Uplink power control for LTE

Systems and methodologies are described that facilitate employing aperiodic closed loop power control corrections in a Long Term Evolution (LTE) based wireless communication environment. An aperiodic power control command can be sent over a downlink to control and/or correct an uplink power level employed by an access terminal. Transmission of the aperiodic power control can be triggered by a measurement (e.g., received power being outside a set margin, . . . ). The aperiodic power control command can include a single-bit and/or a multi-bit correction. Further, the access terminal can alter the uplink power level employed for subsequent uplink transmissions based upon the aperiodic power control command when received. Additionally, regardless whether the aperiodic power control command is received at a given time over the downlink, the access terminal can employ periodic power control commands and an open loop power control mechanism to adjust the uplink power level.

BACKGROUND

The following description relates generally to wireless communications, and more particularly to controlling uplink (UL) power levels employed by access terminals in a Long Term Evolution (LTE) based wireless communication system.

Wireless communication systems are widely deployed to provide various types of communication; for instance, voice and/or data can be provided via such wireless communication systems. A typical wireless communication system, or network, can provide multiple users access to one or more shared resources (e.g., bandwidth, transmit power, . . . ). For instance, a system can use a variety of multiple access techniques such as Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), Orthogonal Frequency Division Multiplexing (OFDM), Single Carrier Frequency Division Multiplexing (SC-FDM) and others. Additionally, the system can conform to specifications such as third generation partnership project (3GPP), 3GPP long term evolution (LTE), etc.

Generally, wireless multiple-access communication systems can simultaneously support communication for multiple access terminals. Each access terminal can communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to access terminals, and the reverse link (or uplink) refers to the communication link from access terminals to base stations. This communication link can be established via a single-input-single-output (SISO), multiple-inputs-single-output (MISO), single-input-multiple-outputs (SIMO) or a multiple-inputs-multiple-outputs (MIMO) system.

Wireless communication systems oftentimes employ one or more base stations and sectors therein that provide a coverage area. A typical sector can transmit multiple data streams for broadcast, multicast and/or unicast services, wherein a data stream may be a stream of data that can be of independent reception interest to an access terminal. An access terminal within the coverage area of such sector can be employed to receive one, more than one, or all the data streams carried by the composite stream. Likewise, an access terminal can transmit data to the base station or another access terminal. With many access terminals transmitting signal data in proximity, power control is important for yielding sufficient signal to noise ratios (SNRs) at different data rates and transmission bandwidths for communications over the uplink. It is desirable to keep the overhead incurred from the transmission of the power adjustments to these access terminals as low as possible while achieving the aforementioned goals.

SUMMARY

In accordance with one or more embodiments and corresponding disclosure thereof, various aspects are described in connection with facilitating employment of aperiodic closed loop power control corrections in a Long Term Evolution (LTE) based wireless communication environment. An aperiodic power control command can be sent over a downlink to control and/or correct an uplink power level employed by an access terminal. Transmission of the aperiodic power control can be triggered by a measurement (e.g. received power being outside a set margin, . . . ) or by the opportunity for transmission of control information from the sector to the access terminal on the downlink. The aperiodic power control command can include a single-bit and/or a multi-bit correction. Further, the access terminal can alter the uplink power level employed for subsequent uplink transmissions based upon the aperiodic power control command when received. Additionally, regardless whether the aperiodic power control command is received at a given time over the downlink, the access terminal can employ periodic power control commands and an open loop power control mechanism to adjust the uplink power level.

According to related aspects, a method that facilitates generating power control commands in a wireless communication environment is described herein. The method can include receiving uplink transmissions from an access terminal. Further, the method can comprise determining whether to adjust an uplink power level employed by the access terminal. Moreover, the method can include transmitting power control commands to the access terminal to alter the uplink power level using a layer1/layer2(L1/L2) control information channel utilized for downlink (DL) assignments and uplink (UL) grants.

Another aspect relates to a wireless communications apparatus. The wireless communications apparatus can include a memory that retains instructions related to obtaining uplink transmissions sent from an access terminal at an uplink power level, deciphering whether to alter the uplink power level, evaluating an amount to adjust the uplink power level when effectuating alteration to the uplink power level, and sending power control commands to the access terminal to alter the uplink power level via a layer1/layer2(L1/L2) control information channel utilized for downlink (DL) assignments and uplink (UL) grants. Further, the wireless communications apparatus can include a processor, coupled to the memory, configured to execute the instructions retained in the memory.

Yet another aspect relates to a wireless communications apparatus that enables yielding power control commands for utilization by access terminals in a wireless communication environment. The wireless communications apparatus can include means for obtaining uplink transmissions sent from an access terminal at an uplink power level. Further, the wireless communications apparatus can comprise means for evaluating whether to alter the uplink power level employed by the access terminal. Moreover, the wireless communications apparatus can include means for sending power control commands via a layer1/layer2(L1/L2) control information channel used for downlink (DL) assignments and uplink (UL) grants, the power control commands adjust the uplink power level by a specified amount.

Still another aspect relates to a machine-readable medium having stored thereon machine-executable instructions for obtaining uplink transmissions sent from an access terminal at an uplink power level; evaluating whether to alter the uplink power level employed by the access terminal; and sending power control commands via a layer1/layer2(L1/L2) control information channel utilized for downlink (DL) assignments and uplink (UL) grants, the power control commands adjust the uplink power level by a specified amount.

In accordance with another aspect, an apparatus in a wireless communication system can include a processor, wherein the processor can be configured to receive uplink transmissions from an access terminal. Moreover, the processor can be configured to determine whether to adjust an uplink power level employed by the access terminal. Further, the processor can be configured to transmit power control commands to the access terminal via a layer1/layer2(L1/L2) control information channel used for downlink (DL) assignments and uplink (UL) grants, the power control commands alter the uplink power level when triggered by a measurement.

According to other aspects, a method that facilitates employing power control commands in wireless communication environment is described herein. The method can include transmitting data upon an uplink at a power level. Further, the method can include receiving a power control command via a layer1/layer2(L1/L2) control information channel used for downlink (DL) assignments and uplink (UL) grants. The method can also include altering the power level based upon the power control command. Moreover, the method can comprise transmitting data upon the uplink at the altered power level.

Yet another aspect relates to a wireless communications apparatus that can include a memory that retains instructions related to sending data upon an uplink at a power level, obtaining a power control command via a layer1/layer2(L1/L2) control information channel used for downlink (DL) assignments and uplink (UL) grants, and adjusting the power level based upon the power control command for a subsequent data transmission. Further, the wireless communications apparatus can comprise a processor, coupled to the memory, configured to execute the instructions retained in the memory.

Another aspect relates to a wireless communications apparatus that enables utilizing power control commands in a wireless communication environment. The wireless communications apparatus can comprise means for sending data upon an uplink at a power level. Moreover, the wireless communications apparatus can include means for obtaining a power control command via a layer1/layer2(L1/L2) control information channel used for downlink (DL) assignments and uplink (UL) grants. Further, the wireless communications apparatus can include means for changing the power level for a subsequent data transmission as a function of the power control command.

