UE transmission schemes with subband precoding and TPMI re-interpretation

Aspects are provided allowing UEs with non-coherent or partially coherent antennas to re-interpret TPMI received in DCI into a set of TPMIs corresponding to different subbands. The UE receives a TPMI associated with at least one first antenna and at least one second antenna which are non-coherent with each other, and the UE determines a set of TPMIs including a first and second TPMI based on the received TPMI. The set of TPMIs include at least one TPMI different from the received TPMI. The UE transmits, based on the first TPMI, from the at least one first antenna within at least one first subband. The UE also transmits, based on the second TPMI, from the at least one second antenna within at least one second subband different from the at least one first subband. Thus, full power transmission based on re-interpreted TPMI with reduced DCI overhead may result.

BACKGROUND

Technical Field

The present disclosure relates generally to communication systems, and more particularly, to a wireless communication system between a user equipment (UE) and a base station.

INTRODUCTION

SUMMARY

A UE may be configured with multiple antennas that are non-coherent, or partially coherent, with respect to each other. Such antennas may lead to challenges for transmissions from the UE since a UE with non-coherent or partially coherent antennas may not transmit using a full transmission power of that UE. Generally, in power control, the UE may scale its transmission power (as determined by power control) by the ratio of the number of antenna ports with a non-zero physical uplink shared channel (PUSCH) transmission to the number of configured antenna ports for the transmission scheme. The resulting scaled power may then be split equally across the antenna ports on which the non-zero PUSCH is transmitted. Moreover, in MIMO codebooks, generally one of the non-coherent antennas (or a set of partially coherent antennas) may include a non-zero precoder while the other antennas (or sets of antennas) include zero precoders such that non-coherent antennas may not transmit data simultaneously on the same layer. The precoders may be based on a transmitted precoding matrix indicator (TPMI) received in downlink control information (DCI). As a result, scaled power may be split equally with non-transmitting antennas (i.e. with zero precoders as configured by TPMI), resulting in less transmission power overall for the UE. For example, a UE with two non-coherent antennas that receives a TPMI of [0, 1] may have power split equally among the antennas (½ power), but since one of the two antennas has a zero precoder and is thus not transmitting, half the power is effectively lost.

To address this problem, the present disclosure allows for the UE to reinterpret the TPMI. When the UE receives a TPMI in DCI, the UE may determine a set of TPMIs based on the received TPMI. The set of TPMIs may then be used to transmit across multiple subbands. Together, the subbands may add to a full power transmission. For example, if a UE with two non-coherent antennas with equally split power (½ power) receives a TPMI of [0, 1], the UE may reinterpret the TPMI to determine a set of TPMIs: [1, 0] for a first subband and [0, 1] for a second subband. The UE may then transmit using the first antenna with non-zero precoder on the first subband based on the first reinterpreted TPMI ([1, 0]), and using the second antenna with non-zero precoder on the second subband based on the second reinterpreted TPMI ([0, 1]). Similar TPMI reinterpretation may be applied for partially coherent antennas. Thus, the UE may achieve full transmission power in such circumstances. Moreover, the present disclosure allows for reduced overhead in DCI, since the UE may interpret multiple TPMIs from a single TPMI in DCI (e.g. without additional bits).

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The apparatus receives a TPMI associated with at least one first antenna and at least one second antenna, where the at least one first antenna and the at least one second antenna are non-coherent with each other. The apparatus determines a set of TPMIs based on the received TPMI, where the set of TPMIs includes at least one TPMI different from the received TPMI. The apparatus transmits, based on a first TPMI of the set of TPMIs, from the at least one first antenna within at least one first subband. The apparatus also transmits, based on a second TPMI of the set of TPMIs, from the at least one second antenna within at least one second subband different from the at least one first subband.

DETAILED DESCRIPTION

Referring again toFIG. 1, in certain aspects, the UE104may include a TPMI reinterpretation component198. The TPMI reinterpretation component198may receive a TPMI associated with at least one first antenna and at least one second antenna, where the at least one first antenna and the at least one second antenna are non-coherent with each other. The TPMI reinterpretation component198may determine a set of TPMIs based on the received TPMI, where the set of TPMIs includes at least one TPMI different from the received TPMI. The TPMI reinterpretation component198may transmit, based on a first TPMI of the set of TPMIs, from the at least one first antenna within at least one first subband, and may transmit, based on a second TPMI of the set of TPMIs, from the at least one second antenna within at least one second subband different from the at least one first subband. Although the following description may be focused on 5G NR, the concepts described herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

At least one of the TX processor368, the RX processor356, and the controller/processor359may be configured to perform aspects in connection with TPMI reinterpretation component198ofFIG. 1.

