U.S. patent application number 15/916728 was filed with the patent office on 2019-09-12 for method and apparatus for controlling power dissipation in a wireless receiver.
The applicant listed for this patent is Atmosic Technologies Inc.. Invention is credited to Jason Chih-way Hou, Teresa Huai-Ying Meng, David Su, Manolis Terrovitis, Masoud Zargari.
Application Number | 20190281555 15/916728 |
Document ID | / |
Family ID | 67844121 |
Filed Date | 2019-09-12 |
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United States Patent
Application |
20190281555 |
Kind Code |
A1 |
Hou; Jason Chih-way ; et
al. |
September 12, 2019 |
METHOD AND APPARATUS FOR CONTROLLING POWER DISSIPATION IN A
WIRELESS RECEIVER
Abstract
Method and apparatus for controlling the power consumption of a
wireless device are provided. A wireless device may include a
configurable radio frequency (RF) front-end that may be configured
to use fewer hardware stages and/or processing steps to reduce
power consumption based at least in part on a signal quality,
detected interference, or system information associated with a
received RF signal. In some implementations, the configurable RF
front-end may be configured to consume less power while receiving
strong RF signals and configured to consume more power while
receiving weak RF signals.
Inventors: |
Hou; Jason Chih-way; (San
Jose, CA) ; Su; David; (Saratoga, CA) ;
Terrovitis; Manolis; (Athens, GR) ; Zargari;
Masoud; (Irvine, CA) ; Meng; Teresa Huai-Ying;
(San Francisco, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Atmosic Technologies Inc. |
Campbell |
CA |
US |
|
|
Family ID: |
67844121 |
Appl. No.: |
15/916728 |
Filed: |
March 9, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 52/0261 20130101;
H04W 52/225 20130101; H04B 17/318 20150115; H04W 52/243 20130101;
H04W 52/0229 20130101; H04W 52/028 20130101; H04W 52/0245 20130101;
H04W 52/241 20130101 |
International
Class: |
H04W 52/02 20060101
H04W052/02; H04W 52/24 20060101 H04W052/24 |
Claims
1. A method comprising: receiving a radio-frequency (RF) signal via
a configurable front-end of a wireless device; determining a power
metric for the wireless device, wherein the power metric indicates
an amount of available power to the wireless device; determining a
link quality metric based at least in part on a signal from a
circuit to harvest power from the received RF signal; determining a
configuration of the configurable front-end based at least in part
on the power metric and the link quality metric; and configuring
the configurable front-end based at least in part on the determined
configuration.
2. The method of claim 1, wherein the signal from the circuit
indicates the received RF signal has a signal strength is greater
than or equal to -10 dBm.
3. The method of claim 1, wherein the power metric indicates an
amount of power harvested from the received RF signal.
4. The method of claim 1, wherein the power metric is based at
least in part on a battery capacity and a charge condition of a
battery supplying power to the wireless device.
5. The method of claim 1, wherein determining the configuration
comprises: selecting a configuration of the configurable front-end
from a selection matrix based at least in part on the power metric
and the link quality metric.
6. The method of claim 5, wherein the selected configuration is
from a group consisting of a high power configuration, a medium
power configuration, and a low power configuration.
7. The method of claim 1, wherein configuring the configurable
front-end comprises: disabling a voltage controlled oscillator; and
operating a ring oscillator to provide a clock signal for the
configurable front-end.
8. The method of claim 1, wherein configuring to configurable
front-end comprises: disabling a first receive chain; enabling a
second receive chain; and receiving the RF signal via the second
receive chain, wherein the second receive chain consumes less power
than the first receive chain.
9. The method of claim 1, wherein configuring the configurable
front-end comprises: reducing a sampling rate of an
analog-to-digital converter to sample the received RF signal.
10. The method of claim 1, wherein configuring the configurable
front-end comprises: disabling a first low noise amplifier;
enabling a second low noise amplifier; and receiving the RF signal
via the second low noise amplifier, wherein the second low noise
amplifier has a higher noise figure than the first low noise
amplifier.
11. A wireless device comprising: a configurable front-end
configured to receive an RF signal; a controller; and a memory
configured to store instructions that, when executed by the
controller, cause the wireless device to: determine a power metric,
wherein the power metric indicates an amount of available power to
the wireless device; determine a link quality metric based at least
in part on a signal from a circuit to harvest power from the
received RF signal; determine a configuration of the configurable
front-end based at least in part on the power metric and the link
quality metric; and configure the configurable front-end based at
least in part on the determined configuration.
12. The wireless device of claim 11, wherein the signal from the
circuit to harvest power is configured to indicate that the
received RF signal has a signal strength greater than or equal to
-10 dBm.
13. The wireless device of claim 11, wherein the power metric is
configured to indicate an amount of power harvested from the
received RF signal.
14. The wireless device of claim 11, wherein the power metric is
based at least in part on a battery capacity and a charge condition
of a battery supplying power to the wireless device.
15. The wireless device of claim 11, wherein execution of the
instructions to configure the configurable front-end cause the
wireless device to further: select a configuration of the
configurable front-end from a selection matrix based on the power
metric and the link quality metric.
16. The wireless device of claim 15, wherein the selected
configuration is from a group consisting of a high power
configuration, a medium power configuration, and a low power
configuration.
17. The wireless device of claim 11, wherein execution of the
instructions to configure the configurable front-end cause the
wireless device to further: disable a voltage controlled
oscillator; and operate a ring oscillator to provide a clock signal
for the configurable front-end.
18. The wireless device of claim 11, wherein execution of the
instructions to configure the configurable front-end cause the
wireless device to further: disable a first receive chain; and
enable a second receive chain; and receive the RF signal via the
second receive chain, wherein the second receive chain consumes
less power than the first receive chain.
19. The wireless device of claim 11, wherein execution of the
instructions to configure the configurable front-end cause the
wireless device to further: reduce a sampling rate of an
analog-to-digital converter configured to sample the received RF
signal.
20. The wireless device of claim 11, wherein execution of the
instructions to configure the configurable front-end cause the
wireless device to further: disable a first low noise amplifier;
enable a second low noise amplifier; and receive the RF signal via
the second low noise amplifier, wherein the second low noise
amplifier has a higher noise figure than the first low noise
amplifier.
21. A method comprising: receiving a radio-frequency (RF) signal
via a configurable front-end of a wireless device; determining an
operating metric based at least in part on a signal indicating an
amount of power harvested from the received RF signal; configuring
the configurable front-end to increase power consumption in
response to determining that the operating metric is less than a
first threshold; and configuring the configurable front-end to
decrease power consumption in response to determining that the
operating metric is greater than a second threshold.
22. (canceled)
23. The method of claim 21, wherein the signal is proportional to
the amount of power harvested from the received RF signal.
24. The method of claim 21, wherein the operating metric is further
based at least in part on at least one of signal quality
characteristics, detected interference information, or system
information.
25. The method of claim 24, wherein signal quality characteristics
include at least one from the group consisting of received signal
power information, received signal quality information, received
signal timing information, signal drift information, and received
packet error rate.
26. The method of claim 24, wherein the detected interference
information includes at least one from the group consisting of
signal strength information associated with signal blockers,
transmission retry rate information, and inferred blocker power
information.
27. The method of claim 24, wherein the system information includes
at least one from the group consisting of a transmission distance,
an amount of data to be transferred, latency information, and
battery state information.
Description
TECHNICAL FIELD
[0001] The present disclosure relates generally to wireless
devices, and specifically to methods and apparatus for controlling
power dissipation in a wireless receiver.
BACKGROUND OF RELATED ART
[0002] Portable devices (such as wireless communication devices,
wireless sensors, and Internet of Things (IoT) devices) are often
battery powered to provide mobility and convenience. Reducing the
power consumption of wireless communication devices may extend
battery life and thereby increase the time between battery
recharging or replacement.
[0003] Wireless communication devices may receive transmitted radio
frequency (RF) signals and perform one or more processing steps to
recover transmitted data. The quality of the received RF signal may
vary widely based on, for example, operating and/or environmental
conditions. For example, if a wireless receiver and transmitter are
near each other, then the received signal quality may be high and
the transmitted data may be easy to recover. On the other hand, if
the wireless receiver and transmitter are far apart, or if one or
more signal blockers exist between the wireless receiver and
transmitter, then the received signal quality may be low, and the
transmitted data may be difficult to recover.
[0004] Wireless receivers may include receivers that accommodate a
wide range of RF signals. However, recovering transmitted data from
a high-quality RF signal may be easier and may require less power
than recovering transmitted data from a low quality RF signal.
Therefore, wireless receivers may expend more power than necessary
when receiving and processing higher quality RF signals. Thus,
there is a need to reduce the power consumption of wireless RF
receivers without decreasing operating bandwidth.
