Tiered control of iterative MIMO receivers

In order to balance the power requirements of a MIMO receiver with the gains that may be achieved through its use, an apparatus determines whether a current configuration of the UE supports iterative MIMO reception. When it is determined that the current configuration of the UE supports iterative MIMO reception, the apparatus determines whether at least one parameter of the received signal is within a corresponding target condition, respectively, for each of the at least one parameters, e.g., including determining whether a scheduling percentage meets a scheduling threshold and whether an error rate is within an error rate range. When both the configuration supports iterative MIMO reception and the signal parameter(s) meet the corresponding target condition(s), the apparatus uses the iterative MIMO receiver. If not, the apparatus uses a serial receiver.

BACKGROUND

Field

The present disclosure relates generally to communication systems, and more particularly, to tiered control for an iterative Multiple-Input Multiple-Output (MIMO) receiver.

Background

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). LTE is designed to support mobile broadband access through improved spectral efficiency, lowered costs, and improved services using OFDMA on the downlink, SC-FDMA on the uplink, and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

Iterative MIMO receivers exchange soft information between a demapper and decoder and may achieve better performance than their non-iterative counterparts. While iterative MIMO receivers improve throughput gains, this improvement comes at the cost of increased power consumption due to the intense computations performed by the iterative MIMO.

SUMMARY

A serial receiver performs just a single demodulation/decoding pass through a demapper and decoder when receiving a signal. In contrast, an iterative MIMO receiver performs multiple iterations, using soft information exchange, e.g., in the form of extrinsic Log Likelihood Ratios (LLRs), between a demapper and decoder when receiving and processing a signal. Iterative MIMO receivers achieve better performance than their non-iterative counterparts. Iterative MIMO receivers achieve greater gains in fading channels when the channel conditions are neither too high nor too low, e.g., when packet error rate is neither below a minimum threshold, e.g., as below 5%, nor above a maximum threshold, e.g., above 50%. While Iterative MIMO receivers may provide improved signal reception, iterative MIMO receivers consume more power than a serial receiver due to the added computations performed by the iterative MIMO receiver. Therefore, there is a need to balance the power requirements of the MIMO receiver with the gains that may be achieved through its use in order to minimize the impact on power consumption while taking advantage of the potential gain improvement.

Aspects presented herein provide modem power control for an iterative MIMO receiver, e.g., using a tiered controller. The tiered controller may make a first determination regarding using the iterative MIMO receiver based on a current configuration. When the current configuration is determined to support iterative MIMO, the controller may make a second determination regarding the suitability of the iterative MIMO receiver based on scheduling rate and/or a signal quality metric such as an error rate. The first determination may be an event driven determination based on slowly varying parameters. The second determination may be a statistical determination that is periodically repeated. Using this tiered control, the iterative MIMO receiver may be enabled only when both the configuration is appropriate and at least a certain amount of gain can be achieved based on the scheduling rate/packet error rate. When the configuration is not appropriate or the operating conditions are not within the defined bounds, the iterative MIMO receiver may not be enabled, and power consumption my be reduced.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided for performing tiered control of an iterative MIMO receiver. The apparatus determines whether at least one parameter of the received signal is within a corresponding target condition, respectively, for each of the at least one parameters, e.g., including determining whether a scheduling percentage meets a scheduling threshold and whether an error rate is within an error rate range. When both the configuration supports iterative MIMO reception and the signal parameter(s) meet the corresponding target condition(s), the apparatus uses the iterative MIMO receiver. If not, the apparatus uses a serial receiver.

DETAILED DESCRIPTION

The small cell102′ may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell102′ may employ LTE and use the same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP150. The small cell102′, employing LTE in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network. LTE in an unlicensed spectrum may be referred to as LTE-unlicensed (LTE-U), licensed assisted access (LAA), or MuLTEfire.

Referring again toFIG. 1, in certain aspects, the UE104may be configured to perform power control of an iterative MIMO receiver (198), e.g., controlling transitions between a serial receiver and an iterative MIMO receiver.

