Reducing power consumption of a multi-antenna transceiver

The present disclosure describes techniques and apparatuses for reducing power consumption of a multi-antenna transceiver. In some aspects, the techniques and apparatuses minimize power consumption while maintaining a threshold level of performance, maximize performance while maintaining a threshold power-consumption limit, or optimize power consumption and performance. To do so, the techniques and apparatuses use a subset of the transceiver's available antennas, RF chains, and/or baseband receive chains.

BACKGROUND

Many conventional transceivers have multiple antennas, such as two transmit antennas and two receive antennas. These multi-antenna transceivers provide, in some cases, improved transmission and reception over transceivers having a single transmit or receive antenna. However, this improved transmission and reception typically comes at a cost of increased power consumption.

SUMMARY

This summary is provided to introduce subject matter that is further described below in the Detailed Description and Drawings. Accordingly, this Summary should not be considered to describe essential features nor used to limit the scope of the claimed subject matter.

In general, in one aspect, this specification describes a method for providing power to a plurality of components respectively associated with a plurality of receive paths. The method determines a first level of performance associated with each receive path of the plurality of receive paths. The method further determines, based on the first level of performance associated with each receive path of the plurality of receive paths and a minimum reception performance metric, whether use of a subset of the plurality of receive paths will meet or exceed the minimum reception performance metric. In response to determining that the use of the subset of the plurality of receive paths with meet or exceed the minimum reception performance metric, the method further includes ceasing to provide power to each component respectively associated with the plurality of receive paths other than the one or more plurality of components respectively associated with the subset of the plurality of receive paths effective to reduce an amount of power consumed by the receiver while meeting or exceeding the minimum reception performance metric.

In general, in another aspect, this specification describes a system that includes a receiver and a controller. The receiver has multiple receive paths, in which each of the receive paths respectively has an antenna. The controller is configured to determine, based on a current level of performance of the receiver and a power-consumption budget, a subset of the multiple receive paths that will meet the power-consumption budget and have a highest reception performance. The controller is also configured to cease to power the antennas, as well as other components, of the multiple receive paths other than those of the subset of the multiple receive paths effective to meet the power-consumption budget.

Another method is described that transmits, to a receiving entity, signals using a single transmission path or multiple transmission paths of a transmitter of a transmitting entity and receiving, from the receiving entity, an indication that a minimum reception performance metric at the receiving entity is not being met or that the multiple transmission paths are not needed. If the minimum reception performance metric is not being met, the method powers one or more additional transmission paths of the transmitter and transmits, to the receiving entity, signals using the single transmission path or the multiple transmission paths and the one or more additional transmission paths. Alternatively, if the multiple transmission paths are not needed, the method ceases to power components of one or more of the multiple transmission paths.

DETAILED DESCRIPTION

Overview

Conventional multi-antenna transceivers use multiple transmit or receive antennas. These transceivers may use multiple antennas even if improved transmission or reception is not needed or even, in some cases, if using multiple transmit or receive antennas reduces performance. For example, when a reception rate of a receive antenna is sufficiently high to receive a signal, use of a second antenna for reception of that signal may not improve reception but will consume additional power. By way of another example, consider a case where two transmit antennas of a transceiver are transmitting with high spatial correlation sufficient to share much of a transmission bandwidth. In this case, use of the second transmit antenna adds little to transmission performance but consumes as much as twice the power of using one transmit antenna.

This document describes techniques and apparatuses for reducing power consumption of a multi-antenna transceiver. In some embodiments, the techniques and apparatuses minimize power consumption while maintaining a threshold level of performance, maximize performance while maintaining a threshold power-consumption limit, or optimize power consumption and performance. To do so, the techniques and apparatuses use a subset of the transceiver's available antennas, RF chains, and/or baseband receive chains.

The following discussion describes an operating environment, techniques that may be employed in the operating environment, and a System-on-Chip (SoC) in which components of the operating environment can be embodied. In the discussion below, reference is made to the operating environment by way of example only.

