Carrier aggregation with self-contained subframe for efficient modem processing

The present disclosure provides for enhanced pipeline processing using different timing characteristics for aggregated carriers. A receiving device may receive a first component carrier and a second component carrier from a transmitting device during a subframe including a first set of symbols on the first component carrier and a second set of symbols on the second component carrier. The first component carrier may be a priority component carrier having a different timing characteristic than the second component carrier. The receiving device may process, using a hardware processing pipeline, the first set of symbols interleaved with the second set of symbols. The receiving device may transmit an acknowledgment, within the subframe, based on the processing of at least all of the first set of symbols.

BACKGROUND

Aspects of this disclosure relate generally to telecommunications, and more particularly to resource management in wireless communication systems.

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single-carrier frequency division multiple access (SC-FDMA) systems.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. For example, 5G new radio (NR) communications technology is envisaged to expand and support diverse usage scenarios and applications with respect to current mobile network generations. In an aspect, 5G communications technology includes enhanced mobile broadband addressing human-centric use cases for access to multimedia content, services and data; ultra-reliable-low latency communications (URLLC) with strict requirements, especially in terms of latency and reliability; and massive machine type communications for a very large number of connected devices and typically transmitting a relatively low volume of non-delay-sensitive information. As the demand for mobile broadband access continues to increase, however, there exists a need for further improvements in 5G communications technology and beyond. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

It is envisaged that 5G NR will, in some cases, be deployed in time division duplexing (TDD) bands using very large spectrum (e.g., greater than 100 MHz). Due to the large spectrum, devices may be able to complete transmission of available data relatively quickly. The large spectrum, however, may require a receiver to process of numerous code blocks for a symbol period. In an aspect, a latency target may be a target time for a receiver to acknowledge a transmission. For example, in a self-contained subframe, the latency target may be the end of the subframe. For example, a latency target may be on the order of 1 or 2 milliseconds. When the large spectrum is combined with the low-latency features of 5G NR, receiver processing operations may present a peak processing hot spot or bottleneck that may drive hardware and power consumption costs. That is additional hardware capacity may be needed to meet the latency targets. The hardware, however, may go unused a majority of the time.

In view of the foregoing, improvements to minimize hardware costs and energy consumption while meeting bandwidth and latency targets is desirable.

SUMMARY

The present disclosure provides for modem processing of received component carriers having different timing characteristics in a manner that reduces processing time of at least a priority carrier. In an aspect, the disclosure provides a method of subframe processing for wireless communications. The method may include receiving a first component carrier and a second component carrier from a transmitting device during a subframe including a first set of symbols on the first component carrier and a second set of symbols on the second component carrier. The first component carrier may be a priority component carrier having a different timing characteristic than the second component carrier. The method may include processing, using a hardware processing pipeline, the first set of symbols interleaved with the second set of symbols. The method may include transmitting an acknowledgment based on the processing of at least all of the first set of symbols within the subframe.

In another aspect, the disclosure provides an apparatus for pipeline processing in wireless communications. The apparatus may include a memory, a receiver, and a processor coupled to the memory and the receiver. The memory may include instructions executable by the processor to receive, via the receiver, a first component carrier and a second component carrier from a transmitting device during a subframe including a first set of symbols on the first component carrier and a second set of symbols on the second component carrier. The first component carrier may be a priority component carrier having a different timing characteristic than the second component carrier. The processor may be configured to process the first set of symbols interleaved with the second set of symbols, wherein the processor includes a processing pipeline. The processor may be configured to transmit, within the subframe, an acknowledgment based on the processing of at least all of the first set of symbols.

In another aspect, the disclosure provides another apparatus for pipeline processing in wireless communications. The apparatus may include means for receiving a first component carrier and a second component carrier from a transmitting device during a subframe including a first set of symbols on the first component carrier and a second set of symbols on the second component carrier. The first component carrier is a priority component carrier having a different timing characteristic than the second component carrier. The apparatus may include means for processing, using a hardware processing pipeline, the first set of symbols interleaved with the second set of symbols. The apparatus may include means for transmitting, within the subframe, an acknowledgment based on the processing of at least all of the first set of symbols.

In another aspect, the disclosure provides a computer readable medium storing computer executable code for wireless communications. The computer readable medium may include code for receiving a first component carrier and a second component carrier from a transmitting device during a subframe including a first set of symbols on the first component carrier and a second set of symbols on the second component carrier, wherein the first component carrier is a priority component carrier having a different timing characteristic than the second component carrier. The computer readable medium may include code for processing, using a hardware processing pipeline, the first set of symbols interleaved with the second set of symbols. The computer readable medium may include code for transmitting, within the subframe, an acknowledgment based on the processing of at least all of the first set of symbols.

