(en)In a cellular communication system, apparatus and methods relating to a power-optimized demodulator front end (demfront) receiver subsystem of a user equipment (UE) can reduce power utilization by optimizing the operation of the demfront receiver subsystem. For example, in an aspect, the apparatus and methods include enabling a first receiver of a device for receiving a control channel on a downlink from a node, determining that the control channel schedules the device to receive data on the downlink, enabling a second receiver of the device that consumes more power than the first receiver to receive the data on the downlink, and re-enabling the first receiver for receiving the control channel on the downlink subsequent to receiving the data.

1.ApplicationNumber: US-201113282648-A
1.PublishNumber: US-2012120860-A1
2.Date Publish: 20120517
3.Inventor: CHUI JIMMY C.
GOPALAN RAVI
LU FENG
XIE GUANG

4.Inventor Harmonized: CHUI JIMMY C(US)
GOPALAN RAVI(US)
LU FENG(US)
XIE GUANG(US)

5.Country: US
6.Claims:
(en)In a cellular communication system, apparatus and methods relating to a power-optimized demodulator front end (demfront) receiver subsystem of a user equipment (UE) can reduce power utilization by optimizing the operation of the demfront receiver subsystem. For example, in an aspect, the apparatus and methods include enabling a first receiver of a device for receiving a control channel on a downlink from a node, determining that the control channel schedules the device to receive data on the downlink, enabling a second receiver of the device that consumes more power than the first receiver to receive the data on the downlink, and re-enabling the first receiver for receiving the control channel on the downlink subsequent to receiving the data.

7.Description:
(en)CLAIM OF PRIORITY UNDER 35 U.S.C. §119
The present Application for Patent claims priority to Provisional Application No. 61/414,064 entitled “POWER OPTIMIZED DEMODULATOR FRONT END (DEMFRONT) RECEIVER SUBSYSTEM” filed Nov. 16, 2010, and assigned to the assignee hereof and hereby expressly incorporated by reference herein.


BACKGROUND
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to power optimization procedures by the receiver subsystem in user equipment or similar devices.
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the UMTS Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the Third Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division—Code Division Multiple Access (TD-CDMA), and Time Division—Synchronous Code Division Multiple Access (TD-SCDMA). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSDPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
As the demand for mobile broadband access continues to increase, research and development continue to advance the UMTS technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.
One way to improve the user experience, and mobile communication performance, is through managing power usage. For example, discontinuous reception (DRX) in connected mode is a power savings specification or feature that aims to reduce power consumption at a User Equipment (UE). Additional improvements in powers savings are desired.
SUMMARY
In a cellular communication system, a power-optimized demodulator front end (demfront) receiver subsystem can reduce power utilization by optimizing the operation of the demfront receiver subsystem. For example, the UE selects a low-power demfront receiver mode when no data is being sent across the access network (e.g., HSDPA, LTE) and enables an advanced demfront receiver mode (e.g., having a relatively higher data rate capability) when valid data has been detected. The realized power optimizations can be in addition to receiver circuitry optimizations in the Discontinuous Reception (DRX) feature.
In one aspect, the present disclosure provides a method of operating a device in a low-power mode for detection or monitoring, detecting a trigger event, operating the device in a high-power mode in response to detection of the trigger event, and reverting to the low-power mode following expiration of a timer, wherein the low-power mode consumes less power than the high-power mode. In an exemplary instance, the present disclosure provides a method of detecting a subsequent trigger event during the high-power mode, and extending a duration of the high-power mode.
In another aspect, at least one processor comprises a first module for operating a device in a low-power mode for detection or monitoring. A second module detects a trigger event. A third module operates the device in a high-power mode in response to detection of the trigger event. A fourth module reverts to the low-power mode following expiration of a timer, wherein the low-power mode consumes less power than the high-power mode. In an exemplary instance, the present disclosure provides at least one processor that further comprises a fifth module for detecting a subsequent trigger event during the high-power mode, and for extending a duration of the high-power mode.
In an additional aspect, a computer program product is provided comprising a non-transitory computer-readable medium for storing sets of code. A first set of code causes a computer to operate a device in a low-power mode for detection or monitoring. A second set of code causes the computer to detect a trigger event. A third set of code causes the computer to operate the device in a high-power mode in response to detection of the trigger event. A fourth set of code causes the computer to revert to the low-power mode following expiration of a timer, wherein the low-power mode consumes less power than the high-power mode. In an exemplary aspect, the computer program product further comprises a fifth set of code for causing the computer to detect a subsequent trigger event during the high-power mode, and to extend a duration of the high-power mode.
In a further aspect, an apparatus comprises means for operating a device in a low-power mode for detection or monitoring. The apparatus further comprises means for detecting a trigger event. The apparatus further comprises means for operating the device in a high-power mode in response to detection of the trigger event. The apparatus further comprises means for reverting to the low-power mode following expiration of a timer, wherein the low-power mode consumes less power than the high-power mode. In an exemplary aspect, the apparatus further comprises means for detecting a subsequent trigger event during the high-power mode and means for extending a duration of the high-power mode.
In yet another aspect, an apparatus comprises first circuitry selectively operable in a low-power mode and a high-power mode, where the low-power mode consumes less power than the high-power mode. The apparatus includes second circuitry for operating the first circuitry in the low-power mode for detection or monitoring, for detecting a trigger event, for operating the device in a high-power mode in response to detection of the trigger event, and for reverting to the low-power mode following expiration of a timer. In an exemplary aspect, the second circuitry is further for detecting a subsequent trigger event during the high-power mode, and for extending a duration of the high-power mode.