Still another aspect relates to a machine-readable medium having stored thereon machine-executable instructions for sending data upon an uplink at a power level, obtaining a power control command via a layer1/layer2(L1/L2) control information channel used for downlink (DL) assignments and uplink (UL) grants, and changing the power level for a subsequent data transmission as a function of the power control command.

In accordance with another aspect, an apparatus in a wireless communication system can include a processor, wherein the processor can be configured to transmit data upon an uplink at a power level. Further, the processor can be configured to receive a power control command via a layer1/layer2(L1/L2) control information channel used for downlink (DL) assignments and uplink (UL) grants. Moreover, the processor can be configured to alter the power level based upon the power control command. Additionally, the processor can be configured to transmit data upon the uplink at the altered power level.

DETAILED DESCRIPTION

Furthermore, various embodiments are described herein in connection with an access terminal. An access terminal can also be called a system, subscriber unit, subscriber station, mobile station, mobile, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, user device, or user equipment (UE). An access terminal can be 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, computing device, or other processing device connected to a wireless modem. Moreover, various embodiments are described herein in connection with a base station. A base station can be utilized for communicating with access terminal(s) and can also be referred to as an access point, Node B, eNode B (eNB), or some other terminology.

Referring now toFIG. 1, a wireless communication system100is illustrated in accordance with various embodiments presented herein. System100comprises a base station102that can include multiple antenna groups. For example, one antenna group can include antennas104and106, another group can comprise antennas108and110, and an additional group can include antennas112and114. Two antennas are illustrated for each antenna group; however, more or fewer antennas can be utilized for each group. Base station102can additionally include a transmitter chain and a receiver chain, each of which can in turn comprise a plurality of components associated with signal transmission and reception (e.g., processors, modulators, multiplexers, demodulators, demultiplexers, antennas, etc.), as will be appreciated by one skilled in the art.

The corresponding sector of base station102can communicate with one or more access terminals such as access terminal116and access terminal122; however, it is to be appreciated that base station102can communicate with substantially any number of access terminals similar to access terminals116and122. Access terminals116and122can be, for example, cellular phones, smart phones, laptops, handheld communication devices, handheld computing devices, satellite radios, global positioning systems, PDAs, and/or any other suitable device for communicating over wireless communication system100. As depicted, access terminal116is in communication with antennas112and114, where antennas112and114transmit information to access terminal116over a forward link118and receive information from access terminal116over a reverse link120. Moreover, access terminal122is in communication with antennas104and106, where antennas104and106transmit information to access terminal122over a forward link124and receive information from access terminal122over a reverse link126. In a frequency division duplex (FDD) system, forward link118can utilize a different frequency band than that used by reverse link120, and forward link124can employ a different frequency band than that employed by reverse link126, for example. Further, in a time division duplex (TDD) system, forward link118and reverse link120can utilize a common frequency band and forward link124and reverse link126can utilize a common frequency band.

Each group of antennas and/or the area in which they are designated to communicate can be referred to as a sector of base station102, or as a cell of an eNB. For example, antenna groups can be designed to communicate to access terminals in a sector of the areas covered by base station102. In communication over forward links118and124, the transmitting antennas of base station102can utilize beamforming to improve signal-to-noise ratio of forward links118and124for access terminals116and122. Also, while base station102utilizes beamforming to transmit to access terminals116and122scattered randomly through an associated coverage, access terminals in neighboring cells can be subject to less interference as compared to a base station transmitting through a single antenna to all its access terminals.

System100can be a Long Term Evolution (LTE) based system, for instance. In such system100, the corresponding sectors of base station102can control uplink power levels utilized by access terminals116and122. Hence, system100can provide uplink (UL) power control which yields compensation of path loss and shadowing (e.g., path loss and shadowing can slowly change over time) and compensation of time-varying interference from adjacent cells (e.g., since system100can be an LTE based system that utilizes frequency reuse1). Moreover, system100can mitigate large variations of receive power obtained at base station102across users (e.g., since the users can be multiplexed within a common band). Further, system100can compensate for multipath fading variations at sufficiently low speeds. For instance, the coherence time of the channel for 3 km/h at different carrier frequencies can be as follows: a carrier frequency of 900 MHz can have a coherence time of 400 ms, a carrier frequency of 2 GHz can have a coherence time of 180 ms, and a carrier frequency of 3 GHz can have a coherence time of 120 ms. Thus, depending on latency and periodicity of adjustments, fast fading effects can be corrected with low Doppler frequencies.

System100can employ uplink power control that combines open loop and closed loop power control mechanisms. According to an example, open loop power control can be utilized by each access terminal116,122for setting power levels of a first preamble of a Random Access Channel (RACH) communication. For the first preamble of a RACH, each access terminal116,122may have obtained downlink (DL) communication(s) from base station102, and the open loop mechanism can enable each access terminal116,122to select an uplink transmit power level that is inversely proportional to a receive power level related to the obtained downlink communication(s). Thus, knowledge of the downlink can be utilized by access terminals116,122for uplink transmissions. The open loop mechanism can allow for very fast adaptation to severe changes of radio conditions (e.g., depending on receive power filtering) by way of instantaneous power adjustments. Further, the open loop mechanism can continue to operate beyond the RACH processing in contrast to conventional techniques oftentimes employed. The closed loop mechanism can be utilized by system100once the random access procedure has succeeded. For example, closed loop techniques can be employed when periodic uplink resources have been allocated to access terminals116,122(e.g., the periodic uplink resources can be Physical Uplink Control Channel (PUCCH) or Sounding Reference Signal (SRS) resources). Moreover, the corresponding sectors in base station102(and/or a network) can control uplink transmit power utilized by access terminals116,122based upon the closed loop control.

The closed loop mechanism employed by system100can be periodic, aperiodic or a combination of the two. Periodic closed-loop corrections can be transmitted by the corresponding sector in base station102to access terminals116,122periodically (e.g., once every 0.5 ms, 1 ms, 2 ms, 4 ms, . . . ). For instance, the periodicity can be dependent upon periodicity of uplink transmissions. Moreover, the periodic corrections can be single-bit corrections (e.g., up/down, ±1 dB, . . . ) and/or multi-bit corrections (e.g., ±1 dB, ±2 dB, ±3 dB, ±4 dB, . . . ). Thus, the power control step and the periodicity of corrections can determine a maximum rate of change of uplink power that the corresponding sector in base station102(and/or the network) can control. According to another example, aperiodic corrections can be sent from the corresponding sector in base station102to corresponding access terminals116,122as needed. Following this example, these corrections can be transmitted aperiodically when triggered by a network measurement (e.g., receive (RX) power outside a set margin, opportunity to send control information to a given access terminal, . . . ). Moreover, aperiodic corrections can be single-bit and/or multi-bit (e.g., the corrections can be multi-bit since a significant portion of overhead associated with aperiodic corrections can relate to correction scheduling rather than correction size). According to yet another example, the aperiodic corrections can be transmitted by the corresponding sector in base station102to access terminals116,122in addition to periodic corrections in order to minimize the overhead incurred with the transmission of these power adjustments.

