TW201521375A - Channel-adaptive configurable MIMO detector for multi-mode wireless systems - Google Patents

Abstract

Various embodiments are generally directed to techniques to perform MIMO detection using a dynamic search radius. An apparatus for a wireless receiver includes circuitry, a multiple-input multiple-output (MIMO) detector for execution by the circuitry to determine a plurality of estimated signals, the plurality of estimated signals corresponding to a plurality of signals transmitted through a wireless channel and received by a plurality of antennas, the MIMO detector to determine the plurality of estimated signals based on a search radius, and a search radius tuner for execution by the circuitry to dynamically modify the search radius based on a quality corresponding to the wireless channel.

Description

Channel adaptability for multi-mode wireless systems can be combined with multiple input multiple outputs (MIMO) detector Field of invention

The embodiments described herein are generally directed to multiple input multiple output (MIMO) systems, and in particular to MIMO detectors.

Background of the invention

Modern wireless systems such as mobile broadband systems can use multiple input multiple output (MIMO) schemes to increase spectral efficiency and data rate. Various wireless communication standards allow MIMO solutions. For example, 802.11n provides a 4x4 system (eg, 4 access point antennas and 4 antennas). As another example, 802.11ac provides an 8x4 system (eg, 8 access point antennas and 4 antennas). Also, as another example, 3GPP Advanced LTE Release 10 provides an 8x8 system (eg, 8 access point antennas and 8 antennas).

In general, a MIMO scheme provides that a stream of data is demultiplexed into multiple streams that are transmitted via a channel and that are received by the receiver using multiple antennas (eg, one stream for each transmit antenna). For example, a data stream can be multiplexed into multiple data streams. Each of these multiple data streams The different symbols can be used to modulate and then transmitted to the receiver. As will be appreciated, the use of multiple transmission channels allows the MIMO system to increase the data rate achievable in the transmission spectrum. At the receiver, then the transmitted data streams must be combined and the original signal estimated. A MIMO system includes a MIMO detector at a receiver that combines the transmitted data stream and estimates the original signal.

A number of different techniques and algorithms for MIMO detection have been proposed. Some of the proposed techniques and algorithms provide a minimum bit error rate (e.g., maximum likelihood (ML) detection, sphere decoder (SD) detection, or the like). However, such techniques are computationally expensive to implement and are often impractical as the number of antennas increases. For example, the ML detection complexity grows exponentially as the number of antennas increases. Therefore, ML detection is not practical for larger MIMO systems. The implementation of SD detection has excessive regional and power requirements. In addition, SD detection may not achieve the best solution within the necessary time constraints. Furthermore, although a particular MIMO detection algorithm may be applicable to transmission channels with high signal-to-noise ratio (SNR), certain MIMO detection algorithms may not be suitable for transmission channels with low SNR. Likewise, MIMO detection algorithms suitable for transmission channels with low SNR may not be suitable for transmission channels with high SNR.

Therefore, there is a need for a MIMO detector that can support multiple standards (e.g., provide a large number of transmission and reception antennas) without making unrealistic regional and power implementation requirements necessary. In addition, there is a need for a MIMO detector that is suitable for high SNR transmission channels as well as low SNR transmission channels. In addition, there is a need for a MIMO detector that balances energy efficiency with bit error rate.

In accordance with an embodiment of the present invention, an apparatus for a wireless receiver is provided that includes: circuitry; a multiple input multiple output (MIMO) detector that is executed by the circuit to determine a plurality of estimated signals The plurality of estimated signals correspond to a plurality of signals transmitted via a wireless channel and received by the plurality of antennas, the MIMO detector determining the plurality of estimated signals based on a search radius; and a search radius tuner The circuitry is operative to dynamically modify the search radius based on a quality corresponding to the wireless channel.

10‧‧‧Wireless channels

11-1 to 11-N‧‧‧ signals

100‧‧‧ MIMO transmitter

118-1 to 118-N‧‧‧Transmission (Tx) antenna

110‧‧‧ Input data

120‧‧‧Transmitter circuit

200‧‧‧MIMO Receiver

210‧‧‧Output signal/output data

218-1 to 218-M‧‧‧ Receive (Rx) antenna

220‧‧‧ Receiver Circuit

222-1‧‧‧Base frequency processor

222-2‧‧‧MIMO detector

222-3‧‧‧Search radius tuner

222-4‧‧‧MIMO decoder

230‧‧‧Channel Quality Indicator (CQI)

300‧‧‧Instance MIMO detector

310‧‧‧

311-i‧‧‧Branch Interference (BI) Elimination Unit

312-i‧‧‧Classification unit

313-i‧‧‧Candidate Recording Unit

314-i‧‧‧Merge unit

315-1 to 315-L‧‧‧K-record blocks

320‧‧‧ Controller

322‧‧‧Controller signal

500‧‧‧ Timing diagram

501‧‧‧ time loop

510-1 to 510-5, 520-1 to 520-5‧‧‧ potential candidates

600‧‧‧Logical flow

Blocks 602, 604, 606, 608‧‧

700‧‧‧Storage media

1000‧‧‧Instance MIMO System

2000‧‧‧Device

2110‧‧‧ radio interface

2112‧‧‧ Receiver

2114‧‧‧ Frequency synthesizer

2116‧‧‧Transmitter

2118-1 to 2118-f‧‧‧Antenna

2120‧‧‧Base frequency circuit

2122‧‧‧ Analog to Digital Converter

2124‧‧‧Digital to analog converter

2126‧‧‧Baseband or physical layer (PHY) processing circuit

2128‧‧‧Processing circuit

2130‧‧‧ Computing Platform

2132‧‧‧Memory Controller

2134‧‧‧ interface

2140‧‧‧Processing components

2150‧‧‧Other platform components

2160‧‧‧Internet interface

2200‧‧‧ device

2600‧‧‧Logical Circuit

FIG. 1 illustrates an example of a MIMO system in accordance with an embodiment.

2 illustrates a portion of a MIMO system in accordance with an embodiment.

FIG. 3 illustrates an example MIMO detector in accordance with an embodiment.

Figure 4 illustrates a portion of a MIMO detector in accordance with an embodiment.

FIG. 5 illustrates a timing diagram showing time interleaving during MIMO detection, in accordance with an embodiment.

FIG. 6 illustrates an example of a logic flow for MIMO detection in accordance with an embodiment.

Figure 7 illustrates an embodiment of a storage medium.

Figure 8 illustrates a device in accordance with an embodiment.

