Wireless resource allocation methods and apparatus

Methods and apparatus for assigning and using resources corresponding to discontinuous portions of bandwidth are described. A single assignment may be used to assign multiple disjoint portions of bandwidth to be used by a wireless terminal, e.g., at the same time, as an uplink or downlink band. Different portions of bandwidth allocated to a terminal may have different numbers and/or locations of guard subcarriers with relevant guard subcarrier information being communicated to the wireless terminal in a broadcast signal or being determined from stored information. The disjoint portions of bandwidth allocated for use to a terminal may be separated by a carrier band, e.g., 1.25 MHz or more, which is not available for use, e.g., because it is owned by another service provider. Some embodiments are implemented using OFDM signals wherein a wireless terminal may generate or receive an OFDM symbol including subcarriers, e.g., tones corresponding to the different discontinuous portions but not the bandwidth separating the discontinuous portions.

FIELD

Various embodiments are directed to wireless communication methods and apparatus, and more particularly, to allocation and/or use of resources.

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 in order to meet consumer needs and to improve portability and convenience. The increase in processing power in mobile devices such as cellular telephones has lead to an increase in demands on wireless network transmission systems. Such systems typically are not as easily updated as the cellular devices that communicate there over. As mobile device capabilities expand, it can be difficult to maintain an older wireless network system in a manner that facilitates fully exploiting new and improved wireless device capabilities.

Wireless communication systems generally utilize different approaches to generate transmission resources in the form of channels. These systems may be code division multiplexing (CDM) systems, frequency division multiplexing (FDM) systems, and time division multiplexing (TDM) systems. One commonly utilized variant of FDM is orthogonal frequency division multiplexing (OFDM) that effectively partitions the overall system bandwidth into multiple orthogonal subcarriers. These subcarriers may also be referred to as tones, bins, and frequency channels. Each subcarrier can be modulated with data. With time division based techniques, each subcarrier can be used in all or a portion of sequential time slices or time slots. Each user may be provided with one or more time slot and subcarrier combinations for transmitting and receiving information in a defined burst period or frame. The hopping schemes may generally be a symbol rate hopping scheme or a block hopping scheme.

Code division based techniques typically transmit data over a number of frequencies available at any time in a range. In general, data is digitized and spread over available bandwidth, wherein multiple users can be overlaid on the channel and respective users can be assigned a unique sequence code. Users can transmit in the same wide-band chunk of spectrum, wherein each user's signal is spread over the entire bandwidth by its respective unique spreading code. This technique can provide for sharing, wherein one or more users can concurrently transmit and receive. Such sharing can be achieved through spread spectrum digital modulation, wherein a user's stream of bits is encoded and spread across a very wide channel in a pseudo-random fashion. The receiver is designed to recognize the associated unique sequence code and undo the randomization in order to collect the bits for a particular user in a coherent manner.

A typical wireless communication network (e.g., employing frequency, time, and/or 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 terminal. 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 transmitted from the base station. Likewise, a mobile terminal can transmit data to the base station or another mobile terminal. In these systems the bandwidth and other system resources are assigned utilizing a scheduler.

As wireless systems have developed over time, service provides have acquired the right to use one or more frequency bands but not others to which they have not purchased the communications rights. This has resulted in cases where a service provider may own the right to use multiple discontinuous portions of bandwidth in a geographic region but be precluded from using bandwidth located between the discontinuous portions of bandwidth to which the service provider has acquired rights.

Discontinuous portions of bandwidth might be used individually, e.g., by one wireless terminal or base station communicating using one discontinuous portion of bandwidth at a time. However, from a frequency diversity and/or throughput perspective it may be desirable for a wireless terminal or base station to be able to use multiple discontinuous portions of bandwidth at the same time, e.g., to support communication in one or multiple directions. For example, in the case of a need to support high uplink or downlink data rates it might be desirable to be able to use multiple discontinuous portions of bandwidth, e.g., portions of bandwidth separated by another service providers carrier, to support communication in an uplink direction or a downlink direction depending on which direction had the need for a high data throughput.

In view of the above, it should be apparent that there is a need for methods and apparatus which would allow a base station and/or wireless terminals to use discontinuous portions of bandwidth without using portions of bandwidth in between the discontinuous bands. It would be desirable if at least some methods and apparatus were well suited for use where the discontinuous bands were separated by a bandwidth corresponding to the width of a service provider's carrier, e.g., 1.25 MHz or more in some cases.

SUMMARY

Methods and apparatus for assigning and using resources corresponding to discontinuous portions of bandwidth are described. A single assignment may be used to assign multiple disjoint portions of bandwidth to be used by a wireless terminal, e.g., at the same time, as an uplink or downlink band. Different portions of bandwidth allocated to a terminal may have different numbers and/or locations of guard subcarriers with relevant guard subcarrier information being communicated to the wireless terminal in a broadcast signal or being determined from stored information. The disjoint portions of bandwidth allocated for use to a terminal may be separated by a carrier band, e.g., 1.25 MHz or more, which is not available for use, e.g., because it is owned by another service provider. Some embodiments are implemented using OFDM signals wherein a wireless terminal may generate or receive an OFDM symbol including subcarriers, e.g., tones corresponding to the different discontinuous portions but not the bandwidth separating the discontinuous portions.

An exemplary method for assigning resources in a wireless communication system comprises: selecting a first wireless terminal to be assigned a communications resource; and assigning the first wireless terminal a resource including at least two discontinuous portions of bandwidth for a period of time separated by a portion of bandwidth not included in said resource. An exemplary communications apparatus for assigning resources in a wireless communication system comprises: a selection module for selecting a first wireless terminal to be assigned a communications resource; and a resource assignment module for assigning the first wireless terminal selected by said selection module a resource including at least two discontinuous portions of bandwidth for a period of time separated by a portion of bandwidth not included in said resource.

