Call sustainability during power imbalance in multicarrier uplink

In aspects for controlling transmit power of dual carrier uplink transmission for wireless communications, a user equipment (UE) determines presence of transmit power imbalance between a first and second radio frequency (RF) carrier of respective dedicated physical control channels for uplink transmission. The UE determines an estimate of a remaining available transmit power after estimating the transmit power used by each of the dedicated physical control channels. The UE allocates the estimated remaining available transmit power to the first and second RF carrier respectively based on both a size of data granted for uplink transmission on each RF carrier and on an effective power per bit on each RF carrier. Additionally, the UE determines a higher reliability value for each RF carrier based on a lower data error rate, identifies priority values for data to be transmitted and sends higher priority data over the RF carrier with higher reliability value.

BACKGROUND

Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to power control for multicarrier uplink transmission.

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 Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN). UTRAN is a radio access network (RAN) defined as a part of UMTS, a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). 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). UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA) and High Speed Uplink Packet Access (HSUPA), which provide higher data transfer speeds and capacity to associated UMTS networks.

In HSUPA systems, a user equipment (UE) may transmit uplink physical channels over multiple carriers that may include a dedicated physical control channel (DPCCH) or enhanced DPCCH (E-DPCCH). When the UE has more than one activated uplink carrier, also referred to as an activated uplink frequency, the UE estimates the remaining power that is available to be allocated to scheduled enhanced dedicated channel (E-DCH) transmissions by taking into account the DPCCH/E-DPCCH for each carrier. In particular, the UE may perform an E-DCH transport format combination (E-TFC) selection procedure that is first applied to a Secondary Uplink Frequency and then to a Primary Uplink Frequency. In observing different field scenarios, however, it has been noticed that different schedulers and different power management techniques at the network level affect the effective UE performance. For instance, if there is any imbalance between the multiple uplink carriers, effective data transmission as well as reliability of the data transmission might be degraded. For example, a UE may have a significant power imbalance (perhaps more than 5 dB) between the first carrier C0(e.g., Primary Uplink Frequency) and the second carrier C1(e.g., Secondary Uplink Frequency), due to strong interference on C1such that it takes significantly more power (perhaps more than twice the power) to send data on carrier C1than on carrier C0. As an example and as illustrated inFIG. 2A(which is described later in detail), a UE may have an allowed maximum power of 24 dBm212, based on an uplink data grant214of 1000 bits on carrier C0and 5000 bits on carrier C1. Power splitting for the carriers C0and C1may be proportionally allocated based on the data grant, where power P0to carrier C0is (1000/6000)24=4 dBm, and power P1to carrier C1is (5000/6000)24=20 dBm. However, due to the significant power imbalance and poor reliability of carrier C1, an E-TFCI assignment to the UE (e.g., the predefined maximum allowable throughput based on reliability of the channel) for the data transmission on carrier C1is severely limited to only 1500 bits of the allocated 5000 bits. Otherwise, if carrier C1was not impeded by interference, the E-TFCI selection could allot significantly more data bits. Meanwhile, the stronger carrier C0may be limited to sending only 500 bits of the allocated 1000 bits based on E-TFCI for 4 dBm, which was due to the low power split based on the proportional grant. As such, current techniques may not maximize an amount of data that can be transmitted.

An additional issue with current 3GPP specifications relating to dual carrier HSUPA (DC-HSUPA) operation is that data to be transmitted is first sent on the second carrier (e.g., the Secondary Uplink Frequency) and then on the first carrier (e.g., the Primary Uplink Frequency). Accordingly, high priority data, which is selected to be sent first, is to be transmitted on the second carrier. In a case where an inferior carrier C1is the second carrier, however, this high priority data is at risk of transmission failure due to the currently specified procedures.

Thus, improvements in transmitting uplink physical channels over multiple carriers are desired.