Detailed description of the preferred embodiment

Instance large system for multiple inputs in MIMO systems Multiple Output (MIMO) detector. Such MIMO detectors may be included with or by receivers in communication components (eg, access points, mobile devices, cells, or the like) that may be configured to Operates according to various wireless network standards. Such wireless network standards may include standards promulgated by the Institute of Electrical Engineers (IEEE). Such wireless network standards may include Ethernet wireless standards (including subsequent standards and variants) associated with IEEE 802.11-2012. For example, some examples may be implemented by the 802.11n and/or 802.11ac standards for operation. In addition, such wireless network standards may include standards promulgated by the Third Generation Partnership Project (3GPP). Such wireless network standards may include Ethernet wireless standards (including subsequent standards and variants) associated with the 3GPP LTE standard. For example, some examples may be implemented by the 3GPP Advanced LTE Release 10 standard.

According to some examples, a MIMO detector adapted to varying channel conditions may be provided in a MIMO receiver. The MIMO receiver can determine a plurality of estimated signals based on the search radius, wherein the search radius is dynamically adjustable based on channel conditions. For example, a MIMO detector can be assembled to apply a K-Best Spherical Decoding (SD) program, where K changes based on channel conditions to provide energy efficiency (eg, power consumption of a MIMO decoder) and bit errors The balance between rates (BER). For example, the K value can be dynamically adjusted based on the channel quality index, the desired bit error rate (BER) target, and/or the channel's signal to noise ratio (SNR).

FIG. 1 is a block diagram illustrating an example MIMO system 1000. In some examples, as shown in FIG. 1, MIMO system 1000 includes MIMO transmitter 100 and MIMO receiver 200. As can be seen, the MIMO transmitter 100 And MIMO receivers 200 each include a number of antennas. For example, MIMO transmitter 100 includes transmit (Tx) antennas 118-1 through 118-N, while MIMO receiver 200 includes receive (Rx) antennas 218-1 through 218-M. Transmitter 100 is assembled to transmit signals 11-1 through 11-N to receiver 200 using wireless channel 10.

It should be appreciated that the number of Tx antennas 118 and Rx antennas 218 can be varied as system 1000 is designed to be implemented by operational implementations and/or standards. Additionally, in some examples, the number of Tx antennas 118 can be the same as the number of Rx antennas 218. In some instances, the number of Tx antennas 118 may be different than the number of Rx antennas 218. Moreover, it should be appreciated that although system 1000 is described as having a transmitter (e.g., transmitter 100) and a receiver (e.g., receiver 200), each of the transmitter and receiver can be configured to transmit And receive the signal again. In other words, although not illustrated, the transmitter 100 can include circuitry that is configured to both transmit and receive signals using the wireless frequency band 10. Similarly, although not illustrated, receiver 200 can include circuitry that is configured to both receive and transmit signals using wireless frequency band 10.

In some examples, transmitter 100 and/or receiver 200 can be a component of a wireless system such as an access point, base station, cell, mobile device, or the like. As a specific illustrative example, transmitter 100 may be an active broadband such as an active broadband network that operates in accordance with at least one or more wireless communication standards (eg, 802.11n, 802.11ac, 3GPP Advanced LTE Release 10, or the like) An access point in the network (eg, a giant cell, a small cell, a base station, or the like), and the receiver 200 can be a mobile device in a mobile broadband network (eg, a smart phone, a tablet, a laptop) Computer, wireless access point or the like).

Turning more specifically to FIG. 1, at transmitter 100, input data 110 is processed by transmitter circuit 120 to transmit input data 110 to receiver 200 using Tx antennas 118-1 through 118-N in accordance with a MIMO scheme. More specifically, the input material 110 can be transmitted to the receiver 200 as signals 11-1 through 11-N using the wireless channel 10. It should be appreciated that a variety of different techniques are known for transmitting data in accordance with the MIMO scheme. In general, however, transmitter circuit 120 can be configured to demultiplex input data 110 into multiple data streams. For example, the input data 110 can be multiplexed into N data streams (eg, one data stream for each of the Tx antennas 118-1 through 118-N). In some examples, the input material 110 can be coded (eg, based on criteria or the like). Transmitter circuit 120 can additionally be configured to modulate the demultiplexed data stream. For example, a demultiplexed data stream can be modulated using different sets of clusters of quadrature amplitude modulation (QAM) symbols. Transmitter circuit 120 may additionally be configured to stream the demultiplexed and modulated data to the receiver using Tx antennas 118-1 through 118-N.

It is important to note that the input material 110 can represent any of a variety of types of material that can be communicated via the wireless channel 10. Additionally, input material 110 may be generated by transmitter 100 or may be generated elsewhere. Additionally, the input material 110 can be retrieved from a storage (not shown), such as a computer readable storage medium.

It should be appreciated that signals 11-1 through 11-N may correspond to symbols (eg, coded symbols or the like). In other words, signals 11-1 through 11-N may each be a stream of symbols or symbols transmitted from transmitter 100 to receiver 200. At the receiver 200, the output data 210 is from the MIMO detection program from signal 11-1. It is judged by 11-N. In other words, the receiver 200 estimates the signal transmitted by the transmitter 100 based on the received signal and the MIMO detection procedure. As will be appreciated, signals 11-1 through 11-N may correspond to one or more symbols. During transmission, the order of the symbols or the symbols themselves may be changed due to the effects of channel 10. The receiver then determines an estimate of the original symbols and their order. Although attention is drawn here to distinguish between signals, symbols, transmitted signals, received signals, estimated signals, etc., it should be understood that the meaning of each phrase should be understood in the context in which each phrase is used. In some instances, such phrases are used interchangeably and are sometimes used interchangeably. Additionally, reference numerals 11-1 through 11-N are used to generally designate signals in the system and may correspond to transmitted signals, received signals, estimated signals, or the like. The examples are not limited to this context.

Signals 11-1 through 11-N are received at Rx antennas 218-1 through 218-M, and the signals are processed by receiver circuit 220. More specifically, the output data 210 can be generated by the receiver circuit 220 from the received signals 11-1 through 11-N. In some examples, receiver circuit 220 can apply various baseband processing (eg, frequency offset compensation, synchronization, equalization, or the like) to signals 11-1 through 11-N. Additionally, receiver circuit 220 can apply a MIMO detection procedure to signals 11-1 through 11-N. In various examples, the receiver circuit applies a K-optimal SD program to signals 11-1 through 11-N. The receiver circuit can dynamically change the K value of the K-best SD program when implementing the K-best SD program. For example, channel value indicator (CQI) 230 can be used to dynamically adjust the K value based on channel estimation feedback. When the CQI 230 indicates a good channel condition, the K value can be decreased. The K value can be increased when the CQI 230 indicates a poor channel condition. Additionally, the K value can be dynamically adjusted based on the signal to noise ratio (SNR) of the wireless channel 10. For example In other words, when the SNR of the wireless channel 10 is high, the K value can be reduced. Where the SNR of the wireless channel 10 is low, the K value can be increased. Additionally, the K value can be dynamically adjusted based on the desired BER target. In other words, the K value can be dynamically adjusted based on the acceptable BER. For example, for a high acceptable BER, the K value can be reduced. For low acceptable BER, the K value can be increased.