In certain cases, a UE with partially coherent or non-coherent antennas may not transmit with full power based on power control. Generally, the UE may scale the transmission power, as determined by power control, by the ratio of the number of antenna ports with a non-zero PUSCH transmission to the number of configured antenna ports for the transmission scheme. The resulting scaled power is then split equally across the antenna ports on which the non-zero PUSCH is transmitted. Moreover, in a MIMO codebook with two or more non-coherent antennas or sets of non-coherent antennas (e.g. partially coherent antennas), only one antenna or set may have a non-zero precoder, while any other antenna or set may have zero precoders. For example, non-coherent antennas may not generally transmit data simultaneously on the same layer.

As a result, a MIMO codebook with two non-coherent antennas or sets of non-coherent antennas may result in a ½ power transmission. For example, for a pair of non-coherent antennas, only one antenna may transmit in cases where the configured antenna ports for the transmission scheme is 2 and the number of antenna ports with a non-zero PUSCH transmission is 1. In such cases, a transmission of ½ power (1 non-zero PUSCH transmission divided by 2 antenna ports for the transmission scheme) will result. For example, a first antenna may have a precoder value of 1/√2, while a second antenna may have a precoder value of 0. Accordingly, the power transmitted will be (0)2+(1/√2)2or ½ power. Similarly, a MMO codebook with three non-coherent antennas or sets of non-coherent antennas may result in a ⅓ power transmission, and so forth for greater numbers of non-coherent antennas or sets.

To compensate for this power reduction, the wireless communication device or UE may re-interpret a TPMI as a set of TPMIs. In other words, when a TPMI is received, the UE may generate a set of TPMIs from the TPMI. For example, the set of TPMIs may include the received TPMI and a second TPMI. The set of TPMIs may be used to transmit, for example 1/X power across X subbands and thus resulting in full power. For example, a set of two TPMIs may be used to transmit on two physical antennas, with each antenna transmitting on a separate subband. The UE will, then transmit full power, for example, (½ power)+(½ power)=Full Power.

FIG. 4illustrates an example400of a wireless communication device402or UE having two non-coherent antennas that may experience power reduction. In this example, the wireless communication device402may not maintain phase coherence between a first antenna (Ant0) and a second antenna (Ant1). The antennas may have different precoder values, as shown. For example, Ant0may be associated with a precoder value of 1/√2while Ant1may be associated with a precoder value of 0 based on a received TPMI (e.g. [1, 0]). Accordingly, inFIG. 4, ½ power may be transmitted because Ant0transmits and antenna1does not transmit, e.g., (0)2+(½)2or ½ power.

FIG. 5illustrates another example500of a wireless communication device502or UE having partially coherent antennas that may also experience power reduction. For example, a first set of antennas504may be coherent with respect to each other. Thus, Ant0and Ant1in set504are capable of maintaining a relative phase difference between each other over time. Similarly, a second set of antennas506may be coherent with respect to each other, with Ant2and Ant3being capable of maintaining a relative phase difference between each other over time. However, the first set of coherent antennas504may be non-coherent with the second set of coherent antennas506. For example, the wireless communication device502may not maintain phase coherence between Ant0in set504and Ant2in set506, and similarly may not maintain phase coherence between Ant1in set504and Ant3in set506. In other words, the wireless communication device can maintain phase coherence between antennas included in each of two antenna groups (e.g., first antenna set504and second antenna set506), but may not maintain phase coherence between the two antenna groups. Therefore, the wireless communication device502may be described as being capable of achieving partial coherence among antenna ports of the wireless communication device or as having partially coherent antennas. The non-coherent antenna sets may be associated with different precoder values, as shown inFIG. 5. For example, Ant0and Ant1in the first coherent set504may be associated with a precoder value of ½ while Ant2and Ant3in the second coherent set506may be associated with a precoder value of 0 based on a received TPMI (e.g. [1, 1, 0, 0]). Accordingly, as discussed in greater detail below, the wireless communication device502may transmit at ½ power, e.g., (½)2+(½)2+(0)2+(0)2.