In one aspect, a method is provided for power-optimizing demodulator front end receiver subsystem selection in a cellular communication system. A first demodulation front end receiver subsystem receives a downlink control channel in a low-power mode. A trigger event is detected indicating a data transmission on a downlink data channel. A second demodulation front end receiver subsystem is enabled to receive the data transmission in response to the trigger event in a high-power mode. The high-power mode continues during a duration of the data transmission by monitoring a timer. The low-power mode is reverted to in response to expiration of the timer, wherein the first demodulation front end receiver subsystem consumes less power than the second demodulation front end receiver subsystem that respectively define the low-power mode and the high-power mode.
In another aspect, at least one processor is provided for power-optimizing demodulator front end receiver subsystem selection in a cellular communication system. A first module receives a downlink control channel with a first demodulation front end receiver subsystem in a low-power mode. A second module detects a trigger event indicating a data transmission on a downlink data channel. A third module enables a second demodulation front end receiver subsystem to receive the data transmission in response to the trigger event in a high-power mode. A fourth module continues the high-power mode during a duration of the data transmission by monitoring a timer. A fifth module reverts to the low-power mode in response to expiration of the timer, wherein the first demodulation front end receiver subsystem consumes less power than the second demodulation front end receiver subsystem that respectively define the low-power mode and the high-power mode.
In an additional aspect, a computer program product is provided for power-optimizing demodulator front end receiver subsystem selection in a cellular communication system. A non-transitory computer-readable medium stores sets of code. A first set of code causes a computer to receive a downlink control channel with a first demodulation front end receiver subsystem in a low-power mode. A second set of code causes the computer to detect a trigger event indicating a data transmission on a downlink data channel. A third set of code causes the computer to enable a second demodulation front end receiver subsystem to receive the data transmission in response to the trigger event in a high-power mode. A fourth set of code causes the computer to continue the high-power mode during a duration of the data transmission by monitoring a timer. A fifth set of code causes the computer to revert to the low-power mode in response to expiration of the timer, wherein the first demodulation front end receiver subsystem consumes less power than the second demodulation front end receiver subsystem that define respectively the low-power mode and the high-power mode.
In a further aspect, an apparatus is provided for power-optimizing demodulator front end receiver subsystem selection in a cellular communication system. The apparatus comprises means for receiving a downlink control channel with a first demodulation front end receiver subsystem in a low-power mode. The apparatus comprises means for detecting a trigger event indicating a data transmission on a downlink data channel. The apparatus comprises means for enabling a second demodulation front end receiver subsystem to receive the data transmission in response to the trigger event in a high-power mode. The apparatus comprises means for continuing the high-power mode during a duration of the data transmission by monitoring a timer. The apparatus comprises means for reverting to the low-power mode in response to expiration of the timer, wherein the first demodulation front end receiver subsystem consumes less power than the second demodulation front end receiver subsystem that define respectively the low-power mode and the high-power mode.
In another aspect, an apparatus is provided for power-optimizing demodulator front end receiver subsystem selection in a cellular communication system. A first demodulation front end receiver subsystem consumes less power than a second demodulation front end receiver subsystem, defining respectively a low-power mode and a high-power mode. The apparatus includes receiver selection circuitry for receiving a downlink control channel with a first demodulation front end receiver subsystem in a low-power mode, detecting a trigger event indicating a data transmission on a downlink data channel, enabling a second demodulation front end receiver subsystem to receive the data transmission in response to the trigger event in a high-power mode, continuing the high-power mode during a duration of the data transmission by monitoring a timer, and reverting to the low-power mode in response to expiration of the timer.
These and other aspects of the invention will become more fully understood upon a review of the detailed description, which follows.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a flow diagram for a methodology for power optimization.
FIG. 2 illustrates a functional block diagram of a cellular communication system with user equipment for power-optimized selection between receivers.
FIG. 3 illustrates a flow diagram for a methodology for power optimization in a cellular communication system according to one aspect.
FIGS. 4A-4C illustrate timing diagrams for a receiver selector of a User Equipment (UE) that performs Discontinuous Reception (DRX) in a connected mode by receiving a control channel with a low power receiver and enabling a high power receiver when a condition is detected.
FIGS. 4D-4F illustrate timing diagrams for a receiver selector of a UE that performs DRX in a connected mode by receiving a control channel with a low power receiver and enabling a high power receiver for a duration of a timer triggered when the control channel intended for the UE is decoded.
FIG. 5 depicts a conceptual diagram illustrating an example of a hardware implementation for one aspect of a power-optimized apparatus.
FIG. 6 depicts a schematic diagram of an aspect of a power-optimized user equipment operating in a UMTS system employing a W-CDMA air interface.
FIG. 7 depicts a schematic block diagram of an aspect of a power-optimized user equipment operating in an access network in a UTRAN architecture.
FIG. 8 depicts a schematic block diagram of an aspect of a base node communicating with an aspect of a power-optimized user equipment.
FIG. 9 illustrates a schematic block diagram for a system for a power-optimizing demodulator front end receiver subsystem selection in a cellular communication system according to one aspect.



DETAILED DESCRIPTION
In wireless technologies, a User Equipment (UE) may have multiple modes of operation for its demodulation front-end (“demfront”) receivers in the receiver subsystem. Demfront receivers employed at the UE include rake receivers, linear equalizer receivers, and equalizers that utilize interference mitigation. In addition, demfront receivers may also take advantage of receive diversity. Multiple receivers may be used because one receiver may outperform another in certain scenarios.