FIG. 2Ais a diagram200illustrating an example of a DL frame structure in LTE.FIG. 2Bis a diagram230illustrating an example of channels within the DL frame structure in LTE.FIG. 2Cis a diagram250illustrating an example of an UL frame structure in LTE.FIG. 2Dis a diagram280illustrating an example of channels within the UL frame structure in LTE. Other wireless communication technologies may have a different frame structure and/or different channels. In LTE, a frame (10 ms) may be divided into 10 equally sized subframes. Each subframe may include two consecutive time slots. A resource grid may be used to represent the two time slots, each time slot including one or more time concurrent resource blocks (RBs) (also referred to as physical RBs (PRBs)). The resource grid is divided into multiple resource elements (REs). In LTE, for a normal cyclic prefix, an RB contains 12 consecutive subcarriers in the frequency domain and 7 consecutive symbols (for DL, OFDM symbols; for UL, SC-FDMA symbols) in the time domain, for a total of 84 REs. For an extended cyclic prefix, an RB contains 12 consecutive subcarriers in the frequency domain and 6 consecutive symbols in the time domain, for a total of 72 REs. The number of bits carried by each RE depends on the modulation scheme.

As illustrated inFIG. 2A, some of the REs carry DL reference (pilot) signals (DL-RS) for channel estimation at the UE. The DL-RS may include cell-specific reference signals (CRS) (also sometimes called common RS), UE-specific reference signals (UE-RS), and channel state information reference signals (CSI-RS).FIG. 2Aillustrates CRS for antenna ports0,1,2, and3(indicated as R0, R1, R2, and R3, respectively), UE-RS for antenna port5(indicated as R5), and CSI-RS for antenna port15(indicated as R).FIG. 2Billustrates an example of various channels within a DL subframe of a frame. The physical control format indicator channel (PCFICH) is within symbol0of slot0, and carries a control format indicator (CFI) that indicates whether the physical downlink control channel (PDCCH) occupies 1, 2, or 3 symbols (FIG. 2Billustrates a PDCCH that occupies 3 symbols). The PDCCH carries downlink control information (DCI) within one or more control channel elements (CCEs), each CCE including nine RE groups (REGs), each REG including four consecutive REs in an OFDM symbol. A UE may be configured with a UE-specific enhanced PDCCH (ePDCCH) that also carries DCI. The ePDCCH may have 2, 4, or 8 RB pairs (FIG. 2Bshows two RB pairs, each subset including one RB pair). The physical hybrid automatic repeat request (ARQ) (HARQ) indicator channel (PHICH) is also within symbol0of slot0and carries the HARQ indicator (HI) that indicates HARQ acknowledgement (ACK)/negative ACK (NACK) feedback based on the physical uplink shared channel (PUSCH). The primary synchronization channel (PSCH) is within symbol6of slot0within subframes0and5of a frame, and carries a primary synchronization signal (PSS) that is used by a UE to determine subframe timing and a physical layer identity. The secondary synchronization channel (SSCH) is within symbol5of slot0within subframes0and5of a frame, and carries a secondary synchronization signal (SSS) that is used by a UE to determine a physical layer cell identity group number. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI). Based on the PCI, the UE can determine the locations of the aforementioned DL-RS. The physical broadcast channel (PBCH) is within symbols0,1,2,3of slot1of subframe0of a frame, and carries a master information block (MIB). The MIB provides a number of RBs in the DL system bandwidth, a PHICH configuration, and a system frame number (SFN). The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs), and paging messages.

As illustrated inFIG. 2C, some of the REs carry demodulation reference signals (DM-RS) for channel estimation at the eNB. The UE may additionally transmit sounding reference signals (SRS) in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by an eNB for channel quality estimation to enable frequency-dependent scheduling on the UL.FIG. 2Dillustrates an example of various channels within an UL subframe of a frame. A physical random access channel (PRACH) may be within one or more subframes within a frame based on the PRACH configuration. The PRACH may include six consecutive RB pairs within a subframe. The PRACH allows the UE to perform initial system access and achieve UL synchronization. A physical uplink control channel (PUCCH) may be located on edges of the UL system bandwidth. The PUCCH carries uplink control information (UCI), such as scheduling requests, a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), and HARQ ACK/NACK feedback. The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and/or UCI.

A serial receiver performs just a single demodulation/decoding pass through a demapper and decoder when receiving a signal.FIG. 4Aillustrates an example model of a communication system400, such as a communication system employed between eNB102and UE104inFIG. 1. Before being transmitted, e.g., by eNB102, information bits b may be encoded by an encoder402that generates coded bits c. The encoded signal c may then be mapped by mapper404onto modulation symbols to generate symbols x that are transmitted by the eNB102using channel406as signal y. The receiver408(e.g., UE104inFIG. 1) receives signal y on the channel and processes the signal in order to determine the information bits that the signal y represents. The receiver408processes the received signal y to estimate the information as b^. A goal of the communication system, and especially of the receiver, is to have the information bits estimated by the receiver408b^ match the original information bits b input into the encoder402as closely as possible.