Thus,FIGS. 4 and 5illustrate examples400,500of wireless communication devices402,502(e.g. UEs) that may experience power reduction. In each example, the wireless communication device may transmit at half power, e.g., (0)2+(1/√2)2(forFIG. 4) or (½)2+(½)2+(0)2+(0)2(forFIG. 5). However, the number of antennas shown inFIGS. 4 and 5are merely examples. For example, whileFIG. 5only illustrates two sets of partially coherent antennas, a wireless communication device may include any number of sets of partially coherent antennas. Further, each partially coherent set may include any number of coherent antennas.

In some wireless networks, a wireless communication device may be assumed to be capable of achieving full coherence. In such cases, a MIMO scheme associated with transmitting a signal using the multiple antennas of the wireless communication device, may be designed under the assumption of full coherence. In other cases, wireless communication involving only partial coherence may have unique challenges for MIMO communication. For example, limitations may be placed on transmission power for a UE with partially coherent antennas that restrict the UE from transmitting with full transmit power. A UE may determine a transmit power for data transmission, e.g., for transmitting PUSCH, based on uplink power control signaling received from the base station. The transmit power is a power level without power scaling by the UE to reduce the transmit power. For example, uplink power control may determine the average power over an OFDM symbol in which the physical channel is transmitted by the UE.

Generally, as part of power control at the UE, the UE may further scale the transmit power that it determined based on the power control signaling from the base station. The UE may first scale the determined transmit power by the ratio of the number of antenna ports with a non-zero PUSCH transmission to the number of configured antenna ports for the transmission scheme. The resulting scaled power may then be split equally across the antenna ports on which the non-zero PUSCH is transmitted. For example, as illustrated inFIG. 5, the wireless communication device502may have four configured antenna ports (Ant0, Ant1, Ant2, Ant3), with two of the four antenna ports having non-zero PUSCH (Ant0, Ant1). When the wireless communication device determines a transmit power of P based on power control signaling from a base station, the transmit power P would be scaled by the ratio of 2 to 4, e.g., 2. Then, the scaled transmit power, P/2, would be split evenly between Ant0and Ant1. Therefore, the two antenna ports, Ant0and Ant1, would each transmit the PUSCH with a transmit power of P/4. The actual transmit power used by the UE would total (P/4+P/4=P/2).

FIG. 6Aillustrates an example600of aspects that may be employed in uplink physical channel processing at a UE. A baseband signal representing the PUSCH may be generated by scrambling602, modulation604of scrambled bits to generate complex-valued symbols, mapping606of the complex-valued modulation symbols onto one or more transmission layers, precoding610of the one or more layers of the complex-valued symbols, mapping612of precoded complex-valued symbols to resource elements, and generation614of complex-valued time-domain Cyclic Prefix Orthogonal Frequency Division Multiplexing (CP-OFDM) signals for each antenna port. In another example, the uplink transmission may be based on Discrete Fourier Transform-spread-OFDM (DFT-s-OFDM), in which a transform precoder608may be applied after the layer mapper606and prior to the precoding610on each layer. Thus, the transform precoder608may be enabled or disabled based on the signal being generated. For precoding610, a precoder may receive input from a layer mapper606and generate a block of vectors to be mapped onto resource elements. Precoding610may be performed for spatial multiplexing, e.g., based on the layers onto which the codewords are mapped as part of layer mapping. Precoding610for spatial multiplexing may be based on a precoding matrix. The precoding matrix may be given by a table entry or a codebook. A matrix may be selected by the UE based on a number of antenna ports, a codebook index, a number of mapped layers, etc. A MIMO codebook may take into account sets of non-coherent antenna ports and may provide only one set of antenna ports with a non-zero precoder value. The other antenna port set(s) may have a zero precoder value. Thus, the codebook prevents simultaneous transmission of the PUSCH from non-coherent antennas.