An exemplary method of operating a wireless terminal comprises: receiving a resource assignment message indicating assignment, for a period of time, to said wireless terminal of a resource including at least two discontinuous portions of bandwidth separated by a portion of bandwidth not included in said resource; and using said assigned resource to communicate with an access point. An exemplary wireless terminal comprises: a receiver module for receiving a resource assignment message indicating assignment, for a period of time, to said wireless terminal of a resource including at least two discontinuous portions of bandwidth separated by a portion of bandwidth not included in said resource; and at least one of: i) a symbol generation module for generating symbols corresponding to the allocated resource and ii) a symbol recovery module for recovering symbols corresponding to the allocated resource.

While various embodiments have been discussed in the summary above, it should be appreciated that not necessarily all embodiments include the same features and some of the features described above are not necessary but can be desirable in some embodiments. Numerous additional features, embodiments and benefits are discussed in the detailed description which follows.

DETAILED DESCRIPTION

Referring toFIG. 1, a multiple access wireless communication system100according to one embodiment is illustrated. A multiple access wireless communication system100includes multiple cells, e.g. cells102,104, and106. In the embodiment ofFIG. 1, each cell (102,104, and106) may include an access point (162,164,166), respectively, that includes multiple sectors. For example cell102includes a first sector102a, a second sector102band a third sector102c. The multiple sectors are formed by groups of antennas each responsible for communication with access terminals in a portion of the cell. In cell102, antenna groups112,114, and116each correspond to a different sector. In cell104, antenna groups118,120, and122each correspond to a different sector. In cell106, antenna groups124,126, and128each correspond to a different sector.

Each cell includes several access terminals which are in communication with one or more sectors of each access point. For example, access terminals130,132,134,136and138are in communication access point162; access terminals140,142,144,146,148and134are in communication with access point164; and access terminals136,148,150,152,154and156are in communication with access point166.

Controller180is coupled to each of the cells102,104, and106. Controller180may contain one or more connections to multiple networks, e.g. the Internet, other packet based networks, or circuit switched voice networks that provide information to, and from, the access terminals in communication with the cells of the multiple access wireless communication system100. The controller180includes, or is coupled with, a scheduler that schedules transmission from and to access terminals. In other embodiments, the scheduler may reside in each individual cell, each sector of a cell, or a combination thereof.

Each of the sectors can operate utilizing one or more of a plurality of carriers. Each carrier is a portion of a larger bandwidth in which the system can operate, or is available for communication. A single sector utilizing one or more carriers may have multiple access terminals scheduled on each of the different carriers during any given time interval, e.g. frame or superframe. Further, one or more access terminals may be scheduled on multiple carriers simultaneously.

An access terminal may be scheduled in one carrier or more than one carrier according to its capabilities. These capabilities may be part of the session information that is generated when the access terminal attempts to acquire communication or that has been negotiated previously, may be part of the identification information that is transmitted by the access terminal, or be established according to any other approach. In certain aspects, the session information may comprise a session identification token that is generated by querying the access terminal or determining its capabilities through its transmissions.

As used herein, an access point may be a fixed station used for communicating with the terminals and may also be referred to as, and include some or all the functionality of, a base station, a Node B, or some other terminology. An access terminal may also be referred to as, and include some or all the functionality of, a user equipment (UE), a wireless communication device, terminal, a wireless terminal, a mobile station, a mobile node, a mobile or some other terminology.

It should be noted that whileFIG. 1, depicts physical sectors, i.e. having different antenna groups for different sectors, other approaches may be utilized. For example, utilizing multiple fixed “beams” that each cover different areas of the cell in frequency space may be utilized in lieu of, or in combination with physical sectors.

Referring toFIGS. 2A and 2B, aspects of superframe structures for a multiple access wireless communication system are illustrated.FIG. 2Aillustrates aspects of superframe structures for a frequency division duplexed (FDD) multiple access wireless communication system, whileFIG. 2Billustrates aspects of superframe structures for a time division duplexed (TDD) multiple access wireless communication system. The superframe preamble is transmitted at the beginning of each superframe, or may be interspersed within the superframe itself, e.g. a preamble and a midamble.

In bothFIGS. 2A and 2B, the forward link transmission is divided into units of superframes. A superframe may comprise a superframe preamble followed by a series of frames. In an FDD system, the reverse link and the forward link transmission may occupy different frequency bandwidths so that transmissions on the links do not or for the most part do not, overlap on any frequency subcarriers. In a TDD system, N forward link frames and M reverse link frames define the number of sequential forward link and reverse link frames that may be continuously transmitted prior to allowing transmission of the opposite type of frame. It should be noted that the number of N and M may vary within a given superframe or between superframes.

Drawing200ofFIG. 2Aillustrates exemplary forward link super frame201which includes super frame preamable202followed by frames (204,206,208,210,212,214,216,218,220,222,224,226,228,230,232,234,236,238,240,242,244,246,248and250). An initial portion of another forward link superframe is illustrated including a super frame preamble202′ followed by a frame204′. An exemplary frame, e.g., frame218, in an exemplary block hopping mode includes a data portion252, a control portion254, a pilot portion256, and a common pilot portion258. An exemplary frame, e.g., frame218, in an exemplary symbol rate hopping mode includes a data portion260, a control portion262, a pilot portion264, and a common pilot portion266.

Drawing270ofFIG. 2Billustrates exemplary forward link super frame271which includes super frame preamable272followed by a sequence of frames utilized for forward link signaling and mute time intervals reserved for reverse link frames (frame274, mute time276, frame278, mute time280, frame282, mute time284, frame286, mute time288, frame290, mute time292, frame294, mute time296, . . . , frame298, mute time299. An initial portion of another forward link superframe is illustrated including a super frame preamble272′ followed by a frame274′. An exemplary frame, e.g., frame286, in an exemplary block hopping mode includes a data portion275, a control portion277, a pilot portion279, and a common pilot portion281. An exemplary frame, e.g., frame286, in an exemplary symbol rate hopping mode includes a data portion283, a control portion285, a pilot portion287, and a common pilot portion289.