FIG. 4Billustrates aspects of a serial receiver410that may be employed as receiver408in the communication system. The receiver includes a demapper412and a decoder414that demodulate/decode the received signal. The demapper410obtains the received signal, distinguishes the channel as part of a channel estimation process, and computes a-posterior LLRs of the coded bits. InFIG. 4B, y represents the received signal, H represents a channel matrix, and W represents a whitening matrix. The LLRs calculated by the demapper indicate a likelihood the coded bits may be a 0 or 1. The demapper412outputs the LLRs of the received, coded bits to the decoder414, as λDEM, APP, λDEM, APPrepresenting an a-posterior LLR from demapper412. The decoder414attempts to undo the operation performed by the encoder402. The decoder computes a-posterior LLRs of the information bits and outputs an estimation b^ of information bits b. The final estimation b^ may be based on a sign of the LLR for a corresponding bit. The serial receiver performs a single pass of the received signal through the demapper412and decoder414in order to generate an estimation of the information bits.

FIG. 5illustrates an example of an iterative MIMO receiver500that may be employed as the receiver408in the communication system400inFIG. 4A. The iterative MIMO receiver500performs multiple iterations, using soft information exchange, e.g., in the form of extrinsic LLRs, between a demapper512and decoder514when receiving a signal. The receiver500inFIG. 5receives a signal, represented by y, H, W, on the transmission channel, e.g., from eNB102inFIG. 1. The receiver500may be a component within UE104inFIG. 1. The demapper512outputs the LLRs of the received signal, e.g., coded bits, to the decoder514, as λDEM, APP. An extrinsic LLR calculator516passes the estimated bits to the decoder514. On the first pass, the estimation λDEM, EXTprovided from the extrinsic LLR calculator516to the decoder514is the same estimation λDEM, APPthat the extrinsic LLR calculator receives from the demapper512, e.g. λDEM, EXT=λDEM, APP. The decoder then computes a-posterior LLRs of the coded bits in addition to the estimation of the information bits. A CRC check may be performed on the information bits. If failed, it may indicate an error, and the iterative MIMO receiver may perform another iteration of the demapper and decoder. The output of the decoder λDEC, APPand the input λDEM, EXTto the decoder may be received by a second extrinsic LLR calculator518in order to determine the new information added by the computation at the decoder. The difference between λDEM, APPand λDEM, EXTis then fed back to the demapper512.

Thus, the feedback extrinsic information λDEC, EXT=λDEM, APP−λDEM, EXTprovided to the demapper for the second iteration. In the second iteration, a second set of estimation is produced by the demapper using the feedback extrinsic information λDEC, EXTLLRs as priors to compute a new, refined set of LLRs estimating the coded bits. Delay520and522illustrate that feedback generated in one iteration may be consumed, e.g., used, during the next iteration. The delays enable the system to clear between iterations. The extrinsic LLR calculator516propagates the extrinsic information for the second iteration as λDEC, EXT=λDEM, APP−λDEM, EXT. The decoder514uses the propagated extrinsic information to perform another iteration of decoding. Another CRC check may be performed, and additional iterations may be performed based on the results of the CRC check. The final estimation b^ may be based on a sign of the LLR for a corresponding bit.

When performing iterative MIMO reception, multiple streams of information may be processed simultaneously. Feedback for one stream of information may be used to improve the estimations for the other streams of information.

Iterative MIMO receivers achieve better performance than their non-iterative counterparts. Iterative MIMO receivers achieve greater gains in fading channels. For example, improved gains may be achieved by an iterative MIMO receiver when the channel conditions are neither too good nor too bad, e.g., when packet error rate, e.g., a BLER, is neither below a minimum threshold nor above a maximum threshold. The minimum threshold may be, e.g., 5% and the maximum threshold may be 50%, providing an error rate range of 5-50%. In another example, the maximum threshold may be 95%, providing a range between 5-95%. In another example, the minimum threshold may be higher, e.g., closer to 10%. Thus, gains from iterative receiver may be observed prominently when error is neither too low nor too high, e.g., when it is between bounds 5% and 95%. Iterative MIMO receivers consumer more power than a serial receiver due to the added computations performed by the iterative MIMO receiver. There is a power impact for performing the multiple iterations. Iterative MIMO requires higher processing power and needs an increased clock speed of the modem, which is related to an increase in voltage and an increase in power consumption. Therefore, there is a need to balance the power requirements of the MIMO receiver with the gains that may be achieved through its use in order to minimize the impact on power consumption while taking advantage of the potential gain improvement.