SUMMARY
[0005] This Summary is provided to introduce in a simplified form a
selection of concepts that are further described below in the
Detailed Description. This Summary is not intended to identify key
features or essential features of the claimed subject matter, nor
is it intended to limit the scope of the claimed subject
matter.
[0006] An apparatus and method are disclosed that may enable a
wireless device to adaptively control power consumption expended by
its wireless receiver. In a first example, a method is disclosed
and may include receiving a radio-frequency (RF) signal via a
configurable front-end of a wireless device, determining a power
metric for the wireless device, wherein the power metric indicates
an amount of available power to the wireless device, determining a
link quality metric based at least in part on a signal from a
circuit to harvest power from the received RF signal, determining a
configuration of the configurable front-end based at least in part
on the power metric and the link quality metric; and configuring
the configurable front-end based at least in part on the determined
configuration.
[0007] In another example, a wireless device is disclosed and may
include a configurable front-end configured to receive an RF
signal, a controller, and a memory configured to store instructions
that, when executed by the controller, cause the wireless device to
determine a power metric, wherein the power metric indicates an
amount of power available to the wireless device, determine a link
quality metric based at least in part on a signal from a circuit to
harvest power from the received RF signal, determine a
configuration of the configurable front-end based at least in part
on the power metric and the link quality metric, and configure the
configurable front-end based at least in part on the determined
configuration.
[0008] In another example, another method may include receiving a
radio-frequency (RF) signal via a configurable front-end of a
wireless device, determining an operating metric based at least in
part on a signal indicating an amount of power harvested from the
received RF signal, and configuring the configurable front-end
based at least in part on the operating metric.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Aspects of the present disclosure are illustrated by way of
example and are not intended to be limited by the figures of the
accompanying drawings. Like numbers reference like elements
throughout the drawings and specification.
[0010] FIG. 1 depicts a wireless communication system 100 within
which aspects of the present disclosure may be implemented
[0011] FIG. 2 is a block diagram of an example client device.
[0012] FIG. 3 is a simplified diagram illustrating example
parameters that may be considered by the front-end control software
of FIG. 2
[0013] FIG. 4 is a block diagram depicting one example of a
configurable front-end.
[0014] FIG. 5 is a block diagram of a clock system.
[0015] FIG. 6 is a simplified graph depicting an example
relationship between an operating metric and regions of operation
of a client device.
[0016] FIG. 7 is a flowchart depicting an example operation for
operating a client device, in accordance with some embodiments.
[0017] FIG. 8 is a diagram depicting example operations that may be
performed to modify analog operations associated with a
configurable front-end of the client device.
[0018] FIG. 9 is a diagram depicting example operations that may be
performed to modify digital operations associated with a
configurable front-end of the client device.
[0019] FIG. 10 is a flowchart depicting another example operation
for operating a client device.
[0020] FIG. 11 is an example selection matrix for determining a
configuration of a configurable front-end.
DETAILED DESCRIPTION
[0021] In the following description, numerous specific details are
set forth such as examples of specific components, circuits, and
processes to provide a thorough understanding of the disclosure.
The term "coupled" as used herein means coupled directly to or
coupled through one or more intervening components or circuits.
Also, in the following description and for purposes of explanation,
specific nomenclature is set forth to provide a thorough
understanding of the example embodiments. However, it will be
apparent to one skilled in the art that these specific details may
not be required to practice the example embodiments. In other
instances, well-known circuits and devices are shown in block
diagram form to avoid obscuring the disclosure. Any of the signals
provided over various buses described herein may be
time-multiplexed with other signals and provided over one or more
common buses. Additionally, the interconnection between circuit
elements or software blocks may be shown as buses or as single
signal lines. Each of the buses may alternatively be a single
signal line, and each of the single signal lines may alternatively
be buses, and a single line or bus might represent any one or more
of a myriad of physical or logical mechanisms for communication
between components. The example embodiments are not to be construed
as limited to specific examples described herein but rather to
include within their scope all embodiments defined by the appended
claims.
[0022] The techniques described herein may be implemented in
hardware, software, firmware, or any combination thereof, unless
specifically described as being implemented in a specific manner.
Any features described as modules or components may also be
implemented together in an integrated logic device or separately as
discrete but interoperable logic devices. If implemented in
software, the techniques may be realized at least in part by a
non-transitory computer-readable storage medium comprising
instructions that, when executed, performs one or more of the
methods described below. The non-transitory computer-readable
storage medium may form part of a computer program product, which
may include packaging materials.
[0023] The non-transitory computer-readable storage medium may
include random access memory (RAM) such as synchronous dynamic
random access memory (SDRAM), read only memory (ROM), non-volatile
random access memory (NVRAM), electrically erasable programmable
read-only memory (EEPROM), FLASH memory, other known storage media,
and the like. The techniques additionally, or alternatively, may be
realized at least in part by a computer-readable communication
medium that carries or communicates code in the form of
instructions or data structures and that may be accessed, read,
and/or executed by a computer or other processor.
[0024] The various illustrative logical blocks, modules, circuits
and instructions described in connection with the implementations
disclosed herein may be executed by one or more processors, such as
one or more digital signal processors (DSPs), general purpose
microprocessors, application specific integrated circuits (ASICs),
application specific instruction set processors (ASIPs), field
programmable gate arrays (FPGAs), or other equivalent integrated or
discrete logic circuitry. The term "processor," as used herein may
refer to any of the foregoing structure or any other structure
suitable for implementation of the techniques described herein. In
addition, in some aspects, the functionality described herein may
be provided within dedicated software modules or hardware modules
configured as described herein. Also, the techniques could be fully
implemented in one or more circuits or logic elements. A
general-purpose processor may be a microprocessor, but in the
alternative, the processor may be any conventional processor,
controller, microcontroller, or state machine. In some
implementations, a state machine may include or be coupled to any
memory as described above. Thus, operation of the state machine may
include retrieval and execution of instructions stored in a memory.
A processor may also be implemented as a combination of computing
devices (such as a combination of a DSP and a microprocessor), a
plurality of microprocessors, one or more microprocessors in
conjunction with a DSP core, or any other suitable
configuration.
[0025] FIG. 1 depicts a wireless communication system 100 within
which aspects of the present disclosure may be implemented. The
wireless communication system 100 may include one or more wireless
communication devices such as a host device 110 and client devices
120 and 130. The host device 110 and the client devices 120 and 130
may be any suitable wireless communication device. Example wireless
communication devices may include a cell phone, personal digital
assistant (PDA), tablet device, laptop computer, or any other
suitable portable device. The host device 110 and the client
devices 120 and 130 may also be referred to as a user equipment
(UE), a subscriber station, a mobile unit, a subscriber unit, a
wireless unit, a remote unit, a mobile device, a wireless device, a
wireless communications device, a remote device, a mobile
subscriber station, an access terminal, a mobile terminal, a
wireless terminal, a remote terminal, a handset, a user agent, a
mobile client, a client, or some other suitable terminology.
[0026] For ease of explanation and clarity, the wireless
communication system 100 depicts a single host device 110 and two
client devices 120 and 130. In other embodiments, the wireless
communication system 100 may include any technically feasible
number of host devices and/or client devices. The host device 110
and the client devices 120 and 130 may communicate with each other
via one or more technically feasible wireless communication
protocols. In some implementations, the host device 110 and the
client devices 120 and 130 may communicate with each other (and
with other devices not shown for simplicity) via Wi-Fi,
Bluetooth.RTM., Bluetooth Low Energy (BLE), Long Term Evolution
(LTE), or any other suitable communication protocol. In some other
implementations, the host device 110 and client devices 120 and 130
may operate within the 900 MHz band, the 2.4 GHz industrial,
scientific, and medical (ISM) band, the 5 GHz ISM band, the 60 GHz
band, or any other technically feasible frequency band.
[0027] The host device 110 may be powered by a battery or through
an external power source (not shown for simplicity) and be well
suited to transmit power via RF energy to the client devices 120
and/or 130. In some implementations, the host device 110 may
include a power transmitter/communication circuit 115. The power
transmitter/communication circuit 115 may provide communications
functionality to transmit and receive data through any technically
feasible communication protocol. For example, the power
transmitter/communication circuit 115 may include a transceiver to
wirelessly transmit and receive data between the host device 110
and a number of other devices (such as the client devices 120 and
130). In addition, the power transmitter/communication circuit 115
may convert power from a local power source into RF energy that may
be transmitted to other wireless devices (such as the client
devices 120 and 130).