Discontinuous Reception (DRX) is a feature in wireless technologies (e.g., HSPA+, LTE, etc.) that defines a subset of downlink channels that a UE is required to monitor over specified time intervals. During these intervals, the UE is allowed to shut down receiver circuitry and hence reduce power usage, thereby increasing battery life. Such receiver circuitry can include but is not limited to radio receivers and hardware used in the demfront receivers. A basic overview of DRX concepts in connected mode can be found in 3GPP TS 25.903 Release 7. With the benefit of the present disclosure, it should be appreciated that this description can be extended outside of Release 7 specifications and to other radio access technologies.
As recognized herein, opportunities to further reduce power usage occur during periods of network inactivity. In particular, if there is no HSDPA (High-Speed Downlink Packet Access) data being scheduled by the network, then the demfront receiver subsystem for HSDPA at the UE is only required to monitor signaling on HS-SCCH (and HS-PDSCH transmission for the case of HS-SCCH-less transmission) to detect the start of network activity intended for the UE.
Moreover, as recognized herein, various demfront receivers may consume different power. In general, demfront receiver performance and power utilization are correlated. For example, a Rake receiver running in a non-receive-diversity mode is assumed and expected to consume less power than an equalizer that supports interference mitigation in receive-diversity mode; performance degradation is also assumed and expected. This power difference can come in the form of either hardware usage by the receivers, or variations in demodulation time.
The present innovation discloses using a low-power receiver subsystem mode of operation during times of network inactivity, and using a higher performing (e.g. relatively higher data rate capability) receiver subsystem mode of operation that consumes more power when network activity is detected. In an aspect, the present innovation may include two parts: one where receiver subsystem selection due to network activity is based on internal UE timers, and the other where receiver subsystem selection due to network activity is based on DRX configuration, if configured. For the latter, power-optimized receiver subsystem selection can be performed in conjunction with power optimizations due to shutdown of receiver circuitry. A combination of the two approaches is also possible.
The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.
In FIG. 1 , the present disclosure provides a methodology 100 for power optimization. In block 102 , a device operates in a low-power mode for detection or monitoring, e.g. of a control channel. For example, the device operates a relatively low power first receiver system to achieve the low-power mode. The device detects a trigger event (e.g., valid High Speed Shared Control Channel (HS-SCCH), valid High-Speed Physical Downlink Shared Channel (HS-PDSCH), etc.) (block 104 ). Subsequently, the device operates in a high-power mode in response to detection of the trigger event (block 106 ). For example, the device operates a relatively high power second receiver system, which may be different from or the same as the first receiver system, and may turn off the relatively low power receiver system. In block 108 , the device starts a timer for a period that corresponds to network activity (e.g., a data transmission). For example, the timer may start substantially at a same time as the initiation of operation of the high-power mode. The device makes a determination whether a subsequent trigger event has occurred while operating in the high-power mode (block 110 ). For example, the subsequent trigger event may include, but is not limited to, detecting that the device is schedule to receive additional data. If the subsequent trigger event is detected, then the timer is reset (block 112 ) and processing returns to block 110 . If the subsequent trigger event is not detected, then a further determination is made as to whether the data transmission has concluded or the timer has expired (e.g., timer threshold has been met) (block 114 ). If met, then processing returns to block 102 to revert to the low-power mode. If not met, then processing returns to block 110 to continue high-power mode.
For example, the timer threshold can be based on a parameter in the network configuration, such as the Continuous Packet Connectivity-Discontinuous Reception (CPC-DRX) parameter Inactivity_Threshold_for_UE_DRX_Cycle. In another example, the timer can be based on a parameter in the network configuration, such as the Enhanced UE DRX T321 parameter. Alternatively or in addition to these timer thresholds based on network configuration parameters, an internal user equipment timer threshold can be used.
In FIG. 2 , in a cellular communication system 200 , an apparatus, depicted as User Equipment (UE) 202 , optimizes power consumption by demodulator front end receiver subsystem selection. A first demodulation front end receiver subsystem 204 consumes less power than the second demodulation front end receiver subsystem 206 , although generally as a trade-off for performance. A computing platform 208 , including a processor 210 and non-transitory computer readable medium 212 for storing codes for a receiver selector 213 , enables the first demodulation front end receiver subsystem 204 to receive a downlink control channel 214 from a node 216 . The computing platform 208 detects a trigger event 218 indicating a data transmission 219 on a downlink data channel 220 . In response, the computing platform 208 enables the second demodulation front end receiver subsystem 206 to receive the data transmission 219 , and may cease operation of the first demodulation front end receiver subsystem 204 during data reception.
It should be appreciated with the benefit of the present disclosure that selection of the first and second demodulation front end receiver subsystems 204 , 206 can be dynamic, selecting among a plurality of receivers or receiver modes provisioned on the UE 202 . For example, which provisioned receiver is relatively low power or relatively better performing can change depending upon a band or communication protocol being used, presence or absence of an interference source, multipath channel fading, etc. For example, a particular provisioned receiver can be relative lower power in one scenario but relatively higher power in another scenario. Alternatively, a selected receiver can be usable in one situation but not in another.
In a first exemplary aspect, the first receiver comprises a rake receiver and the second receiver comprises an equalizer receiver.
In a second exemplary aspect, the first receiver does not perform interference mitigation and the second receiver performs interference mitigation.
In a third exemplary aspect, the first receiver does not perform receive diversity and the second receiver performs receive diversity.
In one aspect, a low-power mode can be a feature-reduced version of a high-power mode. For example, the high-power mode can be a usual mode of operation.
In one aspect, the first demodulation front end receiver subsystem 204 comprises a non-receive-diversity rake receiver. The second demodulation front end receiver subsystem 206 comprises a selected one of a rake receiver with receive diversity, an equalizer receiver without receive diversity, an equalizer receiver with receive diversity, an equalizer with interference mitigation receiver without receive diversity, and an equalizer with interference mitigation receiver with receive diversity.