In both FDD and TDD systems each superframe may comprise a superframe preamble. In certain embodiments, the superframe preamble includes a pilot channel that includes pilots that may be used for channel estimation by access terminals, a broadcast channel that includes configuration information that the access terminal may utilize to demodulate the information contained in the forward link frame. Further acquisition information such as timing and other information sufficient for an access terminal to communicate and basic power control or offset information may also be included in the superframe preamble. In other cases, only some of the above and/or other information may be included in this superframe preamble.

In an aspect, the following information may be included in the superframe preamble: (i) a common pilot channel; (ii) a broadcast channel, including system and configuration information; (iii) an acquisition pilot channel, used to acquire timing and other information; and (iv) an other sector interference channel, including indicators from the sector of its measured interference with respect to other sectors.

Further, in certain aspects messages for channels in the superframe preamble may span multiple superframe preambles of different superframes. This may be utilized to improve decoding capability by allocating greater resources to certain high priority messages.

As shown inFIGS. 2A and 2B, the superframe preamble is followed by a sequence of frames. Each frame may include the same or a different number of OFDM symbols, which may constitute a number of subcarriers that may simultaneously be utilized for transmission over some defined period. Further, each frame may operate according to a symbol rate hopping mode, where one or more non-contiguous OFDM symbols are assigned to a user on a forward link or reverse link, or a block hopping mode, where users hop within a block of OFDM symbols. The actual blocks or OFDM symbols may or may not hop between frames.

FIG. 3illustrates aspects of a bandwidth deployment. The bandwidth spanned by the superframe preamble may be, in one or more aspects, 1.25 MHz. In other aspects, it may be 2.5 MHz, 5 MHz, 20 MHz or some other bandwidth.

InFIG. 3, bandwidth300is divided into multiple carriers, a first carrier302, a second carrier304, and a third carrier306. In certain aspects, acquisition, assignment, access, request, power control, pilot and reporting channels exist in each of the carriers. Further, each carrier may have the superframe preamble and forward link control channels and reverse link control channels. However, the actual encoding, transmission rates, message types and timing, resource allocations, overhead messaging, hop patterns and/or sequences, and other transmission and location parameters may vary from carrier to carrier. The format, transmission rate and hopping information may be signaled or otherwise available to an access terminal. This information may be available via separate control channels not associated with a specific carrier or may be provided via other means.

Some terminals, having a greater capability to demodulate signals, may be scheduled on two or more carriers within a superframe, in consecutive superframes, or during its communication session. These multi-carrier access terminals may be able to utilize different carriers for reverse link frames and forward link frames during a communication session or superframe, may be scheduled on different carriers in different superframes or during the communication session, or may be scheduled over frames that are substantially synchronous in time on different carriers. Such multi-carrier access terminals may be scheduled to provide load balancing of resources for a given carrier and provide statistical multiplexing gains throughout the total bandwidth.

In order to support multi-carrier access terminals operating across several carriers within a superframe, in consecutive superframes, or during its communication session several approaches may be provided. Firstly, the multi-carrier access terminals may demodulate the superframe preambles and forward link control channels for each of the carriers individually. In such a case, assignments, scheduling, power control and the like would be performed on a carrier by carrier basis.

In an aspect, each portion of a carrier that is disjoint is less than or equal to 1.25 MHz. The portions may be scattered over the total bandwidth of ≦20 MHz. Further, in some aspects the spacing between each portion of a same carrier is a multiple of 1.25 MHz. However, other spacing between and sizes of portions may be utilized depending on bandwidth deployments and the like.

In some aspects, one or more acquisition pilots carry the total FFT size, e.g. 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, or 20 MHz, of a sector or access point. In some aspects, this information may be provided by the scrambling of acquisition pilots. In other aspects, this information may be carried in other portions of the superframe preamble.

In an aspect, the specification of non-contiguous allocations of one or more carriers may be provided on one or more overhead channels in a superframe preamble. For example, the information identifying a carrier, in the overhead channels or pilots, may include an allocation bit-map identifying the number and/or location of guard carriers within one or more portions of a carrier.

For the purposes of scheduling, resources in non-contiguous portions may be addressed in a single assignment to a user or users, or may be assigned independent portions of a carrier independently. For example, if channel trees are used for scheduling, resources may be contiguously mapped to channel tree nodes regardless of whether they are in contiguous portions or not. That is, each resource has a resource identification that is based upon the carrier and not its location in the bandwidth.

Referring toFIG. 4, aspects of a channel structure for a multiple access wireless communication system are illustrated. A bandwidth400, which is a virtual bandwidth containing multiple discontinuous portions, is available for communication according to system design parameters. The structure includes one or more forward link frames404and reverse link frames408, each of which may be part of one or more superframes as discussed with respect toFIG. 2Aand/orFIG. 2B.

Each forward link frame404includes control channels406. Each of the control channels406may include information for functions related to, for example, acquisition; acknowledgements; forward link assignments for each access terminal, which may be different or the same for broadcast, multicast, and unicast message types, reverse link assignments for each access terminal; reverse link power control for each access terminal; and reverse link acknowledgements. It should be noted that more or fewer of such functions may be supported in control channels406. Also, the control channels406may hop in each frame according to hopping sequences that are the same or different from hopping sequences assigned to data channels.

Each reverse link frame408includes a number of reverse link transmissions, e.g.412,414, and416from access terminals. InFIG. 4, a reverse link transmission is depicted as being a block, i.e. a group of contiguous OFDM symbols. It should be noted that symbol rate hopping, e.g. non-contiguous symbol blocks may also be utilized.