SUMMARY

In an aspect, the disclosure provides for controlling transmit power over multiple uplink carriers under conditions of a power imbalance, based on size of data in the uplink grant, in wireless communications. For instance, this disclosure provides for determining presence of a transmit power imbalance between a first radio frequency (RF) carrier and a second RF carrier of respective dedicated physical control channels for uplink transmission, determining an estimate of a remaining available transmit power after estimating the transmit power used by each of the dedicated physical control channels; and in response to determining the presence of the transmit power imbalance, the estimated remaining available transmit power to the first RF carrier and the second RF carrier respectively based on both a size of data granted for uplink transmission on each RF carrier and on an effective power per bit on each RF carrier.

In another aspect, this disclosure provides for scheduling higher priority data over a more reliable one of multiple uplink carriers. For instance, this disclosure provides for determining presence of a power imbalance between a first radio frequency (RF) carrier and a second RF carrier of respective dedicated physical control channels for uplink transmission, determining a reliability value for each RF carrier based on a data error rate, wherein a higher reliability value corresponds with a lower data error rate, identifying data to be transmitted as having a first priority value or second priority value, wherein data with the priority value has a higher priority than data with the second priority value; and sending high priority data to the RF carrier with a higher reliability value.

In other aspects, the disclosure provides for apparatuses and computer readable medium storing computer executable code for performing the above methods.

These and other aspects of the disclosure will become more fully understood upon a review of the detailed description, which follows.

DETAILED DESCRIPTION

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 may be shown in block diagram form in order to avoid obscuring such concepts. In an aspect, the term “function” as used herein may be one of the parts that make up a system, may be hardware, firmware, and/or software, and may be divided into other functions.

The present disclosure provides for user equipment (UE) management of uplink carrier transmit power allocation and data routing for multiple uplink RF carriers in the presence of a transmit power imbalance between at least two of the RF uplink carriers. In the case of dual carrier transmission, the chance of having one good carrier is quite high even when the other carrier is in bad condition. In one aspect, the present disclosure includes dividing transmission power to the multiple RF carriers based on both the amount of data granted to each carrier by the network and on the effective power per bit of each carrier, when a detected power imbalance exists among RF carriers. Further, in another aspect, for uplink transmissions having high priority data, an RF carrier having higher reliability is selected to transmit the high priority data upon detection of the power imbalance among the RF carriers.

Referring toFIG. 1, in an aspect, a wireless communication system10includes at least one UE12in the communication coverage of at least one network entity14(e.g., base station or Node B). In an aspect, the network entity14may be a base station or Node B in an UMTS network. UE12may communicate with a network18via network entity14and a radio network controller (RNC)16. In some aspects, multiple UEs including UE12may be in communication coverage with one or more network entities, including network entity14. In an example, UE12may transmit and/or receive wireless communications21to and/or from network entity14.

In some aspects, UE12may also be referred to by those skilled in the art (as well as interchangeably herein) as a mobile station, 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 terminal, a user agent, a mobile client, a client, or some other suitable terminology. A UE12may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a tablet computer, a laptop computer, a cordless phone, a wireless local loop (WLL) station, 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, a wearable computing device (e.g., a smart-watch, smart-glasses, a health or fitness tracker, etc), an appliance, a sensor, a vehicle communication system, a medical device, a vending machine, a device for the Internet-of-Things, or any other similar functioning device. Additionally, network entity14may be a macrocell, picocell, femtocell, relay, Node B, mobile Node B, UE (e.g., communicating in peer-to-peer or ad-hoc mode with UE12), or substantially any type of component that can communicate with UE12to provide wireless network access at the UE12.

According to the present aspects, the UE12may include one or more processors20for executing various functions for controlling transmit power over multiple uplink RF carriers under conditions of a power imbalance as described herein. For instance, in some aspects, the various functions related to controlling transmit power over multiple uplink RF carriers may be executed by a single processor, while in other aspects different ones of the functions may be executed by a combination of two or more different processors. For example, in an aspect, the one or more processors20may include any one or any combination of a modem processor, or a baseband processor, or a digital signal processor, or a transmit processor, or a transceiver processor. In particular, the one or more processors20may execute carrier control function30configured to control transmit power on uplink RF carriers22,24based on the presence of a transmit power imbalance between the at least two uplink RF carriers22,24. In an aspect, the carrier control function30may include hardware and/or software code executable by processor20for controlling carrier data routing of an uplink control channel in the presence of a transmit power imbalance between at least two uplink RF carriers. In an aspect, the teem “function” as used herein may be one of hardware, firmware, and/or software, and may be divided into other functions.