FIG. 6illustrates an example controller architecture600for modem power control for an iterative MIMO receiver, e.g., using a tiered controller. The controller architecture may be implemented in, e.g., UE104,350. A semi-static controller602may receive configuration information from the application layer and may make a first determination regarding using the iterative MIMO receiver based on whether a current configuration supports iterative MIMO reception.

This first determination may be an event driven determination based on parameters that vary infrequently, such as transmission mode. For example, iterative MIMO reception may be determined to be appropriate for a transmission mode where more than one layer is transmitted. Additional configuration information considered by the semi-static controller602may include any of a number of reception antennas, a call type, etc. The determination by the semi-static controller602may be repeated when input parameters change, e.g., when an RRC reconfiguration message is received. The determination by the semi-static controller, also referred to herein as a first tier determination, provides an initial estimate of the feasibility of iterative MIMO reception.

If the current configuration does not support using the iterative MIMO receiver, a serial receiver, similar to the serial receiver discussed in connection withFIG. 4Bmay be used to process the received signal.

When the current configuration is determined to support an iterative MIMO receiver, a statistical controller604may make a second determination regarding the suitability of the iterative MIMO receiver, e.g., based on scheduling rate and/or a signal quality metric such as an error rate. The statistical controller604may receive scheduling information and error rate statistics in order to perform the determination. Based on the determination from the statistical controller604, the iterative MIMO receiver may be enabled or disabled.

The second determination may be a statistical determination that is periodically repeated. For example, the determination may be repeated every 80 ms or every 160 ms. For example, a period of 80 ms may be used. If the number of transitions between iterative MIMO reception and serial reception goes beyond a transition threshold within a defined period of time, the period may be increased to 160 ms in order to avoid having a high number of transitions between the iterative MIMO receiver and the serial receiver. In another example, the length of the evaluation period may initially be set to 80 ms. Whenever the controller makes a transition from iterative receiver to serial receiver, the length of the evaluation period may be doubled until it hits a maximum value of, e.g., 640 ms. Even when the configuration has not changed, the statistical controller604may control transitions between serial reception and iterative MIMO reception based on changing statistical information and error rate statistics.

Using this tiered control, the iterative MIMO receiver may be enabled only when the configuration is appropriate and when at least a certain amount of gain can be achieved based on the scheduling rate/packet error rate. When either the configuration is not appropriate or the operating conditions are not within the defined bounds, the iterative MIMO receiver may not be enabled, and power consumption may be reduced.

In considering the scheduling percentage, the statistical controller604may determine to enable iterative MIMO reception only when scheduling of transmission modes with a rank greater than 1 is frequent enough, e.g., when a percentage of scheduling of transmission modes with a rank greater than 1 is above a threshold.

FIG. 7illustrates an example algorithm700that may be performed by the statistical controller604when considering whether iterative MIMO should be enabled. At702, the evaluation begins at a decision boundary, time T=an initial time t. At704, the statistical controller604determines whether a percentage of transmissions having a rank greater than 1 meets a scheduling threshold. The percentage of transmissions having a rank greater than 1 is determined as a number of subframes (SF) with a rank 1 or more scheduling divided by a total number of downlink (DL) subframes over T ms of time, e.g.:

If the calculated scheduling percentage is not greater than the scheduling threshold, serial reception may be used to demap and decode the received signal at706. If the calculated scheduling percentage is greater than the scheduling threshold, the statistical controller may continue to make additional statistical determinations at708. The additional statistical determination at708may be based on an error rate, as described in connection withFIG. 8.

As there are multiple streams, the statistical controller may monitor the error rate for each of the multiple streams independently as illustrated at710and make its determination regarding iterative MIMO reception based on the error rate for each of the individual streams. If the error rate falls within the defined range for one of the individual streams, the iterative MIMO receiver may be enabled and iterative MIMO reception may be performed for each of the multiple streams at712. In another example, the statistical controller may determine to use the iterative MIMO receiver when a certain number of individual streams have an error rate within the defined range, e.g., when at least 2 streams, at least 3 streams, etc. If the error rates for each of the individual streams is outside the range, then the statistical controller may determine that iterative MIMO is not needed for any of the streams. The statistical controller may disable iterative MIMO reception and instead use serial reception for each of the streams at706.