[0028] The client device 120 may include a power
harvesting/communication circuit 125 to transmit and receive data
and capture (e.g., harvest) power from transmitted RF signals. For
example, the power harvester/communication circuit 125 may include
a transceiver to wirelessly transmit and receive data between the
client device 120 and the host device 110, between the client
device 120 and the client device 130, and/or between the client
device 120 and one or more other wireless devices (not shown for
simplicity). In some implementations, the power
harvesting/communication circuit 125 may transmit and receive data
via a Wi-Fi, Bluetooth.RTM., Bluetooth Low Energy (BLE), Long Term
Evolution (LTE), or any other suitable communication protocol.
[0029] The power harvesting/communication circuit 125 may harvest
power from RF signals (e.g., RF energy) transmitted by the host
device 110 (or any other nearby device that transmits or emits RF
energy). In this manner, some or all of the operations of the
client device 120 may be powered by RF energy transmitted from the
host device 110.
[0030] In some aspects, the RF energy may be transmitted within
frequency bands that may be shared with other transceivers provided
within the client device 120. In one implementation, the host
device 110 may transmit a paging signal to communicate with the
client device 120 and also provide power that may be harvested. The
paging signal may include one or more RF pre-charging pulses. The
RF pre-charging pulses may be used to power, at least partially,
the client device 120.
[0031] Similar to the client device 120, the client device 130 may
also include a power harvester/communication circuit 135 to harvest
power from transmitted RF energy and provide communication
functionality.
[0032] FIG. 2 is a block diagram of an example client device 200.
The client device 200 may be an implementation of the client device
120 and/or the client device 130 of FIG. 1. The client device 200
may include antennas 201 and 202, transceivers 210 and 220, a
battery 230, a charging circuit 235, a controller 240, and a memory
250. Although two antennas and two transceivers are shown in the
example of FIG. 2, in other implementations, the client device 200
may include any suitable number of antennas and transceivers. The
transceiver 210 may be coupled directly or indirectly to the
antenna 201, and the transceiver 220 may be coupled directly or
indirectly to the antenna 202. The transceivers 210 and 220 may be
implementations of the power harvester/communication circuits 125
and 135 of respective client devices 120 and 130 of FIG. 1.
[0033] The transceiver 210 may transmit and receive wireless data
from other wireless devices, including the host device 110. In
addition, the transceiver 210 may harvest energy from RF signals to
power, at least in part, the client device 200. The transceiver 210
may include a configurable front-end 214 and an energy harvester
216. The configurable front-end 214 may be coupled to the antenna
201 and may include analog and/or digital processing blocks to
receive and recover transmitted data from a RF signal. In some
aspects, the configurable front-end 214 may be selectively
configured to reduce power consumption in response to operating
conditions. The energy harvester 216 may also be coupled to the
antenna 201 (in some implementations via the configurable front-end
214) and may include circuits to receive and convert the RF energy
into a voltage and/or current. In one implementation, the energy
harvester 216 may provide a strong RF indicator signal 217 to the
controller 240 to indicate that a strong RF signal is being
received and that energy is being harvested. The energy harvester
216 may harvest energy from strong RF signals but may not be able
to harvest energy from other RF signals. In another implementation,
the strong RF indicator signal 217 may indicate that the received
RF signal has an associated signal strength of -10 dBm or more.
[0034] The controller 240 may configure the configurable front-end
214 based on the strong RF indicator signal 217. Similarly, the
transceiver 220 may include a configurable front-end 224 and an
energy harvester 226. The configurable front-end 224 may be similar
to the configurable front-end 214 and the energy harvester 226 may
be similar to the energy harvester 216. The energy harvester 226
may provide a strong RF indicator signal 227 to the controller 240
to indicate that a strong RF signal is begin received and, in some
cases, that energy is being harvested. In some implementations, the
strong RF indicator signals 217 and 227 may indicate how much
energy is being harvested.
[0035] The configurable front-ends 214 and 224 may be configured to
trade power consumption for performance. For example, transmitted
data may be recovered from strong RF signals using fewer hardware
stages or processing steps (thereby reducing power consumption).
Conversely, transmitted data may be recovered from weak RF signals
using more power hardware stages or processing steps (thereby
increasing power consumption). Operation of the configurable
front-ends 214 and/or 224 is described in more detail below in
conjunction with FIGS. 3-9.
[0036] The battery 230 may provide some or all of the power to
operate the client device 200. The charging circuit 235 may charge
the battery 230 either through an external power supply (such as an
AC powered source not shown for simplicity) or from the energy
harvesters 216 and 226.
[0037] The memory 250 may include a non-transitory
computer-readable storage medium (such as one or more nonvolatile
memory elements, such as EPROM, EEPROM, Flash memory, a hard drive,
etc.) that may store the following software modules: [0038] a
battery monitoring software (SW) module 251 to monitor status and
charge condition of the battery 230, for example as described below
with respect to FIGS. 3-11; [0039] an operating metric SW module
252 to determine an operating metric associated with the client
device 200, for example as described below with respect to FIGS.
3-9; [0040] a power metric SW module 254 to determine a power
metric associated with the client device 200, for example as
described below with respect to FIGS. 10-11; [0041] a link quality
metric SW module 256 to determine a link quality metric associated
with the client device 200, for example as described below with
respect to FIGS. 10-11; and [0042] a front-end control software
(SW) module 258 to control operations of the configurable
front-ends 214 and 224, for example, as described below for one or
more operations associated with FIGS. 7 and 10.
[0043] The controller 240, which may be coupled to the transceivers
210 and 220, and the memory 250, may be any one or more suitable
controllers or processors capable of executing scripts or
instructions of one or more software programs stored in the client
device 200 (e.g., within the memory 250). In some embodiments, the
controller 240 may be implemented with a hardware controller, a
processor, a state machine, or other suitable circuits to provide
the functionality of the controller 240 executing instructions
stored in the memory 250.
[0044] The controller 240 may execute the battery monitoring SW
module 251 to determine a battery charge state of the battery 230.
For example, the battery monitoring SW module 251 may determine
whether the battery is fully charged, fully discharged or any other
feasible charge state. In some implementations, execution of the
battery monitoring SW module 251 may determine a battery capacity
associated with the battery 230 and may also determine if power is
being provided by an external power supply (not shown for
simplicity). Operations of the battery monitoring SW module 251 are
described in more detail below in conjunction with FIGS. 3-11.
[0045] The controller 240 may execute the operating metric SW
module 252 to determine an operating metric associated with the
client device 200. In some implementations, the operating metric
may describe operating conditions of the client device 200. The
operating metric may describe signal quality characteristics,
detected interference, and system information associated with the
client device 200. Operations of the operating metric SW module 252
are described in more detail below in conjunction with FIGS.
3-9.
[0046] The controller 240 may execute the power metric SW module
254 to determine a power metric associated with the client device
200. In some implementations, execution of the power metric SW
module 254 may determine an indicator describing a power state of
the client device 200. The power state may include battery charge
information, battery capacity information, and information
regarding an external power supply. Operation of the power metric
SW module 254 is described in more detail below in conjunction with
FIGS. 10-11.
[0047] The controller 240 may execute the link quality metric SW
module 256 to determine a link quality metric associated with the
client device 200. In some implementations, execution of the link
quality metric SW module 256 may determine an indicator describing
link quality of an RF signal received by the client device 200. In
some implementations, execution of the link quality metric SW
module 256 may determine an indicator describing link quality (for
example, received signal strength, detected signal blockers and the
like) of a received RF signal. Operation of the link quality metric
SW module 256 is described in more detail below in conjunction with
FIGS. 10-11.
[0048] The controller 240 may execute the front-end control SW
module 258 to control and/or configure a configurable front-end
(such as the configurable front-ends 214 and 224). In some
implementations, execution of the front-end control SW module 258
may control and/or configure a configurable front-end based at
least in part on the operating metric determined by the operating
metric SW module 252. In another implementation, execution of the
front-end control SW module 258 may control and/or configure a
configurable front-end based at least in part on a power metric
determined by the power metric SW module 254 and a link quality
metric determined by the link quality metric SW module 256.
Operations of the front-end control SW module 258 are described in
more detail below in conjunction with FIGS. 3-9.
[0049] FIG. 3 is a simplified diagram 300 illustrating example
parameters that may be considered by the front-end control SW
module 258 of FIG. 2. In some implementations, the front-end
control SW module 258 may configure a configurable front-end (such
as the configurable front-end 214 and/or the configurable front-end
224) in response to parameters such as signal quality
characteristics 320, detected interference 330, and/or system
information 340.