Operating Environment

FIG. 1illustrates an example operating environment100having wireless receiving devices102(receiving devices102) and wireless transmitting device104(transmitting device104), each of which are capable of communicating data, packets, and/or frames over a wireless connection106, such as a wireless-local-area network (WLAN). It should be noted that these devices are illustrated as receiving or transmitting devices by way of example only, and each device is capable of both transmission and reception of wireless data via wireless connection106. Thus, during the course of wireless communication, communicative roles of these respective devices may switch corresponding to the flow of data communicated between the devices. As such, in the description that follows, components or features of receiving device102are also shared by transmitting device104and vice-versa.

Receiving devices102include smart-phone108, tablet computer110, and laptop computer112. Although not shown, other configurations of receiving devices102are also contemplated such as a desktop computer, server, mobile-internet device (MID), mobile gaming console, electronic readers or books (e-readers or e-books), internet protocol enabled televisions (IP TVs), and so on.

Each receiving device102includes a multi-antenna receiver114and/or a multi-antenna transmitter116for providing a wireless interface to handle various communication protocols, such as for example IEEE 802.11-2007, IEEE 802.11n, IEEE 802.11s, and the like. Each receiving device102is shown including multi-antenna receiver114(receiver114) but may also or instead include multi-antenna transmitter116(transmitter116), either separately or combined as a transceiver. Thus, while receiver114and transmitter116are shown separately, one for each of receiving devices102and transmitting device104, they may be combined, such as in hardware combined with or separate from firmware or software.

Transmitting device104includes wireless access point118(access point118). Other transmitting devices are contemplated herein, including various networking devices, such as routers, mobile hotspots, wireless repeaters, wireless devices configured to share a wireless connection, and so on. Transmitting device104may provide access to resources, services (e.g., capabilities or functions), the Internet, or other networks communicatively coupled with transmitting device104. For example, tablet computer110is able to access the Internet when connected wirelessly to transmitting device104. Note that while transmitting device104is shown including access point118, it may instead be a wireless device, such as any of receiving devices102.

Multi-antenna receiver114(receiver114) includes two or more receive paths120having chains of one or more components that can be powered or unpowered, such as a receiver antenna chain122(antenna chain122), a receiver radio frequency (RF) chain124(RF chain124), and a receiver baseband chain126(baseband chain126). These chains and their components are described in greater detail below.

Receiver114also includes micro-processors128and computer-readable storage media130(storage media130). Storage media130may include any suitable memory or storage device such as static RAM (SRAM), ROM, or Flash memory useful to store data of applications or firmware. Storage media130includes controller132and switch134. Micro-processors128are capable of executing computer-executable instructions of any of the entities of receiver114, such as controller132and switch134. Note that antenna chain122, RF chain124, and baseband chain126may also include executable instructions and be stored, in whole or in part, on storage media130and executable by micro-processors128. All of these entities may also or instead be implemented in hardware.

Multi-antenna transmitter116(transmitter116) includes two or more transmit paths136having chains of one or more components that can be powered or unpowered, such as a transmitter antenna chain138(antenna chain138), a transmitter radio frequency (RF) chain140(RF chain140), and a transmitter baseband chain142(baseband chain142). These chains and their components may be the same, similar to, or different from those described for receiver114. In some cases, for example, receiver114and transmitter116are embodied together as or part of a transceiver, in which case these chains may share components common to both receive chains and transmit chains.

Transmitter116includes micro-processors144and computer-readable storage media146(storage media146). Storage media146may include any suitable memory or storage device such as static RAM (SRAM), ROM, or Flash memory useful to store data of applications. Storage media146includes controller132and switch134. Micro-processors144are capable of executing computer-executable instructions of any of the entities of transmitter116, such as controller132and switch134. Note that antenna chain138, RF chain140, and baseband chain142, may also include executable instructions and be stored, in whole or in part, on storage media146and executable by microprocessors144. All of these entities may also or instead be implemented in hardware.

As noted in part above, receiver114and/or transmitter116may be embodied as or part of a transceiver, though this is not required. In such a case, the chains and controller132may operate differently, though the chains and controller132can be capable of operating in both scenarios. Furthermore, receiver114, transmitter116, or a transceiver having one or both of receiver114and transmitter116, along with components thereof, may be embodied on a single System-on-Chip (SoC), in whole or in part.