In addition, each reverse link frame408may include one more reverse link control channels440, which may include feedback channels; pilot channels for reverse link channel estimation, and acknowledgment channels that may be included in the reverse link transmission412,414,416. Each of the reverse link control channels440may include information for functions related to, for example, forward link and reverse link resource requests by each access terminal; channel information, e.g. channel quality information (CQI) for different types of transmission; and pilots from the access terminals that may be used by the access point for channel estimation purposes. It should be noted that more or fewer of such functions may be supported in control channel440. Also, the reverse link control channels440may hop in each frame according to hopping sequences that are the same or different from hopping sequences assigned to data channels.

In certain aspects, to multiplex users on the reverse link control channels440, one or more orthogonal codes, scrambling sequences, or the like may be utilized to separate each user and/or different types of information transmitted in the reverse link control channels440. These orthogonal codes may be user specific or may be allocated by the access point to each access terminal per communication session or shorter period, e.g. per superframe.

Additionally, in certain aspects, some of the available subcarriers in an OFDM symbol may be designated as guard subcarriers and may not be modulated, i.e., no energy is transmitted on these subcarriers. The number of guard subcarriers in the superframe preamble and in each frame may be provided via one or more messages in the control channels406or superframe preamble.

Further, in some aspects, in order to reduce overhead transmission to a particular terminal, a packet may be jointly encoded for that access terminal, even if the symbols of the packets are to be transmitted over subcarriers. In this way a single cyclic redundancy check may be utilized for the packet and the transmissions that include symbols from these packets are not subject to overhead transmissions of cyclic redundancy checks.

It should be noted that the bandwidth400may comprise discontinuous subcarriers and need not be adjacent. In such aspects, the control channels may be limited to less than all of the portions of a carrier, randomly placed amongst the portions, or scheduled amongst the portions in some sort of deterministic fashion.

Referring toFIG. 5A, aspects of a forward link frame for a multiple access wireless communication system are illustrated. As shown inFIG. 5A, each forward link frame404is further divided into two segments. The first, a control channel406, which may or may not comprises a contiguous group of subcarriers, has a variable number of subcarriers assigned depending on the desired amount of control data and other considerations. The remaining portions422are generally available for data transmission. Control channel406may include one or more pilot channels512and514. In symbol rate hopping mode, the pilot channels may be present on each of the OFDM symbols in each forward link frame, and need not be included in the control channel406in those instances. In both cases, a signaling channel516and a power control channel518may be present in the control channel406, as depicted inFIG. 5A. The signaling channel516may include assignment, acknowledgement, and/or power references and adjustments for data, control, and pilot transmissions on the reverse link.

Power control channel518may carry information regarding interference generated at other sectors due to transmissions from access terminals of that sector. Also, in certain aspects, the subcarriers420at the edge of the entire bandwidth may function as quasi-guard subcarriers.

It should be noted that where multiple transmit antennas may be used to transmit for a sector, the different transmit antennas should have the same superframe timing (including the superframe index), OFDM symbol characteristics, and hop sequences.

It should be noted that, in some aspects, the control channel512,514,516,518may comprise the same allocations as a data transmission, e.g. if data transmissions are block hopped then blocks of the same or different sizes may be allocated for the control channel.

Referring toFIG. 5B, aspects of a reverse link frame for a multiple access wireless communication system are illustrated. A pilot channel522may include pilots to allow the access point to estimate the reverse link. A request channel524may include information to allow an access terminal to request resources for following reverse link, and forward link, frames.

A reverse link feedback channel526allows access terminals to provide feedback with respect to channel information CQI. The CQI may relate to one or more scheduled modes, or available modes for scheduling, for transmission to the access terminal. Exemplary modes may include beamforming, SDMA, preceding, or combinations thereof. A power control channel528may be used as a reference to allow the access point to generate power control instructions for reverse link transmission, e.g. data transmissions, by the access terminal. In some aspects, the power control channel528may comprise one or more of the feedback channels526. Data channels432may operate according to a symbol rate hopping or block hopping mode in different reverse link frames408. Also, in certain aspects, the subcarriers480at the edge of the entire bandwidth may function as quasi-guard subcarriers.

It should be noted that whileFIGS. 5A and 5Bdepict different channels that make up control channels406and440as being multiplexed in time, this need not be the case. The different channels that make up control channels406and440may be multiplexed using different orthogonal, quasi-orthogonal, or scrambling codes, different frequencies, or any combinations of time, code, and frequency.

Referring toFIG. 6, a block diagram of an embodiment of an exemplary first communications device or system810and an exemplary second communications device or system850in a MIMO system800is illustrated. At first communications device810, traffic data for a number of data streams is provided from a data source812to transmit (TX) data processor814. In an embodiment, each data stream is transmitted over a respective transmit antenna. TX data processor814formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data.

The modulation symbols for each of the data streams are then provided to a TX processor820, which may further process the modulation symbols (e.g., for OFDM). TX processor820then provides NTmodulation symbol streams to NTtransmitters (TMTR822athrough822t). Each transmitter822receives and processes a respective symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. NTmodulated signals from transmitters822athrough822tare then transmitted from NTantennas824athrough824t, respectively.

At second communications device850, the transmitted modulated signals are received by NRantennas852athrough852rand the received signal from each antenna852is provided to a respective receiver (RCVR)854. Each receiver854(854athrough854r) conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding “received” symbol stream.

An RX data processor860then receives and processes the NRreceived symbol streams from NRreceivers854based on a particular receiver processing technique to provide NT“detected” symbol streams. The processing by RX data processor860is described in further detail below. Each detected symbol stream includes symbols that are estimates of the modulation symbols transmitted for the corresponding data stream. RX data processor860then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. Recovered data is stored in data sink864. The processing by RX data processor860is complementary to that performed by TX processor820and TX data processor814at first communications device810.

RX data processor860may be limited in the number of subcarriers that it may simultaneously demodulate, e.g. 512 subcarriers or 5 MHz, 128 subcarriers or 1.25 MHz. 256 subcarriers or 2.5 MHz.