[0050] The front-end control SW module 258 may receive signal
quality characteristics 320 to configure the configurable front-end
214 or 224. In some implementations, signal quality characteristics
320 may determine, at least in part, whether the received RF signal
is strong or weak. As used herein, a strong RF signal may
correspond to a signal having a power level greater than a value,
and a weak RF signal may correspond to a signal having a power
level that is less than (or equal to) the value. The signal quality
characteristics 320 may include receive signal power, received
signal quality, received timing/frequency error and drift, and/or a
packet error rate or retry rate information. In one implementation,
a receive signal power indicator may be a received signal strength
indicator (RSSI) provided by the transceiver 210 or 220. Large
amounts of error and/or drift may indicate a weak RF signal. A
packet error may occur when a weak RF signal is received and the
transmitted data cannot be recovered. A large packet error rate
may, therefore, indicate a weak RF signal. Further, a high retry
rate (e.g., a rate of signal retransmissions determined, for
example, by comparing the retry rate to a threshold) may also
indicate a weak RF signal. The front-end control SW module 258 may
configure the configurable front-end 214 and/or 224 to use more
processing steps and/or more hardware stages to recover data from a
weak RF signal. On the other hand, the front-end control SW module
258 may configure the configurable front-end 214 and/or 224 to use
fewer processing steps and/or fewer hardware stages to recover data
from a strong RF signal
[0051] In some implementations, the signal quality characteristics
320 may include received signal quality information provided by the
energy harvester 216 and/or 226. The received signal power
indicator may indicate the presence of a strong RF signal or that
energy is being harvested by the energy harvester 216 or 226. If
the received signal quality indicator indicates that a strong RF
signal is being received or that power is being harvested, then the
front-end control SW module 258 may configure the configurable
front-end 214 or 224 to user fewer processing steps and/or fewer
hardware stages to recover the transmitted data. On the other hand,
if the received signal quality indicator indicates that a strong RF
signal is not being received or that power is not being harvested,
then the front-end control SW module 258 may configure the
configurable front-end 214 or 224 to use more processing steps
and/or more hardware stages to recover the transmitted data. In
some implementations, the receive signal power indicator may be
compared to a threshold to determine whether a strong (or weak) RF
signal is received. Additional signal quality characteristics may
be considered but not mentioned here.
[0052] The front-end control SW module 258 may also receive
detected interference 330 to configure the configurable front-end
214 or 224. When the client device 200 operates in the presence of
one or more signal blockers, recovery of the transmitted data may
be more difficult than when the client device operates in the
absence of signal blockers. Therefore, additional signal filtering
or other processing steps and/or additional hardware stages
(compared to a present configuration of the configurable front-end
214 or 224) may be used to receive and recover transmitted data
when operating in the presence of signal blockers. On the other
hand, fewer signal processing steps and/or fewer hardware stages
(again, compared to a present configuration of the configurable
front-end 214 or 224) may be used to receive and recover
transmitted data when operating in the absence of signal blockers.
The detected interference 330 may include signal blocker
information provided by background scanning, inferred signal
blocker power based on adjacent/alternate channel power sensor, and
inferred signal blocker power based on the difference between total
received RF power (including any blocker) and power filtered signal
power after out-of-band blockers are removed. Background scanning
(e.g., scanning by a transceiver when not transmitting an RF
signal) may provide information regarding signal blockers within a
wireless communication channel used by the client device 200. For
example, background scanning may provide signal strength
information associated with signal blockers.
[0053] In some implementations, signal blocker power may be
inferred by measuring power within an adjacent or alternate
wireless communication channel. If measured adjacent or alternate
channel power is high (e.g., when compared to a threshold), then
the client device 200 may be operating in the presence of a signal
blocker. On the other hand, if the measured adjacent or alternate
channel power is not high (e.g., lower than a threshold), then the
client device 200 may not be operating in the presence of a signal
blocker. In some implementations, signal blocker power may be an
inferred power based on a difference between total received RF
power and power filtered signal power without out-of-band blockers.
Therefore, the front-end control SW module 258 may configure the
configurable front-end 214 or 224 to use more processing steps
and/or hardware stages when a signal blocker is present or use
fewer processing steps and/or hardware stages when a signal blocker
is not present.
[0054] The front-end control SW module 258 may also receive system
information 340 to configure the configurable front-end 214 or 224.
The system information 340 may include, for example, application
information (e.g., use information) of the client device 200. For
example, the application information may indicate that the client
device 200 is operating as a wireless mouse or keyboard, wireless
sensor, camera, etc. Because typical transmission distances
associated with a wireless mouse or keyboard are typically limited
to only a few feet, the front-end control SW module 258 may
configure the configurable front-end 214 or 224 to preferentially
use fewer processing steps and/or hardware stages to receive and
decode the transmitted data. On the other hand, if the additional
information indicates that the client device 200 is not operating
as a wireless mouse or keyboard but rather as a sensor, for
example, the front-end control SW module 258 may configure the
configurable front-end 214 or 224 to use additional processing
steps and/or additional hardware stages to receive and decode the
transmitted data.
[0055] In another implementation, the system information 340 may
include information indicating the amount of data to be
transferred. Large amounts of data (e.g., an amount that is greater
than a threshold) may be more efficiently received (e.g., fewer
data retransmissions) by configuring the configurable front-end 214
or 224 to use additional processing steps and/or additional
hardware stages to receive and decode the transmitted data. On the
other hand, smaller amounts of data (e.g., an amount that is less
than a threshold) may be received and decoded by the configurable
front-end 214 or 224 using fewer processing steps and/or fewer
hardware stages to conserve power even if occasional retries are
required.
[0056] In some implementations, the system information 340 may
include urgency or latency information. Urgent communications or
communications with a low latency time may benefit from additional
processing steps and/or additional hardware stages. Therefore, the
front-end control SW module 258 may configure the configurable
front-end 214 or 224 to use additional processing steps and/or
additional hardware stages when urgent communications or a low
latency time is indicated in the system information 340. On the
other hand, the front-end control SW module 258 may configure the
configurable front-end 214 or 224 to use fewer processing steps
and/or fewer hardware stages when urgent communications or low
latency times are not indicated in the system information 340.
[0057] The system information 340 may include intended use
information such as, for example, mobile use or stationary use
information. When the system information 340 includes mobile usage
information, the front-end control SW module 258 may configure the
configurable front-end 214 or 224 to use fewer processing steps
and/or fewer hardware processing stages to reduce power
consumption. On the other hand, when the system information 340
includes stationary usage information, power may be supplied by an
external power supply. Therefore, the front-end-control SW module
258 may configure the configurable front-end 214 or 224 to use more
processing steps and/or more hardware stages since power may be
provided by the external power supply instead of a limited capacity
battery.
[0058] The system information 340 may include battery state
information. When the battery state information indicates a low
battery charge (e.g., compared to a battery charge threshold) then
the front-end control SW module 258 may configure the configurable
front-end 214 and/or 224 to use fewer processing steps and/or fewer
hardware processing stages. On the other hand, when the battery
state information indicates a sufficient battery charge, then the
front-end control SW module 258 may configure the configurable
front-end 214 or 224 to use more processing steps and/or more
hardware processing stages to receive and recover the transmitted
data. Additionally, or alternatively, the system information 340
may include battery capacity information. The battery capacity
information may be used together with battery state information to
indicate a charge capacity information associated the battery.
[0059] The system information 340 may include information regarding
nearby devices and their operating frequencies. Nearby devices may
cause interference, especially if the nearby devices are operating
in or near the same frequencies used by the client device 200.
Thus, if the system information 340 includes information indicating
the presence of nearby devices and/or devices using the same or
nearby operating frequencies, the front-end control SW module 258
may configure the configurable front-end 214 or 224 to use more
processing steps and/or more hardware processing stages to recover
the transmitted data (e.g., to overcome potential interference). On
the other hand, if the system information 340 includes information
indicating that there are no nearby devices and/or devices using
the same or nearby operating frequencies, then the front-end
control SW module 258 may configure the configurable front-end 214
or 224 to use fewer processing steps and/or fewer hardware
processing stages to recover the transmitted data.
[0060] FIG. 4 is a block diagram depicting one example of a
configurable front-end 400. The configurable front-end 400 may an
implementation of the configurable front-end 214 or 224 of FIG. 2.
The configurable front-end 400 may include a first receive chain
410, a second receive chain 450, a first selector 460, a first
demodulator 461, a second demodulator 462, and a second selector
463. The second receive chain 450 may be a reduced feature receive
chain that includes fewer hardware stages and/or capabilities than
the first receive chain 410. In some implementations, first receive
chain 410 may be used to receive and process weak RF signals, while
the second receive chain 450 may be used to receive and process
strong RF signals. In other implementations, the first receive
chain 410 may be used to process not only weak RF signals, but also
"normal" RF signals having power levels less than strong RF
signals. For such implementations, weak RF signals: 0<RF signal
power<V.sub.1, normal RF signals: V.sub.1<RF signal
power<V.sub.2, and strong RF signals: V.sub.2<=RF signal
power. Since the second receive chain 450 includes fewer hardware
stages and/or capabilities than the first receive chain 410, the
second receive chain 450 may consume less power than the first
receive chain 410.