Now turning toFIG. 2, illustrated is a system200that controls uplink power level(s) employed by access terminal(s) in an LTE based wireless communication environment. System200includes a sector in a base station202that can communicate with substantially any number of access terminal(s) (not shown). Moreover, the sector in base station202can include a received power monitor204that evaluates power level(s) associated with uplink signal(s) obtained from access terminal(s). Further, the sector in base station202can comprise an uplink (UL) power adjuster206that utilizes the analyzed power level(s) to generate command(s) to alter access terminal power levels.

Various physical (PHY) channels208can be leveraged for communication between base station202and the access terminal(s); these physical channels208can include downlink physical channels and uplink physical channels. Examples of downlink physical channels include Physical Downlink Control Channel (PDCCH), Physical Downlink Shared Channel (PDSCH), and Common Power Control Channel (CPCCH). PDCCH is a DL layer1/layer2(L1/L2) control channel (e.g., assigning PHY layer resources for DL or UL transmission) that has a capacity of around 30-60 bits and is cyclic redundancy check (CRC) protected. PDCCH can carry uplink grants and downlink assignments. PDSCH is a DL shared data channel; PDSCH can be a DL data channel shared amongst different users. CPCCH is transmitted on the DL for UL power controlling multiple access terminals. Corrections sent on the CPCCH can be single-bit or multi-bit. Further, the CPCCH can be a particular instantiation of the PDCCH. Examples of uplink physical channels include Physical Uplink Control Channel (PUCCH), Physical Uplink Shared Channel (PUSCH), Sounding Reference Signal (SRS), and Random Access Channel (RACH). PUCCH includes the report of Channel Quality Indicator (CQI) channel, the ACK channel and the UL requests. PUSCH is an UL shared data channel. The SRS can lack information and can enable sounding the channel on the UL to allow for the channel to be sampled over part or the full system bandwidth. It is to be appreciated that the claimed subject matter is not limited to these example physical channels208.

Received power monitor204and UL power adjuster206can provide closed loop power control for uplink transmissions effectuated by access terminal(s). Operation on the LTE system can entail transmissions at a given time over bandwidths that can be significantly less than the entirety of the bandwidth of system200. Each access terminal can transmit over a small portion of the entire bandwidth of system200at a given time. Moreover, frequency hopping can be employed by the access terminals; thus, the corresponding sector in base station202can encounter difficulty when attempting to evaluate adjustments to make to uplink power levels of the access terminals. Therefore, an adequate closed loop power control mechanism provided by received power monitor204and UL power adjuster206constructs a wideband receive power estimate from transmissions over possibly multiple instants and on possibly multiple UL PHY channels enabling adequate correction of the path loss and shadowing effects irrespective of access terminal transmission bandwidth at any time.

Received power monitor204constructs the wideband receive power estimate from the sampling of the channel based upon access terminal transmissions in a variety of manners. For instance, received power monitor204can employ the PUSCH for sampling. Following this example, the transmission band of the PUSCH is localized on a given slot. Frequency diverse scheduling can apply a pseudo-random hopping pattern to the transmission band at slot boundaries and possibly over re-transmissions to fully exploit the frequency diversity. PUSCH transmissions exploiting frequency selective scheduling will not apply a frequency hopping pattern onto the transmit data and therefore may require a long time in order to sample the channel at all (or most) frequencies. Moreover, frequency selective scheduling can leverage transmission of an SRS or PUCCH. Frequency selective scheduling is a scheduling strategy exploiting the selectivity of the channel; for instance, frequency selective scheduling attempts to confine transmissions onto the best sub-bands. This scheduling strategy can be relevant for low mobility access terminals. Further, these transmissions are usually exclusive of frequency hopping techniques. Frequency diverse scheduling is a disparate scheduling strategy employing the entire system bandwidth (e.g., modulo the minimum transmit bandwidth capability, . . . ) to naturally obtain frequency diversity. Transmissions associated with frequency diverse scheduling can be associated with frequency hopping. Moreover, frequency hopping can include changing the transmit frequency of a waveform in a pseudo-random manner to exploit frequency diversity from the point of view of a channel as well as interference.

According to another example, received power monitor204can utilize the PUCCH for sampling the UL channel and therefore to construct the wideband receive power estimate. The transmission band of the PUCCH can also be localized on a given slot with hopping at the slot boundary on each transmission time interval (TTI). An occupied band can depend on whether there is PUSCH transmission on a particular TTI. When PUSCH is transmitted over a given TTI, the control information that would be transmitted over PUCCH can be transmitted in-band with the remainder of the data transmission (e.g., to retain the single-carrier property of the UL waveform) over PUSCH. When PUSCH is not transmitted over a particular TTI, the PUCCH can be transmitted over a localized band set aside for transmission of the PUCCH at the edges of the system band.

Pursuant to another illustration, SRS transmissions can be utilized by received power monitor204to sample the channel and construct the wideband receive power estimate. The transmission band (over time) of the SRS can be substantially equal to the entire system band (or the minimum access terminal transmit bandwidth capability). At a given SC-FDMA symbol (e.g., SC-FDMA symbol is a minimum unit of transmission on the UL of LTE), the transmission can be localized (e.g., spanning a set of consecutive subcarriers that hops over time) or distributed (e.g., spanning the entire system band or a portion thereof, which may or may not hop, . . . ).

Received power monitor204constructs the wideband receive power estimate from sampling of the channel over the entire system bandwidth. However, depending upon the manner by which the channel is sampled and/or whether frequency hopping is applied to the transmissions, the time span to construct the wideband receive power estimate from the sampling of the UL channel by received power monitor204can vary.

PUCCH transmissions when there is no UL data take place at the edges of the system band. PUCCH transmission where there is UL data can be located in-band with the data transmission over the PUSCH. Further, PUSCH transmissions may not change transmit frequency or may not be hopping at all to exploit UL frequency selective scheduling; however, to enable frequency selective scheduling, SRS transmissions can be leveraged for FDD/TDD systems. Moreover, when the PUSCH uses frequency diverse scheduling, frequency hopping is applied to transmissions.

Moreover, based upon the channel sampling effectuated by received power monitor204, UL power adjuster206can generate a command that can alter the UL power level employed by a particular access terminal. The command can be a single-bit correction (e.g., up/down, ±1 dB, . . . ) and/or a multi-bit correction (e.g., ±1 dB, ±2 dB, ±3 dB, ±4 dB, . . . ). Further, UL power adjuster206(and/or the sector in the corresponding base station202) can transmit the generated command to the access terminal to which the command is intended.

Further, the access terminal(s) can each be associated with a particular state at a given time. Examples of access terminal states include LTE_IDLE, LTE_ACTIVE and LTE_ACTIVE_CPC. However, it is to be appreciated that the claimed subject matter is not limited to these illustrative states.