The channel response estimate generated by RX processor860may be used to perform space, space/time processing at the receiver, adjust power levels, change modulation rates or schemes, or other actions. RX processor860may further estimate the signal-to-noise-and-interference ratios (SNRs) of the detected symbol streams, and possibly other channel characteristics, and provides these quantities to a processor870. RX data processor860or processor870may further derive an estimate of the “operating” SNR for the system. Processor870then provides channel state information (CSI), which may comprise various types of information regarding the communication link and/or the received data stream. For example, the CSI may comprise the operating SNR. The CSI is then processed by a TX data processor818, modulated by a modulator880, conditioned by transmitters854athrough854r, and transmitted back to first communications device810. Additional data from data source816, e.g., including reverse link traffic, may be, and sometimes is, received by TX data processor818, modulated by modulator880, conditioned by transmitters854athrough854r, and transmitted to first communications device810.

At first communications device810, the modulated signals from second communications device850are received by antennas824, conditioned by receivers822, demodulated by a demodulator840, and processed by a RX data processor842to recover the CSI reported by the receiver system. The reported CSI is then provided to processor830and used to (1) determine the data rates and coding and modulation schemes to be used for the data streams and (2) generate various controls for TX data processor814and TX processor820. Alternatively, the CSI may be utilized by processor870to determine modulation schemes and/or coding rates for transmission, along with other information. This may then be provided to the transmitter of the first communications device which uses this information, which may be quantized, to provide later transmissions to the receiver of the second communications device. Data recovered by RX data processor842may be, and sometimes is, stored in data sink844. Recovered data may, and sometimes does, included reverse link traffic data.

Processors830and870direct the operation at the first and second communications devices, respectively. Memories832and872provide storage for program codes and data used by processors830and870, respectively.

At the receiver, various processing techniques may be used to process the NRreceived signals to detect the NTtransmitted symbol streams. These receiver processing techniques may be grouped into two primary categories (i) spatial and space-time receiver processing techniques (which are also referred to as equalization techniques); and (ii) “successive nulling/equalization and interference cancellation” receiver processing technique (which is also referred to as “successive interference cancellation” or “successive cancellation” receiver processing technique).

WhileFIG. 6describes a MIMO system, the same system may be applied to a multi-input single-output system where multiple transmit antennas, e.g. those on a base station, transmit one or more symbol streams to a single antenna device, e.g. a mobile station. Also, a single output to single input antenna system may be utilized in the same manner as described with respect toFIG. 6.

The transmission techniques described herein may be implemented by various means. For example, these techniques may be implemented in hardware, firmware, software, or a combination thereof. For a hardware implementation, the processing units at a transmitter may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, or a combination thereof. The processing units at a receiver may also be implemented within one or more ASICs, DSPs, processors, and so on.

For a software implementation, the transmission techniques may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in a memory (e.g., memory832or872inFIG. 6) and executed by a processor (e.g., processor830or870). The memory may be implemented within the processor or external to the processor.

It should be noted that the concept of channels herein refers to information or transmission types that may be transmitted by the access point or access terminal. It does not require or utilize fixed or predetermined blocks of subcarriers, time periods, or other resources dedicated to such transmissions.

FIG. 7is a flowchart700of an exemplary method of operating a communications device, e.g., a base station, access point, or central controller, for assigning resources in a wireless communications system. Operation starts in step702, where the communications device is powered on and initialized and proceeds to step704. In step704the communications device selects a first wireless terminal to be assigned communications resources, and in step706the communications device selects a second wireless terminal to be assigned communications resources. Operation proceeds from step706to step708.

In step708, the communications device assigns the first wireless terminal a resource including at least two discontinuous portions of bandwidth for a period of time, the two discontinuous portions of bandwidth separated by a portion of bandwidth not included in said resource. In various embodiments, the discontinuous portions of bandwidth are separated by at least 1.25 M Hz.

Operation proceeds from step708to step710. In step710, the communications device assigns the second wireless terminal a resource corresponding to one of said discontinuous portions of bandwidth during a second period of time, said one of said discontinuous portions of bandwidth being shared by said first and second wireless terminals on one of a time division multiplexing basis and a frequency division multiplexing basis. Operation proceeds from step710to step711.

In step711, the communications device transmits guard sub-carrier information indicating at least one of the number and location of guard sub-carriers in at least one of said discontinuous portions of bandwidth. In some embodiments, different numbers of guard sub-carriers are associated with different discontinuous portions of bandwidth. In some embodiments at least some of the discontinuous portions of bandwidth have guard sub-carriers at different locations. In various embodiments, guard sub-carrier information is broadcast in a preamble, e.g., a super-frame preamble. Operation proceeds from step711to step712.

In step712, the communications device transmits a single assignment message communicating the assignment of the resource including the at least two discontinuous portions of bandwidth to the first wireless terminal. In some embodiments, the transmitted assignment information includes a node identifier corresponding to a set of sub-carriers, the set of sub-carriers including at least one sub-carrier from each of the at least two discontinuous portions of bandwidth. In various embodiments, assigning comprises assigning the first wireless terminal to resources based upon a channel tree which indicates sub-carriers corresponding to a communications channel constructed from a plurality of discontinuous portions of bandwidth.

Operation proceeds from step712to step714. In step714the communications device transmits assignment information communicating to the second wireless terminal.

In some embodiments, steps706,710and714are optional steps and are omitted.

In some embodiments, the second wireless terminal is assigned a resource including at least two discontinuous portions of bandwidth to be used for a period of time, the two discontinuous portions of bandwidth being separated by a portion of bandwidth not included in said resource.