DETAILED DESCRIPTION

As discussed above, emerging 5G or New Radio (NR) communications technology, may employ large spectrum and have low latency targets. For example, in a self-contained subframe, a receiver may be expected to receive data during a data portion of the subframe and transmit an acknowledgment (ACK) at the end of the same subframe. In an aspect, such a self-contained subframe presents a processing bottleneck or hotspot for the last symbol in the data portion, which must be quickly decoded to determine the ACK. Accordingly, the low latency target may drive peak hardware capability.

Pipelining is a technique for improving the utilization of hardware processing blocks without substantially increasing chip area. If the pipeline depth is longer than the time available from the last symbol to the ACK, the last symbol may require padding or tapering. A shorter pipeline depth may be used to meet a latency target. A shorter pipeline depth, however, means adding hardware capability. Increasing hardware capability, however, may not be ideal because, for example, the additional hardware capability added to meet peak processing points may not be utilized during normal processing.

Some aspects of the present disclosure provide for efficient processing pipelining at the modem of a wireless communication device, with a general aim to reduce communication latency even in a wide bandwidth network. Various aspects of the disclosure provide for reducing pipeline processing demands using carrier aggregation techniques. Different component carriers may have different timing characteristics that allow a latency target to be met for each of the component carriers. A transmitter may schedule data on the component carriers based on the timing characteristics such that the receiver may decode the data and meet a respective latency target for transmitting the ACK for each component carrier.

Various aspects are now described in more detail with reference to theFIGS. 1-11. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. It may be evident, however, that such aspect(s) may be practiced without these specific details. Additionally, the term “component” as used herein may be one of the parts that make up a system, may be hardware, firmware, and/or software stored on a computer-readable medium, and may be divided into other components.

Referring toFIG. 1, in accordance with various aspects of the present disclosure, an example wireless communication network100includes at least one UE110having a modem component160configured to perform one or more techniques described herein. A base station105may also include a modem component160configured to perform similar or complementary techniques described herein at the base station105.

In particular, modem component160may include a carrier aggregation component170configured to receive at least two component carriers. The component carriers may be continuous component carriers or non-continuous component carriers. The component carriers may be received via different antennas and be initially processed by different receive chains. For example, the component carriers may be associated with different radio frequency (RF) front ends. The carrier aggregation component170may determine symbols of the component carriers based on timing characteristics of each component carrier. For example, the timing characteristics may determine the number of symbols for each carrier during a sub-frame. The timing characteristics may also determine any offset in the start timing of the symbols on each component carrier. The carrier aggregation component170may interleave the symbols from the different components for processing by the receive processing pipeline180. In an aspect, for example, the carrier aggregation component170may alternate symbols from component carriers to provide to the receive processing pipeline180. If multiple component carriers are used, the carrier aggregation component170may use a round-robin method to feed symbols to the receive processing pipeline180. In an aspect, one of the component carriers may be considered a priority component carrier and the carrier aggregation component170may select a first symbol in a subframe from the priority component carrier.

In some examples of the present disclosure, the modem component160may further include the receive processing pipeline180. The receive processing pipeline180may be configured to perform modem processing of received symbols. That is, the receive processing pipeline180may receive baseband symbols and produce decoded bits. The receive processing pipeline180may include a plurality of hardware processing blocks. For example, the receive processing pipeline180may include one or more processing blocks (Block1)182, (Block2)184. The processing blocks182,184, may be, for example, vector processors. Each of processing blocks182,184may perform a sequential processing operation. For example, the processing block182may determine logarithmic likelihood ratios (LLRs) for each symbol, or each code block, and the processing block184may perform a demapper operation. As used herein, a code block (CB) may refer to a self-contained unit that can be decoded into bits. For example, a system utilizing a wide bandwidth, may include many CB during each symbol period. For example, the sub-carriers received during a symbol period may be divided into 30 or more CB. The receive processing pipeline180may also include a decoder186. The decoder186may be a specialized hardware block for decoding LLRs for a code block into bits. For example, the decoder186may be a Viterbi decoder.

As discussed above, a general approach to improving pipeline processing is to increase hardware capacity by expanding the width of the processing pipeline. For example, the receive processing pipeline180may be expanded by adding additional processing blocks or decoders that operate in parallel with the processing blocks182,184and decoder186.