[0061] The first receive chain 410 may include an antenna 411, a
low noise amplifier (LNA) 412, a first mixer 413, a second mixer
414, a first variable gain amplifier (VGA) 415, a second VGA 416, a
first low pass filter (LPF) 417, a second LPF 418, a first
analog-to-digital converter (ADC) 419, a second ADC 420, and a
digital filtering block 421. The first receive chain 410 may
receive quadrature-encoded RF signals. For example, a
quadrature-encoded RF signal may be received by the antenna 411 and
amplified by the LNA 412. The first mixer 413 may mix (e.g.,
multiply) the amplified RF signal with an in-phase clock signal
(denoted as CLK I). The mixed signal may be amplified by and
filtered by the first LPF 417. The filtered output signal output
from the first LPF 417 may be sampled by the first ADC 419.
[0062] The second mixer 414 may mix the amplified RF signal output
from the LNA 412 with a quadrature clock signal (denoted as CLK Q).
The mixed signal may be amplified by and filtered by the second LPF
418. The filtered output signal output from the second LPF 418 may
be sampled by the second ADC 420. Output signals from the first ADC
419 and the second ADC 420 may be combined and filtered by the
digital filtering block 421. An output signal from the digital
filtering block 421 may be provided to the first selector 460.
[0063] In some implementations, the first receive chain 410 may be
designed to receive and process a range of transmitted RF signals
varying in signal strength from weak to very strong. The range of
permitted signal strengths may be specified by a communication
standard (e.g., IEEE 802.11 standards, one or more Bluetooth
standards set forth by the Bluetooth Special Interest Group, or
similar). In addition, performance of some hardware stages may be
specified by communication standards. For example, LPF filter
parameters (frequency cut off point, amount of attenuation, etc.)
may be determined at least in part by a communication standard.
Performance, design, and/or selection of other hardware stages may
also be based on communication standards such as ADC resolution,
word width, sample rate, and digital filtering to process the
received signal.
[0064] When the client device 200 is receiving a strong RF signal,
the receive chain may be simplified. The simplified receive chain
may trade signal processing capabilities for power savings. For
example, the simplified receive chain may not satisfy one or more
performance requirements associated with a particular communication
standard. The simplified receive chain may only be able to receive
and recover data from strong RF signals. However, since the
received RF signal is strong, the reduced capabilities of the
simplified receive chain may not adversely affect the reception and
decoding of the strong RF signal. The simplified receive chain may
reduce the power consumption of the client device. The second
receive chain 450 may be one implementation of a simplified receive
chain.
[0065] The second receive chain 450 may include an antenna 451, a
third mixer 452, a third VGA 453, and a third ADC 454. The hardware
stages of the second receive chain 450 may be simplified versions
(e.g., lower performing versions) of corresponding hardware stages
included within the first receive chain 410. In addition, the
simplified hardware stages may consume less power than
corresponding hardware stages of the first receive chain 410.
[0066] In some implementations, a strong quadrature-encoded RF
signal may be received by the antenna 451. Since the RF signal is
strong, an LNA may not be needed between the antenna 451 and the
third mixer 452. In some aspects, a full quadrature demodulation
may not be necessary to at least partially decode the strong RF
signal. Thus, the third mixer 452 may be used to mix a single clock
signal (denoted CLK) with the strong RF signal. In some
implementations, the CLK signal may be either an in-phase clock
signal or a quadrature clock signal. The mixed signal from the
third mixer 452 is provided to the third VGA 453. Compared to the
first VGA 415 and the second VGA 416, the third VGA 453 may have a
smaller gain range. A VGA with a large gain range may consume more
power than a VGA with a smaller gain range. Further, a large gain
range may not be necessary since the RF signal is strong. The
amplified signal from the third VGA 453 is provided to the third
ADC 454. The third ADC 454 may have less resolution than the first
ADC 419 or the second ADC 420. In addition, the sampling rate of
the third ADC 454 may be slower compared to the first ADC 419 or
the second ADC 420. An ADC with less resolution and/or and ADC
running at a slower sampling rate may use less power than an ADC
with relatively more resolution and/or an ADC running at a higher
sampling rate. The output of the third ADC 454 is provided to the
first selector 460.
[0067] The first selector 460 may select the output of the first
receive chain 410 or the second receive chain 450 based on a select
signal 465. For example, when the select signal 465 is driven to a
first state, the output of the first receive chain 410 may be
selected. When the select signal 465 is driven to a second state,
the output of the second receive chain 450 may be selected. In some
implementations, when one of the outputs of one of the receive
chains is selected, the unused receive chain may be powered down or
placed in a standby mode. Thus, power may be saved by not powering
the unused receive chain.
[0068] The output of the first selector 460 is provided to the
first demodulator 461 and the second demodulator 462. The first
demodulator 461 may be a "full feature" demodulator used to
demodulate RF signals including quadrature encoded RF signals. The
second demodulator 462 may be a simplified demodulator capable of
partial demodulation of a received RF signal. In some
implementations, the first demodulator 461 may consume more power
than the second demodulator 462.
[0069] The output of the first demodulator 461 and the second
demodulator 462 are coupled to the second selector 463. In some
implementations, the unused demodulator (e.g., the demodulator
whose output is not selected by the second selector 463), may be
powered down or placed in a standby mode.
[0070] Although only two receive chains (first receive chain 410
and second receive chain 450) are shown here for simplicity, in
other implementations, the configurable front-end 400 may include
any feasible number of receive chains.
[0071] FIG. 5 is a block diagram of a clock system 500. The clock
system 500 may be included within the client device 200 of FIG. 2
(not shown in FIG. 2 for simplicity). The clock system 500 may
include a voltage controlled oscillator (VCO) 510, a ring
oscillator 520, and an oscillator controller 530. The clock system
500 may provide clock signals for the first receive chain 410
and/or the second receive chain 450 of FIG. 4. In some
implementations, the VCO 510 may be an oscillator with low phase
noise that generates both the CLK I and the CLK Q signals. The ring
oscillator 520 may be an oscillator with high phase noise that
generates the CLK signal. The ring oscillator 520 may consume less
power than the VCO 510. In some implementations, instead of a
single CLK signal, the ring oscillator 520 may generate the CLK I
and CLK Q signals (not shown for simplicity).
[0072] The oscillator controller 530 may control operations of the
VCO 510 and the ring oscillator 520. For example, the oscillator
controller 530 may enable the VCO 510 while disabling (e.g.,
placing in a low-power or standby mode) the ring oscillator 520,
thereby enabling the clock system 500 to provide low phase noise
clock signals while increasing power consumption. In another
example, the oscillator controller 530 may enable the ring
oscillator 520 while disabling the VCO 510, thereby enabling the
clock system 500 to provide a high phase noise clock while reducing
power consumption.
[0073] In some implementations, the front-end control SW module 258
may configure the configurable front-end 214 or 224 by determining
an operating metric based at least in part on signal quality
characteristics 320, detected interference 330, and/or system
information 340. The operating metric may provide an indication of
the operating conditions of the client device 200. In some
implementations, a low or small operating metric (e.g., less than a
first threshold) may indicate that RF signal is received and the
associated data recovered with a high and unacceptable number of
errors. In response thereto, the front-end control SW module 258
may configure the configurable front-end 214 or 224 to increase
power consumption and use more processing steps or hardware stages
to process the RF signal to reduce the number of errors. On the
other hand, a high or large operating metric (e.g., greater than a
second threshold) may indicate that the RF signal is received and
the associated data is recovered with a small number of errors. In
response thereto, the front-end control SW module 258 may configure
the configurable front-end 214 or 224 to decrease power consumption
and use fewer processing steps or fewer hardware stages to process
the RF signal. Operation of the front-end control SW module 258 is
described below in conjunction with FIGS. 6-9.
[0074] FIG. 6 is a simplified graph 600 depicting an example
relationship between the operating metric and regions of operation
of the client device 200. The graph 600 shows three operating
regions. A first region 610 may correspond to an operating metric
that is less than a first threshold. When the client device 200 is
operating in the first region 610, the number of errors associated
with the received RF signal may exceed a first amount. In some
implementations, when the number of errors exceeds the first
amount, the transmitted data cannot be recovered. In response to
operating in the first region 610, the front-end control SW module
258 may enable more hardware stages and/or processing steps to
increase the operating metric (thereby reducing the number of
errors).
