted to assigning only carriers corresponding to carriers found in the R-CM contained in the previously received request from the access terminal 292. In other words, the access point may only assign to a particular access terminal the carriers found in the carrier group listed by the CM (i.e., R-CM) contained in the previous request from the particular access terminal.

Once all possible grants are generated in 1510, they are sent to their respective requesting access terminal (e.g., access terminal 292) in 1512.

According to related aspects, an access point may periodically and/or continuously evaluate whether it has unprocessed data from one or more of its served access terminals. The access point has unprocessed data if it has received a current request, or if it has received a previous request that it has not granted. In either case, when the access point determines that there is a warranty grant, the access point may send out this grant. In addition, based on the determined grant rate (e.g., whenever the average transmission rate is below the target rate), the access point may send a RUM to reserve more bandwidth for its associated access terminal. Additionally, upon receiving the grant, the access terminal may transmit a data frame, which may be received by the access point.

Fig. 16 shows an exemplary wireless communication system 1600. The wireless communication system 1600 depicts access points and terminals for sake of brevity. It is to be appreciated, however, that the system can include more than one access point and/or more than one terminal, wherein additional access points and/or terminals can be substantially similar or different for the exemplary access point and terminal described below. Further, it is to be appreciated that the access point and/or the terminal can employ the methods and/or systems described herein to facilitate wireless communication there between. For example, a node (e.g., an access point and/or a terminal) in system 1600 may store and execute instructions for performing any of the above-described methods (e.g., generating a RUM, responding to a RUM, determining a node disadvantage, selecting a number of carriers for RUM transmission, etc.), as well as data associated with performing such actions and any other suitable actions for performing the various protocols described herein.

Referring now to fig. 16, on the downlink, at access point 1605, a Transmit (TX) data processor 1610 receives, formats, codes, interleaves, and modulates (or symbol maps) traffic data and provides modulation symbols ("data symbols"). A symbol modulator 1615 receives and processes the data symbols and pilot symbols and provides a stream of symbols. In particular, a symbol modulator 1615 multiplexes data and pilot symbols and provides them to a transmitter unit (TMTR) 1620. Each transmit symbol may be a data symbol, a pilot symbol, or a signal value of zero. The pilot symbols may be sent continuously in each symbol period. The pilot symbols may be Frequency Division Multiplexed (FDM), Orthogonal Frequency Division Multiplexed (OFDM), Time Division Multiplexed (TDM), Frequency Division Multiplexed (FDM), or Code Division Multiplexed (CDM).

TMTR 1620 receives and converts the stream of symbols into one or more analog signals and further conditions (e.g., amplifies, filters, and frequency upconverts) the analog signals to generate a downlink signal suitable for transmission over the wireless channel. The downlink signal is then transmitted via antenna 1625 to the terminals. At terminal 1630, an antenna 1635 receives the downlink signal and provides a received signal to a receiver unit (RCVR) 1640. Receiver unit 1640 conditions (e.g., filters, amplifies, and frequency downconverts) the received signal and digitizes the conditioned signal to obtain samples. A symbol demodulator 1645 demodulates and provides received pilot symbols to a processing system 1650 for channel estimation. A symbol demodulator 1645 further receives a frequency response estimate for the downlink from processing system 1650, performs data demodulation on the received data symbols to obtain data symbol estimates (which are estimates of the transmitted data symbols), and provides the data symbol estimates to an RX data processor 1655, which RX data processor 1655 demodulates (i.e., symbol demaps), deinterleaves, and decodes the data symbol estimates to recover the transmitted traffic data. The processing by symbol demodulator 1645 and RX data processor 1655 is complementary to the processing by symbol modulator 1615 and TX data processor 1610, respectively, at access point 1605.

On the uplink, a TX data processor 1660 processes traffic data and provides data symbols to a symbol modulator 1665, which receives and multiplexes data symbols with pilot symbols and performs modulation to create a stream of symbols. A transmitter unit 1670 then receives and processes the stream of symbols to generate an uplink signal, which is transmitted by antenna 1635 to access point 1605.