In another aspect, the first demodulation front end receiver subsystem 204 comprises a receive-diversity rake receiver. The second demodulation front end receiver subsystem 206 comprises a selected one of an equalizer receiver without receive diversity, an equalizer receiver with receive diversity, an equalizer with interference mitigation receiver without receive diversity, and an equalizer with interference mitigation receiver with receive diversity.
In an additional aspect, first demodulation front end receiver subsystem 204 comprises a non-receive-diversity receiver and the second demodulation front end receiver subsystem 206 comprises a receive-diversity receiver.
A rake receiver is a radio receiver designed to counter the effects of multipath fading. It does this by using several “sub-receivers” called fingers, that is, several correlators each assigned to a different multipath component. Each finger independently decodes a single multipath component; at a later stage the contribution of all fingers are combined in order to make the most use of the different transmission characteristics of each transmission path. This could very well result in higher signal-to-noise ratio, or the energy per bit to noise power spectral density ratio (E b /N 0 ), in a multipath environment than in a “clean” environment. The multipath channel through which a radio wave transmits can be viewed as transmitting the original (line of sight) wave plus a number of multipath components. Multipath components are delayed copies of the original transmitted wave traveling through a different echo path, each with a different magnitude and time-of-arrival at the receiver. Since each component contains the original information, if the magnitude and time-of-arrival (phase) of each component is computed at the receiver (through a process called channel estimation), then all the components can be added coherently to improve the information reliability. The rake receiver is so named because it reminds one of the function of a garden rake, each finger of the rake receiver collecting symbol energy similarly to how tines on a rake collect leaves. Rake receivers are common in a wide variety of CDMA and W-CDMA radio devices such as mobile phones and wireless LAN equipment.
In FIG. 3 , the present disclosure provides, in one aspect, a methodology 300 for power optimization in a cellular communication system. In block 302 , a first demodulation front end receiver subsystem of a device operates in a relatively low power mode to receive a downlink control channel. The device detects a trigger event indicating a data transmission on a downlink data channel (block 304 ). The device enables or switches to use of a second demodulation front end receiver subsystem, operating in a relatively high power mode with respect to the first demodulation front end receiver subsystem, to receive the data transmission in response to the trigger event, optionally providing higher performance, e.g. a higher data rate capability (block 306 ). After the network activity concludes, the device returns or switches back to use of the low-power mode for detection or monitoring of the downlink control channel, depicted as returning to block 302 . In block 308 , the device starts a timer for a period that corresponds to network activity (e.g., data transmission, or reception of the data transmission). For example, the timer may be started when the device switches to using the second demodulation front end receiver subsystem, e.g., the higher power mode. The device makes a determination whether a subsequent trigger event has occurred while operating in the high-power mode (block 310 ). For example, the subsequent trigger event may include, but is not limited to, detecting that the device is schedule to receive additional data. If the subsequent trigger event is detected, then the timer is reset (block 312 ) and processing returns to block 310 . If not detected, then a further determination is made as to whether the data transmission has concluded (e.g., timer threshold has been met) (block 314 ). If met, then processing returns to block 302 to revert to operating the receiver in the low-power mode. If not met, then processing returns to block 310 to continue operating the receiver in the high-power mode.
In FIGS. 4A-4F , illustrative timing diagrams for operation of the receiver selector 213 of a UE 202 ( FIG. 2 ) are depicted for enabling either a low power receiver 400 (e.g., Rake receiver, a non-receive diversity receiver, a non-interference mitigating receiver, etc.) or a high power receiver 402 (e.g., equalizer receiver, receive diversity receiver, interference mitigating receiver, etc.). Although not depicted to scale, a DRX cycle of N=10 subframes is depicted in these examples. For clarity, the number of SCCH to monitor in a reception pattern is M=1, although aspects described herein can be applied to more than one SCCH. An inactivity threshold “T” kicks in if the SCCH is valid for the UE.
A block labeled SCCH is not annotated (e.g. not represented in bold text, but instead represented as a thin line) for a SCCH subframe that is monitored by the UE and the SCCH CRC fails to indicate that the SCCH is not intended for the UE. A block labeled SCCH is annotated (e.g. represented as bold text or a heavy line) for a SCCH subframe that is monitored by the UE and the SCCH CRC passes, thereby indicating that the SCCH is intended for the UE.
Each block including a delta “Δ” indicates a decoding delay following a SCCH subframe. For clarity, the decoding delay is depicted as identical between low and high power modes; however, the high power receiver can take longer to decode. Additionally, all figures depict an offset between the timelines for the lower power receiver 400 and the high power receiver 402 and the end of the SCCH subframe due to this modeling of the decoding delay (delta “Δ”).
In FIGS. 4A-4C , in a first version of the receiver selector 213 , a threshold for advanced receiver enablement is depicted. An underlying aspect is that enablement of the advanced receiver (high-power receiver 402 ) is in response to a valid SCCH for the duration of some condition. In this case, the condition is to continue using the high power receiver 402 for “X” subframes beyond the last SCCH valid for the UE. FIG. 4A shows only the low power receiver 400 being enabled during DRX to decode SCCH frames that are intended for the UE. In FIGS. 4B-4C , for the advanced receiver 402 , a rectangle annotated with hatching indicates that the advanced receiver 402 is still active. Since the HS channels do not need monitoring, the advanced receiver 402 can be disabled during these intervals. The advanced receiver is enabled during the next SCCH reception pattern if timer “X” has not expired. In FIG. 4C , the repeated sequence of T's and X's indicate that the timers are reset on each occurrence of a valid SCCH.