[0075] A third region 630 may correspond to an operating metric
that is greater than a second threshold. When the client device 200
is operating in the third region 630, the number of errors may be
less than a second amount. In some implementations, when the number
of errors is less than the second amount, the additional errors may
be tolerated and the transmitted data may still be recovered. In
response to operating in the third region 630, the front-end
control SW module 258 may enable fewer hardware stages and/or
processing steps to reduce power consumption but increase the
number of errors.
[0076] A second region 620 may correspond to an operating metric
that is between the first threshold and the second threshold. When
the client device 200 is operating in the second region 620, the
number of errors may be less than the first amount, but more than
the second amount. In response to operating in the second region
620, the front-end control SW module 258 may not change the number
of hardware stages or processing steps used to recover the
transmitted data. In this region, the number of errors may be
acceptable and allow the transmitted data to be recovered.
[0077] FIG. 7 is a flowchart depicting an example operation 700 for
operating a client device, in accordance with some embodiments. In
some implementations, the client device described herein may be the
client device 200 of FIG. 2, the client device 120 or the client
device 130 of FIG. 1, or any other suitable device. The operation
700 is described herein as performed by the controller 240
executing the front-end control SW module 258. In other
implementations, the operation 700 may be performed by any other
suitable controller or processor. The operation begins as the
controller 240 operates a configurable front-end in a maximum power
consuming configuration (702). The configurable front-end may be
the configurable front-end 214. In other implementations, the
configurable front-end may be the configurable front-end 224 or any
other suitable configurable front-end. In the maximum power
consuming configuration, most or all of the available hardware
stages and/or processing steps associated with the configurable
front-end 214 may be operated. When the configurable front-end 214
is in the maximum power consuming configuration, an RF signal
received through the configurable front-end 214 may receive the
most processing available and, the transmitted data may be
recovered with the lowest error rate. Thus, operating the
configurable front-end 214 in this manner may provide the highest
operating metric for any received RF signal.
[0078] Next, the controller 240 determines the operating metric
(704). The operating metric may provide an indication of error rate
and/or operating conditions. In some implementations, the operating
metric may be determined based on signal quality characteristics
320, detected interference 330, and/or system information 340 as
described with respect to FIG. 3. Next, the controller 240 compares
the determined operating metric to a first threshold (706). In some
implementations, if the operating metric is less than the first
threshold, then the error rate may be unacceptably high. If the
operating metric is less than the first threshold, then the
controller 240 may configure the configurable front-end 214 to
increase power consumption to recover the data from the RF signal
(708). For example, the controller 240 may use more hardware stages
and/or more processing steps within the configurable front-end 214
to recover the data from the RF signal. Thus, power consumption may
be increased while improving data recovery. Managing the use of
hardware stages and/or processing steps is described in more detail
below in conjunction with FIGS. 8 and 9. The operation then returns
to 704.
[0079] If the operating metric is not less than the first threshold
(as tested in 706), then the operating metric is compared to a
second threshold (710). The second threshold may be associated with
an error rate/performance level that is acceptable. In some
implementations, the second threshold may be related to the first
threshold. For example, the second threshold may be a percentage
(e.g., 10%) greater than the first threshold. The first threshold
in combination with the second threshold may provide hysteresis
with respect to changing the configuration of the configurable
front-end 214. Thus, if the operating metric is greater than the
second threshold, then the controller 240 may configure the
configurable front-end 214 to decrease power consumption to recover
the data from the RF signal (712). For example, the controller 240
may use fewer hardware stages and/or fewer processing steps to
recover the data from the RF signal. Thus, power consumption may be
reduced while recovering the transmitted data within an acceptable
error rate. The operation then returns to 704.
[0080] If the operating metric is not greater than the second
threshold, then the controller 240 makes no changes to the hardware
stages and/or processing steps to recover transmitted data (714).
The operation returns to 704. Although operations 708, 712, and 714
each return to 704, the return to and execution of 704 need not be
immediate. The repeated execution of operation 700 enables the
controller 240 to adapt to operating conditions, conserve power,
and recover transmitted data. In some implementations, the
execution of 704 may occur as each data packet is received. In some
other implementations, the operation 700 may return to 702 as each
data packet is received. In some other implementations, the
operation 700 may be performed periodically. For example, another
device may transmit a periodic beacon or broadcast signal to
trigger the controller 240 to configure the configurable front-end
214.
[0081] As described above, the controller 240 may change how the
received RF signal is processed (e.g., change a configuration of
the configurable front-end 214) based on a determined operating
metric. Using more processing steps and/or hardware stages may
improve the recovery of transmitted data at a higher level of power
consumption. Using fewer processing steps or hardware stages may
reduce power consumption while degrading the recovered data. The
configurable front-end 214 may include many different processing
steps and hardware stages that may be configured/enabled/disabled
to affect power consumption and data recovery. Some of the possible
changes that may be applied to an analog receive path are described
below in conjunction with FIG. 8. Some of the possible changes that
may be applied to a digital configuration of the configurable
front-end 214 are described below in conjunction with FIG. 9.
[0082] FIG. 8 is a diagram 800 depicting example operations that
may be performed to modify the analog operations associated with a
configurable front-end of the client device 200. The operations
described herein are described with respect to the configurable
front-end 214. In other implementations, operations described
herein may apply to the configurable front-end 224 or any other
suitable front-end or circuit. The diagram 800 shows a modify an
analog configuration of the configurable front-end operation 214
(810) which may correspond to the increase power consumption
operation 708 or the decrease power consumption operation 712 of
FIG. 7.
[0083] One operation to modify the configuration of the
configurable front-end 214 may include changing the number of gain
stages (820). Using additional gain stages may improve (increase)
the determined operating metric while also increasing power
consumption. On the other hand, using fewer gain stages may
decrease the determined operating metric and decrease power
consumption. Therefore, the controller 240 of FIG. 2 may use
additional gain stages with respect to operation 708 or use fewer
gain stages with respect to operation 712. In some implementations,
the configurable front-end 214 may include several additional gain
stages (e.g., LNAs, VGAs, etc.). that may be used (e.g., enabled)
to improve the operating metric and increase power consumption or
bypassed (e.g., disabled) to decrease power consumption and
decrease the operating metric.
[0084] Another operation to modify the configuration of the
configurable front-end 214 may include changing a configuration of
a receive chain (821). For example, in a first configuration the
receive chain may perform a quadrature signal demodulation (e.g.,
use two mixers, an in-phase signal and a quadrature signal) to
recover the transmitted data. One example of a receive chain that
may perform a quadrature signal demodulation may be the first
receive chain 410 of FIG. 4. In a second configuration, the receive
chain may perform a one-half quadrature signal demodulation (e.g.,
use one mixer and one clock signal) to recover the transmitted
data. One example of a receive chain that may perform a one-half
quadrature modulation may be the second receive chain 450.
Therefore, the controller 240 may change a receive chain
configuration in response to a determined operating metric. For
example, the controller 240 may configure the receive chain to
perform quadrature signal demodulation corresponding to operation
708 or perform one-half quadrature signal demodulation
corresponding to operation 712.
[0085] Another operation to modify the configuration of the
configurable front-end 214 may include changing the clock source
(822). For example, a first clock source may be a ring oscillator.
The ring oscillator may consume less power compared to a VCO but
may have a higher phase noise that may reduce the operating metric.
A second clock source may be a VCO. The VCO may consume more power
than the ring oscillator, but may have a lower phase noise that may
increase the operating metric. Therefore, the controller 240 may
configure the configurable front-end 214 by selecting the ring
oscillator corresponding to operation 712 or selecting the VCO
corresponding to operation 708 in response a determined operating
metric.
[0086] Another operation to modify the configuration of the
configurable front-end 214 may include changing an LNA selection
(823). For example, the configurable front-end 214 may include a
first LNA which may have a first noise figure and a first level of
power consumption. The configurable front-end 214 may also include
a second LNA which may include a second noise figure (higher than
the first noise figure) and a second level of power consumption
(lower than the first level of power consumption). Therefore, the
controller 240 may configure the configurable front-end 214 by
selecting the first LNA to corresponding to the operation 708 or
the second LNA corresponding to the operation 712 in response to a
determined operating metric. In some implementations, the
configurable front-end 214 may include several different LNAs that
may be selected (e.g., enabled) based on the operating metric.
[0087] Another operation to modify the configuration of the
configurable front-end 214 may include selecting a mixer (824). For
example, the configurable front-end 214 may include a first mixer
which may be an active mixer (e.g., a gilbert cell mixer or
suitable active mixer). The configurable front-end 214 may also
include a second mixer which may be a passive mixer (e.g., a diode
based mixer or any other suitable passive mixer). The first mixer
may improve the operating metric while increasing power
consumption, whereas the second mixer may reduce power consumption
while reducing the operating metric. Therefore, the controller 240
may configure the configurable front-end 214 by selecting the first
mixer corresponding to the operation 708 or the second mixer
corresponding to the operation 712 in response a determined
operating metric.