Steps716,718and720are steps which are included in some embodiments, but omitted in other embodiments. Operation proceeds from step714to step716. In step716, if the resource is assigned to the first wireless terminal is a downlink resource then, the communications device is controlled to proceed from step716to step718; however, if the resource assigned to the first wireless terminal is an uplink resource then the communications device is controlled to proceed from step716to step720. Returning to step718, in step718the communications device transmits an OFDM signal including information directed to said wireless terminal including tones corresponding to said discontinuous portions but not said portion of bandwidth not included in said resource. Returning to step720in step720the communications device processes a received OFDM signal including information from said first wireless terminal, wherein said processing includes filtering out sub-carriers corresponding to said portion of said bandwidth not included in said resource.

In one exemplary embodiment, the communications device is a base station which supports communications in a first band represented by302inFIG. 3and a second band represented by306inFIG. 3; however the base station does not support communications in band304ofFIG. 3. Assume that the region represented by304is at least 1.25 MHz. Continuing with the example, assume the first wireless terminal is assigned to use band302which includes 2 discontinuous portions. The base station may be restricted from using band304due to the communications service provider not being licensed in that bandwidth at that location. Alternatively, the base station may not be communicating in band304for interference control purposes.

FIG. 8is a flowchart1100of an exemplary method of operating a wireless terminal, e.g., access terminal, in accordance with various embodiments. Operation starts in step1102, where the wireless terminal is powered on and initialized. Operation proceeds from start step1102to step1104. In step1104, the wireless terminal receives a resource assignment message indicating assignment, for a period of time, to said wireless terminal of a resource including at least two discontinuous portions of bandwidth separated by a portion of bandwidth not included in said resource. In some embodiments, the discontinuous portions of bandwidth are separated by at least 1.25 MHz. In some embodiments, different numbers of guard sub-carriers are associated with different discontinuous portions of bandwidth. The assigned resource may be, and sometime is an uplink resource. The assigned resource may be, and sometime is a downlink resource. Operation proceeds from step1104to step1106.

In step1106, the wireless terminal determines from a node identifier received in said received resource assignment message and stored information, a set of sub-carriers corresponding to said node identifier to be used by said wireless terminal. In some embodiments, the set of sub-carriers includes at least one guard sub-carrier from each of the at least two discontinuous portions of bandwidth. Operation proceeds from step1106to step1108.

In step1108, the wireless terminal receives guard sub-carrier information indicating at least one of the number and location of guard sub-carriers in at least one of the discontinuous portion of bandwidth which have been assigned to the wireless terminal. In various embodiments, receiving guard sub-carrier information includes receiving a broadcast preamble, e.g., a superframe preamble, including guard sub-carrier information. In some embodiments, the number of guard sub-carriers at the edge of a portion of a band is a function of the communications protocol being used in the adjacent band, e.g., a CDMA protocol or an OFDM protocol. Then, in step1110the wireless terminal stores at least some of said received guard sub-carrier information, said stored guard sub-carrier information indicating different guard sub-carrier locations within different portions of bandwidth. Operation proceeds from step1110to step1112.

In step1112, the wireless terminal uses said assigned resource to communicate with an access point, e.g., a base station. In some embodiments, step1112includes one or more of steps1114,1116,1118and1120. In step1114, the wireless terminal determines whether the assigned resource is an uplink or downlink resource. If the assigned resource is an uplink resource then operation proceeds from step1114to step1116. If the assigned resource is a downlink resource, then operation proceeds from step1114to step1120. Returning to step1116, in step1116the wireless terminal generates an OFDM symbol including information directed to said access point, said OFDM symbol including tones corresponding to said discontinuous portions but not said portion of bandwidth not included in said resource. Then in step1118the wireless terminal transmits the generated OFDM symbol using the assigned resource. Returning to step1120, in step1120, the wireless terminal processes a received OFDM symbol including information from said access point, wherein said processing includes filtering out sub-carriers corresponding to said portion of said bandwidth not included in said assigned resource but including sub-carriers from said at least two discontinuous portions.

FIG. 9is a drawing of an exemplary communications apparatus900, e.g., a base station, access point or centralized controller node, used for assigning resources in a wireless communications system, in accordance with various embodiments. Exemplary communications apparatus900includes a wireless receiver module902, a wireless transmitter module904, a processor906, a network interface module908and memory910coupled together via a bus912over which the various elements may interchange data and information. Memory910includes routines918and data/information920. The processor906, e.g., a CPU, executes the routines918and uses the data/information920in memory910to control the operation of the communications apparatus900and implement methods, e.g., the methods of flowchart700ofFIG. 7.

Wireless receiver module902, e.g., an OFDM or CDMA receiver, is coupled to receive antenna914via which the communications apparatus receives signals including signals from which interference is measured.

Wireless transmitter module904, e.g., an OFDM or CDMA transmitter, is coupled to transmit antenna916, via which the communications apparatus transmits signals. Wireless transmitter module904transmits resource assignments and at least some of the resource assignments include allocation of discontinuous portions of bandwidth to a wireless terminal. Wireless transmitter module904transmits generated assignment messages (938, . . . ,940). In some embodiments, wireless transmitter module904transmits an OFDM symbol including information directed to a wireless terminal including tones corresponding to discontinuous portions but refrains from transmitting on said portion of bandwidth not included in said assigned resource, e.g., there is a null region in the transmitted OFDM symbol between the discontinuous portions. Wireless transmitter module904also broadcasts a preamble including guard band information, e.g., information identifying the number and/or location of guard sub-carriers in one or more discontinuous portions of a band.

In some embodiments, the same antenna is used for transmission and reception. In some embodiments multiple antennas and/or multiple antenna elements are used for reception. In some embodiments multiple antennas and/or multiple antenna elements are used for transmission. In some embodiments at least some of the same antennas or antenna elements are used for both transmission and reception. In some embodiments, the wireless communications apparatus900uses MIMO techniques.

Network interface module908is coupled to other network nodes, e.g., other access points/base stations, AAA node, home agent node, etc, and/or the Internet via network link909.