In FIGS. 4D-4F , a second version of the receiver selector 213 a timer for advanced receiver enablement is depicted. An underlying aspect is that enablement of the advanced receiver (high-power receiver 402 ) is in response to a valid SCCH for the duration of a timer (inactivity threshold “T”). FIG. 4D shows only the low power receiver 400 being enabled during DRX to decode SCCH frames that are intended for the UE. In FIGS. 4E-4F , for the advanced receiver 402 , a rectangle annotated with hatching indicates that the advanced receiver 402 is still active. Since the HS channels do not need monitoring, the advanced receiver 402 can be disabled during these intervals. The advanced receiver is enabled during the next SCCH reception pattern if timer “T” has not expired. In FIG. 4F , the repeated sequence of T's indicate that the timer is reset on each occurrence of a valid SCCH.
Power-Optimized Demfront Selection for Discontinuous Reception (DRX): As one of two examples, in 3GPP UMTS Release 7 CPC-DRX specifications, required monitoring of HS-SCCH and HS-PDSCH during the subframes in the HS-SCCH reception pattern is known based on Continuous Packet Connectivity (CPC) configuration, as defined in Section 6C.3 of 3GPP TS 25.214 Release 7. This monitoring is required and independent of network activity. The requirement is to monitor HS-SCCH and HS-PDSCH (if required) every UE_DRX_Cycle subframes, which can be configured to be one of 4, 5, 8, 10, 16, or 20 subframes. All other requirements on downlink channel monitoring are dependent on either uplink or downlink activity.
The parameter Inactivity_Threshold_for_UE_DRX_Cycle is the number of subframes required for monitoring after a valid HS-SCCH (or HS-PDSCH) intended for the UE has been detected. This means that if HS-SCCH intended for the UE has been transmitted by the network, then network can schedule HS-SCCH and HS-PDSCH for the UE outside of the HS-SCCH reception pattern as long as it is within the inactivity threshold. This also means that high throughputs are possible if data scheduling is made continuous.
Power savings are realized by having a UE default to a low-power demfront receiver subsystem mode of operation (e.g., only using a rake receiver without receive diversity) when the UE is outside of the Inactivity_Threshold_for_UE_DRX_Cycle, and by not having any advanced demfront receivers enabled. For the case where demfront receivers have different timelines, an alternative is for multiple demfront receivers to be enabled but the low-power demfront receiver is the selected one. In either case, this means that during the network inactivity (e.g. outside the inactivity threshold for this case), the UE may not be as capable of decoding high data rates (as compared to advanced receivers). However, high data rates are not required because there is no network activity being sent on HSDPA channels.
Once a valid HS-SCCH (or HS-PDSCH) for the UE has been detected with the low-power demfront receiver subsystem, then the UE enables the demfront receiver subsystem high-power mode of operation (e.g. one that includes an equalizer with interference mitigation and receive diversity). Multiple demfront receivers may be in operation in the subsystem high-power mode of operation, with one being selected for demodulation of data (e.g. selection through CQI). Demfront receivers include an equalizer without receive diversity, an equalizer with interference mitigation with receive diversity, Rake receiver with receive diversity, and others, depending on UE functionality. At this point, the UE is monitoring HS-SCCH and HS-PDSCH for further data from the base station.
Once the inactivity threshold expires, then the UE can revert back to operation using the low-power demfront receiver, where it is only monitoring HS-SCCH and HS-PDSCH on the HS-SCCH reception pattern.
This can be combined with the UE-side timer as proposed in a second example of power-optimizing demfront selection by network prediction.
In a second example, in 3GPP UMTS Release 8 Enhanced UE DRX specifications, required monitoring of HS-SCCH and HS-PDSCH during the subframes in the HS-SCCH reception pattern is known based on enhanced UE DRX configuration, as defined in Section 8.5.49 of 3GPP TS 25.331 Release 8. This monitoring is required and independent of network activity. The requirement is to monitor HS-SCCH and HS-PDSCH (if required) in Rx_burst frames out of every DRX_Cycle frames. In addition, there is a T321 timer that indicates that UE is required to monitor HS-SCCH and HS-PDSCH continuously during this time, if set.
In the same manner as in example 1 , a receiver subsystem low-power mode of operation can be used if no HS-SCCH and HS-PDSCH is detected, until the T321 timer is reset. Unlike Example 1, the T321 timer can be reset due to network activity outside of HS-SCCH and HS-PDSCH, which can be combined with the UE-side timer as proposed in the second example.
Power-Optimized Demfront Selection through Internal UE Network Activity Timer:
In general UE operation (not limited to DRX), the UE can perform this power-optimized receiver subsystem similar to that in the first example. Instead of relying on the Inactivity_Threshold_for_UE_DRX ' Cycle parameter, the UE can use its own thresholds to estimate network activity usage.
In an aspect, the exception between this general UE operation and the DRX specific operation is that the low-power receiver subsystem will be used to decode all HS-SCCH outside the timer threshold instead of only on a subset of HS-SCCH subframes (the latter is not defined outside DRX). This implies that power optimizations based on receiver circuitry are not possible in the general UE operation; power optimizations can occur based on the selection of the demfront receiver subsystem mode of operation.
FIG. 5 is a conceptual diagram illustrating an example of a hardware implementation for an apparatus 500 employing a processing system 514 . In this example, the processing system 514 may be implemented with a bus architecture, represented generally by the bus 502 . The bus 502 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 514 and the overall design constraints. The bus 502 links together various circuits including one or more processors, represented generally by the processor 504 , and computer-readable media, represented generally by the computer-readable medium 506 . The bus 502 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. A bus interface 508 provides an interface between the bus 502 and a transceiver 510 . The transceiver 510 provides a means for communicating with various other apparatuses over a transmission medium. Depending upon the nature of the apparatus, a user interface 512 (e.g., keypad, display, speaker, microphone, joystick) may also be provided.