[0088] Another operation to modify the configuration of the
configurable front-end 214 may include selecting an ADC (825). For
example, the configurable front-end 214 may include a first ADC
which may have a first resolution (e.g., a first number of bits)
bits that may improve the operating metric while increasing power
consumption. The configurable front-end 214 may also include a
second ADC which may have a second resolution (e.g., a second
number of bits less than the first number of bits) that may reduce
the operating metric while decreasing power consumption. Therefore,
the controller 240 may configure the configurable front-end 214 by
selecting the first ADC corresponding to the operation 708 or
selecting the second ADC corresponding to the operation 712 in
response a determined operating metric.
[0089] Another operation to modify the configuration of the
configurable front-end 214 may include changing the dynamic range
of a receive chain (826). For example, a first configuration of a
receive chain may have a dynamic range that may enable reception of
both weak and strong RF signals. The first configuration may
improve the operating metric while increasing power consumption. A
second configuration of the receive chain may have a reduced
dynamic range that may enable the reception of very strong RF
signals. The second configuration may reduce the operating metric,
while decreasing power consumption. Therefore, the controller 240
may configure the configurable front-end 214 by selecting the first
configuration corresponding to the operation 708 or the second
configuration corresponding to the operation 712 in response a
determined operating metric.
[0090] Another operation to modify the configuration of the
configurable front-end 214 may include changing the filtering used
in the configurable front-end 214 (827). For example, in a first
configuration the configurable front-end 214 may use a passive
filter with a reduced dynamic range. The passive filter may
decrease the operating metric, while reducing power consumption. In
a second configuration, the configurable front-end 214 may use an
active filter with a wide dynamic range (e.g., with respect to the
passive filter). The active filter may increase the operating
metric, while increasing power consumption. Therefore, the
controller 240 may configure the configurable front-end 214 by
selecting the passive filter corresponding to the operation 712 or
selecting the active filter corresponding to the operation 708 in
response to a determined operating metric.
[0091] FIG. 9 is a diagram 900 depicting example operations that
may be performed to modify the digital operations associated with a
configurable front-end of the client device 200. The operations
described herein are described with respect to the configurable
front-end 214. In other implementations, operations described
herein may apply to the configurable front-end 224 or any other
suitable front-end or circuit. The diagram 900 shows a modify a
digital configuration of the configurable front-end 214 operation
(910) which may correspond to the operation 708 or the operation
712 of FIG. 7.
[0092] One operation to modify the digital configuration of the
configurable front-end 214 may include changing an oversampling
rate (920). A faster oversampling rate (e.g., a clock rate of an
ADC included in the configurable front-end 214) may increase the
operating metric by extending a dynamic range of an associated
receive chain (while increasing power consumption). A slower
oversampling rate may decrease the operating metric (while reducing
power consumption). Therefore, the controller 240 may configure the
configurable front-end 214 to increase oversampling rate
corresponding to the operation 708 or to decrease the oversampling
rage corresponding to the operation 712 in response to the
determined operating metric.
[0093] Another operation to modify the digital configuration of the
configurable front-end 214 may include modifying digital filtering,
signal detection, and/or sizing (921). For example, if no strong
interference blocker is present, digital filtering is not need and
the actual sizing of digital signal can be adjusted to avoid using
a width digital word. These configurations can reduce power
consumption.
[0094] Another operation to modify the digital configuration of the
configurable front-end 214 may include disabling digital quadrature
processing (922). For example, digital processing of only in-phase
or quadrature data samples may decrease the operating metric while
reducing power consumption. In some implementations, data may be
recovered at least in part from very strong RF signals using only
in-phase or quadrature data samples. On the other hand, digital
processing of both in-phase and quadrature data samples may
increase the operating metric while increasing power consumption.
Therefore, the controller 240 may configure the configurable
front-end 214 to processes both in-phase and quadrature data
samples corresponding to the operation 708 or process just the
in-phase or quadrature data samples corresponding to the operation
712 in response to the determined operating metric.
[0095] Another operation to modify the digital configuration of the
configurable front-end 214 may include modifying demodulation,
timing synchronization, and/or frequency synchronization (923).
With a strong signal with a large signal-to-noise ratio, simpler
and less power-hungry techniques for demodulation, synchronization
can be used. However, to successfully decode a weak, distorted
signal, sophisticated algorithms for demodulation and
synchronization are required. Such algorithms typically require
substantial logic and consume more power.
[0096] FIGS. 6-9 describe configuration of a configurable front-end
based on a single operating metric. Thus, based on a value of the
operating metric, additional or fewer processing steps and/or
hardware stages may be used by the configurable front-end to
recover data from a received RF signal. In some other
implementations, configuration of a configurable front-end may be
based on two metrics. This is described below in conjunction with
FIGS. 10 and 11.
[0097] FIG. 10 is a flowchart depicting another example operation
1000 for operating a client device. In some implementations, the
client device described herein may be the client device 200 of FIG.
2, the client device 120 or the client device 130 of FIG. 1, or any
other suitable device. The operation 1000 is described herein as
performed by the controller 240 executing the battery monitoring SW
module 251, the power metric SW module 254, the link quality metric
SW module 256 and/or the front-end control SW module 258. In other
implementations, the operation 1000 may be performed by any other
suitable controller or processor.
[0098] The operation begins as the controller 240 determines a
power metric (1002). In some implementations, the power metric may
be determined by the controller 240 executing the power metric SW
module 254 and/or the battery monitoring SW module 251. The power
metric may provide an indication of an amount of power available to
operate the client device. For example, the power metric may be
based on power resources available to the client device. In some
implementations, the power metric may be based on battery charge
and/or battery capacity. A fully charged battery may provide a
higher power metric than a partially or fully discharged battery.
The power metric may alternatively or additionally be based on a
determination of whether power is supplied by an external power
source. For example, if the client device is powered by an external
power supply (such as an AC power supply), then the amount of
available power may be unlimited (or limited only by the presence
of AC power). As a result, the associated power metric may be high.
In some implementations, the power metric may alternatively or
additionally be based at least in part on a signal from an energy
harvesting circuit (such as the energy harvesters 216 and 226).
[0099] In some other implementations, the power metric may be
determined by a formula based at least in part on a weighted sum of
various power resources.
Power Metric=w.sub.1Rsc.sub.1+w.sub.2Rsc.sub.2+ . . .
+w.sub.iRsc.sub.i (equation 1) [0100] Where: Rsc.sub.i is an ith
power resource (e.g., battery charge, battery capacity,
determination of external power source, etc.); and [0101] w.sub.i
is a corresponding ith weighting factor.
[0102] In some implementations, the power metric may be normalized
such that the value of the power metric may range from 0 (a minimum
power capacity) to 100 (a maximum power capacity). For example, if
a power resource is an external power supply powered by an external
power source, then the associated power metric may be 100. In
another example, a power resource may be battery charge and/or
battery capacity. The amount of battery charge may be weighted by
50% (w.sub.i=0.5) and the battery capacity may be weighted 25%
(w.sub.i=0.25). Therefore, a higher power metric may indicate
larger power reserves that may be used to power the client device.
Thus, the client device 200 may be configured to consume more power
than when the power metric is low. Although only three power
resources are described here for simplicity, other power resources
are contemplated. For example, other possible power resources may
be described above with respect to system information 340 of FIG.
3.
[0103] Next, the controller 240 determines a link quality metric
(1004). In some implementations, the link quality metric may be
determined by the controller 240 executing the link quality metric
SW module 256. The link quality metric may describe an overall
quality of a communication link used by the client device to
receive an RF signal. In some implementations, the link quality
metric may be based on an RSSI of the received RF signal. In
another implementation, the link quality metric may be based on a
signal from the energy harvester 216 or 226. For example, if the
signal from the energy harvester 216 or 226 indicates that energy
is being harvested, then the associated signal strength of the
received RF signal may be relatively large (compared to when no
energy is being harvested). A large RF signal may provide a large
link quality metric while a small RF signal may provide a low link
quality metric. In another implementation, packet error rate,
detected signal blockers, detected interference, and/or urgent
communications may be used to determine the link quality metric.
High packet error rates, large numbers of detected signal blockers,
large amounts of detected interference, and the presence of urgent
communications may provide a low link quality metric. On the other
hand, low packet error rates, small numbers of detected signal
blockers, small amounts of detected interference, and an absence of
urgent communications may provide a high link quality metric.
[0104] In some embodiments, the link quality metric may be based on
the signal quality characteristics 320, the detected interference
330, and the system information 340 described above with respect to
FIG. 3. In some implementations, the link quality metric may be
determined by a weighted sum of various link quality
indicators.