It is important to note that the CQI 230 may be generated by the receiver 200 or may be generated elsewhere in the system 1000. In addition, a number of different techniques for measuring and or quantifying channel quality are known. For example, some standards (eg, 3GPP LTE) specify that the receiver generates CQI as a 4-bit value and transmits the CQI to the transmitter to adapt the transmitter to the modulation scheme based on current channel conditions. CQI 230 can correspond to this 4-bit value. However, the examples are not limited to this context.

Thus, system 1000 provides a MIMO receiver that can be adapted for a variety of different wireless channel conditions and/or can operate with a variety of communication standards. In particular, the receiver can provide a reduction in power consumption while performing MIMO detection while maintaining an acceptable BER level in a variety of channel conditions.

2 is a block of the receiver 200. Although the receiver 200 shown in Figure 2 has a limited number of components in a certain topology or configuration, it should be understood that the receiver 200 may include more or fewer components in alternative configurations as required for a given implementation. . Receiver 200 can include a computer and/or firmware implementation having circuitry 220 configured to execute one or more components 222- a . Please note that " a " and " b " and " c " as used herein and similar designators are intended to mean any positive integer variable. Thus, for example, if a set a value = 4 is implemented, the complete set of components 222- a can include modules 222-1, 222-2, 222-3, or 222-4. The examples are not limited to this context.

According to some examples, receiver 200 may be included in a receiver (eg, an access point, a cell, a mobile device, or the like) in a MIMO system. The receiver and MIMO system may be capable of operating in accordance with one or more wireless technologies such as those described herein. For example, a receiver as shown in FIG. 2 can be configured or assembled to wirelessly receive multiple signals using multiple antennas and detect the transmitted signals using a MIMO detector. Please note that although the receiver 200 is discussed in connection with the MIMO system of FIG. 1, the examples are not limited in this context.

In some examples, as shown in FIG. 2, receiver 200 includes circuitry 220 (eg, as shown in FIG. 1). Circuitry 220 can be generally configured to execute one or more components 222- a . Circuitry 220 can be any of a variety of commercially available processors including, but not limited to, AMD® Athlon®, Duron®, and Opteron® processors; ARM® applications, embedded and secure processors; IBM® and Motorola® DragonBall® and PowerPC® processors; IBM and Sony® Cell processors; Qualcomm® Snapdragon®; Intel® Celeron®, Core(2)Duo®, Core i3, Core i5, Core i7, Itanium®, Pentium®, Xeon® , Atom® and XScale® processors; and similar processors. Dual microprocessors, multi-core processors, and other multi-processor architectures can also be used as circuit 220. According to some examples, circuit 220 may also be a special application integrated circuit (ASIC), and component 222-a may be implemented as a hardware component of an ASIC. According to some examples, circuit 220 may also be a field programmable gate array (FPGA), and component 222-a may be implemented as a hardware component of the FPGA.

According to some examples, receiver 200 may include a baseband processor 222-1. Circuitry 220 can execute baseband processor 222-1 to receive a plurality of signals transmitted via a wireless channel using a plurality of receive antennas. For example, circuit 220 can execute baseband processor 222-1 to receive signals 11-1 through 11-N using Rx antennas 218-1 through 218-M. In some instances, signals 11-1 through 11-N may use different sets of symbols (eg, ASK, APSK, FSK, PSK, QAM, 16-QAM, 64-QAM, 256-QAM, or the like) coding. It should be understood that although not shown in this figure for simplicity, signals 11-1 through 11-N may be processed between being received by Rx antennas 218-1 through 218-M and processed by baseband processor 222-1 ( For example, down conversion from RF to baseband or the like).

Additionally, circuit 220 can execute baseband processor 222-1 to perform one or more baseband processing operations on received signals 11-1 through 11-N. For example, baseband processor 222-1 can apply frequency offset compensation, synchronization, and/or equalization to received signals 11-1 through 11-N.

In some examples, device 200 can include MIMO detector 222-2. Circuitry 220 can perform MIMO detector 222-2 to determine a plurality of estimated signals corresponding to a plurality of received signals. In other words, MIMO detector 222-2 can estimate transmitted signals 11-1 through 11-N. More specifically, MIMO detector 222-2 may estimate the symbols corresponding to signals 11-1 through 11-N. As will be appreciated, signals 11-1 through 11-N will be subject to noise, interference or other errors due to transmission via wireless channel 10. Therefore, MIMO detector 222-2 determines the estimate of these signals. In general, MIMO detector 222-2 is configured to implement a MIMO detection procedure and determine an estimated signal based on the search radius, wherein the search radius is dynamically adjusted. For example, MIMO detector 222-2 may implement a K-best SD procedure to estimate signals 11-1 through 11-N, where the K value is based on frequency The track condition (eg, CQI 230) can be dynamically adjusted.

According to some examples, device 200 can include a search radius tuner 222-3. Circuitry 220 may perform a search radius tuner 222-3 to dynamically adjust the search radius. For example, the search radius tuner 222-3 can dynamically adjust the K value that is used by the MIMO detector 222-2 to estimate the transmitted signal. In the case of some examples, the search radius tuner 222-3 may determine the optimal value of K based on the CQI 230 (eg, using a lookup table, function, fuzzy logic, or the like). The search radius tuner 222-3 can then assemble a MIMO detector to determine the estimated signal using the determined optimal value of K.

In the case of some examples, the maximum seek radius that may be implemented by MIMO detector 222-2 may be determined based on the worst case possible channel condition estimate for wireless channel 10. Subsequently, during operation, the search radius can be dynamically adjusted between a maximum and a minimum (eg, 1 or the like). Additionally, the search radius tuner 222-3 can dynamically adjust the search radius based on user feedback, BER targets, or the like. In other words, the K value can be adjusted (eg, increased or decreased) to achieve an acceptable BER or to improve the user experience. Thus, the power consumption of MIMO detector 222-2 can be balanced between achieving an acceptable BER level and increasing energy efficiency and throughput (eg, the time to perform MIMO detection).