The processor 504 is responsible for managing the bus 502 and general processing, including the execution of software stored on the computer-readable medium 506 . The software, when executed by the processor 504 , causes the processing system 514 to perform the various functions described infra for any particular apparatus. The computer-readable medium 506 may also be used for storing data that is manipulated by the processor 504 when executing software.
The apparatus 500 can be the UE 202 ( FIG. 2 ), wherein the computer-readable medium 506 comprises the receiver selector 213 ( FIG. 2 ) to perform the methodology 100 ( FIG. 1 ) according to aspects disclosed herein.
The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. By way of example and without limitation, the aspects of the present disclosure illustrated in FIG. 6 are presented with reference to a UMTS system 600 employing a W-CDMA air interface. A UMTS network includes three interacting domains: a Core Network (CN) 604 , a UMTS Terrestrial Radio Access Network (UTRAN) 602 , and User Equipment (UE) 610 . In this example, the UTRAN 602 provides various wireless services including telephony, video, data, messaging, broadcasts, and/or other services. The UTRAN 602 may include a plurality of Radio Network Subsystems (RNSs) such as an RNS 607 , each controlled by a respective Radio Network Controller (RNC) such as an RNC 606 . Here, the UTRAN 602 may include any number of RNCs 606 and RNSs 607 in addition to the RNCs 606 and RNSs 607 illustrated herein. The RNC 606 is an apparatus responsible for, among other things, assigning, reconfiguring and releasing radio resources within the RNS 607 . The RNC 606 may be interconnected to other RNCs (not shown) in the UTRAN 602 through various types of interfaces such as a direct physical connection, a virtual network, or the like, using any suitable transport network.
Communication between a UE 610 and a Node B 608 may be considered as including a physical (PHY) layer and a medium access control (MAC) layer. Further, communication between a UE 610 and an RNC 606 by way of a respective Node B 608 may be considered as including a radio resource control (RRC) layer. In the instant specification, the PHY layer may be considered layer 1; the MAC layer may be considered layer 2; and the RRC layer may be considered layer 3. Information herein below utilizes terminology introduced in Radio Resource Control (RRC) Protocol Specification, 3GPP TS 25.331 v9.1.0, incorporated herein by reference.
The geographic region covered by the SRNS 607 may be divided into a number of cells, with a radio transceiver apparatus serving each cell. A radio transceiver apparatus is commonly referred to as a Node B in UMTS applications, but may also be referred to by those skilled in the art as a base station (BS), a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), or some other suitable terminology. For clarity, three Node Bs 608 are shown in each SRNS 607 ; however, the SRNSs 607 may include any number of wireless Node Bs. The Node Bs 608 provide wireless access points to a core network (CN) 604 for any number of mobile apparatuses. Examples of a mobile apparatus include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a notebook, a netbook, a smartbook, a personal digital assistant (PDA), a satellite radio, a global positioning system (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device. The mobile apparatus is commonly referred to as user equipment (UE) in UMTS applications, but may also be referred to by those skilled in the art as a mobile station (MS), 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 (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. In a UMTS system, the UE 610 may further include a universal subscriber identity module (USIM) 611 , which contains a user's subscription information to a network. For illustrative purposes, one UE 610 is shown in communication with a number of the Node Bs 608 . The downlink (DL), also called the forward link, refers to the communication link from a Node B 608 to a UE 610 , and the uplink (UL), also called the reverse link, refers to the communication link from a UE 610 to a Node B 608 .
The core network 604 interfaces with one or more access networks, such as the UTRAN 602 . As shown, the core network 604 is a GSM core network. However, as those skilled in the art will recognize, the various concepts presented throughout this disclosure may be implemented in a Radio Access Network (RAN), or other suitable access network, to provide UEs with access to types of core networks other than GSM networks.
The core network 604 includes a circuit-switched (CS) domain and a packet-switched (PS) domain. Some of the circuit-switched elements are a Mobile Services Switching Centre (MSC), a Visitor location register (VLR) and a Gateway MSC. Packet-switched elements include a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN). Some network elements, like EIR, HLR, VLR and AuC may be shared by both of the circuit-switched and packet-switched domains. In the illustrated example, the core network 604 supports circuit-switched services with a MSC 612 and a GMSC 614 . In some applications, the GMSC 614 may be referred to as a media gateway (MGW). One or more RNCs, such as the RNC 606 , may be connected to the MSC 612 . The MSC 612 is an apparatus that controls call setup, call routing, and UE mobility functions. The MSC 612 also includes a visitor location register (VLR) that contains subscriber-related information for the duration that a UE is in the coverage area of the MSC 612 . The GMSC 614 provides a gateway through the MSC 612 for the UE 610 to access a circuit-switched network 616 . The GMSC 614 includes a home location register (HLR) 615 containing subscriber data, such as the data reflecting the details of the services to which a particular user has subscribed. The HLR is also associated with an authentication center (AuC) that contains subscriber-specific authentication data. When a call is received for a particular UE, the GMSC 614 queries the HLR 615 to determine the UE's location and forwards the call to the particular MSC serving that location.
The core network 604 also supports packet-data services with a serving GPRS support node (SGSN) 618 and a gateway GPRS support node (GGSN) 620 . GPRS, which stands for General Packet Radio Service, is designed to provide packet-data services at speeds higher than those available with standard circuit-switched data services. The GGSN 620 provides a connection for the UTRAN 602 to a packet-based network 622 . The packet-based network 622 may be the Internet, a private data network, or some other suitable packet-based network. The primary function of the GGSN 620 is to provide the UEs 610 with packet-based network connectivity. Data packets may be transferred between the GGSN 620 and the UEs 610 through the SGSN 618 , which performs primarily the same functions in the packet-based domain as the MSC 612 performs in the circuit-switched domain.