In an aspect, for example, the carrier control function30may be implemented to include, be in communication with, or control, one or more subfunctions. Although illustrated as being a part of carrier control function30, it should be understood that the subfunctions discussed herein may be implemented independently on the same or on a different processor. For instance, the carrier control function30may include a power imbalance function32for detecting the power imbalance, a carrier power division function40, including a power remaining function42for determining an estimate of remaining power for uplink data transmission, and a power allocation function44for allocating the remaining power between the at least two uplink RF carriers22,24. The carrier control function30may also include a carrier data division function50including a carrier reliability function52for determining reliability of each of the at least two uplink RF carriers22,24, and a data priority function54for determining presence of high priority data for the uplink transmission and scheduling the high priority data on the one of the at least two uplink RF carriers22,24having a higher reliability.

The power imbalance function32may include hardware and/or software code executable by a processor for determining a power imbalance between a first RF carrier and a second RF carrier in uplink transmissions. For example, the power imbalance function32may monitor a control channel such as a dedicated physical control channel (DPCCH) being transmitted over the at least two uplink RF carriers22,24by the UE12.

Carrier power division function40may include hardware and/or software code executable by a processor for determining an estimate of a remaining available transmit power after estimating the transmit power used by each of the dedicated physical control channels. For example, carrier power division function40may include subfunctions, such as power remaining function42for determining the estimate of remaining available transmit power, and power allocation function44for allocating, in response to determining the presence of the transmit power imbalance, an estimated remaining available transmit power to the at least two RF carriers22,24based on both a size of data granted for uplink transmission on each RF carrier and on an effective power per bit on each RF carrier.

Carrier data division function50may include hardware and/or software code executable by a processor for determining a reliability value for each RF carrier based on a data error rate, where a higher reliability value corresponds with a lower data error rate. For example, carrier data division function50may include subfunctions, such as carrier reliability function52for determining the reliability value, and a data priority function54for identifying data to be transmitted as having a first priority value or second priority value, where data with the first priority value may be a higher priority than data with the second priority value.

Moreover, in an aspect, UE12may include a transceiver60for receiving and transmitting radio transmissions. For example, in an aspect, the transceiver60may be in communication with, or connected to, a radio frequency front end61defined by, for instance, one or more power amplifiers63, one or more band specific filters62, and one or more antennas64. When a downlink signal is received by UE12, such as a BLER report for example, antenna64converts radio waves to an electrical signal. Antenna switch65may be a duplex switch that may selectively operate to select either a transmit path or a receive path for the signal (e.g., to select a receive path in this example). Filters62perform frequency filtering on the signal to obtain the desired frequency band. Transceiver60may perform a downconversion of the received signal from the RF front end61, and may split the signal into in-phase and quadrature (I and Q) components. Amplifiers63may include a first amplifier to boost the filtered signal initially received from the filters62, and a second amplifer for boosting the I and Q components. The I and Q components may then be converted to a digital format and demodulated by the transceiver60. The I and Q components of received signal leaving the transceiver60may be a baseband signal that may be then further processed by the at least one processor20. For example, transceiver60may receive a block error rate (BLER) report transmitted by the network entity14, which may be used by carrier reliability function52to determine a reliability of each of the at least two uplink RF carriers22,24. In an aspect, the transceiver60may be a component or function separate from the processor20. Transceiver60may transmit uplink data on at least one RF carrier, such as on at least one of the at least two uplink RF carriers22,24. In an aspect, transceiver60may send data having a higher priority data over an RF carrier with a higher reliability value. Although transceiver60is shown as a separate component from the one or more processors20, it should be understood that in some implementations transceiver60may be included as a part of the one or more processors20.