Routines918include a selection module922, an assignment module924, a transmission control module930, a symbol generation module927, a symbol recovery module929, and a preamble generation module925. The assignment module924includes a resource assignment module926and an assignment message generation module928.

Data/information920includes air link resource structure information932, selected wireless terminal information934, assignment information936, generated assignment messages (assignment message for WT1938, . . . , assignment message for WT n940), and channel tree resource information942. Air link resource structure information932includes information corresponding to a plurality of air link resources (air link resource1information944, . . . , air link resource M information946) and information identifying discontinuous portions of bandwidth948. Air link resource1information944includes information corresponding to a plurality of portions (portion1information950, . . . , portion N information952). Portion1information950includes frequency/time structure information954, channel information956and guard band information958. Portion N information952includes frequency/time structure information960, channel information962and guard band information964. At least some of the portions in air link resource information944are discontinuous with another portion, e.g., there is an intermediate frequency band region that is not part of the air link resource1.

For example, air link resource1information944represents stored airlink resource information indicating a first communications band available for assignment, while air link resource M information946represents stored airlink resource information indicating a second communications band available for assignment. Portion1information950represents information corresponding to a first discontinuous portion of bandwidth in the first communications band, while portion N information952represents information corresponding to a second discontinuous portion of bandwidth in the first communications band. The discontinuous portions of bandwidth, in some embodiments, are separated by at least 1.25 MHz. Guard band information958includes information about at least one of the number and location of guard bands within portion1of the first communications band. Guard band information964includes information about at least one of the number and location of guard bands within portion N of the first communications band. A guard band, in some embodiments, is a set of one or a few sub-carriers at a boundary area, e.g., sub-carriers at a boundary which are intentionally left unused.

Selected wireless terminal information934includes information identifying a plurality of wireless terminals which have been selected by communications device900to be assigned air link resources (selected wireless terminal1identification information966, . . . , selected WT n identification information968). Assignment information936includes a plurality of set of resource assignment information (WT1resource assignment information970including node identifier974, . . . , WT n resource assignment information972including node identifier976).

Channel tree resource information942includes information indicating sub-carriers corresponding to a communications channel constructed from a plurality of discontinuous portions of bandwidth.

Selection module922selects wireless terminals to be assigned communication resources. For example, selection module922selects a first wireless terminal to be assigned a communication resource. Selected wireless terminal information934is an output of selection module922.

Resource assignment module926assigns a wireless terminal selected by the selection module922a resource. For example, the resource assignment module926assigns the first wireless terminal selected by the selection module922a resource including at least two discontinuous portions of bandwidth for a period of time, said two discontinuous portions of bandwidth being separated by a portion of bandwidth not included in said assigned resource. The assigned resource may be, and sometimes is an uplink resource. The assigned resource may be, and sometimes is, a downlink resource. Assignment information936represents outputs of resource assignment module926.

Assignment message generation module928generates assignment messages communicating resource assignments to wireless terminals. For example, assignment message generation module928generates a single assignment message communicating the assignment of a resource including the at least tow discontinuous portions of bandwidth to the first wireless terminal. In some embodiments, the assignment message generation module928generates an assignment message including a node identifier corresponding to a set of sub-carriers, the set of sub-carriers including at least one sub-carrier from each of at least two discontinuous portions of bandwidth. Generated assignment messages (938, . . . ,940) represent outputs of assignment message generation module928.

Transmission control module930controls the wireless transmitter module904to transmit signals, e.g., preambles, assignment messages, downlink traffic channel signals and downlink control channel signals.

Symbol generation module927generates OFDM symbols. In some embodiments, at least some of the generated OFDM symbols include tones corresponding to discontinuous portions of a band but not said portion of bandwidth not included in said assigned resource. For example, consider that the generated OFDM symbol corresponds to the band represented by element302ofFIG. 3and that band304is not used by the communications device, an exemplary generated OFDM symbol includes sub-carriers corresponding to the upper portion of302and the lower portion of302, but does not include sub-carriers corresponding to the region of band304.

Symbol recovery module929recovers information from received OFDM symbols. In some embodiments for at least some bands which include discontinuous portions, the symbol recovery module929filters out sub-carriers in the portion of bandwidth not included in the assigned resource, e.g., the portion between the two discontinuous portions.

Preamble generation module925generates a preamble, e.g., a preamble for a super-frame, which conveys guard band information, e.g., at least some of guard band information (958,964).

FIG. 10is a drawing of an exemplary wireless terminal1000, e.g., an access terminal, in accordance with various embodiments. Exemplary wireless terminal1000includes a wireless receiver module1002, a wireless transmitter module1004, a processor1006, user I/O devices1008and memory1010coupled together via a bus1012over which the various elements may interchange data and information. Memory1010includes routines1018and data/information1020. The processor1006, e.g., a CPU, executes the routines1018and uses the data/information1020in memory1010to control the operation of the wireless terminal1000and implement methods, e.g., the methods of flowchart1100ofFIG. 8.

Wireless receiver module1002, e.g., an OFDM receiver, is coupled to receive antenna1014via which the wireless terminal1000receives downlink signals from communications devices, e.g., access points. Wireless receiver module1002receives a preamble, said preamble conveying guard sub-carrier information. Wireless receiver module1002also receives information communicated in forward link frames, e.g., downlink traffic data and control data. Wireless receiver module1002receives a resource assignment message, e.g., message1028, said resource assignment message indicating assignment, for a period of time, to said wireless terminal1000of a resource including at least tow discontinuous portions of bandwidth separated by a portion of bandwidth not included in said resource. For example, the resource assignment message1028may indicate that wireless terminal1000has been assigned the air link resource designated302inFIG. 3. The assigned resource may be, and sometimes is an uplink resource. The assigned resource may be, and sometimes is, a downlink resource.

In some embodiments, different numbers of guard sub-carriers can be, and sometimes are, associated with different discontinuous portions of bandwidth. In various embodiments, the discontinuous portions of bandwidth are separated by at least 1.25 MHz.