FIG. 7Aillustrates an example codebook matrix702that prevents such simultaneous transmission between the non-coherent antenna ports in the example ofFIG. 5. InFIG. 7A, Ant2and Ant3will have a precoder value of 0 and will not transmit PUSCH, while Ant0and Ant1will have a non-zero precoder value of 2 for the PUSCH transmission. Similarly, the matrix706inFIG. 7Cgives Ant2and Ant3a precoder value of 0, while Ant0and Ant1have a non-zero precoder value for the PUSCH transmission. Thus, the matrices inFIGS. 7A and 7Cavoid simultaneous transmission from the non-coherent antenna sets. A UE may comprise partial coherent antenna ports, e.g., as described in connection withFIG. 5. In the example illustrated inFIG. 5, the UE may use a codebook that limits non-zero PUSCH transmission to either the first coherent antenna set504or the second coherent antenna set506, but that does not provide for simultaneous, non-zero PUSCH transmission from both sets of antennas that are non-coherent with each other. Thus, the UE may apply a codebook with matrix values similar to the example matrices702,706inFIGS. 7A and 7C.

In one example approach to increase power transmission, the UE may split a non-scaled transmit power, e.g., P, across the antenna ports on which the non-zero PUSCH is transmitted. In the example ofFIG. 5, the transmit power per antenna port would be P/2 for Ant0and P/2 for Ant1. Thus, the total transmit power (P/2+P/2) for the antenna ports having a non-zero PUSCH transmission would be equal to the full transmit power P, e.g., the full transmit power determined by the UE based on the power control signaling from the base station. Thus, the total actual transmit power by the UE is P, the full, determined transmit power, e.g., without scaling by the ratio of the number of antenna ports with a non-zero PUSCH transmission to the number of configured antenna ports for the transmission scheme.

In another example approach, the UE may improve the use of its transmission power through simultaneous transmission of data using non-coherent antennas. The UE may use a different transmit scheme that enables non-coherent antenna sets to transmit PUSCH simultaneously. For example, the UE may use a MIMO codebook that provides non-zero values for antennas that are non-coherent with each other, e.g., antenna(s) in a first set that are non-coherent with antenna(s) in a second set.FIGS. 7B and 7Dillustrate example matrices704,708that provide non-zero values for simultaneous transmission between the non-coherent antennas in the example ofFIG. 5. The four antennas ofFIG. 5may simultaneously transmit PUSCH using the matrices in eitherFIG. 7B or 7D. The UE may split the transmission power among the antenna ports. By using all four antennas to transmit the PUSCH, the transmit power may be split evenly among the 4 antennas, with each antenna port transmitting the PUSCH using a power P/4. Therefore, the total transmit power actually used for the transmission at the four antenna ports (e.g., P/4+P/4+P/4+P/4) will be equal to the full transmit power, P, determined by the UE based on the power control signaling from the base station.

In a further example approach, as the relative phase difference between the non-coherent antenna sets may vary, the UE may apply a diversity scheme among the non-coherent sets of antennas.FIG. 6Billustrates an example650that may be employed at a UE to generate a baseband signal representing PUSCH. Similar to the example inFIG. 6A, a baseband signal representing the PUSCH may be generated by scrambling652, modulation654of scrambled bits to generate complex-valued symbols, mapping656of the complex-valued modulation symbols onto one or more transmission layers, precoding658,660of the one or more layers of the complex-valued symbols, mapping662of precoded complex-valued symbols to resource elements, and generation664of complex-valued time-domain Cyclic Prefix Orthogonal Frequency Division Multiplexing (CP-OFDM) signals for each antenna port. However, inFIG. 6B, the UE may also apply a diversity scheme at661. While the diversity scheme is illustrated after precoding660, the diversity scheme may also be applied prior to precoding, in other examples. In the example inFIG. 5, the diversity scheme would be applied among the first antenna set504and the second antenna set506. In another example, the UE may apply an open-loop, non-transparent diversity scheme among the first antenna set504and the second antenna set506.

When the UE (e.g. wireless device402,502ofFIGS. 4 and 5) receives a TPMI from a base station indicating a zero precoder, such as the matrices702,706illustrated inFIGS. 7A and 7Band described above (e.g. [0, 1], [1, 1, 0, 0], etc.), the UE's overall uplink (UL) transmission power may be reduced since the TPMI is typically applied to an entire bandwidth of the UE. To resolve this issue, when the UE receives a TPMI with a zero precoder, the UE may re-interpret the TPMI to apply it differently for different subbands. For example, if the UE receives a TPMI of [0, 1], then rather than applying the received TPMI of [0, 1] across the entire bandwidth, the UE may re-interpret the TPMI such that it applies [1, 0] for one subband of a PUSCH allocation (e.g. one half of the total bandwidth) and [0, 1] for the other subband of the PUSCH allocation (e.g. the other half of the total bandwidth). In this way, rather than having one antenna or set of antennas transmit at reduced power across the entire bandwidth as described above, the UE may have different antennas or set of antennas transmit at reduced power in different subbands such that the combined transmission power across the different subbands totals the UE's full UL transmission power. For instance, referring toFIG. 4, if the UE receives a TPMI of [0, 1], then rather than having Ant1transmit at half power across the entire PUSCH allocation, the UE may have Ant1transmit at half power across a first subband of the PUSCH allocation, and Ant0transmit at half power across a second subband of the PUSCH allocation, such that full power is transmitted in combination across both subbands. In this way, non-coherent antennas may be simultaneously used in different subbands with full transmission power.