Link Quality Metric=y.sub.1Lqi.sub.1+y.sub.2Lqi.sub.2+ . . .
+y.sub.iLqi.sub.i (equation 2) [0105] Where: Lqi.sub.i is an ith
link quality characteristic; and [0106] y.sub.i is an ith weighting
factor.
[0107] In some implementations, the link quality metric may be
normalized such that the value of the link quality metric may range
from 0 (a minimum link quality) to 100 (a maximum link quality). A
low link quality metric may indicate a poor communication link
while a high link quality metric may indicate a good communication
link. In response to a low link quality metric, additional
processing steps and/or hardware stages may be used by a
configurable front-end to receive and decode an RF signal. Possible
link quality indicators may include RSSI, a signal from energy
harvesters 216 and 226, packet error rate, detected signal
blockers, detected interference, and/or urgent communications as
described above. Other link quality indicators are contemplated.
For example, other link quality indicators may be described above
with respect to the signal quality characteristics 320 of FIG.
3.
[0108] Next, the controller 240 determines a configuration of a
configurable front-end based at least in part on the power and link
quality metrics (1006). In some implementations, the configurable
front-end may use additional or fewer processing steps and/or
hardware stages to receive and decode RF signals in response to low
power and/or link quality metrics. For example, the configurable
front-end may use additional or fewer gain stages, additional or
fewer filtering stages, additional or fewer digital filtering
stages, using a VCO or a ring oscillator clock source, using
additional or fewer ADC bits and/or a higher or lower sampling
rate, and increased or decreased analog signal sensitivity in
response to the power and link quality metrics. In some
implementations, other configuration changes associated with the
configurable front-end may be made, such as those described above
with respect to FIGS. 2-5.
[0109] In some implementations. the configuration of the
configurable front-end may be based on a selection matrix of
possible configurations using the power metric and the link quality
metric. An example approach is described below in conjunction with
FIG. 11.
[0110] FIG. 11 is an example selection matrix 1100 for determining
a configuration of a configurable front-end. Possible power metrics
are shown across the top of the selection matrix 1100. As shown, a
low power metric is to the left and a high power metric is to the
right of the selection matrix 1100. Thus, an increasing power
metric goes from left to right. Possible link quality metrics are
shown on the left side of the selection matrix 1100. A low link
quality metric is toward the top of the selection matrix 1100 and a
high link quality metric is toward the bottom of the selection
matrix 1100. Thus, an increasing link quality metric goes from the
top to the bottom of the selection matrix 1100.
[0111] The power metric 1110 may be compared to a first power
metric threshold PMT1 and a second power metric threshold PMT2. If
the power metric 1110 is less than the first power metric threshold
PMT1, then the power metric 1110 may fall within the first column
of the selection matrix 1100. If the power metric 1110 is greater
than the first power metric threshold PMT1, but less than the
second power metric threshold PMT2, then the power metric 1110 may
fall within the middle column of the selection matrix. If the power
metric 1110 is greater than the second power metric threshold PMT2,
then the power metric 1110 may fall in the right column of the
selection matrix 1100. In this manner, the power metric 1110 may be
used to index a first dimension of the selection matrix 1100.
[0112] In a similar manner, the link quality metric 1120 may be
compared to a first link quality threshold LQT1 and a second link
quality threshold LQT2. Thus, the link quality metric 1120 may fall
within the upper row, the middle row, or the lower row. In this
manner, the link quality metric 1120 may be used to index a second
dimension of the selection matrix 1100.
[0113] A configurable front-end (for example, the configurable
front-end 214 and/or 224) may be configured through the selection
matrix 1100. Each entry in the selection matrix 1100 may represent
a different configuration (sometimes referred to as a power
profile) of the configurable front-end. The example selection
matrix 1100 shows nine possible independent power profiles. For
ease of explanation, three different power profiles are described
herein (a high, medium, and lower power configuration). In other
embodiments, the selection matrix 1100 may include any feasible
number of distinct power profiles. By way of example and not
limitation, a high power configuration may use full resolution
ADCs, a high quality VCO, full I and Q signal processing to receive
and decode RF signals. Similarly, a medium power configuration may
use reduced resolution ADC and slower sampling rates (compared to
the high power configuration) to receive and decode RF signals
thereby consuming moderate amounts of power (compared to the high
power configuration). A low power configuration may use reduced
resolution ADCs and LNAs, and slower sampling rates (compared to
corresponding elements of the medium power configuration) to
receive and decode RF signals, thereby consuming less power
(compared to the medium power configuration). The above
descriptions associated with the high, medium, and low power
configurations are simplified for ease of discussion. Each
configuration (power profile) may include settings for one or more
of the hardware stages and/or processing steps described above with
respect to FIGS. 3-5, but not described here for simplicity.
[0114] In a first example, if the power metric 1110 is greater than
the second power metric threshold PMT2 and the link quality metric
1120 is less than the first link quality threshold LQT1, then the
configurable front-end may be configured to have a high power
configuration 1131. Other high power configurations 1132 and 1133
may be similar to the high power configuration 1131. The high power
configuration 1131 may be a configuration of a configurable
front-end that consumes more power than a medium power
configuration and a low power configuration. The high power metric
may indicate that the client device 200 has sufficient (greater
than a threshold) power resources. Further, the low signal quality
metric may indicate that the RF signal may be difficult to receive
and decode. For example, the configurable front-end may be
configured in the high power configuration 1131 and use
substantially all available processing steps and/or hardware stages
to receive the RF signal (full resolution ADC, high-quality VCO,
full I and Q processing, etc.).
[0115] In another example, if the power metric 1110 is less than
the first power metric threshold PMT1 and the link quality metric
1120 is greater than the second link quality threshold LQT2, then
the configurable front-end may be configured to operate in a low
power configuration 1141. The low power configuration 1141 may be a
configuration of the configurable front-end that consumes less
power than the high power configuration 1131. Other low power
configurations 1142 and 1143 may be similar to the low power
configuration 1141. A low power metric 1110 may indicate low power
resources (a low battery, for example) and a high link quality
metric 1120 may indicate a strong RF signal. Thus, the configurable
front-end may be configured to operate in a low power configuration
to use fewer processing steps and/or hardware stages to conserve
power while receiving a strong RF signal. For example, the
configurable front-end may be configured to operate in the low
power configuration 1141 to use a reduced resolution ADC, a ring
oscillator, and a slower sample rate.
[0116] In another example, if the power metric 1110 is between the
first power metric threshold PMT1 and the second power metric
threshold PMT2, and the link quality metric is between the first
link quality threshold LQT1 and the second link quality threshold
LQT2, then the configurable front-end may be configured to operate
in a medium power configuration 1151. A medium power configuration
1151 may use more power than the low power configuration 1141, but
less power than the high power configuration 1131. Other medium
power configurations 1152 and 153 may be similar to the medium
power configuration 1151. When operating in the medium power
configuration 1151, the configurable front-end may use more
hardware stages and/or processing steps than a low power
configuration 1141 and fewer hardware stages and/or processing
steps than the high power configuration 1131.
[0117] The high power configuration, the medium power
configuration, and the low power configuration described above are
meant to be illustrative rather than limiting. Other numbers of
configurations (less than or more than three) are possible.
Furthermore, the detailed configuration associated with each power
configuration described above has been omitted for clarity. Persons
skilled in the art will appreciated that many possible
configurations may exist for each power configuration. In some
implementations, a configuration may change as the client device
200 operates to enable the link quality metric 1120 and the power
metric 1110 to continually or periodically guide operation of the
configurable front-end. For example, if the power metric 1110 is
relatively low (lower than a threshold), then the configurable
front-end may be configured to compromise performance for power.
That is, to conserve power, the configurable front-end may use a
minimal number of processing steps and/or hardware stages to
receive the RF signal. The limited (minimal) configuration may not
allow weak RF signals to be decoded, but may extend battery life.
In another example, if the power metric 1110 is relatively high,
then the configurable front-end may use a near maximal number of
processing steps and/or hardware stages to receive and decode the
RF signal to enable both strong and weak RF signals to be
decoded.
[0118] The selection matrix 1100 is described herein in terms of
two power metric thresholds (PMT1 and PMT2) and two link quality
metric thresholds (LQT1 and LQT2). In other implementations, any
number of thresholds may be used for either the power metric or the
link quality metric. Similarly, although only three RF front-end
configurations are described, in other implementations, any
feasible number of front-end configurations may be used.
[0119] In the foregoing specification, the example embodiments have
been described with reference to specific exemplary embodiments
thereof. It will, however, be evident that various modifications
and changes may be made thereto without departing from the broader
scope of the disclosure as set forth in the appended claims. The
specification and drawings are, accordingly, to be regarded in an
illustrative sense rather than a restrictive sense.
* * * * *