The UMTS air interface is a spread spectrum Direct-Sequence Code Division Multiple Access (DS-CDMA) system. The spread spectrum DS-CDMA spreads user data through multiplication by a sequence of pseudorandom bits called chips. The W-CDMA air interface for UMTS is based on such direct sequence spread spectrum technology and additionally calls for a frequency division duplexing (FDD). FDD uses a different carrier frequency for the uplink (UL) and downlink (DL) between a Node B 608 and a UE 610 . Another air interface for UMTS that utilizes DS-CDMA, and uses time division duplexing, is the TD-SCDMA air interface. Those skilled in the art will recognize that although various examples described herein may refer to a WCDMA air interface, the underlying principles are equally applicable to a TD-SCDMA air interface.
The UE 610 can be the UE 202 ( FIG. 2 ), wherein the computing platform 698 comprises the receiver selector 213 ( FIG. 2 ) to perform the methodology 100 ( FIG. 1 ) according to aspects disclosed herein.
Referring to FIG. 7 , an access network 700 in a UTRAN architecture is illustrated. The multiple access wireless communication system includes multiple cellular regions (cells), including cells 702 , 704 , and 706 , each of which may include one or more sectors. The multiple sectors can be formed by groups of antennas with each antenna responsible for communication with UEs in a portion of the cell. For example, in cell 702 , antenna groups 712 , 714 , and 716 may each correspond to a different sector. In cell 704 , antenna groups 718 , 720 , and 722 each correspond to a different sector. In cell 706 , antenna groups 724 , 726 , and 728 each correspond to a different sector. The cells 702 , 704 and 706 may include several wireless communication devices, e.g., User Equipment or UEs, which may be in communication with one or more sectors of each cell 702 , 704 or 706 . For example, UEs 730 and 732 may be in communication with Node B 742 , UEs 734 and 736 may be in communication with Node B 744 , and UEs 738 and 740 can be in communication with Node B 746 . Here, each Node B 742 , 744 , 746 is configured to provide an access point to a core network for all the UEs 730 , 732 , 734 , 736 , 738 , 740 in the respective cells 702 , 704 , and 706 .
As the UE 734 moves from the illustrated location in cell 704 into cell 706 , a serving cell change (SCC) or handover may occur in which communication with the UE 734 transitions from the cell 704 , which may be referred to as the source cell, to cell 706 , which may be referred to as the target cell. Management of the handover procedure may take place at the UE 734 , at the Node Bs corresponding to the respective cells, at a radio network controller, or at another suitable node in the wireless network. For example, during a call with the source cell 704 , or at any other time, the UE 734 may monitor various parameters of the source cell 704 as well as various parameters of neighboring cells such as cells 706 and 702 . Further, depending on the quality of these parameters, the UE 734 may maintain communication with one or more of the neighboring cells. During this time, the UE 734 may maintain an Active Set, that is, a list of cells that the UE 734 is simultaneously connected to (e.g., the UTRA cells that are currently assigning a downlink dedicated physical channel DPCH or fractional downlink dedicated physical channel F-DPCH to the UE 734 may constitute the Active Set).
The modulation and multiple access scheme employed by the access network 700 may vary depending on the particular telecommunications standard being deployed. By way of example, the standard may include Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interface standards promulgated by the Third Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations. The standard may alternately be Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA; Global System for Mobile Communications (GSM) employing TDMA; and Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.7 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM employing OFDMA. UTRA, E-UTRA, UMTS, LTE, LTE Advanced, and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.
At least one of the UEs 730 , 732 , 734 , 736 , 738 , 740 comprises a power-optimized demfront selection component 799 for selection of multiple receivers according to aspects disclosed herein.
The UE 732 can be the UE 202 ( FIG. 2 ), including the receiver selector 213 ( FIG. 2 ) to perform the methodology 100 ( FIG. 1 ) according to aspects disclosed herein.
FIG. 8 is a block diagram of a Node B 810 in communication with a UE 850 . In the downlink communication, a transmit processor 820 may receive data from a data source 812 and control signals from a controller/processor 840 . The transmit processor 820 provides various signal processing functions for the data and control signals, as well as reference signals (e.g., pilot signals). For example, the transmit processor 820 may provide cyclic redundancy check (CRC) codes for error detection, coding and interleaving to facilitate forward error correction (FEC), mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM), and the like), spreading with orthogonal variable spreading factors (OVSF), and multiplying with scrambling codes to produce a series of symbols. Channel estimates from a channel processor 844 may be used by a controller/processor 840 to determine the coding, modulation, spreading, and/or scrambling schemes for the transmit processor 820 . These channel estimates may be derived from a reference signal transmitted by the UE 850 or from feedback from the UE 850 . The symbols generated by the transmit processor 820 are provided to a transmit frame processor 830 to create a frame structure. The transmit frame processor 830 creates this frame structure by multiplexing the symbols with information from the controller/processor 840 , resulting in a series of frames. The frames are then provided to a transmitter 832 , which provides various signal conditioning functions including amplifying, filtering, and modulating the frames onto a carrier for downlink transmission over the wireless medium through antenna 834 . The antenna 834 may include one or more antennas, for example, including beam steering bidirectional adaptive antenna arrays or other similar beam technologies.