LTE_IDLE is an access terminal state where the access terminal does not have a unique cell ID. While in the LTE_IDLE state, the access terminal can lack a connection to base station202. Further, transitioning to LTE_ACTIVE state from LTE_IDLE can be effectuated via utilization of RACH.

LTE_ACTIVE is an access terminal state where the access terminal has a unique cell ID. Further, when in LTE_ACTIVE state, the access terminal can actively transfer data via the uplink and/or downlink. Access terminals in this state have UL dedicated resources (e.g., CQI, SRS that are transmitted periodically, . . . ). According to an example, access terminals in the LTE_ACTIVE state can employ discontinuous transmission/discontinuous reception (DTX/DRX) procedures with a cycle not expected to be much longer than approximately 20 ms or 40 ms. Access terminals in this state start PUSCH transmissions either directly in response to DL activity (e.g., with possibly an UL grant in-band with DL data or through the PDCCH) or by sending an UL request over the PUCCH. Further, users in this state can be access terminals with an active exchange of UL/DL data taking place or access terminals running a high Grade of Service (GoS) application (e.g., Voice over Internet Protocol (VoIP), . . . ).

LTE_ACTIVE_CPC (Continuous Packet Connectivity) is a substate of LTE_ACTIVE where access terminals retain their unique cell ID but where the UL dedicated resources have been released. Utilization of LTE_ACTIVE_CPC enables extending battery life. Access terminals in this substate start transmissions either in response to DL activity (e.g., with possibly an UL grant in-band with DL data or through the PDCCH, . . . ) or by sending an UL request over the RACH. The initial transmit power can be either based on an open loop mechanism (e.g., response to DL activity) or a last successful preamble (e.g., RACH).

Referring toFIG. 3, illustrated is a system300that periodically corrects an uplink power level employed by an access terminal. System300includes base station202that communicates with an access terminal302(and/or any number of disparate access terminals (not shown)). Access terminal302comprises an UL power manager304, which further includes an UL power initializer306. Moreover, access terminal302includes an UL periodic transmitter308. Base station202further includes received power monitor204and UL power adjuster206; UL power adjuster206further comprises a periodic corrector310.

UL power manager304controls the uplink power level employed by access terminal302for uplink transmissions. UL power manager304can receive the periodic power control commands from base station202and alter the uplink power level utilized for transmission based upon the obtained commands. According to another illustration, UL power initializer306can set an initial uplink transmit power. UL power initializer306can employ an open loop mechanism to determine the initial uplink transmit power based upon downlink activity, for example. Additionally or alternatively, UL power initializer306can assign the initial uplink power level to a power level associated with a previous (e.g., immediately prior, . . . ) successful preamble (e.g., RACH).

UL periodic transmitter308can send periodic transmissions over the uplink to base station202. For instance, UL periodic transmitter308can operate while access terminal302is in LTE_ACTIVE state. Moreover, the periodic transmissions transferred by UL periodic transmitter308can be a set of SRS transmissions; however, it is to be appreciated that the claimed subject matter is not so limited as any type of periodic uplink transmission can be employed (e.g., periodic CQI transmissions, periodic PUCCH transmissions, . . . ). Thus, UL periodic transmitter308can send SRS transmissions over the uplink to sound the channel over the entire system bandwidth since the SRS transmissions can be sounding signals; therefore, at the same time as enabling uplink frequency selective scheduling, the sounding signal can be used to compute the closed loop corrections for UL power control. Transmissions sent by UL periodic transmitter308can be received and/or employed by received power monitor204of base station202in connection with sampling the channel. Moreover, UL power adjuster206and/or periodic corrector310can generate commands corresponding to such sampling.

According to an illustration, periodicity of UL transmissions sent by UL periodic transmitter308of access terminal302can be linked to DL TPC command transmission cycle employed by periodic corrector310for access terminal302; hence, access terminals with differing UL transmission periodicity can be sent DL TPC commands with disparate transmission cycles. Further, the periodicity of UL transmissions can correlate to a number of bits allocated for access terminal power adjustments yielded by periodic corrector310employed for a particular access terminal (e.g., access terminal302, . . . ). For example, a mapping between the number of bits allocated for uplink power control correction and an uplink periodic transmission rate (e.g., SRS transmission rate, PUCCH transmission rate, . . . ) can be predetermined. Following this example, an uplink periodic transmission rate of 200 Hz can map to 1 bit, a rate of 100 Hz can map to 1 bit, a rate of 50 Hz can map to 2 bits, a rate of 25 Hz can map to 2 bits, and a rate of 0 Hz can map to x>2 bits. According to the aforementioned example, the number of bits allocated for the power adjustments at the access terminal becomes larger as the uplink periodic transmission rate decreases. At the limit for an uplink periodic transmission rate of 0 Hz (e.g., no transmission of the SRS, PUCCH, . . . ), the power adjustment can be x>2 bits, which can be the case of open loop transmissions with closed loop adjustments on an as needed basis.

Periodic corrector310can send corrections on a periodic basis to substantially all users in LTE_ACTIVE state associated with base station202. Pursuant to an example, users to which periodic corrector310sends commands can be grouped based upon, for example, GoS requirements, DRX/DTX cycle and offset, and so forth. The transmission of the power control commands for the group of users can be made by periodic corrector310on a particular instantiation of the PDCCH that can be denoted CPCCH or TPC-PDCCH. According to another illustration, periodic corrector310can utilize in-band signaling to a group of users, where the size of the group can be greater than or equal to 1. Overhead associated with periodic correction can be based on a number of bits that the correction requires and the associated control (if any) required to convey the information to the relevant access terminals.

For transfer of transmission power control (TPC) commands over the PDCCH by periodic corrector310, a 32 bit payload and an 8 bit CRC can be employed. For instance, 32 single-bit TPC commands in a 1 ms interval can be used for one PDCCH instant. Thus, 320 users in LTE_ACTIVE state can be supported at 100 Hz using a single PDCCH on each TTI assuming FDD is employed. Accordingly, single bit corrections can be provided every 10 ms, which can allow for 100 dB/s corrections. According to another example, 16 dual-bit TPC commands can be employed in a 1 ms interval. Thus, 320 users can be supported in LTE_ACTIVE state with 50 Hz using a single PDCCH on each TTI assuming FDD is employed. Hence, dual bit corrections every 20 ms allow for 100 dB/s corrections.

Now turning toFIG. 4, illustrated is a system400that aperiodically transfers power control commands to access terminals in an LTE based wireless communication environment. System400includes base station202that communicates with access terminal302(and/or any number of differing access terminal(s) (not shown)). Base station202includes received power monitor204and UL power adjuster206, which further comprises an aperiodic corrector402. Moreover, access terminal302includes UL power manager304, which further includes an aperiodic command receiver404.