Additionally, the modem component160may further include an acknowledgment component190for transmitting an acknowledgment to a transmitting device. For example, the acknowledgment component190may perform a cyclic redundancy check (CRC) to determine whether one or more subframes, component carriers, symbols, or CBs were decoded correctly. The acknowledgment component190may also transmit an ACK to the transmitting component indicating the decoding status. That is, the acknowledgment component190may transmit ACK when the decoding was successful and transmit a negative acknowledgment (NACK) when the decoding was unsuccessful. The ACK/NACK may be used by the transmitting device to determine whether to retransmit the subframe.

The wireless communication network100may include one or more base stations105, one or more UEs110, and a core network115. The core network115may provide user authentication, access authorization, tracking, internet protocol (IP) connectivity, and other access, routing, or mobility functions. The base stations105may interface with the core network115through backhaul links120(e.g., S1, etc.). The base stations105may perform radio configuration and scheduling for communication with the UEs110, or may operate under the control of a base station controller (not shown). In various examples, the base stations105may communicate, either directly or indirectly (e.g., through core network115), with one another over backhaul links125(e.g., X1, etc.), which may be wired or wireless communication links.

The base stations105may wirelessly communicate with the UEs110via one or more base station antennas. Each of the base stations105may provide communication coverage for a respective geographic coverage area130. In some examples, base stations105may be referred to as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, eNodeB (eNB), Home NodeB, a Home eNodeB, a relay, or some other suitable terminology. The geographic coverage area130for a base station105may be divided into sectors or cells making up only a portion of the coverage area (not shown). The wireless communication network100may include base stations105of different types (e.g., macro base stations or small cell base stations, described below). Additionally, the plurality of base stations105may operate according to different ones of a plurality of communication technologies (e.g., 5G, 4G/LTE, 3G, Wi-Fi, Bluetooth, etc.), and thus there may be overlapping geographic coverage areas130for different communication technologies.

In some examples, the wireless communication network100may be or include a Long Term Evolution (LTE) or LTE-Advanced (LTE-A) technology network. The wireless communication network100may also be a next generation technology network, such as a 5G wireless communication network. Moreover, the wireless communication network100may support high frequency operations such as millimeter wave communications. In LTE/LTE-A networks, the term evolved node B (eNB) may be generally used to describe the base stations105, while the term UE may be generally used to describe the UEs110. The wireless communication network100may be a heterogeneous LTE/LTE-A network in which different types of eNBs provide coverage for various geographical regions. For example, each eNB or base station105may provide communication coverage for a macro cell, a small cell, or other types of cell. The term “cell” is a 3GPP term that can be used to describe a base station, a carrier or component carrier associated with a base station, or a coverage area (e.g., sector, etc.) of a carrier or base station, depending on context.

A macro cell may generally cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by the UEs110with service subscriptions with the network provider. A small cell may include a relative lower transmit-powered base station, as compared with a macro cell, that may operate in the same or different frequency bands (e.g., licensed, unlicensed, etc.) as macro cells. Small cells may include pico cells, femto cells, and micro cells according to various examples. A pico cell, for example, may cover a small geographic area and may allow unrestricted access by the UEs110with service subscriptions with the network provider. A femto cell may also cover a small geographic area (e.g., a home) and may provide restricted access and/or unrestricted access by the UEs110having an association with the femto cell (e.g., in the restricted access case, the UEs110in a closed subscriber group (CSG) of the base station105, which may include the UEs110for users in the home, and the like). An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one or multiple (e.g., two, three, four, and the like) cells (e.g., component carriers).

The communication networks that may accommodate some of the various disclosed examples may be packet-based networks that operate according to a layered protocol stack and data in the user plane may be based on the IP. A radio link control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A MAC layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use HARQ to provide retransmission at the MAC layer to improve link efficiency. In an aspect, the acknowledgment component190may operate at the MAC layer. In the control plane, the radio resource control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE110and the base stations105. The RRC protocol layer may also be used for core network115support of radio bearers for the user plane data. At the physical (PHY) layer, the transport channels may be mapped to physical channels.

The UEs110may be dispersed throughout the wireless communication network100, and each UE110may be stationary or mobile. A UE110may also include or be referred to by those skilled in the art 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 user agent, a mobile client, a client, or some other suitable terminology. A UE110may 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, an entertainment device, a vehicular component, or any device capable of communicating in wireless communication network100. Additionally, a UE110may be Internet of Things (IoT) and/or machine-to-machine (M2M) type of device, e.g., a low power, low data rate (relative to a wireless phone, for example) type of device, that may in some aspects communicate infrequently with wireless communication network100or other UEs. A UE110may be able to communicate with various types of base stations105and network equipment including macro eNBs, small cell eNBs, relay base stations, and the like.