The next evaluation boundary will occur at time T=t+Tp, where Tp is the length of the evaluation period, e.g., 80 ms or 160 ms.

In considering the error rate, the statistical controller604may disable iterative MIMO reception and use serial reception for the exceptional scenarios, when an error rate such as a block error rate (BLER) is either too high or too low. Thus, the statistical controller604may determine whether the error rate is within a range, being both above a bottom threshold and below and upper threshold. An example of such an error rate range may be, e.g., between 5%-50%. This is one example, only. The range may encompass a different error rate range.

FIG. 8illustrates an example algorithm800that may be performed by the statistical controller604when considering the error rate, e.g., at708. As there are multiple streams, the statistical controller may monitor the error rate for each of the multiple streams independently and make its determination regarding iterative MIMO reception based on the error rate for each of the individual streams, e.g., as discussed in connection with710. Thus, the algorithm illustrated inFIG. 8may be performed individually for each of the individual streams. For example, as a part of the determination, the UE may maintain error rate statistics for new transmissions having a rank greater than 1. In the iterative MIMO reception mode, the UE may segregate the error rate statistics across different iterative MIMO iterations and also across different streams.

At802, the statistical controller determines whether an error rate, such as a BLER, for the stream is within a defined error rate range. For example the statistical controller may determine whether the BLER is above a first error rate threshold and below a second error rate threshold. This ensures that the error rate is not too low or too high to make use of the benefits of iterative MIMO reception. In the figure, Bler_1Tx is the first BLER over a period T for the transmission. If the BLER for the stream does not fall within the error rate range because it is lower than the first threshold or higher than the second threshold, the statistical controller determines to disable iterative MIMO reception and use serial reception at804. If the BLER does fall within the range, the statistical controller determines whether iterative MIMO reception was already enabled at806. As the statistical controller makes periodic determinations, the UE may currently be performing iterative MIMO reception when the determination at806is made. If the BLER is within the error rate range and iterative MIMO reception has not been enabled, the statistical controller determines to enable iterative MIMO reception at808. If iterative MIMO reception is enabled at806, then the statistical controller determines at810whether a difference between the error rate after a first iteration and the error rate of the original transmission meets an error rate change threshold BLER_Delta_Thr. InFIG. 8, Bler_1Tx_QED1is a first BLER after a first iteration of iterative MIMO reception. If the change in error rate is less than the error rate change threshold, the statistical controller determines to use serial reception at804. If the change in error rate is greater than the error rate change threshold, the statistical controller determines to use iterative MIMO reception at808.

FIG. 9is a flowchart900of a method of wireless communication for performing tiered control of an iterative MIMO receiver. The method may be performed by a UE (e.g., the UE104,350, the apparatus1002/1002′). At902, the UE determines whether a current configuration of the UE supports iterative MIMO reception. This determination may include aspects of the determination made by the semi-static controller602inFIG. 6. The determination at902may be based on at least one of a number of reception antennas, a transmission mode, and a call type. If the UE determines that the current configuration does not support iterative MIMO reception, the UE determines to use a serial receiver. Then, the UE receives a signal using serial reception at906, e.g., as described in connection withFIG. 4B.

When the UE determines at902that the current configuration of the UE supports iterative MIMO reception, the UE then determines at904whether at least one parameter of the received signal is within a corresponding target condition, respectively, for each of the at least one parameters. The determination at904may include aspects of the determination made by the statistical controller604inFIG. 6. When it is determined at904that the at least one parameter of the received signal is not within a corresponding target condition, the UE receives a signal using serial reception at906, e.g., by disabling the iterative MIMO receiver. When the UE determines that the at least one parameter of the received signal is within a corresponding target condition, the UE receives the signal using iterative MIMO reception at908, e.g., by enabling the iterative MIMO receiver. The UE then receives the signal using iterative MIMO reception, e.g., as described in connection withFIG. 5.

The determination at904may include multiple determinations. For example, the determination at904may include determining whether a percentage of scheduling is above a first threshold at910. This may include aspects of the algorithm ofFIG. 7.

The determination at904may include determining whether an error rate is within a target range at912. For example, the UE may determine whether the error rate is above a first error rate threshold and below a second error rate threshold. This may include aspects of the algorithms ofFIG. 7andFIG. 8. For example, a received signal may comprise multiple streams, and the US may determine at904whether the packet erasure rate is within the target range individually for each of the multiple streams, and if the packet erasure rate for at least one of the multiple streams is within the target range, the iterative MIMO receiver is used at908. As another example, the determination at904may include determining whether a difference between a first error rate at the first iteration and an overall error rate meets an error rate change threshold at914. The UE may use the iterative MIMO receiver at908when the difference meets the error rate change threshold and may use the serial receiver at906when the difference does not meet the error rate change threshold.