Wireless transmitter module1004, e.g., an OFDM transmitter, is coupled to transmit antenna1016via which the wireless terminal1000transmits uplink signals to communications devices, e.g., to access points. Transmitter module1004transmits symbols, e.g., OFDM symbols, generated by symbol generation module1022. At times, the generated symbols include subcarriers corresponding to two discontinuous portions of a resource which has been assigned and include an intentional null region between the two discontinuous portions.

In some embodiments, the same antenna is used for transmission and reception. In some embodiments multiple antennas and/or multiple antenna elements are used for reception. In some embodiments multiple antennas and/or multiple antenna elements are used for transmission. In some embodiments at least some of the same antennas or antenna elements are used for both transmission and reception. In some embodiments, the wireless terminal1000uses MIMO techniques.

User I/O devices1008include, e.g., microphone, keyboard, keypad, switches, camera, speaker, display, etc. User I/O devices1008allow a user of wireless terminal1000to input data/information, access output data/information, and control at least some functions of the wireless terminal1000, e.g., initiate a communications session with a peer node, e.g., another wireless terminal.

Routines1018include a symbol generation module1022, a symbol recovery module1024and a guard sub-carrier information recovery module1026. Data/information1020includes a received resource assignment message1028, received guard sub-carrier information1032and node identifier/sub-carrier mapping information1033. The received resource assignment message1028includes a node identifier1030. Received guard sub-carrier information1032includes information indicating different guard sub-carrier locations within different discontinuous portions of bandwidth. In some embodiments, the guard sub-carrier information is extracted from a received preamble, e.g., a preamble of a superframe. The node identifier/sub-carrier mapping information1033includes sets of sub-carriers corresponding to node identifiers ((node identifier11034and corresponding set1of sub-carriers1038), . . . , (node identifier N1036and corresponding set N of sub-carriers1040)). In various embodiments, a set of sub-carriers corresponding to a node identifier includes at least one guard sub-carrier from each of the at least two discontinuous portions of bandwidth corresponding to the resource identified by the node identifier.

Symbol generation module1022generates symbols corresponding to the allocated resource. In some embodiments, the symbol generation module1022is an OFDM symbol generation module which generates an OFDM symbol including information directed to an access point, said OFDM symbol including tones corresponding to said discontinuous portions but not said portion of bandwidth not included in said resource. Tones may be, and sometimes are, also referred to as sub-carriers.

Symbol recovery module1024recovers symbols, e.g., OFDM symbols, corresponding to an allocated resource. If the allocated resource includes two discontinuous portions separated by a portion of bandwidth not included in the resource, the symbol recovery module1024filters out the sub-carriers in the portion of bandwidth not included in the resource as part of the recovery operation.

Guard sub-carrier information recovery module1026recovers received information indicating at least one of the number and location of guard sub-carriers in at least one of said discontinuous portions of bandwidth.

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

In various embodiments, nodes described herein are implemented using one or more modules to perform the steps corresponding to one or more methods of the aspect, for example, signal processing, message generation and/or transmission steps. Thus, in some embodiments various features are implemented using modules. Such modules may be implemented using software, hardware or a combination of software and hardware. Many of the above described methods or method steps can be implemented using machine executable instructions, such as software, included in a machine readable medium such as a memory device, e.g., RAM, floppy disk, compact disc, DVD, etc. to control a machine, e.g., general purpose computer with or without additional hardware, to implement all or portions of the above described methods, e.g., in one or more nodes. Accordingly, among other things, the aspect is directed to a machine-readable medium including machine executable instructions for causing a machine, e.g., processor and associated hardware, to perform one or more of the steps of the above-described method(s).

In various embodiments nodes described herein are implemented using one or more modules to perform the steps corresponding to one or more methods, for example, signal processing, message generation, information recovery, and/or transmission steps. In some embodiments various features are implemented using modules. Such modules may be implemented using software, hardware or a combination of software and hardware. Many of the above described methods or method steps can be implemented using machine executable instructions, such as software, included in a machine readable medium such as a memory device, e.g., RAM, floppy disk, compact disc, DVD, etc. to control a machine, e.g., general purpose computer with or without additional hardware, to implement all or portions of the above described methods, e.g., in one or more nodes. Accordingly, among other things, various embodiments are directed to a machine-readable medium including machine executable instructions for causing a machine, e.g., processor and associated hardware, to perform one or more of the steps of the above-described method(s).

In some embodiments, the processor or processors, e.g., CPUs, of one or more devices, e.g., communications devices such as access terminals and/or access points, are configured to perform the steps of the methods described as being performed by the communications device. The configuration of the processor may be achieved by using one or more modules, e.g., software modules, to control processor configuration and/or by including hardware in the processor, e.g., hardware modules, to perform the recited steps and/or control processor configuration. Accordingly, some but not all embodiments are directed to a device, e.g., communications device, with a processor which includes a module corresponding to each of the steps of the various described methods performed by the device in which the processor is included. In some but not all embodiments a device, e.g., communications device, includes a module corresponding to each of the steps of the various described methods performed by the device in which the processor is included. The modules may be implemented using software and/or hardware.

Numerous additional variations on the methods and apparatus described above will be apparent to those skilled in the art in view of the above descriptions. Such variations are to be considered within scope. The methods and apparatus of various embodiments may be, and in various embodiments are, used with CDMA, orthogonal frequency division multiplexing (OFDM), and/or various other types of communications techniques which may be used to provide wireless communications links between access nodes and mobile nodes. In some embodiments the access nodes are implemented as base stations which establish communications links with mobile nodes using OFDM and/or CDMA. In various embodiments the mobile nodes are implemented as notebook computers, personal data assistants (PDAs), or other portable devices including receiver/transmitter circuits and logic and/or routines, for implementing the methods of various embodiments.