A UE110may be configured to establish one or more wireless communication links135with one or more base stations105. The wireless communication links135shown in wireless communication network100may carry UL transmissions from a UE110to a base station105, or downlink (DL) transmissions, from a base station105to a UE110. The downlink transmissions may also be called forward link transmissions while the uplink transmissions may also be called reverse link transmissions. In an aspect, in the UL, the base station105may be considered a receiving device and a modem component160may perform the methods disclosed herein. In an aspect, in the DL, a UE110may be considered a receiving device and a modem component160at the UE110may perform the methods described herein. Each wireless communication link135may include one or more carriers, where each carrier may be a signal made up of multiple subcarriers (e.g., waveform signals of different frequencies) modulated according to the various radio technologies described above. Each modulated signal may be sent on a different subcarrier and may carry control information (e.g., reference signals, control channels, etc.), overhead information, user data, etc. In an aspect, the communication links135may transmit bidirectional communications using frequency division duplex (FDD) (e.g., using paired spectrum resources) or time division duplex (TDD) operation (e.g., using unpaired spectrum resources). Moreover, in some aspects, the communication links135may represent one or more broadcast channels.

In some aspects of the wireless communication network100, base stations105or UEs110may include multiple antennas for employing antenna diversity schemes to improve communication quality and reliability between base stations105and UEs110. Additionally or alternatively, base stations105or UEs110may employ multiple input multiple output (MIMO) techniques that may take advantage of multi-path environments to transmit multiple spatial layers carrying the same or different coded data.

FIG. 2is an example frame structure200utilizing time-division duplexing. The frame structure200may be used for a burst of traffic in one or both of the uplink or downlink. Each subframe in the frame structure200may be either an uplink-centric subframe or a downlink-centric subframe. For example, subframes210and230may be uplink-centric subframes, and subframes250and270may be downlink-centric subframes. Each subframe may actually include both uplink and downlink portions. The direction of the subframe may refer to the direction of the data portion. The subframes in frame structure200may be referred to as self-contained subframes. A self-contained subframe may include control information, a data portion, and an acknowledgment of the data portion in the same subframe.

For example, the subframe210may be an uplink-centric subframe. The subframe210may include a physical dedicated control channel (PDCCH)205transmitted in a downlink direction that provides initial control information for the subframe210. The PDCCH212may be referred to as an uplink grant because it provides information to a UE for transmitting on the uplink. The PDCCH212may be followed by a guard period (GP)214. The GP214may separate a downlink portion of the subframe from an uplink portion. The GP214may allow the transmitting device and the receiving device to switch directions. An uplink portion of the subframe210may include a physical uplink control channel (PUCCH)216. The PUCCH may include control information (e.g., reference signals, transmit format, etc.) from the UE110regarding a physical uplink shared channel (PUSCH)218. The PUSCH218may include encoded data transmitted in the uplink by the UE110. As will be discussed in further detail below, the PUSCH may include multiple symbols transmitted over a wide bandwidth using multiple component carriers using carrier aggregation. The PUSCH may be followed by another GP220to allow the base station105process the PUSCH218. The base station105may then transmit the ACK/NACK222indicating whether the base station105correctly decoded the PUSCH218. In some examples, the ACK/NACK222may be combined with the PDCCH212of the following subframe.

Subframe250may be an example of a downlink centric subframe. The subframe250may include a PDCCH252transmitted by the base station105. The PDCCH252may be referred to as a downlink grant because PDCCH252carries information for a UE110to receive a physical downlink shared channel (PDSCH)254. In a downlink centric subframe, there is no need for a GP between the PDCCH252and the PDSCH254because both the PDCCH252and the PDSCH254are in the downlink direction. The PDSCH254may carry multiple symbols transmitted over a wide bandwidth using multiple component carriers using carrier aggregation. The modem component160of the UE110may receive and decode the PDSCH254. The subframe250may further include a GP256allowing the UE110to finish decoding the PDSCH254. The subframe210may include an ACK/NACK258transmitted by the UE110indicating whether the PDSCH254was correctly decoded.