The determination at902may be repeated each time the current configuration of the UE changes. Therefore, the determination at902may be event drive, such as described for semi-static controller602. The determination at904may be repeated on a periodic basis, e.g., every 80 ms or 160 ms, as described for the statistical controller604inFIG. 6. For example, the UE may transition between iterative MIMO reception at908and serial reception at906depending on a periodic determination at904of whether at least one parameter of the received signal is within the corresponding target condition.

FIG. 10is a conceptual data flow diagram1000illustrating the data flow between different means/components in an exemplary apparatus1002. The apparatus may be a UE (e.g., UE104,350). The apparatus includes a reception component1004that receives DL communication from eNB1050, a transmission component1006that transmits UL communication to eNB1050. The apparatus includes a configuration component1008that whether a current configuration of the UE supports iterative MIMO reception, e.g., at902. When the configuration is supported, as indicated by at1012, a signal parameter component1010determines whether at least one parameter of the received signal is within a corresponding target condition, respectively, for each of the at least one parameters. The signal parameter component1010may include a scheduling rate component that determines whether a percentage of scheduling is above a first threshold and an error rate component that determines whether an error rate is within a target range. Based upon the determinations at configuration component1008and/or signal parameter component1010, these components enable either an iterative MIMO reception component1018or serial reception component1020or reception component1004. The iterative MIMO reception component receives the DL signal from eNB1050using iterative MIMO reception, e.g., as described inFIG. 5. The serial reception component receives the DL signal from eNB1050using serial reception, e.g., as described inFIG. 4B.

FIG. 11is a diagram1100illustrating an example of a hardware implementation for an apparatus1002′ employing a processing system1114. The processing system1114may be implemented with a bus architecture, represented generally by the bus1124. The bus1124may include any number of interconnecting buses and bridges depending on the specific application of the processing system1114and the overall design constraints. The bus1124links together various circuits including one or more processors and/or hardware components, represented by the processor1104, the components1004,1006,1008,1012,1014,1018,1020and the computer-readable medium/memory1106. The bus1124may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system1114may be coupled to a transceiver1110. The transceiver1110is coupled to one or more antennas1120. The transceiver1110provides a means for communicating with various other apparatus over a transmission medium. The transceiver1110receives a signal from the one or more antennas1120, extracts information from the received signal, and provides the extracted information to the processing system1114, specifically the reception component1004. In addition, the transceiver1110receives information from the processing system1114, specifically the transmission component1006, and based on the received information, generates a signal to be applied to the one or more antennas1120. The processing system1114includes a processor1104coupled to a computer-readable medium/memory1106. The processor1104is responsible for general processing, including the execution of software stored on the computer-readable medium/memory1106. The software, when executed by the processor1104, causes the processing system1114to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory1106may also be used for storing data that is manipulated by the processor1104when executing software. The processing system1114further includes at least one of the components1004,1006,1008,1012,1014,1018,1020. The components may be software components running in the processor1104, resident/stored in the computer readable medium/memory1106, one or more hardware components coupled to the processor1104, or some combination thereof. The processing system1114may be a component of the UE350and may include the memory360and/or at least one of the TX processor368, the RX processor356, and the controller/processor359.

In one configuration, the apparatus1002/1002′ for wireless communication includes means for determining whether a current configuration of the UE supports iterative MIMO reception, means for determining whether at least one parameter of the received signal is within a corresponding target condition, respectively, for each of the at least one parameters, means for receiving a signal using serial reception, means for receiving a signal using iterative MIMO reception means for determining whether a percentage of scheduling is above a first threshold, means for determining whether an error rate is within a target range, means for determining whether a difference between a first error rate at the first iteration and an overall error rate meets an error rate change threshold, and means for transitioning between iterative MIMO reception and serial reception. The aforementioned means may be one or more of the aforementioned components of the apparatus1002and/or the processing system1114of the apparatus1002′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system1114may include the TX Processor368, the RX Processor356, and the controller/processor359. As such, in one configuration, the aforementioned means may be the TX Processor368, the RX Processor356, and the controller/processor359configured to perform the functions recited by the aforementioned means.