At the UE 850 , a receiver 854 receives the downlink transmission through an antenna 852 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 854 is provided to a receive frame processor 860 , which parses each frame, and provides information from the frames to a channel processor 894 and the data, control, and reference signals to a receive processor 870 . The receive processor 870 then performs the inverse of the processing performed by the transmit processor 820 in the Node B 810 . More specifically, the receive processor 870 descrambles and despreads the symbols, and then determines the most likely signal constellation points transmitted by the Node B 810 based on the modulation scheme. These soft decisions may be based on channel estimates computed by the channel processor 894 . The soft decisions are then decoded and deinterleaved to recover the data, control, and reference signals. The CRC codes are then checked to determine whether the frames were successfully decoded. The data carried by the successfully decoded frames will then be provided to a data sink 872 , which represents applications running in the UE 850 and/or various user interfaces (e.g., display). Control signals carried by successfully decoded frames will be provided to a controller/processor 890 . When frames are unsuccessfully decoded by the receiver processor 870 , the controller/processor 890 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.
In the uplink, data from a data source 878 and control signals from the controller/processor 890 are provided to a transmit processor 880 . The data source 878 may represent applications running in the UE 850 and various user interfaces (e.g., keyboard). Similar to the functionality described in connection with the downlink transmission by the Node B 810 , the transmit processor 880 provides various signal processing functions including CRC codes, coding and interleaving to facilitate FEC, mapping to signal constellations, spreading with OVSFs, and scrambling to produce a series of symbols. Channel estimates, derived by the channel processor 894 from a reference signal transmitted by the Node B 810 or from feedback contained in the midamble transmitted by the Node B 810 , may be used to select the appropriate coding, modulation, spreading, and/or scrambling schemes. The symbols produced by the transmit processor 880 will be provided to a transmit frame processor 882 to create a frame structure. The transmit frame processor 882 creates this frame structure by multiplexing the symbols with information from the controller/processor 890 , resulting in a series of frames. The frames are then provided to a transmitter 856 , which provides various signal conditioning functions including amplification, filtering, and modulating the frames onto a carrier for uplink transmission over the wireless medium through the antenna 852 .
The uplink transmission is processed at the Node B 810 in a manner similar to that described in connection with the receiver function at the UE 850 . A receiver 835 receives the uplink transmission through the antenna 834 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 835 is provided to a receive frame processor 836 , which parses each frame, and provides information from the frames to the channel processor 844 and the data, control, and reference signals to a receive processor 838 . The receive processor 838 performs the inverse of the processing performed by the transmit processor 880 in the UE 850 . The data and control signals carried by the successfully decoded frames may then be provided to a data sink 839 and the controller/processor, respectively. If some of the frames were unsuccessfully decoded by the receive processor, the controller/processor 840 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.
The controller/processors 840 and 890 may be used to direct the operation at the Node B 810 and the UE 850 , respectively. For example, the controller/processors 840 and 890 may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. The computer readable media of memories 842 and 892 may store data and software for the Node B 810 and the UE 850 , respectively. A scheduler/processor 846 at the Node B 810 may be used to allocate resources to the UEs and schedule downlink and/or uplink transmissions for the UEs.
The UE 850 can be the UE 202 ( FIG. 2 ) wherein the memory 892 comprises the receiver selector 213 ( FIG. 2 ) to perform the methodology 100 ( FIG. 1 ) according to aspects disclosed herein.
With reference to FIG. 9 , illustrated is a system 900 for power-optimizing demodulator front end receiver subsystem selection in a cellular communication system. For example, system 900 can reside at least partially within user equipment (UE). It is to be appreciated that system 900 is represented as including functional blocks, which can be functional blocks that represent functions implemented by a computing platform, processor, software, or combination thereof (e.g., firmware). System 900 includes a logical grouping 902 of electrical components that can act in conjunction. For instance, logical grouping 902 can include an electrical component 904 for receiving a downlink control channel with a first demodulation front end receiver subsystem. Moreover, logical grouping 902 can include an electrical component 906 for detecting a trigger event indicating a data transmission on a downlink data channel. Further, logical grouping 902 can include an electrical component 908 for enabling a second demodulation front end receiver subsystem to receive the data transmission in response to the trigger event, wherein the first demodulation front end receiver subsystem consumes less power than the second demodulation front end receiver subsystem. Additionally, system 900 can include a memory 920 that retains instructions for executing functions associated with electrical components 904 - 908 . While shown as being external to memory 920 , it is to be understood that one or more of electrical components 904 - 908 can exist within memory 920 .
With the benefit of the present disclosure, it should be appreciated that adaptive CRE has potential to respond faster to deep fades although better estimation of speed/channel, and may yield even better performance. It is further contemplated that detection of TPC delay in SHO can be addressed. Adaptive CRE optimization of R, H (parameters) can be based upon desired missed detection or false alarm (e.g., across speed/channel). Operation in dynamic channel (e.g., change of speed/channel during operation) can be addressed.
Several aspects of a telecommunication system have been presented with reference to a W-CDMA system. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards.
By way of example, various aspects may be extended to other UMTS systems such as TD-SCDMA, High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), High Speed Packet Access Plus (HSPA+) and TD-CDMA. Various aspects may also be extended to systems employing Long Term Evolution (LTE) (in FDD, TDD, or both modes), LTE-Advanced (LTE-A) (in FDD, TDD, or both modes), CDMA2000, Evolution-Data Optimized (EV-DO), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB), Bluetooth, and/or other suitable systems. The actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.
In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium. The computer-readable medium may be a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disk (CD), digital versatile disk (DVD)), a smart card, a flash memory device (e.g., card, stick, key drive), random access memory (RAM), read only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer. The computer-readable medium may also include, by way of example, a carrier wave, a transmission line, and any other suitable medium for transmitting software and/or instructions that may be accessed and read by a computer. The computer-readable medium may be resident in the processing system, external to the processing system, or distributed across multiple entities including the processing system. The computer-readable medium may be embodied in a computer-program product. By way of example, a computer-program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.
It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited therein.
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a; b; c; a and b; a and c; b and c; and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”