At access point 1605, the uplink signal from terminal 1630 is received by antenna 1625 and processed by a receiver unit 1675 to obtain samples. A symbol demodulator 1680 then processes the samples and provides received pilot symbols and data symbol estimates for the uplink. An RX data processor 1685 processes the data symbol estimates to recover the traffic data transmitted by terminal 1630. Processing system 1690 performs channel estimation for each active terminal transmitting on the uplink. Multiple terminals may transmit pilot concurrently on the uplink on their respective assigned sets of pilot subbands, where the sets of pilot subbands may be interlaced.

Processing systems 1690 and 1650 direct (e.g., control, coordinate, manage, etc.) operation at access point 1605 and terminal 1630, respectively. Respective processing systems 1690 and 1650 can be associated with memory units (not shown) that store program codes and data. Processing systems 1690 and 1650 may also perform computations to derive frequency and impulse response estimates for the uplink and downlink, respectively. The processing systems 1690 and 1650 may include one or more processors. The processor may be a general purpose microprocessor, a microcontroller, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Digital Signal Processing Device (DSPD), a Programmable Logic Device (PLD), a logic circuit, a discrete hardware component, or any other suitable entity that can perform calculations or other manipulations of information.

The processing system may also include one or more machine-readable media that provide data storage, including look-up tables for translating identifiers to IP addresses for access terminal applications, and/or support for software applications. Software should be construed broadly to mean instructions, programs, code, or any other electronic media content, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The machine-readable medium may include storage integrated with the processor, which may be the case, for example, with an ASIC. The machine-readable medium may also include memory external to the processor, such as Random Access Memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable PROM (eprom), registers, a hard disk, a removable disk, a CD-ROM, a DVD, or any other suitable storage device. Further, a machine-readable medium may include a carrier wave transmitting a data signal or encoded with a data signal. Those skilled in the art will recognize how best to implement the described functionality for a processing system.

For a multiple-access system (e.g., FDMA, OFDMA, CDMA, TDMA, etc.), multiple terminals may transmit simultaneously on the uplink. For this system, the pilot subbands may be shared among different terminals. The channel estimation techniques may be used where the pilot subbands for each terminal span the entire operating band (possibly except for the band edges). This pilot subband structure would be needed to obtain frequency diversity for each terminal. The techniques described herein may be implemented by various means. For example, these techniques may be implemented in hardware, software, or a combination thereof.

Turning now to fig. 17-19 and the various modules described in relation thereto, it should be appreciated that the module for transmitting may comprise, for example, a transmitter and/or may be implemented in a processor or the like. Similarly, the means for receiving may comprise the receiver and/or may be implemented in a processor or the like. Additionally, modules for comparing, determining, calculating, and/or performing other analytical actions may include a processor executing instructions for performing various and respective actions.

Fig. 17 is an illustration of a channel selection apparatus 1700 that facilitates wireless data communication in accordance with various aspects. Channel selection apparatus 1700 is represented as a series of interrelated functional blocks, which can represent functions implemented by a processor, software, or combination thereof (e.g., firmware). For example, channel selection apparatus 1700 may provide means for performing various acts such as those described above with respect to various figures. Channel selection apparatus 1700 includes a module 1702 for determining a number of carriers required for transmission by a node, e.g., an access terminal. When used for an access point, module for determining 1702 may also determine a number of carriers to grant based on the requested desired number of channels. The determination may be performed in accordance with a weight associated with a node using the apparatus, a weight associated with one or more other nodes, a number of carriers available for transmission, and so on. In addition, each weight may be a function of the number of streams supported by the node associated with the weight. Additionally or alternatively, the given weight may be a function of the interference experienced by the node.