By way of example, considerFIG. 2, which illustrates some of the chains and components thereof that the techniques may selectively power.FIG. 2illustrates two example receive paths (receive path120-1and receive path120-2) of receiver114, in which the receive paths120-1,120-2include examples of antenna chains122-1,122-2, radio frequency (RF) chains124-1,124-2, and baseband chains126-1,126-2, respectively. While not shown for visual brevity, antenna chains122may include components in addition to receive antennas202-1,202-2, such as low-noise amplifiers, filters, and the like. Likewise, radio-frequency chains124are shown including analog-to-digital converters204-1,204-2(analogs204), though other components may also be included (including linear de-precoders, for example). Baseband chains126include digital de-precoders206-1,206-2(De-PreC206), demodulators208-1,208-2(demods208), and decoders210-1,210-2, all respectively.

FIG. 2also illustrates an example implementation of controller132and switch134. In this example, controller132receives information about receive performance after processing of received signals by RF chains124-1and124-2(e.g., signal-to-noise ratios) and/or baseband chains126-1and126-2. Controller132controls switch134effective to selectively power various components of receiver114. As shown in this example, controller132can cause switch134to turn off the chains and their components of either receive path120-1or120-2, in whole or in part. Note that chains and/or components thereof can be shared by antenna chains122, such as two antennas for one RF chain, or two antennas and RF chains for one baseband chain, for example.

FIG. 3illustrates an example of transmitter116ofFIG. 1, along with some of the chains and components thereof that the techniques may selectively power.FIG. 3illustrates two example transmit paths136-1and136-2, which includes examples of antenna chains138-1,138-2, transmit radio frequency (RF) chains140-1,140-2, and transmit baseband chains142-1,142-2, respectively. While not shown for visual brevity, transmit antenna chains136may include more than transmit antennas302-1,302-2, such as low-noise amplifiers, filters, and the like. Transmit radio-frequency chains140are shown including analog-to-digital converters304-1,304-2(analogs304), though other components may also be included. Transmit baseband chains142include digital precoders306-1,306-2(precoders306), modulators308-1,308-2, and encoders310-1,310-2, all respectively.

Ways in which entities ofFIGS. 1,2, and3act and interact are set forth in greater detail below. The entities illustrated can be separate or integrated to the extent permitted by the techniques described herein, such as controller132and switch134or components of various chains, for example. These entities are shown as computer-executable instructions executable by microprocessor(s)128,144, but may instead be hardware or firmware, or a combination of hardware, firmware, and/or software.

Reducing Power Consumption of a Multi-Antenna Transceiver

The following discussion describes techniques for reducing power consumption of a multi-antenna transceiver. These techniques can be implemented in the previously described environments and by entities thereof, such as controller132ofFIGS. 1-3. These techniques include methods illustrated inFIGS. 4-6, each of which is shown as a set of operations performed by one or more entities. These methods are not necessarily limited to the orders shown for performing the operations. Further, these methods may be used in conjunction with one another, whether performed by the same entity, separate entities, or any combination thereof. In portions of the following discussion, reference will be made to operating environment100ofFIG. 1by way of example. Such reference is not to be taken as limited to operating environment100but rather as illustrative of one of a variety of examples.

FIG. 4illustrates a method400for reducing power consumption of a multi-antenna receiver. At402, signals are received from multiple receive paths of a receiver. As illustrated inFIG. 2, these signals may be received by multiple antennas through multiple receive paths, through a wireless medium, and from a transmitter. As described above, the multiple receive paths each include various components, which consume power during the process of receiving the signals. The transmitter may or may not transmit with multiple antennas, as will be described below.

At404, a current (or first) level of performance of the receive paths is determined based on the signals received at402or information about the signals. This current level of performance may be based on various measures of performance, such as error rates, signal-to-noise ratios (SNRs), achievable data rates, or quality-of-service (QoS) for each of the receive paths120-1,120-2based on signals received by antennas202-1,202-2. Based on any one or a combination of these rates, ratios, or qualities, controller132determines a current level of performance. In some cases, power is provided to previously un-powered components of receive paths to include these receive paths in the determination of the level of performance. For example, components associated with one or more antenna paths to which power was previously ceased or reduced may be re-powered at, or prior to, operation404. In one embodiment, the current level of performance of each receive path is separately determined based on the signals received at402or information about the signals. In another embodiment, the current level of performance corresponding to a combination of all receive paths is determined based on the signals received at402or information about the signals.