FIG. 3is a conceptual diagram showing an example of resource allocation for pipeline processing. The resource allocation may be used, for example, by the receive processing pipeline180. As illustrated, a symbol310is received over the air (OTA) for example as an RF signal at time n. Columns refer to the OFDM symbols. The symbol310is fed to a first processing block182(P0) at time n+1. The different rows, P0, P1, and DEC, refer to the example processors and decoder usage as shown inFIG. 1. When P0finishes processing, the symbol310is fed to a second processing block184(P1) at time n+2. Meanwhile, at time n+1, a second symbol,320is received OTA and begins working through the processing pipeline180starting at time n+2. Once the P2finishes processing the symbol310, the symbol310is fed to the decoder186(DEC) at time n+3. As illustrated three symbols310,320,330are processed through the pipeline. In this case, processing the third symbol finishes at n+5, and an ACK340may be transmitted at n+6. The ACK is represented by the vertical arrow labeled “ACK” on the right ofFIG. 3. The arrow indicates the earliest ACK possibility for the transport block (contained within a transmission time interval (TTI)), which spans over multiple symbols and contains many codeblocks. Accordingly, a guard period350may be used between the end of the third symbol330received OTA and the transmission of the ACK340.

FIG. 4is a conceptual diagram showing an example technique for enhancing pipeline processing. In this case, the second processing block184may pipeline with the decoder186(shown as row DEC inFIG. 4) at a finer granularity than the symbol level. For example, the second processing block184(shown as row P1inFIG. 4.) may run a demapper operation and may be able to pipeline with the decoder186at a code block level. That is, the decoder186may start processing the same symbol as soon as the first CB from that symbol becomes available from the output of the processing block184. In the case where a symbol period includes many code blocks, the processing delay before the decoder186may start processing may be negligible. Similarly, the time the decoder186finishes after the second processing block184may be negligible. Such negligible difference may be managed by slightly increasing the clock speed. Accordingly, in this example, the ACK440may be transmitted at time n+5 and the guard period may be shortened such that guard period450may be shorter than guard period350inFIG. 3.

FIG. 5is a conceptual diagram showing another example technique for enhancing pipeline processing. In this case, the hardware capabilities of the processing pipeline180may be increased (e.g., by adding additional processing blocks and decoders). The increased capacity may also be achieved by significantly increasing the clock speed. For example,FIG. 5illustrates a doubled capacity compared toFIG. 4. In this case, the increased processing capabilities allow the processing pipeline180to process the third symbol330in a shorter time. Accordingly, the ACK540, may be transmitted at time n+4 and the guard period550may be shorter than the guard period450. By enhancing the peak capability of the hardware, however, the hardware duty cycle may not be fully utilized. In this example, the hardware utilization is roughly half of the previous example. Accordingly, even though additional hardware capability is being provided, merely adding hardware capacity may not be efficient in terms of costs paid to reduce latency.

FIG. 6is a conceptual diagram showing another example technique for enhancing pipeline processing. In this case, the hardware capabilities of the processing pipeline180may be increased as inFIG. 5, but may not be used for every time slot. For example, a modem component160may be provisioned with additional hardware (e.g. additional processing blocks or decoders, which utilize additional chip space and is more expensive). In another example, the increased capacity may also be achieved by increasing clock speed. The additional hardware capabilities may be utilized dynamically. For example, the hardware capabilities may be powered only when needed. In an aspect, the increased capabilities may be utilized by P0in every time slot, and used by P1and DEC only for processing the third symbol330. Accordingly, the symbol310may finish processing at time n+3 and the ACK640may be transmitted at time n+4. The guard period550in this example may be maintained compared to the example described above in connection withFIG. 5. This dynamic switching of hardware allocation may help lower average power consumption by spreading out the processing load for a majority of processing stages and for a majority of the symbols. However, this technique may not reduce the costs of increased hardware provisioning in that this technique uses the same hardware as inFIG. 5.

FIG. 7is a conceptual diagram showing an example technique for enhancing pipeline processing using carrier aggregation. In this example, data may be transmitted on two component carriers CC1and CC2. The two component carriers may have different timing characteristics. In this example, CC1may be associated with a first guard period750that is different than a second guard period752associated with CC2. The component carrier with the smallest guard period would be more time sensitive, and should be processed first in the pipeline shared across component carriers. The component carrier with the largest guard period would be processed last. In an aspect, a UE110may signal a UE capability indicating which timing characteristic differences are supported for different component carriers. A base station105may select one or more timing characteristic differences to apply in a carrier aggregation configuration. In an aspect, for example, CC2may carry fewer symbols during a transmission block (e.g., PDSCH254) than CC1. It should be appreciated that although three symbols are illustrated for CC1and two symbols for CC2, in practice, a larger number of symbols may be carried by each CC depending on the duration of a subframe and the numerology being used. It should also be appreciated that because the symbols are being transmitted on two component carriers, in comparison toFIGS. 3-6, each component carrier may use less bandwidth, but the total bandwidth may remain constant.