Referring toFIGS. 2A and 2B, respective examples of power allocation and data allocation on two RF carriers before and after operation according to the aspects described herein are illustrated in respective power allocation graph200, data allocation and actual amount of data transmitted graph202, and summary table204. In an operational aspect, a UE such as UE12(FIG. 1) may control transmit power of uplink data transmissions on multiple carriers having a transmit power imbalance. In an aspect, UE12may have two uplink RF carriers22,24available for uplink transmission, such as a primary carrier C0and a secondary carrier C1, and may monitor uplink transmissions on the RF carriers22,24to determine that a power imbalance206between the carriers is present and exceeds a predetermined threshold208. In response to the determination of the power imbalance206exceeding the predetermined threshold208, UE12may then proceed to allocate the data and power on the uplink RF carriers22,24in a manner to increase the amount of data transmitted210(e.g., total number of bits). The UE12is capable of determining available maximum transmit power and the transmit power required to send control signals on dedicated uplink control channels. The remaining available UL power212may then be allocated for uplink data transmission.

Turning toFIG. 2A, referring to power allocation graph200and summary table204, UE12may estimate, for example, that there is 24 dBm remaining available UL power212for the data transmission on uplink RF carriers22,24, e.g., C0and C1. From the network entity14, and now referring to the data allocation graph202and summary table204, UE12may receive an uplink data grant214of 6000 bits, with 5000 bits allocated to carrier C1and 1000 bits allocated to C0.

Based on the uplink data grant214to each carrier, UE12may allocate the 24 dBm estimated remaining available UL power212, then adjust the split of allocated power218to each carrier based on the effective power per bit216on each of the RF carriers C0and C1(seeFIG. 2Bfor the redistribution of allocated power218). For example, as shown inFIG. 2A, the initial allocated power218for the carriers C0and C1may be proportionally based on the respective UL data grant214, where power P0to carrier C0is (1000/6000)×24=4 dBm, and power P1to carrier C1is (5000/6000)×24=20 dBm.

Then, based on the amount of actual data transmitted210relative to the allocated power218, the UE12may redistribute the allocated power218. For example, if the UE12determines that carrier C0has an effective power per bit216(e.g., for each carrier, allocated power218divided by amount of actual data transmitted210) that is less than that of carrier C1(e.g., carrier C0is more power efficient than carrier C1based on the allocated power and the amount of data transmitted), for example but not limited to meeting a predetermined threshold, then an adjustment to the allocated power218to each carrier may be performed to increase an amount of the allocated power218to the more power efficient carrier in order to increase the amount of data that may be transmitted.

For example, using a data allocation based on E-TFCI selection, the actual data transmitted210by RF carriers C0and C1may be 500 bits and 1500 bits, respectively, based on the initial allocated power218to each carrier that is proportional to the respective UL data grant214, as shown inFIG. 2A. As such, in this example, the effective power per bit216for RF carrier C0may then be determined by UE12as 4 dBm/500 bits=0.0008 dBm/bit. For RF carrier C1, the effective power per bit216may be determined by UE12as 20 dBm/1500 bits=0.013 dBm/bit. Thus, in this example, RF carrier C0has a better power efficiency by consuming less power for each bit actually transmitted. Based on this determination, according to the present aspects, UE12may operate carrier control function30to redistribute allocated power218between the RF carriers C0and C1to increase an amount of allocated power218apportioned to the carrier having the better effective power per bit216, as shown inFIG. 2B.