According to some examples, apparatus 200 may include a MIMO decoder 222-4. Circuitry 220 can execute MIMO decoder 222-4 to decode the estimated signal based on a coding scheme. For example, if transmitter 100 encodes a signal using a different cluster set of 16-QAM symbols, MIMO decoder 222-4 can decode the estimated signal using the same set of clusters of 16-QAM symbols. In addition, The MIMO decoder 222-4 can multiplex the decoded signal to produce an output signal 210.

3 through 4 illustrate block diagrams of an example MIMO detector 300. In the case of some examples, MIMO detector 300 may be implemented as MIMO detector 222-2 of receiver 200 described above. In general, FIG. 3 illustrates a MIMO detector 300 that is assembled to implement a K-best SD procedure, while FIG. 4 illustrates a portion (eg, a single stage) of the MIMO detector 300. Before describing the MIMO detector 300, it is worth noting that a MIMO system with N transmit antennas and M receive antennas operating in a symmetric X-QAM scheme ( log ₂ X bits per symbol) can be obtained by the following equation To model: y = Hs + v , where s = [ S ₁ , S _{2 ,} ... , S _N ] ^T , ( S _i δ ) is the transmitted N-dimensional composite information symbol vector. The set δ is a cluster set of QAM symbols, and y = [ y ₁ , y ₂ , ... , y _M ] ^T is the received M-dimensional composite information symbol vector. The equivalent fundamental frequency model of the Rayleigh fading channel between the transmitter and the receiver is described by a complex matrix of N x M channel matrices H. The vector v = [ v ₁ , v ₂ , ... , v _M ] ^T represents an M-dimensional composite zero-mean Gaussian noise vector having a variance σ ² .

Since MIMO systems are modeled using composite signals (eg, signals include both real and imaginary components), the K-best SD program results in a single 2N-dimensional search. In some instances, the search can begin at the Nth layer. For each nth layer, MIMO detector 300 may derive K best local candidates [ s ₁ ^{( n )} , s ₂ ^{( n )} , ... , s _k ^{( n )} ], where local candidates s _i ^{( n )} represents the ith path from the root node through the search tree to level n , and is represented by [ s _{i, 1} ^{( n )} , s _{i, 2} ^{( n )} , ... , s _{i, N} ^{( n )} ] Given. For a given path through the search tree, the error at each step is measured by the local Euclidean distance (PED), which represents the resulting error at a given level of the search tree. . As will be appreciated, the K candidates at level n represent the K local candidates with the smallest PED in all of the K candidates of the (n + 1) th level, where the distance is calculated according to the following equation :

Where R _j,k is the component of the triangular matrix R on N×N such that H=QR, where Q is an (N+M)×N orthogonal matrix.

Turning now more specifically to FIG. 3, MIMO detector 300 includes a number of stages 310. Since signals 11-1 through 11-N can be composite signals, a separate stage 310 can be provided for the real and imaginary components of each received signal. For example, for a 4x4 MIMO system, eight stages 310 can be provided, two stages for each transmitted signal (eg, one level for the real part and one level for the imaginary part or Every signal). Thus, detector 300 is shown to include stages 310-1 through 310-2N. However, it is important to note that stage 310 is ordered from 310-2N, 310-(2N-1), ..., 310-2, 310-1) to indicate that the detection procedure begins at the Nth level of the search tree. For any level of the tree (eg, any level 310), the K best nodes are collected and passed to the next stage 310 for consideration. At the end (eg, stage 310-1), the path with the smallest overall error (eg, the smallest PED) is selected as the most likely candidate. During operation, the K value implemented by stage 310 can be dynamically adjusted based on channel conditions, SNR, desired BER, or the like. For example, K may vary based on the SNR of the wireless channel 10. The MIMO detector 300 includes a controller 320 for adjustment to be implemented at each level The value of K in 310. In general, controller 320 can electrically gate and/or clock gate various stages of each stage (e.g., see FIG. 4) to turn "on" or "off" to dynamically adjust the K value. Controller 320 may generate controller signal 322 that is output to stage 310 to cause stage 310 to implement the desired search radius (e.g., change the K value of the K-optimal SD program or the like).

Referring now more specifically to Figure 4, a MIMO detector stage 310-i is shown. The MIMO detector stage 310-i may correspond to any of the stages 310-1 through 310-2N of the MIMO detector 300 illustrated in FIG. As depicted, stage 310-i includes a branch interference (BI) cancellation unit 311-i, a classification unit 312-i, a candidate recording unit 313-i, and a merging unit 314-i. Further, the candidate recording unit 313-i includes a plurality of K-item recording blocks 315-1 to 315-L, where L is equal to the maximum value of K. For example, where the maximum value of K is equal to 5, L can be equal to 5. In some examples, the value of L may be determined based on a worst case channel condition estimate. In some examples, L can be an integer multiple of the maximum of K to provide time interleaving (see, for example, Figure 5).

It should be appreciated that a variety of techniques for implementing stages 311 through 314 are known. However, in general, the BI cancellation unit 311-i calculates interference to symbol candidates from the detected signals and mitigates interference. In other words, the BI elimination unit 311-i derives a PED for each potential candidate at the i-th level of the search tree. Classification unit 312-i classifies potential candidates. For example, classification unit 312-i may classify potential candidates based on the Schnorr-Euchner (SE) enumeration scheme and PED. The candidate recorder unit 313-i stores the K-best potential candidates that have been found so far, and updates the PED through each candidate path of the search tree. Merging unit 314-i selects each loop based on PED The K-best symbol candidate for the ring and propagate it to the next level.

The candidate recording unit 313-i includes a plurality of K-item recording blocks 315-1 to 315-L. Each of the K-item record blocks 315 can be assembled to store a K-th best potential candidate (eg, a potential candidate with a Kth lowest PED). In other words, the first K-term recording block can store potential candidates with the lowest PED, and the second K-item recording block can store potential candidates with the next lowest PED, and the like.

Since the K value is dynamically adjustable (eg, by the search radius tuner 222-3 described above), the recording block 315 is assembled to be based on a search radius (eg, a K value or the like). Turn it on and off. For example, for a K value = 2, all (except 2) of the K-term recording block 315 may be turned off to reduce the power consumption of the MIMO detector 300. Controller 320 may power gate and/or clock gate K-term record block 315 to turn "on" or "off" based on the K value. For example, the controller 320 can generate a power gating and/or a clock gating signal as the controller signal 322, which are output to the candidate recording unit 313 such that the candidate recording unit is based on the search radius. One or more K-item recording blocks 315 are turned off (or turned on).