By way of one example, assume that controller132ofFIG. 2determines a Signal-to-Interference plus Noise Ratio (SINR), represented mathematically as:
SINR=P/(I+N)
Here P is signal power, I is interference power, and N is noise power. The current level of performance of each of the receive paths120-1,120-2is then determined to be each path's SINR as determined by controller132.

At406, a subset of the multiple receive paths is determined to meet or exceed a minimum reception performance metric based on the current level of performance of the multiple receive paths. Assume that controller132determines that a maximum achievable data rate for receive path120-1is sufficient to meet or exceed a minimum data rate metric. Further still, controller132may determine which of receive paths120(here receive path120-1) has a highest data rate among receive paths120thereby determining a subset that meets a minimum data rate metric and also that has a highest data rate. In another embodiment, at406, in addition to (or in lieu of) determining whether a subset of the multiple receive paths can meet or exceed a minimum reception performance metric, a determination can be made whether a subset of the multiple receive paths can maintain the current level of performance corresponding to the combination of all receive paths.

At408, power is reduced or ceased to one or more components of the multiple receive paths other than those of the subset of the multiple receive paths. This may include ceasing to provide power to or reducing an amount of power provided to the one or more components. This may be effective to reduce an amount of power consumed by the receiver while meeting or exceeding the minimum reception performance metric and/or maintaining the current level of performance as previously determined across all receive paths. Continuing the ongoing example, controller132ofFIG. 2causes switch134to switch off power to receive path120-2, which here includes antenna chain122-2, RF chain124-2, and baseband chain126-2, and thus antenna202-2, analog204-2, de-precoder206-2, demodulator208-2, and decoder210-2.

Alternatively or additionally, method400may proceed, either after block404,406, or408to block410. At410, a transmitting entity is caused to enable the subset of receive paths to meet or exceed the minimum reception performance metric and/or maintain the current level of performance as previously determined across all receive paths. Controller132can transmit information about the signals received sufficient to cause the transmitting entity (e.g., access point118ofFIG. 1) to change transmission parameters. For example, controller132may transmit a supportable modulation and coding rate (MCS) or a multiple-in multiple-out (MIMO) scheme to access point118. This may allow access point118to alter transmission to permit use of a subset of receive paths by receiver114. Note also that method400may transmit information sufficient for transmitter116of access point118to reduce power consumption as well. This is addressed in greater detail below.

Optionally, method400, in whole or in part, may be re-performed. Reception performance may change over time or due to some particular cause. To maintain the minimum reception performance or further reduce power consumption, method400may proceed, along the dashed line ofFIG. 4, from block408to block402. Method400may do so responsive to a time period elapsing, a power-consumption trigger, or a performance trigger. The time period may have a regular interval or an interval that varies with each repetition of method400, such as a timer set by receiving device102at each iteration of method400. This time period may be set in part based on an amount of power consumed to perform one or more operations of method400. Thus, controller132may balance potential power savings by ceasing or reducing power provided to power one or more components of a receive path with power consumption of performing the method. If the potential savings are high and the cost to determine current levels of performance and the subset of receive paths at404and406are low, for example, the time period may be short. Conversely, if the potential savings are low, such as when one path only is being powered, controller132may adjust the time period to be rather long or set not based on saving power but instead based on appropriate time periods to meet or exceed a minimum reception performance metric.

Example performance triggers include an indication, whether internal or received from an entity external to controller132, of a performance metric not being met or being easily met. A power consumption trigger may be an indication from receiving device102indicating that transmitter116is consuming too much power or that power consumption is no longer important, such as when receiving device102transitions from battery power to an external power source (AC or DC external power).

Assume, for example, that a time period elapses after which method400proceeds from block408to block402. Assume also that the receiver includes four receive paths and that, during a first performance of method400, controller132ceases to power two receive paths and maintains two other receive paths to receive signals. In such a case, the techniques may add a receive path (or two) to meet the minimum performance requirement and/or maintain the current level of performance as previously determined across all receive paths or, if power consumption is no longer a consideration, maximize performance without concern as to power consumption. Also in this case, one of the two receive paths being used may be powered down if controller132determines that only one of the two receive paths is needed to meet the minimum reception performance metric and/or maintain the current level of performance as previously determined across all receive paths. Thus, a more-current level of performance determined by repeating block404when the receiver is using the subset of the multiple receive paths, and again based on the minimum reception performance metric, may indicate that a smaller subset of the subset of the multiple receive paths will meet or exceed the minimum reception performance metric. Further, the determined more-current level of performance of the receiver may indicate that the metric is not being met and thus the techniques may re-power the receive paths to which power was previously reduced.