The carrier aggregation component170may interleave the received symbols for feeding to the processing pipeline180. For example, the carrier aggregation component170may select a symbol from a priority CC as the first symbol, then alternate symbols or select symbols in a round-robin manner if multiple CC are available. Each of the processing blocks182,184, and the decoder186(shown as P0, P1and DEC inFIG. 7) may process the symbols710,712,720,722,730in less time than the symbols310,320,330because the symbols use less bandwidth. For example, if the symbols use half of the bandwidth, each processing block may process the symbol in approximately half of the time. Accordingly, as illustrated, the processing pipeline180may complete processing of the five symbols at time n+3, and the ACK740may be transmitted at time n+4. That is, the same target latency for the ACK740can be met using component carriers without increasing hardware capability. The hardware may be operated with a high duty cycle, only being idle when waiting for the first symbol received OTA. In an aspect, this technique may reduce throughput on the component carrier with the longer guard period. However, the reduction may be a single symbol. Accordingly, when a larger number of symbols are transmitted in a sub-frame, the loss of throughput may be negligible.

FIG. 8is a conceptual diagram showing another example technique for enhancing pipeline processing using carrier aggregation. Once again, a timing characteristic may be different for CC1and CC2. In this example, an ACK latency target may be different between the CCs. For a priority CC1, the ACK may be transmitted in the same subframe as the data. That is, CC1may carry self-contained subframes. The subframe860may include a PDCCH862, data864, GP866, and ACK868. The subframe870may include a PDCCH872, data874, GP876, and ACK878. For example, in subframe860, the data864may be acknowledged by the ACK868, and in subframe870, the data874may be acknowledged by the ACK878. The CC1may have two hybrid automatic repeat request (HARD) interlaces. Subframes in CC2may have a relaxed ACK latency target. The subframe880may include a PDCCH882, data884, GP886, and ACK888. The subframe890may include a PDCCH892, data894, GP896, and ACK898. In an aspect, the ACK for subframe880on CC2may be transmitted in the subsequent subframe890. For example, the data884may be acknowledged by the ACK898. Accordingly, CC2may have three HARQ interlaces.

Each of the component carriers may carry the same number of symbols and have the same guard period850. As illustrated, the processing pipeline180may not finish processing a last symbol832of CC2by the end of the guard period850. In this example, due to the relaxed latency target and acknowledgment schedule for CC2, the ACK840may acknowledge symbols810,820, and830for CC1and the symbols of the previous subframe (not shown) for CC2. The symbols812,822, and832may be acknowledged in the subsequent subframe. In this case, although CC2may not be a self-contained subframe, a transmitting device may be able to meet a low latency target by scheduling time critical data on CC1. It should also be noted that although the P0and DEC are still processing the symbol832for CC2, the ACK840may still be transmitted for the current subframe of CC1and the previous subframe of CC2. Once again, use of carrier aggregation allows the latency target to be met on CC1without increasing hardware capability. Further, the hardware is operated with a high duty cycle.

FIG. 9is a conceptual diagram showing another example technique for enhancing pipeline processing using carrier aggregation. Once again, a timing characteristic may be different for CC1and CC2. In this example, a subframe timing may be different between CC1and CC2. For example, a subframe on CC2may be offset from a subframe timing of CC1. The offset may be less than a symbol period. The offset could be due to timing misalignment between component carriers in an asynchronous carrier aggregation deployment. The offset could also be introduced by design in a synchronous carrier aggregation deployment. Each component carrier may be transmitted with the same number of symbols and the same guard period950. When the processing pipeline180finishes processing the symbol930for CC1, an ACK940may be transmitted for CC1. When the processing pipeline180finishes processing the symbol932for CC2, an ACK942may be transmitted for CC2. As seen inFIG. 9, the ACK timing may be staggered.

In an aspect, the offset between the sub-frame timings may result in more opportunities for DL-UL or UL-DL interference. For example, the transmission of ACK942may effectively shorten the guard period between the ACK940and a following PDCCH on CC1. To avoid such interference, an inter-subframe guard period may be increased. Although an increased guard period may reduce spectral efficiency, the reduction may be an acceptable tradeoff. For example, when a guard period budget relative to round trip delay (RTD) is not an issue, the increased guard period may be acceptable. In another aspect where longer durations are allocated for ACK, the offset between ACK940and ACK942may still comply with the longer duration. In another aspect, there may be sufficient isolation between CC1and CC2such that interference is minimal or can be cancelled. For example, a full duplex system may be able to receive ACK942while transmitting a PDCCH. Also, in the case of uplink centric subframes, the ACK942may be transmitted in the downlink and the PDCCH of the subsequent subframe may be transmitted in the same direction, so no inter-subframe guard period may be needed.