For example, where the SNR of channel 10 is low (eg, the channel condition is poor), the majority of the K-term recording block 315 can be turned on to provide a higher K value and reduce the BER of the estimated signal. . Similarly, where the SNR of channel 10 is high (e.g., the channel conditions are good), a majority of the K-term recording block 315 can be turned off to provide reduced power requirements for the MIMO detector while maintaining Estimate the BER of the signal.

Figure 5 illustrates a timing diagram 500 showing time interleaving The effect on potential candidates in the decision level. More specifically, FIG. 5 illustrates a timing diagram for determining potential candidates for stage 310-i of MIMO detector 300 and storing them in K-term record block 315 of candidate record unit 313-i. For example, diagram 500 shows a first set of potential candidates 510 that determine a first received symbol, and a second set of potential candidates 520 of a second received symbol. Note that five potential candidates (for example, 510-1 to 510-5 and 520-1 to 520-5) that are determined for each symbol are illustrated. Figure 5 shows, by cycle 501, the time required to determine each of the K-best candidates for the symbol. As depicted, it takes 5 cycles 501 (eg, for Cycle 1 to Cycle 5 of 510-1) to determine a single candidate and spend an extra loop to store the candidate. It should be appreciated that if all K-item recorded blocks are used (eg, a maximum search radius of 5 and five K-item recorded blocks are provided), then the action of the potential candidate is determined to require a stall. More specifically, stage 310-i will pause between determining potential candidate 510-5 and potential candidate 520-1, since the K-term recording block is still determining and storing potential candidates. However, as illustrated, if the number of K-term recording blocks 315 is an integer greater than 2 times the multiple of the maximum of the search radius, stalling can be avoided. This situation can increase the throughput of the MIMO detection procedure and provide for detecting MIMO signals transmitted by time interleaving without necessitating pauses in each stage.

FIG. 6 illustrates an example of a logic flow 600. Logic flow 600 may represent some or all of the operations performed by one or more of the logic, features, or devices described herein, such as receiver 200, circuit 220, and/or MIMO detector 300. In particular, the receiver can implement logic flow 600 in a MIMO system to detect MIMO signals. For example, the baseband processor 222-1, MIMO Detector 222-2, search radius tuner 222-3, and/or channel decoder 222-4 may implement logic flow 600.

In logic flow 600, at block 602, a receiver in a MIMO system can receive multiple signals transmitted over a wireless channel by multiple antennas. For example, receiver 200 in MIMO system 1000 can receive signals 11-1 through 11-N transmitted via wireless channel 10 using antennas 218-1 through 218-M. More specifically, the baseband processor 222-1 can receive the signals 11-1 through 11-N.

At block 604, the quality corresponding to the wireless channel can be determined. For example, receiver 200 can determine CQI 230.

At block 606, a quality based search radius can be determined. For example, receiver 200 can determine a search radius (eg, a K value or the like based on CQI 230). More specifically, the search radius tuner 222-3 can determine the search radius based on the CQI 230.

At block 608, a plurality of estimated signals corresponding to the transmitted signals can be determined based on the search radius. For example, receiver 200 can perform MIMO detection (eg, using a K-best SD procedure, where the K value determines the search radius or the like) to determine an estimate of the signal. More specifically, MIMO detector 222-2 can determine an estimate of the signal.

FIG. 7 illustrates an embodiment of a storage medium 700. Storage medium 700 can include articles of manufacture. In some examples, storage medium 700 can include any non-transitory computer readable medium or machine readable medium, such as an optical, magnetic, or semiconductor storage. Storage medium 700 can store various types of computer executable instructions, such as instructions that implement logic flow 600. Computer readable or machine readable Examples of storage media may include any tangible medium capable of storing electronic data, including electrical or non-electrical memory, removable or non-removable memory, erasable or non-erasable memory, Write or rewritable memory and more. Examples of computer executable instructions may include any suitable type of code, such as raw code, compiled code, decoded, executable code, static code, dynamic code, object oriented code, visual code, and the like. . The examples are not limited to this context.

FIG. 8 illustrates an embodiment of device 2000. In some examples, device 2000 can be assembled or configured for wireless communication, such as in a wireless MIMO system shown in MIMO system 1000 in FIG. In some examples, receiver 200 can be implemented in device 2000. For example, device 2000 can implement receiver 200 as device 2200. Additionally, device 2000 can implement storage medium 700 and/or logic circuit 2600. Logic circuit 2600 can include physical circuitry to perform the operations described for device 2200, storage medium 700, and/or logic flow 600. As shown in FIG. 8, device 2000 can include a radio interface 2110, a baseband circuit 2120, and a computing platform 2130, although the examples are not limited to this configuration.

Device 2000 can implement some or all of the structure and/or operation of device 2200, storage medium 700, and/or logic circuit 2600 in a single computing entity, such as entirely within a single device. Embodiments are not limited in this context.

The radio interface 2110 can include adaptations for transmitting and/or receiving single carrier or multi-carrier modulated signals (eg, including complementary code keying (CCK) and/or orthogonal frequency division multiplexing (OFDM) symbols and/or Single carrier frequency division multiplexing (SC-FDM symbol) component or combination of components), although the embodiment is not limited For any particular empty mediation or modulation scheme. The radio interface 2110 can include, for example, a receiver 2112, a transmitter 2116, and/or a frequency synthesizer 2114. The radio interface 2110 can include a bias control, a crystal oscillator, and antennas 2118-1 through 2118-f. In another embodiment, the radio interface 2110 can use an external voltage controlled oscillator (VCO), a surface acoustic wave filter, an intermediate frequency (IF) filter, and/or an RF filter as needed. Due to the diversity of potential RF interface designs, extensive description thereof is omitted.

The baseband circuit 2120 can communicate with the radio interface 2110 to process receive and/or transmit signals, and can include an analog to digital converter 2122 and/or a digital to analog converter 2124 for processing received/transmitted signals (eg, upscaling) Conversion, down conversion, filtering, sampling, or the like). Additionally, baseband circuitry 2120 can include baseband or physical layer (PHY) processing circuitry 2126 for PHY link layer processing of individual receive/transmit signals. The baseband circuit 2120 can include, for example, processing circuitry 2128 for media access control (MAC)/data link layer processing. The baseband circuit 2120 can include a memory controller 2132 for communicating with the MAC processing circuitry 2128 and/or the computing platform 2130, for example, via one or more interfaces 2134.