Aperiodic corrector402can generate a power control command directed towards access terminal302on an as needed basis. For instance, aperiodic corrector402can transmit aperiodically when triggered by a measurement (e.g., measurement of a condition recognized utilizing data from received power monitor204such as received power being outside of a set margin, . . . ). Aperiodic corrector402can determine that an uplink power level of access terminal302deviates from a target at a particular time; thus, aperiodic corrector402can send a command to adjust this power level in response. Further, aperiodic corrector402can yield a single-bit correction (e.g., up/down, ±1 dB, . . . ) and/or a multi-bit correction (e.g., ±1 dB, ±2 dB, ±3 dB, ±4 dB, . . . ).

Aperiodic command receiver404can obtain the corrections sent by aperiodic corrector402(and/or UL power adjuster206and/or corresponding sector in base station202in general). For instance, aperiodic command receiver404can decipher that a particular correction sent by the corresponding sector in base station202is intended for access terminal302. Moreover, based upon the obtained corrections, aperiodic command receiver404and/or UL power manager304can alter an uplink power level employed by access terminal302.

Aperiodic corrections of uplink power levels employed by access terminal302and yielded by aperiodic corrector402can be trigger based. Thus, the aperiodic corrections can be associated with larger overhead as compared to periodic corrections due to the unicast nature of the aperiodic corrections. Additionally, according to an example where multi-bit aperiodic corrections are employed, these corrections can be mapped to a particular instantiation of the PDCCH (e.g., in which case the power correction can be transmitted as part of the DL assignment or UL grant) or a PDCCH/PDSCH pair (e.g., in which case the power correction can be transmitted stand-alone or in-band with other data transmission).

Now referring toFIG. 5, illustrated is a system500that groups access terminals for sending power control commands over a downlink. System500includes base station202that communicates with an access terminal1502, an access terminal2504, . . . , and an access terminal N506, where N can be any integer. Each access terminal502-506can further include a respective UL power manager (e.g., access terminal1502includes a UL power manager1508, access terminal2504includes a UL power manager2510, . . . , access terminal N506includes a UL power manager N512). Moreover, the corresponding sector in base station202can comprise received power monitor204, UL power adjuster206and an access terminal (AT) grouper514that combines a subset of access terminals502-506into a group for transmitting power control commands over the downlink.

AT grouper514can group access terminals502-506as a function of various factors. For instance, AT grouper514can assign one or more access terminals502-506to a group based upon DRX cycle and phase. Pursuant to another illustration, AT grouper514can allocate access terminal(s)502-506to groups based upon uplink periodic transmission rates (e.g., SRS transmission rate, PUCCH transmission interval, . . . ) employed by access terminals502-506. By combining subsets of access terminals502-506into disparate groups, transmission of power control commands by UL power adjuster206on the DL over the PDCCH (or CPCCH) can be effectuated more efficiently (e.g., by sending power control commands for multiple access terminals grouped together in a common message). By way of example, AT grouper514can form groups for utilization with periodic uplink power control; however, the claimed subject matter is not so limited.

According to an illustration, access terminal1502can employ a transmission rate of 200 Hz for SRS transmission, access terminal2504can utilize a transmission rate of 50 Hz for SRS transmission, and access terminal N506can use a transmission rate of 100 Hz for SRS transmission. AT grouper514can recognize these respective transmission rates (e.g., utilizing signals obtained via received power monitor204, . . . ). Thereafter, AT grouper514can assign access terminal1502and access terminal N506to a group A (along with any other access terminal(s) that employ 100 Hz or 200 Hz transmission rates). AT grouper514can also allocate access terminal2504(and any disparate access terminal(s) that employ 25 Hz or 50 Hz transmission rates) to a group B. It is to be appreciated, however, that the claimed subject matter is not limited to the aforementioned illustration. Further, AT grouper514can assign group IDs to each of the groups (e.g., for use on the PDCCH or CPCCH). Upon assigning access terminals502-506to respective groups, commands sent by UL power adjuster206can employ downlink resources corresponding to a particular group associated with an intended recipient access terminal. For instance, AT grouper514and UL power adjuster206can operate in conjunction to send TPC commands to multiple access terminals502-506in each PDCCH transmission. Moreover, each UL power manager508-512can recognize appropriate PDCCH transmission(s) to listen to for obtaining TPC command(s) directed thereto (e.g., based upon corresponding group IDs, . . . ).

Turning toFIG. 6, illustrated are example transmission structures for communicating power control commands to access terminal groups. For example, the transmission structures can be employed for PDCCH transmissions. Two example transmission structures are depicted (e.g., transmission structure600and transmission structure602); however, it is contemplated that the claimed subject matter is not limited to these examples. Transmission structures600and602can reduce overhead by grouping power control commands for multiple users into each PDCCH transmission. As illustrated, transmission structure600groups power control commands for users in group A upon a first PDCCH transmission and power control commands for users in group B upon a second PDCCH transmission. Further, both the first and second PDCCH transmissions include a cyclic redundancy check (CRC). Moreover, transmission structure602combines power control commands for users in groups A and B upon a common PDCCH transmission. By way of illustration, for transmission structure602, power control commands for users in group A can be included in a first segment of the common PDCCH transmission and power control commands for users in group B can be included in a second segment of the common PDCCH transmission.

Referring toFIG. 7, illustrated is an example timing diagram700for a periodic uplink power control procedure for LTE. At702, power control procedures for an access terminal in LTE_ACTIVE state are illustrated. In this state, the access terminal sends periodic SRS transmissions to a base station, and the base station replies to the periodic SRS transmissions with periodic TPC commands. As shown in the illustrated example, the transmit power of the access terminal is corrected by a single TPC bit transmitted periodically on the downlink. It is to be noted that the periodic SRS transmissions can be replaced by periodic CQI transmissions, periodic PUCCH transmissions, and the like. Periodic CQI transmissions or periodic PUCCH transmissions may be less efficient from a channel sounding standpoint since these transmissions may not span the entire system band; however, such transmissions can be leveraged for closed loop corrections based on UL measurements at the base station.

At704, an inactivity period for the access terminal is depicted. After the inactivity period (e.g., predetermined or use of a threshold period), the access terminal is transitioned to an LTE_ACTIVE_CPC substate. In this substate, the PHY UL resources are de-allocated from the access terminal; accordingly, it may not be possible to use closed loop power control when UL transmissions resume.

At706, the access terminal resumes uplink transmissions. The RACH is employed to resume uplink transmissions using an open loop estimate. Pursuant to an example, the open loop estimate can be modified in according to a last transmission power with some forgetting factor if deemed beneficial. In response to the RACH sent by the access terminal, the base station can transmit an in-band power adjustment for the access terminal (e.g., x bit power adjustment, where x can be substantially any integer).

At708, an identity of the access terminal can be verified through the RACH procedure. Further, PHY UL resource re-allocation can be effectuated (e.g., along with SRS configuration) at708.