FIG. 10is a flowchart of an example method1000of wireless communications. The method1000may be performed using an apparatus (e.g., the UE110or a base station105, for example). Although the method1000is described below with respect to the elements of the modem component160, other components may be used to implement one or more of the steps described herein.

In block1010, the method1000may include receiving a first component carrier and a second component carrier from a transmitting device during a subframe including a first set of symbols on the first component carrier and a second set of symbols on the second component carrier. In an aspect, for example, the carrier aggregation component170may receive the first component carrier and the second component carrier from a transmitting device (e.g., base station105) during a subframe including a first set of symbols on the first component carrier and a second set of symbols on the second component carrier. The first component carrier may be a priority component carrier having a different timing characteristic than the second component carrier. The carrier aggregation component170may also receive additional component carriers, which may have the same timing characteristic as the priority component carrier, or different timing characteristic. In an aspect, the timing characteristic may be a length of a guard period between receiving a last symbol of the respective first set of symbols and the respective second set of symbols and transmitting the acknowledgment. In another aspect, the timing characteristic is a latency target for the respective component carriers. The latency target may also correspond to a number of HARQ interlaces. In another aspect, the timing characteristic may be a subframe timing. For example, the subframe timing of the second component carrier may be offset from the timing of the first component carrier (e.g., delayed by less than a symbol period).

In block1020, the method1000may optionally include interleaving the first set of symbols and the second set of symbols. In an aspect, for example, the carrier aggregation component170may interleave the first set of symbols and the second set of symbols. For example, the carrier aggregation component170may select symbols from alternating component carriers starting with the priority component carrier. If multiple component carriers are received, the carrier aggregation component170may select symbols in a round-robin manner.

In block1030, the method1000may include processing, using a hardware processing pipeline, the first set of symbols interleaved with the second set of symbols. In an aspect, for example, the processing pipeline180may process the first set of symbols interleaved with the second set of symbols. For example, the processing may optionally include, in sub-block1035, any of: performing a Fourier transform, determining log likelihood ratios based on the received symbols, demapping the received symbols, or decoding the received symbols. In an aspect, the processing pipeline180may include a hardware block (e.g., processing block182, processing block184, decoder186) for each processing operation. The receive processing pipeline180may interleave the first set of symbols and the second set of symbols to produce an interleaved set of symbols. Receive processing pipeline180may then sequentially process the interleaved set of symbols using the hardware blocks.

In block1040, the method1000may include transmitting, within the subframe, a first acknowledgment based on the processing of at least all of the first set of symbols. In an aspect, for example, the acknowledgment component190may transmit (e.g., via a transmitter) the first acknowledgment based on the processing of at least all of the first set of symbols within the subframe. The acknowledgment may be either an ACK or a NACK depending on the result of the processing. In an aspect, the first acknowledgment may also be based on processing of all of the second set of symbols. For example, if the processing pipeline180has finished processing both the first set of symbols and the second set of symbols at the end of a guard period for the first component carrier, the first acknowledgment may correspond to both the first set of symbols and the second set of symbols.

In block1050, the method1000may optionally include transmitting, during a subsequent subframe, a second acknowledgment based on the processing of at least one symbol of the second set of symbols. In an aspect, for example, the acknowledgment component190may transmit, during the subsequent subframe, the second acknowledgment based on the processing of at least one symbol of the second set of symbols. The processing may occur during the original subframe, but the acknowledgment may be sent during the subsequent subframe. The second acknowledgment may correspond to the second set of symbols that are received on the second component carrier. Accordingly, the second set of symbols may be associated with a relaxed latency target.

In block1060, the method1000may optionally include transmitting a second acknowledgment based on the processing of at least all of the second set of symbols within the subframe according to a subframe timing of the second component carrier. In an aspect, for example, the acknowledgment component190may transmit the second acknowledgment based on the processing of at least all of the second set of symbols within the subframe according to the subframe timing of the second component carrier. The subframe timing of the second component carrier may be offset from the subframe timing of the first component carrier. For example, the second acknowledgment may be transmitted after the first acknowledgment. The timing offset may be less than a symbol period.

FIG. 11schematically illustrates hardware components and subcomponents of the UE110for implementing one or more methods (e.g., method1000) described herein in accordance with various aspects of the present disclosure. For example, one example of an implementation of UE110may include a variety of components, some of which have already been described above, but including components such as one or more processors1112and memory1116and transceiver1102in communication via one or more buses1144, which may operate in conjunction with the modem component160to enable one or more of the functions described herein related to including one or more methods of the present disclosure. Further, the one or more processors1112, modem1114, memory1116, transceiver1102, RF front end1188and one or more antennas1165, may be configured to support voice and/or data calls (simultaneously or non-simultaneously) in one or more radio access technologies. AlthoughFIG. 11illustrates a UE110, it should be appreciated that a base station105may be implemented using similar components and sub-components (as illustrated inFIG. 1).