In some examples, MAC 2128 can be combined to include and/or perform the structures and/or methods described herein. In other words, MAC 2128 can be assembled to include MIMO detector 200 (eg, embodied as device 2200). As another example, MAC 2128 can be assembled to include storage medium 700. As another example, MAC 2128 can be assembled to implement logic circuit 600 (eg, embodied as logic circuit 2600). As another example, the MAC 2128 can access the computing platform 2130 to implement and/or perform the methods described herein. Structure and / or method.

In some embodiments, PHY processing circuitry 2126 can include a frame construction and/or detection module that is combined with additional circuitry, such as buffer memory, to construct and/or deconstruct a communication frame (eg, containing sub-frames). Alternatively or in addition, the MAC processing circuitry 2128 may share the processing of some of these functions, or execute the programs independently of the PHY processing circuitry 2126. In some embodiments, the MAC and PHY processing can be integrated into a single circuit.

Computing platform 2130 can provide the computational functionality of device 2000. As shown, computing platform 2130 can include processing component 2140. Additionally or alternatively, the baseband circuit 2120 of the device 2000 can perform processing operations or logic for the device 2200, the storage medium 700, and the logic circuit 2600 using the processing component 2130. Processing component 2140 (and/or PHY 2126 and/or MAC 2128) can include various hardware components, software components, or a combination of both. Examples of hardware components can include devices, logic devices, components, processors, microprocessors, circuits, processor circuits, circuit components (eg, transistors, resistors, capacitors, inductors, etc.), integrated circuits, Special Application Integrated Circuit (ASIC), Programmable Logic Device (PLD), Digital Signal Processor (DSP), Field Programmable Gate Array (FPGA), Memory Unit, Logic Gate, Scratchpad, Semiconductor Device, Wafers, microchips, wafer sets, and the like. Examples of software components may include software components, programs, applications, computer programs, application programs, system programs, software development programs, machine programs, operating system software, intermediates, firmware, and software modules. , routine, subroutine, function, method, program, software interface, application interface (API), instruction set, calculation code, computer code, code segment, computer code segment, word Group, value, symbol, or any combination thereof. Determining whether to use hardware components and/or software component implementation examples may vary depending on many factors such as those required for a given instance: rate to be calculated, power level, thermal tolerance, processing cycle budget, input Data rate, output data rate, memory resources, data bus speed, and other design or performance constraints.

Computing platform 2130 can further include other platform components 2150. Other platform components 2150 include common computing elements such as one or more processors, multi-core processors, coprocessors, memory cells, wafer sets, controllers, peripherals, interfaces, oscillators, timers, video cards, Audio cards, multimedia input/output (I/O) components (eg, digital displays), power supplies, and the like. Examples of memory cells can include, but are not limited to, various types of computer readable and machine readable storage media in the form of one or more higher speed memory cells, such as read only memory (ROM), random access Memory (RAM), Dynamic RAM (DRAM), Dual Data Rate DRAM (DDRAM), Synchronous DRAM (SDRAM), Static RAM (SRAM), Programmable ROM (PROM), Erasable Programmable ROM (EPROM), Power Can erase programmable ROM (EEPROM), flash memory, polymer memory such as ferroelectric polymer memory, bidirectional memory, phase change or ferroelectric memory, tantalum oxide nitride oxide -oxide-nitride-oxide-silicon, SONOS) memory, magnetic or optical cards, device arrays such as Redundant Array of Independent Disks (RAID) drives, solid state memory devices (eg, USB devices, solid state drives) Solid state drive (SSD)), and any other type of storage medium suitable for storing information.

Computing platform 2130 can further include a network interface 2160. In a In some examples, network interface 2160 can include logic and/or features to support a network interface that operates in accordance with one or more wireless broadband technologies, such as associated with IEEE 802.11, such as IEEE 802.11u, or such as The technologies described in one or more of the standards associated with the technical specifications of WFA Hotspot 2.0.

Device 2000 can be part of a source or destination node in a MIMO system and can be included in various types of computing devices to include, but is not limited to, user equipment, computers, personal computers (PCs), desktop computers , laptop, notebook, mini-notebook, tablet, lightweight notebook, smart phone, embedded electronics, game console, server, server array or server group, web server , web server, internet server, workstation, mini computer, mainframe computer, supercomputer, network appliance, web appliance, distributed computing system, multiprocessor system, processor-based system, wearable computing Device or combination thereof. Accordingly, the functionality and/or the particular configuration of device 2000 described herein may be included or omitted in various embodiments of device 2000 as appropriate. In some embodiments, device 2000 can be configured to be compatible with protocols and frequencies associated with IEEE 802.11 standards or specifications and/or 3GPP standards or specifications for MIMO systems, although the examples are not limited in this respect.

The components and features of device 2000 can be implemented using discrete circuits, special application integrated circuits (ASICs), logic gates, and/or any combination of single wafer architectures. In addition, features of device 2000 may be implemented as appropriate using a microcontroller, a programmable logic array, and/or a microprocessor, or any combination of the foregoing. Please note that hardware, firmware and / or software components They may be referred to collectively or individually as "logic" or "circuitry."

It should be appreciated that the illustrative device 2000 shown in the block diagram of FIG. 8 can represent one functional descriptive example of many potential implementations. Therefore, the partitioning, omission, or inclusion of the block functions described in the accompanying drawings does not necessarily indicate that the hardware components, circuits, software, and/or components used to implement the functions in the embodiments will be Omitted or included.

Some examples may be described using the expression "in one instance" or "an instance" along with its derivatives. The words "a" or "an" or "an" The appearance of the phrase "in one instance" in various places in the specification is not necessarily referring to the same.

Some examples may be described using the expression "coupled", "connected" or "capable of coupling" along with their derivatives. These words are not necessarily intended as synonyms for each other. For example, the use of the terms "connected" and/or "coupled" may indicate that two or more elements are in direct physical or electrical contact with each other. However, the term "coupled" may also mean that two or more elements are not in direct contact with each other, but still cooperate or interact with each other.

What has been described above includes examples of the disclosed architecture. Of course, it is not possible to describe every conceivable combination of components and/or methods, but those skilled in the art will recognize that many further combinations and permutations are possible. Therefore, the novel architecture is intended to embrace all alternatives, modifications and variations in the spirit and scope of the appended claims. The detailed disclosure now turns to providing examples of other embodiments. The examples provided below are not intended to be limiting.