Channel selection apparatus 1700 additionally includes a module for selecting 1704 that selects a carrier for which a node may transmit a request. A module for selecting 1704 may additionally evaluate the received RUM to determine which carriers are available and which are unavailable. For example, each RUM may include information associated with an unavailable carrier, and module for selecting 1754 may determine that a given carrier not indicated by the RUM is available. A module for transmitting 1706 may transmit a request for at least one carrier selected by the module for selecting 1704. It will be appreciated that the channel selection apparatus 1700 may be employed in an access point or an access terminal, and may include any suitable functionality to carry out the various methods described herein.

Fig. 18 is an illustration of an RUM generation apparatus 1800 that facilitates wireless communication using RUMs, in accordance with one or more aspects. The RUM generation apparatus 1800 is represented as a series of interrelated functional blocks, which can represent functions implemented by a processor, software, or combination thereof (e.g., firmware). For example, the RUM generation apparatus 1800 may provide modules for performing various acts such as those described above with respect to previous figures. The RUM generation apparatus 1800 includes: a module for determining 1802 that determines a level of a disadvantage of a node; and a module 1804 for generating a RUM that generates a RUM if the module for determining 1802 determines that a first predetermined threshold has been exceeded (e.g., a level of received service at a node is at or below a predetermined threshold level). Alternatively, module for determining 1802 may also or alternatively determine whether the interference level is above a predetermined threshold level prior to generating the RUM. The predetermined threshold may be associated with and/or representative of IOT, data rate, C/I, throughput level, spectral efficiency level, latency level, etc. Module for selecting 1808 may select one or more resources for which to send a RUM, and module for generating a RUM 1804 may then indicate such carriers in the RUM. The module for transmitting 1810 may then transmit the RUM.

The RUM generation apparatus 1800 may additionally include a module for weighting the RUM 1806, which may weight the RUM with a value indicating a degree to which a second predetermined threshold has been exceeded, which may include determining a ratio of an actual value to a target or desired value of a parameter implemented at the node (e.g., IOT, data rate, C/I, throughput level, spectral efficiency level, latency level, etc.). Additionally, the weighted value may be a quantized value.

Module for selecting resources 1808 may adjust the number of selected resources for subsequent RUM transmissions based on a determination by module for determining 1802 that a level of received service has improved in response to a previous RUM. For example, in this case, module for selecting 1808 may reduce the number of resources indicated in a subsequent RUM in response to an improved level of received service at the node, and may increase the number of selected resources in response to a reduced or static level of received service. The resources may relate to the number and identity of carriers selected to be included in the RUM (e.g., in the CM of the RUM).

It is to be appreciated that the RUM generation apparatus 1800 may be employed in an access point, an access terminal, etc., and may comprise any suitable functionality to carry out the various methods described herein.

Fig. 19 is an illustration of a reservation apparatus 1900 that facilitates reserving resources based on determined conditions, in accordance with one or more aspects. Reservation 1900 is represented as a series of interrelated functional blocks that can represent functions implemented by a processor, software, or combination thereof (e.g., firmware). For example, reservation device 1900 may provide modules for performing various actions such as those described above with respect to various figures. The reservation apparatus 1900 may be employed in a first node and comprises a module 1902 for receiving at least one RUM associated with a plurality of resources. The reservation apparatus 1900 may additionally include a module 1904 for determining a transmission profile for at least one resource of a plurality of resources based on the at least one RUM, and a module 1906 for scheduling transmission on the at least one resource based on the transmission profile.

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, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, 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 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 may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium may be coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal. Further, in some aspects any suitable computer program product may comprise a computer-readable medium having code (e.g., executable by at least one computer) relating to one or more of the aspects of the disclosure. In some aspects, a computer program product may include packaging materials.

The teachings herein may be incorporated into (e.g., implemented within or performed by) a variety of apparatuses (e.g., devices). For example, each node may be configured as, or referred to in the art as, an Access Point (AP), a NodeB, a Radio Network Controller (RNC), an eNodeB, a Base Station Controller (BSC), a Base Transceiver Station (BTS), a Base Station (BS), a Transceiver Function (TF), a radio router, a radio transceiver, a basic service set (BSs), an Extended Service Set (ESS), a 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 comprise a cellular telephone, a cordless telephone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) 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 data 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 via a wireless medium.