FIG. 5illustrates a method500for reducing power consumption of a multi-antenna transceiver or receiver, including maximizing performance at a power-consumption budget. At502, signals are received through receive paths of a receiver or transceiver, similarly as noted for method400and as illustrated inFIG. 2.

At504, a current level of performance of each of the receive paths is determined based on the signals received at502or information about the signals. Manners in which to base a current level of performance for a receive path include an error rate, signal-to-noise ratio (SNR), achievable data rate, or quality-of-service (QoS). Assume, by way of example, that one of receive paths120-1,120-2(here receive path120-1) receives the signal at502and has a first error rate and that the other receive path120-2has a second, higher error rate. Thus, the current level of performance is higher for receive path120-1based on its lower error rate.

At506, a subset of the multiple receive paths that will meet a power-consumption budget and have a highest current level of performance is determined based on the current levels of performance of the receive paths.

Continuing the present example, assume that controller132receives the power-consumption budget from receiving device102, such as an operating system. Assume further that this power-consumption budget is determined based on receiving device102being on battery power and an amount of power available from the battery. At506, controller132determines which of receive paths120ofFIG. 2have a higher performance. In some cases, however, there are three or more receive paths. In such a case, controller132determines not only which receive path has a highest reception performance, but, if two or more of the available receive paths can be used to meet the power-consumption budget, which of the receive paths, as a group, have a highest performance level. It is not necessary that the receive paths that each have highest levels of performance will necessarily be the receive paths that will have a highest aggregate level of performance when used together. In some cases, rather, the highest aggregate level of performance is instead achieved using a subset of the available receive paths that do not, individually, have highest levels of performance. This can be caused, for example, by noise and interference issues.

Further still, each receive path120may use different amounts of power. Two receive paths may share a same baseband chain126, for example, while a third receive path has its own baseband chain126. In such a case, controller132is capable of weighing different power usage, shared components, and how well receive paths perform operating together. In so doing, a highest reception performance overall can be met while meeting the power-consumption budget.

At508, power is reduced or ceased to one or more components of the multiple receive paths other than those of the subset of the multiple receive paths. In some cases, power is reduced or ceased to components other than those of the subset of the multiple receive paths that are not shared with those of the subset of the multiple receive paths. This may be effective to reduce an amount of power consumed by the receiver while meeting or exceeding the minimum reception performance metric or power consumption budget. Continuing the ongoing example, controller132ofFIG. 2causes switch134to switch off power to receive path120-2, which here includes antenna chain122-2, RF chain124-2, and baseband chain126-2, and thus antenna202-2, analog204-2, de-precoder206-2, demodulator208-2, and decoder210-2.

Similarly as noted for block410of method400ofFIG. 4, method500may, alternatively or additionally, proceed to block510after block504,506, or508. At510, a transmitting entity is caused to alter the signals sufficient to enable the subset of receive paths to have the highest reception performance. Controller132can transmit information about the signals received sufficient to cause the transmitting entity (e.g., access point118ofFIG. 1) to change transmission. For example, controller132may transmit a supportable modulation and coding rate (MCS) or a multiple-in multiple-out (MIMO) scheme to access point118. Also similarly to method400, method500may, in whole or in part, be re-performed responsive to triggers, an amount of time elapsing, and so forth.

FIG. 6illustrates a method600for reducing power consumption of a multi-antenna transmitter. At602, signals are transmitted, to a receiving entity, using a single transmission path or multiple transmission paths of a transmitter of a transmitting entity. By way of example considerFIGS. 1 and 3, in which transmitter116of transmitting device104transmits signals through transmit paths136and using antennas302.