Example 1: A device for a wireless receiver. An example apparatus includes: circuitry; a multiple input multiple output (MIMO) detector that is executed by circuitry to determine a plurality of estimated signals corresponding to transmissions over a wireless channel and received by a plurality of antennas A plurality of signals, the MIMO detector determining a plurality of estimated signals based on a search radius; and a search radius tuner executed by the circuit to dynamically modify the search radius based on a quality corresponding to the wireless channel.

Example 2: The apparatus of Example 1, the MIMO detector determining a plurality of estimated signals based on a K-Best Spherical Decoding (SD) program, wherein the search radius corresponds to a K value in the K-best SD program .

Example 3: The apparatus of any one of examples 1 to 2, wherein the search radius tuner increases the search radius as the quality decreases.

Example 4: The apparatus of any one of examples 1 to 3, wherein the search radius tuner reduces the search radius as the quality increases.

The apparatus of any one of the preceding claims, wherein the MIMO detector comprises a plurality of stages, each of the plurality of stages determining a plurality of potential candidates for estimating at least a portion of one of the received signals .

Example 6: The apparatus of Example 5, each of the stages comprising a classification unit to be executed by the circuit to classify the plurality of potential candidates.

Example 7: The apparatus of example 6, wherein the transmitted signal is encoded using a set of symbolic clusters, each of the plurality of potential candidates indicating an estimate of the symbol, the symbol corresponding to the symbol by which the transmitted signal is encoded, the classification The unit is based on a local Euclidean distance (PED) determined for the symbols of each of the plurality of potential candidates for the plurality of potential candidates classification.

Example 8: The apparatus of example 7, each of the stages comprising a candidate recording unit to be executed by circuitry to store one or more of the plurality of potential candidates, and the update corresponds to one or more stored potential candidates PED for each of them.

Example 9: The device of example 8, each of the candidate recording units comprising a plurality of K-item recording blocks, each of the K-item recording blocks storing one of a plurality of potential candidates.

Example 10: The apparatus of Example 9, the MIMO detector comprising a search radius controller to turn on or off one or more of the plurality of K-item recording blocks of each of the candidate recording units to adjust The K value implemented by the MIMO detector.

Example 11: As in the device of Example 10, the search radius controller is provided by a power gating K-item recording block, a clock gating K-item recording block, or a power gating and a timely gating gate K-term recording block. Turn one or more of the plurality of K-item recording blocks on or off.

Example 12: The apparatus of Example 10, wherein the number of K-term recording blocks that are turned on for each candidate recording unit corresponds to a K value.

The apparatus of any one of examples 9 to 12, wherein each of the candidate recording units comprises a number of K-term recording blocks corresponding to a maximum value of K.

Example 14: The device of Example 13, wherein the maximum value of K is determined based on a worst condition condition for wireless channel estimation.

Example 15: The apparatus of Example 13, wherein each candidate record The number of K-term recording blocks in the cell is an integer multiple of the maximum value of K to provide time interleaving.

Example 16: The apparatus of Example 13, wherein the number of K-item recording blocks in each candidate recording unit is five.

The apparatus of any one of examples 5 to 12, each of the levels comprising a merging unit to be executed by the circuit to identify one or more of the plurality of potential candidates based at least in part on the PED, The PED corresponds to each of the one or more potential candidates stored in one or more K-term blocks.

The device of any of examples 5 to 12, further comprising a baseband processor that is executed by the circuit to receive the plurality of signals.

Example 19: The apparatus of example 18, the baseband processor performing one or more baseband processing operations on the plurality of received signals.

Example 20: The apparatus of Example 19, wherein the one or more fundamental frequency processing operations are selected from the group consisting of: frequency offset compensation, synchronization, and equalization.

The apparatus of any one of examples 5 to 12, further comprising a MIMO decoder to determine the output signal from the plurality of estimated signals.

Example 22: The apparatus of Example 21, the MIMO decoder decoding the plurality of estimated signals based on a coding scheme.

Example 23: The apparatus of Example 22, wherein the coding scheme is selected from the group consisting of: ASK, APSK, FSK, PSK, QAM, and 16-QAM.

Example 24: A method implemented by a receiver in a MIMO system. The method includes receiving, by a plurality of antennas, multiple transmissions via a wireless channel a signal; determining a quality corresponding to the wireless channel; determining a search radius based on the quality; and determining a plurality of estimated signals corresponding to the plurality of transmitted signals based on the search radius.

Example 25: The method of example 24, determining the plurality of estimated signals comprises determining a plurality of estimated signals based on a K-Best Spherical Decoding (SD) program, wherein the search radius corresponds to a K-optimal SD program K value.

Example 26: The method of any of embodiments 24 to 25, determining that the quality corresponding to the wireless channel comprises determining a signal to noise ratio (SNR) of the wireless channel.

Example 27: The method of Example 26, based on the quality determination, the dynamic search radius comprises increasing the search radius when the SNR is low.

Example 28: The method of Example 26, wherein the dynamic search radius based on the quality determination comprises decreasing the search radius when the SNR is high.

Embodiment 29. The method of example 25, comprising determining, in a plurality of stages, a plurality of potential candidates for estimating at least a portion of one of the received signals, at least one of each of the plurality of received signals Part of the association.

Example 30: The method of Example 29, comprising classifying a plurality of potential candidates at each stage.

The method of example 30, wherein the transmitted signals are encoded using a set of symbol clusters, each of the plurality of potential candidates indicating an estimate of the symbol, the symbol corresponding to the transmitted signal The encoded symbol classifies a plurality of potential candidates based on a local Euclidean distance (PED) determined for the symbols of each of a plurality of potential candidates at each stage.

Example 32: The method of example 31, storing one or more of a plurality of potential candidates at each level and updating a PED corresponding to each of the one or more stored potential candidates.

Example 33: The method of Example 32, wherein the number of potential candidates stored at each level corresponds to a search radius.

Example 34: The method of Example 33, turning on or off portions of the MIMO detector circuit to store a number of potential candidates corresponding to the search radius to reduce MIMO detection during a reduced search radius Power consumption of the device.

The method of any one of examples 24 to 25, further comprising performing one or more fundamental frequency processing operations on the plurality of received signals.

Example 36: The method of Example 35, wherein the one or more fundamental frequency processing operations are selected from the group consisting of: frequency offset compensation, synchronization, and equalization.

The method of any one of examples 24 to 25, further comprising determining the output signal from the plurality of estimated signals.

Example 38: The method of example 37, determining the output signal comprises decoding the plurality of estimated signals based on a coding scheme.