The wireless devices may communicate via one or more wireless communication links that are based on or otherwise support any suitable wireless communication technology. For example, in some aspects, a wireless device may be associated with a network. In some aspects, the network may comprise a human body area network or a personal area network (e.g., an ultra-wideband network). In some aspects, the network may comprise a local area network or a wide area network. A wireless device may support or otherwise use one or more of a variety of wireless communication technologies, protocols, or standards, such as CDMA, TDMA, OFDM, OFDMA, WiMAX, and Wi-Fi. Similarly, a wireless device may support or otherwise use one or more of a variety of corresponding modulation or multiplexing schemes. Accordingly, a wireless device may include appropriate components (e.g., air interfaces) to establish and communicate via one or more wireless communication links using the above or other wireless communication techniques. For example, a device may include a wireless transceiver with associated transmitter and receiver components that may include various components (e.g., a signal generator and a signal processor) that facilitate communication over a wireless medium.

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. An IC may comprise a general purpose processor, a DSP, an ASIC, an 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.

The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present invention. 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 invention 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 (33)

1. A method for communicating data, comprising:

receiving at least one Resource Utilization Message (RUM) associated with a plurality of resources;

determining a transmission profile for at least one resource of the plurality of resources based on the at least one RUM; and

scheduling a transmission on the at least one resource based on the transmission profile.

2. The method of claim 1, wherein the transmission profile is determined based on at least one of a level of interference over thermal noise (IOT), a carrier-to-interference ratio (C/I), and a level of spectral efficiency for the plurality of resources.

3. The method of claim 1, wherein the RUM comprises a quality of service (QoS) requirement for the plurality of resources, wherein the QoS requirement comprises at least one of a data rate, an amount of data transmitted, a latency level, and a traffic class.

4. The method of claim 1, wherein the RUM comprises a measurement of at least one of a level of interference over thermal noise (IOT), a carrier-to-interference ratio (C/I), a level of spectral efficiency, and a received RUM for the plurality of resources at an associated node.

5. The method of claim 1, wherein the transmission profile comprises a determined transmission power range for the at least one of the plurality of resources.

6. The method of claim 5, wherein the scheduling comprises transmitting on the at least one resource, wherein the transmitting comprises transmitting at a transmit power constrained by the determined transmit power range.

7. The method of claim 1, wherein the scheduling comprises requesting transmission to an associated node on the at least one resource.

8. The method of claim 1, wherein the scheduling comprises communicating the transmission profile to an associated node on the at least one resource.

9. The method of claim 1, wherein ordering is based on a result of previous RUMs transmitted for the plurality of resources.

10. The method of claim 9, wherein the result of previous RUMs transmitted comprises at least one of a number of successful transmissions, a number of unsuccessful transmissions, a number of previously transmitted RUMs, and a number of RUMs previously transmitted by other nodes for the plurality of resources.

11. An apparatus for communicating data, comprising:

means for receiving at least one Resource Utilization Message (RUM) related to a plurality of resources;

means for determining a transmission profile for at least one resource of the plurality of resources based on the at least one RUM; and

means for scheduling a transmission on the at least one resource based on the transmission profile.

12. The apparatus of claim 11, wherein the transmission profile is determined based on at least one of a level of interference over thermal noise (IOT), a carrier-to-interference ratio (C/I), and a level of spectral efficiency for the plurality of resources.

13. The apparatus of claim 11, wherein the RUM comprises a quality of service (QoS) requirement for the plurality of resources, wherein the QoS requirement comprises at least one of a data rate, an amount of data transmitted, a latency level, and a traffic class.

14. The apparatus of claim 11, wherein the RUM comprises a measurement of at least one of a level of interference over thermal noise (IOT), a carrier-to-interference ratio (C/I), a level of spectral efficiency, and a received RUM for the plurality of resources at an associated node.