At710, the access terminal is in LTE_ACTIVE state. Hence, the access terminal resumes periodic transmissions of the SRS. As depicted, the periodicity of the periodic SRS transmissions at710differ from the periodicity of the periodic SRS transmissions at702; however, the claimed subject matter is not so limited. In response to the periodic SRS transmissions, the base station sends TPC commands that in this case account for 2 bits (e.g., ±1 dB, ±2 dB). Further, although not illustrated, access terminal transmissions can continue to utilize open loop corrections determined from the receive power level at the access terminal. Therefore, the closed loop corrections can be exclusive and/or on top of the open loop corrections determined from the changes in the receive power at the access terminal.

Now turning toFIG. 8, illustrated is an example timing diagram800for an aperiodic uplink power control procedure for LTE. Illustrated are power control procedures for an access terminal in LTE_ACTIVE state. Timing diagram800can lack periodic uplink transmissions. Further, power corrections can be sent from a base station to the access terminal based on power received over the PUSCH. The base station evaluates PUSCH transmissions to determine whether to effectuate a power adjustment. Aperiodic power adjustments can be relied upon where the base station sends a message (e.g., TPC command on UL grant) to the access terminal if a power adjustment is deemed to be needed by the base station upon evaluation of a particular PUSCH transmission. When the base station determines that such power adjustment is not necessary at a particular time for a given PUSCH transmission, the base station need not transmit a TPC command at such time in response to the given PUSCH transmission (e.g., rather, an ACK can be transmitted in response to the given PUSCH transmission, . . . ). Moreover, regardless whether a TPC command is obtained by the access terminal at a given time, the access terminal can constantly rely on corrections based on an open loop mechanism. Further, the corrections sent by the base station can be single bit and/or multi-bit corrections.

It is to be appreciated that a similar scheme can be employed with periodic UL transmissions where corrections can be sent on the DL on an as needed basis. Thus, the access terminal can periodically send SRS transmissions on the uplink, which can be evaluated by the base station to determine power adjustments to be effectuated. Thereafter, upon determining that a power adjustment is needed at a particular time, the base station can send a TPC command over the downlink to the access terminal (e.g., aperiodic downlink transmission of power control commands).

The uplink power control procedures depicted inFIGS. 7 and 8include common aspects. Namely, the notion of ΔPSD (Delta Power Spectral Density) used for the UL data transmissions can be employed for both periodic and aperiodic uplink power control. The ΔPSD can provide a maximum transmit power that is allowed for a given user in order to minimize an impact to adjacent cells. The ΔPSD can evolve over time as a function of, for example, the load indicator from adjacent cells, channel conditions, and so forth. Further, the ΔPSD can be reported to the access terminal (e.g., in-band) when possible. In the LTE systems, the network can choose which MCS/Max data-to-pilot power ratio the access terminal is allowed to transmit. The initial ΔPSD, however, can be based on the MCS in the UL grant (e.g., relationship between the UL grant and the initial ΔPSD can be formula based). Moreover, much of the aforementioned relates to intra-cell power control. Other mechanisms for inter-cell power control (e.g., load control) can be complementary to the mechanisms described herein.

According to another illustration, periodic and aperiodic uplink power control procedures can operate in combination. Following this illustration, periodic updates can be utilized on top of aperiodic updates. If there are scheduled PUSCH transmissions, they can require corresponding PDCCH transmissions with the UL grant, and therefore, the power control commands can be transmitted in the PDCCHs with the UL grants. If the PDCCH is not available, for instance, for persistent UL transmissions (e.g., not requiring the UL grants because the PHY resources are configured by higher layers), then power control commands can be transmitted on TPC-PDDCH1. Also, if there are scheduled PDSCH on the DL, then the power controlling of PUCCH (e.g., CQI and ACK/NAK) can become more critical. In such a case, the power control commands for PUCCH can be communicated on the PDCCHs with the DL assignments. For DL transmissions without associated control or for the case of no DL data activity, the periodic transmissions on TPC-DPCCH2can be used to power control PUCCH. Accordingly, power control commands can be transmitted when needed (e.g., aperiodically) while making use of available resources (e.g., PDCCH with UL grants for PUSCH, PDCCH with DL assignments for PUCCH, periodic TPC commands on TPC-PDCCH which can be relevant for PUCCH and persistently scheduled PUSCH, . . . ).

Referring toFIGS. 9-10, methodologies relating to controlling uplink power employing corrections in a wireless communication environment are illustrated. While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of acts, it is to be understood and appreciated that the methodologies are not limited by the order of acts, as some acts can, in accordance with one or more embodiments, occur in different orders and/or concurrently with other acts from that shown and described herein. For example, those skilled in the art will understand and appreciate that a methodology could alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all illustrated acts can be required to implement a methodology in accordance with one or more embodiments.

With reference toFIG. 9, illustrated is a methodology900that facilitates generating power control commands in a wireless communication environment. At902, uplink transmissions can be received from an access terminal. The uplink transmissions can be Physical Uplink Shared Channel (PUSCH) transmissions, for example. According to another illustration, the uplink transmissions can be from a set of periodic uplink transmissions sent by the access terminal; as such, the periodic uplink transmissions can be Sounding Reference Signal (SRS) transmissions, Channel Quality Indicator (CQI) transmissions, Physical Uplink Control Channel (PUCCH) transmissions, and so forth. At904, a determination can be effectuated concerning whether to adjust an uplink power level employed by the access terminal. The uplink power level being analyzed is associated with the received uplink transmissions. According to an example, the uplink power level can be compared to a target, and if the difference exceeds a threshold, then adjustment can be triggered; otherwise, if the difference is less than the threshold, then adjustment need not be effectuated at that time. Further, an amount of adjustment to the uplink power level of the access terminal can be determined. Pursuant to another illustration, a quality metric can be employed for determining whether to adjust the uplink power level based on construction of a wideband receive power or signal to noise ratio (SNR) estimate from the collection of received uplink transmissions sent on the uplink by the access terminal (e.g., the collection of received uplink transmissions can include periodically transmitted signals such as PUCCH, SRS, and the like, aperiodically transmitted signals such as PUSCH, . . . ). If adjustment to the uplink power level is determined to not be needed at904, then the methodology900ends. If it is determined that the uplink power level should be adjusted at904, then the methodology900continues at906. At906, power control commands can be transmitted to the access terminal to alter the uplink power level using a layer1/layer2(L1/L2) control information channel utilized for downlink (DL) assignments and uplink (UL) grants. For instance, transmission of the power control commands can be triggered by a measurement (e.g., measure of received power level being outside a set margin, . . . ) or by the opportunity to transmit a power control command (e.g., because the transmission of an UL grant). Based upon the determination at904, the power control commands can be sent on an as needed basis. Thus, the power control commands can be transmitted when necessary and on an available channel (as opposed to a fixed preset location and channel). For instance, the power control commands can be sent on the PDCCH with the DL assignments or UL grants at a subset of times when available, and at other times the power control commands can be transferred on TPC-PDCCH when available. Each power control command can be a single-bit correction (e.g., up/down, ±1 dB, . . . ) and/or a multi-bit correction (e.g., 0 dB, ±1 dB, ±2 dB, ±3 dB, ±4 dB, . . . ). Further, the power control command can be mapped to a particular instantiation of a Physical Downlink Control Channel (PDCCH) or a PDCCH/PDSCH (Physical Downlink Shared Channel) pair. Moreover, the power control command can be transmitted stand-alone or in-band with other data transmissions. Additionally, for example, the power control command can be sent via a unicast transmission.