Example 39: The method of Example 38, wherein the coding scheme is selected from the group consisting of: ASK, APSK, FSK, PSK, QAM, and 16-QAM.

Example 40: Apparatus comprising a member that performs the method of any of Examples 24-39.

Example 41: At least one machine readable medium comprising a plurality of instructions responsive to execution on a receiver in a Multiple Input Multiple Output (MIMO) communication system such that the receiver performs as in Examples 24-39 One way.

10‧‧‧Wireless channels

11-1 to 11-N‧‧‧ signals

100‧‧‧ MIMO transmitter

118-1 to 118-N‧‧‧Transmission (Tx) antenna

110‧‧‧ Input data

120‧‧‧Transmitter circuit

200‧‧‧MIMO Receiver

210‧‧‧Output signal/output data

218-1 to 218-M‧‧‧ Receive (Rx) antenna

220‧‧‧ Receiver Circuit

230‧‧‧Channel Quality Indicator (CQI)

1000‧‧‧Instance MIMO System

Claims (25)

An apparatus for a wireless receiver, comprising: circuitry; a multiple input multiple output (MIMO) detector for performing by the circuitry to determine a plurality of estimated signals, the plurality of estimated signals Corresponding to a plurality of signals transmitted via a wireless channel and received by a plurality of antennas, the MIMO detector determines a plurality of estimated signals based on a search radius; and a search radius tuner for using the circuit Executing to dynamically modify the search radius based on a quality corresponding to the wireless channel. The apparatus of claim 1, the MIMO detector determining the plurality of estimated signals based on a K-Best Spherical Decoding (SD) program, wherein the search radius corresponds to a K value in the K-best SD program. The apparatus of claim 1, the search radius tuner increases the search radius when the quality is reduced, and decreases the search radius as the quality increases. The apparatus of claim 3, the MIMO detector comprising a plurality of stages, each of the levels determining a plurality of potential candidates for estimating at least a portion of one of the received signals. The apparatus of claim 4, wherein the transmitted signals are encoded using a cluster set of symbols, each of the plurality of potential candidates indicating an estimate for a symbol corresponding to the Transmitting a signal encoded symbol, each of the levels including a classification unit, the a classifying unit for performing, by the circuit, classifying the plurality of potential candidates based on a local Euclidean distance (PED) determined for the symbols of each of the plurality of potential candidates . The apparatus of claim 5, each of the levels comprising a candidate recording unit for performing by the circuit to store one or more of the plurality of potential candidates and updating corresponding to the one or more The PED of each of the potential candidates stored, each of the candidate recording units comprising a plurality of K-item recording blocks, each of the K-item recording blocks being used Storing one of the plurality of potential candidates. The apparatus of claim 6, the MIMO detector comprising a search radius controller to turn on or off one or more of the plurality of K-item recording blocks of each of the candidate recording units To adjust the K value implemented by the MIMO detector. The device of claim 7, the search radius controller turns on or off one or more of the plurality of K-item recording blocks by: power gating the K-item recording blocks, The clock gates control the K-item recording blocks, or the power gates and clock gates control the K-item recording blocks. The apparatus of claim 8, wherein the number of K-item recording blocks of each candidate recording unit is turned on corresponding to the K value. The apparatus of claim 9, wherein each of the candidate recording units includes a number of K-term recording blocks corresponding to a maximum value of K. The apparatus of claim 4, each of the levels comprising a merging unit for performing, by the circuitry, identifying one or more of the plurality of potential candidates based at least in part on the PED, the PED corresponding Stored in Each of the one or more potential candidates in the one or more K-term blocks. The device of claim 4, further comprising a baseband processor for performing the following actions by the circuit; the baseband processor is configured to receive the plurality of signals; and the baseband processor is configured to receive the plurality of received signals To perform one or more fundamental frequency processing operations. The apparatus of claim 4, further comprising a MIMO decoder to decode the plurality of estimated signals based on a coding scheme. A method implemented by a receiver in a MIMO system, comprising: receiving, by a plurality of antennas, a plurality of signals transmitted via a wireless channel; determining a quality corresponding to the wireless channel; Quality determining a search radius; and determining a plurality of estimated signals corresponding to the plurality of transmitted signals based on the search radius. The method of claim 14, determining that the plurality of estimated signals comprises determining the plurality of estimated signals based on a K-Best Spherical Decoding (SD) program, wherein the search radius corresponds to the K-optimal SD program K value. As in the method of claim 14, determining that the quality corresponding to one of the wireless channels includes determining a signal-to-noise ratio (SNR) for the wireless channel. As in the method of claim 16, determining, based on the quality, a dynamic search radius includes increasing the search radius when the SNR is low, and when the SNR is high Reduce the search radius. The method of claim 17, comprising determining that a plurality of potential candidates are used to estimate at least a portion of one of the received signals in the plurality of stages, the level being associated with one of the plurality of received signals At least a part is associated. The method of claim 18, wherein the transmitted signals are encoded using a cluster set of symbols, each of the plurality of potential candidates indicating an estimate for a symbol corresponding to the Transmitting a signal encoded symbol, the method comprising classifying the plurality of potential candidates at each stage, the classification being determined based on the symbols for each of the plurality of potential candidates at each level A partial Euclidean distance (PED). As in the method of claim 19, one or more of the plurality of potential candidates are stored at each level and the PED corresponding to each of the one or more stored potential candidates is updated. The method of claim 20, wherein the number of the plurality of potential candidates stored at each level corresponds to the search radius. As in the method of claim 21, turning on or off portions of a MIMO detector circuit to store the number of potential candidates corresponding to the search radius to decrease during the reduced search radius The power consumption of the MIMO detector. An at least one machine readable medium comprising a plurality of instructions responsive to being executed on a receiver in a multiple input multiple output (MIMO) communication system such that the receiver performs the following actions: Receiving, by a plurality of antennas, one of a plurality of signals transmitted through a wireless channel; determining a quality corresponding to the wireless channel; determining a search radius based on the quality; and based on a K-best spherical decoding (SD) program A plurality of estimated signals are determined, wherein the search radius corresponds to a K value in the K-best SD program, the estimated signals corresponding to the plurality of transmitted signals based on the search radius. The at least one machine readable medium of claim 23, wherein the receiver is configured to determine a plurality of potential candidates for estimating at least a portion of one of the plurality of signals in the plurality of stages, At least a portion of one of the received signals is associated. In at least one machine readable medium of claim 23, the receiver turns a portion of a MIMO detector circuit on or off to store a number of potential candidates corresponding to the search radius to be at the search radius The reduced time period reduces the power consumption of the MIMO detector.