At604, an indication that a minimum reception performance metric is not being met or that multiple transmission paths are not needed is received from the receiving entity. Controller132ofFIG. 3, for example, may receive, as the indication, a performance indicator for reception of the signals at the receiving entity. Controller132may then determine, based on the performance indicator, that transmission using the single transmission path or the multiple transmission paths is not sufficient to meet the minimum reception performance metric at the receiving entity. Assume for this example, that transmitting device104is a mobile, battery-powered access point. Assume also that one of multiple transmit paths are used at block602. At604, controller132receives the performance indicator from receiving device102indicating that a data rate is too low or that a SNR is too low. In response, controller132may add another transmit path, alter how the signal is being transmitted by the single transmit path, or increase power to one or additional transmit paths.

Note also that the indication may include information sufficient to permit transmitter116to improve reception performance at receiver114, such as by receiving an MCS and MIMO scheme for transmission to the receiving entity, and then altering the transmission in accordance with the MCS or MIMO scheme. This can save power at the receiver and in some cases the transmitter as well. Consider a case where altering the transmission permits the receiver to meet a minimum reception performance with one less receive path while transmitting also with one less transmit path. In such a case both the receiver and transmitter reduce power consumption.

Method600proceeds to either block608or610based on the determination at block604. Thus, responsive to receiving the indication that the minimum reception performance metric is not being met, method600proceeds along the “MRP Not Met” path to block608. At608, another transmission path is powered and transmission of signals begins. Here, transmitting the signals using the previously powered single transmission path or multiple transmission paths and this additional other transmission path may be effective to permit the receiving entity to meet its MRP metric. Method600may repeat blocks, such as periodically or responsive to a trigger, to maintain reception performance while reducing power consumption when reception performance is being met.

Thus, assume that method600is re-performed following block608in which another transmission path is powered and transmits. At a later point, a second indication is received at block604in which transmission of the signals using the transmission paths and the other transmission path is indicated as not needed to meet the minimum reception performance metric of the receiving entity. In response, method600proceeds to block610to cease to power one of the transmit paths or components thereof. A transmit path having a lowest transmission performance or highest power consumption may be selected for ceasing to power at block610if such information is known.

Alternatively or additionally, method600may receive information by which controller132of transmitter116may determine which transmit path has a lowest transmission performance. If such information is received, controller132may cease to power lower-performing transmit paths before higher-performing transmit paths, such as at block610.

FIG. 7illustrates a System-on-Chip (SoC)700, which can implement various aspects described above. A SoC can be implemented in any suitable device, such as a video game console, IP enabled television, desktop computer, laptop computer, tablet computer, smart-phone, server, network-enabled printer, set-top box, printer, scanner, camera, picture frame, mobile internet device, and/or any other type of device that may implement wireless connective technology. Although described as a System-on-Chip, entities described herein may be configured as any suitable type of system, such as a wireless device, a digital signal processor (DSP) and associated software, integrated-circuits (ICs), application-specific ICs (ASICs), and the like.

SoC700can be integrated with electronic circuitry, a microprocessor, memory, input-output (I/O) logic control, communication interfaces and components, other hardware, firmware, and/or software needed to provide communicative coupling for a device, such as any of the above-listed devices. SoC700can also include an integrated data bus (not shown) that couples the various components of the SoC for data communication between the components. A wireless communication device that includes SoC700can also be implemented with many combinations of differing components. In some cases, these differing components may be configured to implement concepts described herein over a wireless connection or interface.

In this example, SoC700includes various components such as an input-output (I/O) logic control702(e.g., to include electronic circuitry) and a microprocessor704(e.g., any of a microcontroller or digital signal processor). SoC700also includes a memory706, which can be any type of RAM, low-latency nonvolatile memory (e.g., flash memory), ROM, and/or other suitable electronic data storage. SoC700can also include various firmware and/or software, such as an operating system708, which can be computer-executable instructions maintained by memory706and executed by microprocessor704. SoC700can also include other various communication interfaces and components, communication components, such as one or multiple receivers and transmitters (and components thereof) other hardware, firmware, and/or software.

SoC700includes controller132and switch134, examples of which are described with reference to the respective components of the environment100shown inFIG. 1andFIGS. 2and/or3. Controller132and the other components can be implemented as hardware, firmware, fixed logic circuitry, or any combination thereof that is implemented in connection with the I/O logic control702and/or other signal processing and control circuits of SoC700.

Although the subject matter has been described in language specific to structural features and/or methodological operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or operations described above, including orders in which the structural features and/or methodological operations are presented and/or described.