The power control commands can be communicated in multiple places. The power control commands can be sent over PDCCH with DL assignments or UL grants, for example. For instance, the power control commands can be sent via PDCCH with DL assignments, which can be relevant to PUCCH. Further, the power control commands can be transmitted via PDCCH with UL grants, which can be relevant for PUSCH. According to another illustration, the power control commands can be sent over PDCCH with power control commands for multiple access terminals (e.g., Transmission Power Control-Physical Downlink Control Channel (TPC-PDCCH)). As such, PDCCH can be the L1/L2control information channel (e.g., for LTE, . . . ). Thus, a first TPC-PDCCH can be associated with PUCCH and second TPC-PDCCH can be associated with PUSCH (e.g., which can be especially relevant for persistently scheduled PUSCH). By way of further example, periodic updates of the uplink power level can be sent on top of aperiodic adjustments.

Turning toFIG. 10, illustrated is a methodology1000that facilitates employing power control commands in a wireless communication environment. At1002, data can be transmitted upon an uplink at a power level. The data can be sent upon a PUSCH, for instance; thus, the data can be aperiodically transmitted. Pursuant to a further example, the data transmission can be periodically transmitted (e.g., related to a set of periodic transmissions such as, for instance, SRS transmissions, CQI transmissions, PUCCH transmissions, . . . ). At1004, a power control command can be received via a layer1/layer2(L1/L2) control information channel used for downlink (DL) assignments and uplink (UL) grants. The power control command can be sent over a downlink upon occurrence of a triggering condition or by the opportunity to transmit a power control command (e.g., because the transmission of an UL grant). For example, the power control command can be transferred over the downlink when necessary and on an available channel in contrast to techniques whereby a fixed, preset location and channel are utilized for communicating a power control command. Following this example, the power control command can be obtained on a PDCCH with DL assignments or UL grants at a first time, while at a disparate time the power control command can be received on a TPC-PDCCH. Moreover, the power control command sent over the L1/L2control information channel can be generated at an eNode B receiver based on construction of a wideband receive power or signal to noise ratio (SNR) estimate from a collection of signals transmitted on the uplink (e.g., data transmitted upon the uplink at1002). The power control command can be a single-bit command and/or a multi-bit command. Further, the power control command can be obtained via a PDCCH or a PDCCH/PDSCH pair. Moreover, the power control command can be received as a stand-alone transmission or in-band with other data transmitted from a base station. By way of further illustration, the power control command can be received at multiple locations; namely, the power control command can be obtained over the PDCCH with DL assignments or UL grants and/or over the PDCCH with power control commands for multiple access terminals (e.g., TPC-PDCCH). Pursuant to this illustration, a power control command obtained via PDCCH with DL assignments can be relevant to PUCCH and a power control command received via PDCCH with UL grants can be relevant for PUSCH. According to another example, two TPC-PDCCH's can be utilized: a first TPC-PDCCH can be employed for providing power control commands relevant for PUCCH and a second TPC-PDCCH can be utilized for communicating power control commands relevant for PUSCH (e.g., which can be especially relevant for persistently scheduled PUSCH). At1006, the power level can be altered based upon the power control command. Further, at a time when a power control command is not obtained, such alterations to the power level need not be effectuated. According to another example, whether or not the power control command is received and utilized to adjust the power level, open loop power control mechanisms can be employed to alter the power level. At1008, data can be transmitted upon the uplink at the altered power level. Further, data can be transmitted at a particular time and a first power level without receiving a power control command in response, and a next data transmission upon the uplink can employ the first power level. By way of further example, periodic updates to the uplink power level can be received on top of aperiodic adjustments.

According to an example, one or more methods presented above can include making inferences pertaining to determining whether to send a power control command based upon a received transmission at a base station. By way of further illustration, an inference can be made related to determining when to listen for a power control command being sent upon a downlink. It will be appreciated that the foregoing examples are illustrative in nature and are not intended to limit the number of inferences that can be made or the manner in which such inferences are made in conjunction with the various embodiments and/or methods described herein.

FIG. 11is an illustration of an access terminal1100that facilitates utilizing aperiodic power control commands in an LTE based wireless communication system. Access terminal1100comprises a receiver1102that receives a signal from, for instance, a receive antenna (not shown), and performs typical actions thereon (e.g., filters, amplifies, downconverts, etc.) the received signal and digitizes the conditioned signal to obtain samples. Receiver1102can be, for example, an MMSE receiver, and can comprise a demodulator1104that can demodulate received symbols and provide them to a processor1106for channel estimation. Processor1106can be a processor dedicated to analyzing information received by receiver1102and/or generating information for transmission by a transmitter1116, a processor that controls one or more components of access terminal1100, and/or a processor that both analyzes information received by receiver1102, generates information for transmission by transmitter1116, and controls one or more components of access terminal1100.

Access terminal1100can additionally comprise memory1108that is operatively coupled to processor1106and that can store data to be transmitted, received data, identifier(s) assigned to access terminal1100, information related to obtained aperiodic power control commands, and any other suitable information for selecting whether to implement the aperiodic power control commands. Memory1108can additionally store protocols and/or algorithms associated with deciphering whether an aperiodic power control command is directed towards access terminal1100.

Receiver1102is further operatively coupled to an UL power manager1110that controls a power level utilized by access terminal1100for transmitting via an uplink. UL power manager1110can set the uplink power level for transmitting data, control signals, and so forth via any type of uplink channel. UL power manager1110can employ open loop mechanisms for selecting the uplink power level. Additionally, receiver1102and UL power manager1110can be coupled to an aperiodic command receiver1112that evaluates aperiodic power control commands obtained by receiver1102. Aperiodic command receiver1112deciphers when to listen for aperiodic power control commands directed towards access terminal1100. Further, aperiodic command receiver1112determines that a particular aperiodic power control command should be decoded, employed, etc. Moreover, aperiodic command receiver1112(and/or UL power manager1110) alters the uplink power level utilized by access terminal1100as a function of the aperiodic power control command. Access terminal1100still further comprises a modulator1114and a transmitter1116that transmits the signal to, for instance, a base station, another access terminal, etc. Although depicted as being separate from the processor1106, it is to be appreciated that UL power manager1110, aperiodic command receiver1112and/or modulator1114can be part of processor1106or a number of processors (not shown).