Referring toFIG. 2B, continuning with this example, since uplink RF carrier C0was determined to have a better power efficiency (as illustrated inFIG. 2A), UE12operating carrier control function30may redistribute allocated power218by allocating a power P0value of 8 dBm to carrier C0(e.g., doubling the initial allocation of 4 dBm, as illustrated by increased allocation220) and allocating the remaining 16 dBm as power P1to uplink RF carrier C1(e.g., decreasing the allocation, as illustrated by decreased allocation222). In other words, for instance, UE12operating carrier control function30may redistribute allocated power218to each carrier C0and C1to provide the more power efficient carrier, C0in this example, with a sufficient amount of power to maximize the amount of actual data transmitted210. The result of the adjusted power allocation is that RF carrier C0is enabled for greater data throughput with the increased power allocation, which may effectively provide an increased total amount of uplink data transmission across both carriers C0and C1. For instance, as shown in data transmitted graph202and summary table204ofFIG. 2B, using the redistributed power allocation for uplink transmission based on a subsequent E-TFCI selection based on UE12operating carrier control function30, the actual data transmitted210may be 1300 bits on RF carrier C0and 1000 bits on RF carrier C1, for an improved total transmission of 2300 bits as compared to the initial total data transmission of 2000 bits based on proportional uplink data grant alone (FIG. 2A).

Referring toFIG. 3A, in an operational aspect, a UE such as UE12(FIG. 1) may perform one aspect of a method300for controlling transmit power of uplink data transmissions on multiple carriers having a transmit power imbalance. While, for purposes of simplicity of explanation, the method300is shown and described as a series of acts, it is to be understood and appreciated that the method (and further methods related thereto) is/are not limited by the order of acts, as some acts may, in accordance with one or more aspects, occur in different orders and/or concurrently with other acts from that shown and described herein. For example, it is to be appreciated that a method could alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all illustrated acts may be required to implement a method in accordance with one or more features described herein. In an aspect, method300may be implemented by UE12and/or the one or more processors20executing carrier control function30and/or one or more of its sub-functions as described herein.

In an aspect, the method300may start at block310, and at block320, the method300may include determining presence of power imbalance on two or more RF carriers. For example, in an aspect, UE12and/or carrier control function30and/or power imbalance function32may monitor each uplink channel, such as each DPCCH corresponding to each of at least two uplink RF carriers22and24, may determine a transmit power of each RF carrier for the uplink channel, may compute an imbalance between at least the first RF carrier22and a second RF carrier24, and may compare the imbalance to a threshold value, such as, but not limited to, 2 dB for example, representing an amount of a power imbalance sufficient to trigger an adjustment to the division of remaining power between carriers, as described herein. If no imbalance is detected at block320, then method300may return to start at block310and/or re-perform block320on a periodic basis.

If the presence of a power imbalance is detected in block320, then in an aspect at block330, the method300may include determining an estimate of remaining power available for uplink data transmission after power allocation to the dedicated physical control channel has been determined. For example, there may be a maximum power available for the uplink transmission, with some amount of transmit power used by the dedicated physical control channels, where the remaining power may be estimated by the difference. In an aspect, for example, UE12and/or carrier control function30and/or carrier power division function40and/or power remaining function42(FIG. 1) may estimate an amount of power available for scheduled E-DCH transmission as a difference between a maximum UE transmitter power and an estimate of current power for the dedicated physical control channel on each carrier. For instance, in an aspect, the estimate of the remaining available power remaining may be perfottned according to 3GPP Technical Specification 25.321 (Rel. 9), section 6.4.2.