In an aspect, the one or more processors1112can include a modem1114that uses one or more modem processors. The various functions related to modem component160may be included in modem1114and/or processors1112and, in an aspect, can 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 processors1112may 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 receiver processor, or a transceiver processor associated with transceiver1102. In other aspects, some of the features of the one or more processors1112and/or modem1114associated with modem component160may be performed by transceiver1102.

Also, memory1116may be configured to store data used herein and/or local versions of applications or modem component160and/or one or more of its subcomponents being executed by at least one processor1112. Memory1116can include any type of computer-readable medium usable by a computer or at least one processor1112, such as random access memory (RAM), read only memory (ROM), tapes, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. In an aspect, for example, memory1116may be a non-transitory computer-readable storage medium that stores one or more computer-executable codes defining modem component160and/or one or more of its subcomponents, and/or data associated therewith, when UE110is operating at least one processor1112to execute UE modem component160and/or one or more of its subcomponents.

Transceiver1102may include at least one receiver1106and at least one transmitter1108. Receiver1106may include hardware, firmware, and/or software code executable by a processor for receiving data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). Receiver1106may be, for example, a radio frequency (RF) receiver. In an aspect, receiver1106may receive signals transmitted by at least one base station105. Additionally, receiver1106may process such received signals, and also may obtain measurements of the signals, such as, but not limited to, Ec/Io, SNR, RSRP, RSSI, etc. Transmitter1108may include hardware, firmware, and/or software code executable by a processor for transmitting data, the code comprising instructions and being stored in a memory (e.g., computer-readable medium). A suitable example of transmitter1108may including, but is not limited to, an RF transmitter.

Moreover, in an aspect, UE110may include RF front end1188, which may operate in communication with one or more antennas1165and transceiver1102for receiving and transmitting radio transmissions, for example, wireless communications transmitted by at least one base station105or wireless transmissions transmitted by UE110. RF front end588may be connected to one or more antennas1165and can include one or more low-noise amplifiers (LNAs)1190, one or more switches1192, one or more power amplifiers (PAs)1198, and one or more filters1196for transmitting and receiving RF signals.

In an aspect, LNA1190can amplify a received signal at a desired output level. In an aspect, each LNA1190may have a specified minimum and maximum gain values. In an aspect, RF front end1188may use one or more switches1192to select a particular LNA590and its specified gain value based on a desired gain value for a particular application.

Further, for example, one or more PA(s)1198may be used by RF front end1188to amplify a signal for an RF output at a desired output power level. In an aspect, each PA1198may have specified minimum and maximum gain values. In an aspect, RF front end1188may use one or more switches1192to select a particular PA1198and its specified gain value based on a desired gain value for a particular application.

Also, for example, one or more filters1196can be used by RF front end1188to filter a received signal to obtain an input RF signal. Similarly, in an aspect, for example, a respective filter1196can be used to filter an output from a respective PA1198to produce an output signal for transmission. In an aspect, each filter1196can be connected to a specific LNA1190and/or PA1198. In an aspect, RF front end1188can use one or more switches1192to select a transmit or receive path using a specified filter1196, LNA1190, and/or PA1198, based on a configuration as specified by transceiver1102and/or processor1112.

As such, transceiver1102may be configured to transmit and receive wireless signals through one or more antennas1165via RF front end1188. In an aspect, transceiver may be tuned to operate at specified frequencies such that UE110can communicate with, for example, one or more base stations105or one or more cells associated with one or more base stations105. In an aspect, for example, modem1114can configure transceiver1102to operate at a specified frequency and power level based on the UE configuration of the UE110and the communication protocol used by modem1114.

In an aspect, modem1114can be a multiband-multimode modem, which can process digital data and communicate with transceiver1102such that the digital data is sent and received using transceiver1102. In an aspect, modem1114can be multiband and be configured to support multiple frequency bands for a specific communications protocol. In an aspect, modem1114can be multimode and be configured to support multiple operating networks and communications protocols. In an aspect, modem1114can control one or more components of UE110(e.g., RF front end1188, transceiver1102) to enable transmission and/or reception of signals from the network based on a specified modem configuration. In an aspect, the modem configuration can be based on the mode of the modem and the frequency band in use. In another aspect, the modem configuration can be based on UE configuration information associated with UE110as provided by the network during cell selection and/or cell reselection.