FIG. 12is an illustration of a system1200that facilitates yielding aperiodic power control commands in an LTE based wireless communication environment. System1200comprises a base station1202(e.g., access point, . . . ) with a receiver1210that receives signal(s) from one or more access terminals1204through a plurality of receive antennas1206, and a transmitter1224that transmits to the one or more access terminals1204through a transmit antenna1208. Receiver1210can receive information from receive antennas1206and is operatively associated with a demodulator1212that demodulates received information. Demodulated symbols are analyzed by a processor1214that can be similar to the processor described above with regard toFIG. 11, and which is coupled to a memory1216that stores information related to access terminal identifiers (e.g., MACIDs, . . . ), data to be transmitted to or received from access terminal(s)1204(or a disparate base station (not shown)) (e.g., aperiodic power control command(s) . . . ), and/or any other suitable information related to performing the various actions and functions set forth herein. Processor1214is further coupled to a received power monitor1218that assesses uplink power levels employed by access terminal(s)1204based upon signals obtained at base station1202. For instance, received power monitor1218can analyze an uplink power level from a PUSCH transmission. According to another illustration, received power monitor1218can evaluate an uplink power level from a periodic uplink transmission.

Received power monitor1218can be operatively coupled to an aperiodic corrector1220that alters the evaluated uplink power level(s) on an as needed basis. Adjustments effectuated by aperiodic corrector1220can be triggered based upon occurrence of a predetermined condition, which can be identified based upon a measurement. Moreover, aperiodic corrector1220can determine how much of an adjustment to make to uplink power level(s) when such adjustments are deemed to be needed. Further, aperiodic corrector1220can generate aperiodic power control commands that can thereafter be sent to intended, corresponding access terminal(s)1204. Aperiodic corrector1220can additionally be operatively coupled to a modulator1222. Modulator1222can multiplex aperiodic power control commands for transmission by a transmitter1226through antenna1208to access terminal(s)1204. Although depicted as being separate from the processor1214, it is to be appreciated that received power monitor1218, aperiodic corrector1220and/or modulator1222can be part of processor1214or a number of processors (not shown).

FIG. 13shows an example wireless communication system1300. The wireless communication system1300depicts one base station1310and one access terminal1350for sake of brevity. However, it is to be appreciated that system1300can include more than one base station and/or more than one access terminal, wherein additional base stations and/or access terminals can be substantially similar or different from example base station1310and access terminal1350described below. In addition, it is to be appreciated that base station1310and/or access terminal1350can employ the systems (FIGS. 1-5,11-12, and14-15) and/or methods (FIGS. 9-10) described herein to facilitate wireless communication there between.

At base station1310, traffic data for a number of data streams is provided from a data source1312to a transmit (TX) data processor1314. According to an example, each data stream can be transmitted over a respective antenna. TX data processor1314formats, codes, and interleaves the traffic data stream based on a particular coding scheme selected for that data stream to provide coded data.

The modulation symbols for the data streams can be provided to a TX MIMO processor1320, which can further process the modulation symbols (e.g., for OFDM). TX MIMO processor1320then provides NTmodulation symbol streams to NTtransmitters (TMTR)1322athrough1322t. In various embodiments, TX MIMO processor1320applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

Each transmitter1322receives 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. Further, NTmodulated signals from transmitters1322athrough1322tare transmitted from NTantennas1324athrough1324t, respectively.

At access terminal1350, the transmitted modulated signals are received by NRantennas1352athrough1352rand the received signal from each antenna1352is provided to a respective receiver (RCVR)1354athrough1354r. Each receiver1354conditions (e.g., filters, amplifies, and downconverts) a respective signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding “received” symbol stream.

An RX data processor1360can receive and process the NRreceived symbol streams from NRreceivers1354based on a particular receiver processing technique to provide NT“detected” symbol streams. RX data processor1360can demodulate, deinterleave, and decode each detected symbol stream to recover the traffic data for the data stream. The processing by RX data processor1360is complementary to that performed by TX MIMO processor1320and TX data processor1314at base station1310.

A processor1370can periodically determine which available technology to utilize as discussed above. Further, processor1370can formulate a reverse link message comprising a matrix index portion and a rank value portion.

The reverse link message can comprise various types of information regarding the communication link and/or the received data stream. The reverse link message can be processed by a TX data processor1338, which also receives traffic data for a number of data streams from a data source1336, modulated by a modulator1380, conditioned by transmitters1354athrough1354r, and transmitted back to base station1310.

At base station1310, the modulated signals from access terminal1350are received by antennas1324, conditioned by receivers1322, demodulated by a demodulator1340, and processed by a RX data processor1342to extract the reverse link message transmitted by access terminal1350. Further, processor1330can process the extracted message to determine which precoding matrix to use for determining the beamforming weights.

Processors1330and1370can direct (e.g., control, coordinate, manage, etc.) operation at base station1310and access terminal1350, respectively. Respective processors1330and1370can be associated with memory1332and1372that store program codes and data. Processors1330and1370can also perform computations to derive frequency and impulse response estimates for the uplink and downlink, respectively.

It is to be understood that the embodiments described herein can be implemented in hardware, software, firmware, middleware, microcode, or any combination thereof. For a hardware implementation, the processing units can 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, other electronic units designed to perform the functions described herein, or a combination thereof.

With reference toFIG. 14, illustrated is a system1400that enables yielding power control commands for utilization by access terminals in a wireless communication environment. For example, system1400can reside at least partially within a base station. It is to be appreciated that system1400is represented as including functional blocks, which can be functional blocks that represent functions implemented by a processor, software, or combination thereof (e.g., firmware). System1400includes a logical grouping1402of electrical components that can act in conjunction. For instance, logical grouping1402can include an electrical component for obtaining uplink transmissions sent from an access terminal at an uplink power level1404. Further, logical grouping1402can comprise an electrical component for evaluating whether to alter the uplink power level employed by the access terminal1406. Moreover, logical grouping1402can include an electrical component for sending power control commands via a L1/L2control information channel used for downlink (DL) assignments and uplink (UL) grants, where the power control commands adjust the uplink power level by a specified amount1408. For example, the power control commands can be generated and transmitted on an as needed basis. Additionally, system1400can include a memory1410that retains instructions for executing functions associated with electrical components1404,1406, and1408. While shown as being external to memory1410, it is to be understood that one or more of electrical components1404,1406, and1408can exist within memory1410.

Turning toFIG. 15, illustrated is a system1500that enables utilizing power control commands in a wireless communication environment. System1500can reside within an access terminal, for instance. As depicted, system1500includes functional blocks that can represent functions implemented by a processor, software, or combination thereof (e.g., firmware). System1500includes a logical grouping1502of electrical components that can act in conjunction. Logical grouping1502can include an electrical component for sending data upon an uplink at a power level1504. Moreover, logical grouping1502can include an electrical component for obtaining a power control command via a L1/L2control information channel used for downlink (DL) assignments and uplink (UL) grants1506. Further, logical grouping1502can include an electrical component for changing the power level for a subsequent data transmission as a function of the power control command1508. According to another illustration, the power level can additionally or alternatively be changed for subsequent data transmission based upon an open loop power control mechanism. Additionally, system1500can include a memory1510that retains instructions for executing functions associated with electrical components1504,1506, and1508. While shown as being external to memory1510, it is to be understood that electrical components1504,1506, and1508can exist within memory1510.