In an aspect, at block340, the method300may include allocating the estimated remaining power to the first RF carrier and the second RF carrier based on size of data granted for uplink transmission on each RF carrier and effective power per bit on each RF carrier. In an aspect, for example, UE12and/or carrier control function30and/or carrier power division function40and/or power allocation function44(FIG. 1) may determine a power split among the RF carriers based on the data grant, then adjust the power split to account for effective power per bit on each RF carrier. For example, if UE12is allowed a maximum power of 24 dBm, with an uplink data grant of 1000 bits on RF carrier C0and 5000 bits on carrier RF carrier C1, power splitting for the RF carriers C0and C1may be initially based proportionally on the data grant, where power P0to RF carrier C0is 4 dBm, and power P1to RF carrier C1is 20 dBm as described and illustrated above in reference toFIG. 2A. If the UE12and/or carrier control function30and/or carrier power division function40and/or power allocation function44determines that RF carrier C0has an effective power per bit that is less than that of RF carrier C1(e.g., carrier C0is more power efficient in transmitting data), for example but not limited to achieving a predetermined threshold, then an adjustment to the power split accordingly may result in changing the power allocation to the more power efficient carrier in order to increase the amount of data that may be transmitted as described and illustrated above in reference toFIG. 2B. The change in the power allocation may be implemented, for example, by applying a power efficiency factor to the power allocation equation so that power is allocated based on a combination of grant and power efficiency per carrier. For example, the grant values and power efficiency values may be normalized, and/or a weighting value may be applied to at least the power efficiency to bias the power allocation to the more efficient carrier. For instance, using the above example, the change in power allocation based on power efficiency may result in allocating 8 dBm to RF carrier C0(e.g., doubling the initial allocation of 4 dBm) and allocating the remaining 16 dBm to RF carrier C1.

Referring toFIG. 3B, in an operational aspect, a UE such as UE12(FIG. 1) may perform one aspect of a method305for multiple carrier uplink transmission based on reliability of the RF carriers. In an aspect, method305may be implemented by UE12executing carrier control function30and/or one or more of its sub-functions as described herein. In an aspect, method305determines reliability of the RF carriers so that high priority data may be sent on a more reliable RF carrier.

In an aspect, the method305starts at block315, and at block325, the method305may include determining presence of a power imbalance between a first radio frequency (RF) carrier and a second RF carrier of respective dedicated physical control channels for uplink transmission. For example, in an aspect, UE12and/or carrier control function30and/or power imbalance function32may monitor each uplink channel, such as each DPCCH corresponding to the at least two uplink RF carriers22and24, may determine a transmit power of each RF carrier for the uplink channel, may compute an imbalance between at least the first RF carrier22and a second RF carrier24, and may compare the imbalance to a threshold value, such as 2 dB for example, for establishing presence of a power imbalance. If no power imbalance is detected at block325, then method305may return to start at block315and/or repeat block325on a periodic basis.

If the presence of a power imbalance is detected in block325, then in an aspect at block335, the method305may include determining a reliability value for each RF carrier based on a data error rate, wherein a higher reliability value corresponds with a lower data error rate. In an aspect, for example, UE12and/or carrier data division function50and/or carrier reliability function52(FIG. 1) may determine a reliability value for each RF carrier based on a data error rate (e.g., bit error rate (BER) or block error rate (BLER)). For example, an RF carrier C0may have a lower BER than RF carrier C1, and a relatively higher reliability value may be assigned to carrier C0than carrier C1accordingly. In another aspect, a relatively higher reliability value may be based on a relatively lower power requirement for a particular RF carrier, indicating favorable channel conditions.

In an aspect, at block345, method305may include sending at least a portion of the high priority data to the RF carrier with a higher reliability value. In an aspect, for example, UE12and/or carrier control function30and/or carrier data division function50and/or data priority function54(FIG. 1) may determine from a transmit data buffer (e.g., which may include, but is not limited to, a layer2transmit buffer) that there is data identified as high priority data and other data with a relatively lower priority or no priority. In an aspect, for example, the priority of the data may be identified based on a logical channel priority status. In any case, some or all of the high priority data may be sent on the one of the at least two uplink RF carriers22,24having the relatively higher reliability value as determined in block335. In another aspect, for example, UE12and/or carrier control function30and/or carrier data division function50and/or data priority function54(FIG. 1) may send redundant high priority data concurrently on the at least two uplink RF carriers22,24. Herein, the term “concurrently” means the same data is intended to be transmitted on both carriers at approximately the same time (within a few seconds). This aspect allows for increased reliability in the transmitted data reaching the destination, as the same data is sent over two different carriers. In another aspect, less data or no data may be allocated and sent on the relatively lower reliability RF carrier.

Several aspects of a telecommunications 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.