15. The apparatus of claim 11, wherein the transmission profile comprises a determined transmission power range for the at least one of the plurality of resources.

16. The apparatus of claim 15, wherein the scheduling means comprises means for transmitting on the at least one resource, wherein the transmitting comprises transmitting at a transmit power constrained by the determined transmit power range.

17. The apparatus of claim 11, wherein the scheduling means comprises means for requesting transmission to an associated node on the at least one resource.

18. The apparatus of claim 11, wherein the scheduling means comprises means for communicating the transmission profile for the at least one resource to an associated node.

19. The apparatus of claim 11, wherein ordering is based on a result of previous RUMs transmitted for the plurality of resources.

20. The apparatus of claim 19, wherein the result of previous RUMs transmitted comprises at least one of a number of successful transmissions, a number of unsuccessful transmissions, a number of previously transmitted RUMs, and a number of RUMs previously transmitted for the plurality of resources by other nodes.

21. An access point, comprising:

an antenna; and

a processing system coupled to the antenna and configured to:

receiving, via the antenna, at least one Resource Utilization Message (RUM) related to a plurality of resources;

determining a transmission profile for at least one resource of the plurality of resources based on the at least one RUM; and

scheduling a transmission on the at least one resource based on the transmission profile.

22. An access terminal, comprising:

a converter; and

a processing system coupled to the transformer and configured to:

receiving at least one Resource Utilization Message (RUM) related to a plurality of resources used to transmit data that can be rendered with the transformer;

determining a transmission profile for at least one resource of the plurality of resources based on the at least one RUM; and

scheduling a transmission on the at least one resource based on the transmission profile.

23. A computer program product for communicating data, comprising:

a computer-readable medium comprising code executable to:

receiving at least one Resource Utilization Message (RUM) associated with a plurality of resources;

determining a transmission profile for at least one resource of the plurality of resources based on the at least one RUM; and

scheduling a transmission on the at least one resource based on the transmission profile.

24. An apparatus for communicating data, comprising:

a processing system configured to:

receiving at least one Resource Utilization Message (RUM) associated with a plurality of resources;

determining a transmission profile for at least one resource of the plurality of resources based on the at least one RUM; and

scheduling a transmission on the at least one resource based on the transmission profile.

25. The apparatus of claim 24, wherein the transmission profile is determined based on at least one of a level of interference over thermal noise (IOT), a carrier-to-interference ratio (C/I), and a level of spectral efficiency for the plurality of resources.

26. The apparatus of claim 24, wherein the RUM comprises a quality of service (QoS) requirement for the plurality of resources, wherein the QoS requirement comprises at least one of a data rate, an amount of data transmitted, a latency level, and a traffic class.

27. The apparatus of claim 24, wherein the RUM comprises a measurement of at least one of a level of interference over thermal noise (IOT), a carrier-to-interference ratio (C/I), a level of spectral efficiency, and a received RUM for the plurality of resources at an associated node.

28. The apparatus of claim 24, wherein the transmission profile comprises a determined transmission power range for the at least one of the plurality of resources.

29. The apparatus of claim 28, wherein the processing system is further configured to transmit on the at least one resource, wherein the transmitting comprises transmitting at a transmit power constrained by the determined transmit power range.

30. The apparatus of claim 24 wherein the processing system is further configured to request transmission to an associated node on the at least one resource.

31. The apparatus of claim 24, wherein the processing system is further configured to communicate the transmission profile for the at least one resource to an associated node.

32. The apparatus of claim 24, wherein ordering is based on a result of previous RUMs transmitted for the plurality of resources.

33. The apparatus of claim 32, wherein the result of previous RUMs transmitted comprises at least one of a number of successful transmissions, a number of unsuccessful transmissions, a number of previously transmitted RUMs, and a number of RUMs previously transmitted for the plurality of resources by other nodes.