The UE may autonomously determine whether to re-interpret the TPMI as described above, or to simply use the received TPMI without re-interpretation, based on whether the UE has reached a power amplifier (PA) power limit. If the UE has not reached the PA power limit, the UE may interpret the TPMI as originally indicated (e.g. [0, 1]) since the UE may still increase its transmission power up to the PA limit to compensate for any reduced transmission power due to precoding. However, if the UE has reached the PA power limit, the UE may not be able to increase its transmission power further, and so the UE may determine to re-interpret the TPMI (e.g. re-interpret [0, 1] as: [1, 0] for one subband and [0, 1] for another subband) to compensate for the reduced transmission power. For example, if the UE has non-coherent antennas or partially coherent antennas such as illustrated in the examples ofFIGS. 4 and 5(e.g. the UE has “capability2”), the UE may determine whether to re-interpret a received TPMI or not based on a location of the UE. For instance, if the UE is located near a base station at the center of the cell, the UE may be below the PA limit and determine not to re-interpret TPMI, while if the UE is at a cell edge, the UE may have reached the PA limit and may determine to re-interpret TPMI.

The base station may configure the UE with respect to how each TPMI indication (received TPMI) is mapped into TPMI bundles for re-interpretation, e.g., in a RRC message or a Medium Access Control (MAC) Control Element (MAC-CE). For example, if the UE has two non-coherent antennas such as illustrated inFIG. 4, the UE may be configured via RRC or MAC-CE with a mapping that a received TPMI of [0, 1] may correspond to the following example TPMI bundle: [1, 0] for the first subband and [0, 1] for the second subband. The UE may similarly be configured with different mappings or TPMI bundles for different received TPMIs and numbers of antennas. For example, if the UE has two partially coherent sets of non-coherent antennas such as illustrated inFIG. 5(four antennas total), the UE may be configured by the base station with a mapping that a received TPMI of [1, 1, 0, 0] may correspond to the following example TPMI bundle: [1, 0, 1, 0] for a first subband, [0, 1, 0, 1] for a second subband, [0, 1, 1, 0] for a third subband, and [1, 0, 0, 1] for a fourth subband. The number of subbands may be equal to the number of antennas.

The base station may also configure the UE with respect to how the PUSCH allocation is to be split in different subbands. For instance, if the base station schedules an allocation of PUSCH resources (e.g. in DCI) to the UE of 20 PRBs, the base station may configure the UE to split the PUSCH allocation equally (e.g. 10 PRBs in one subband and 10 PRBs in another subband) or unequally (e.g. 5 PRBs in one subband and 15 PRBs in another subband).

When the PUSCH allocation is split into a given number of subbands, the UE may apply a different TPMI from the TPMI bundle to each subband. The number of subbands may correspond to a number of TPMIs in a TPMI bundle or a number of antennas of the UE (e.g. two subbands for two antennas as illustrated inFIG. 4, four subbands for four antennas as illustrated inFIG. 5, etc.). The subbands may also be split among RBs with an equal or near equal distribution. For example, assuming a PUSCH allocation of B RBs over X subbands, the number of RBs for each subband may be floor(B/X), with any remainder of RBs being in the last subband. Thus, a PUSCH allocation of 20 RBs for a TPMI bundle of 4 TPMIs may be split equally into four subbands of 5 RBs each, while a PUSCH allocation of 22 RBs for the same TPMI bundle may be split into three subbands of 5 RB and one subband of 7 RB.

When the total PUSCH allocation of all subbands is smaller than a threshold (e.g. 3 RBs), or when the difference in PUSCH allocation between two subbands is greater than the threshold, the UE may refrain from re-interpreting TPMI and instead use the received TPMI for all subbands in order to prevent a high imbalance across the antennas. For example, assuming a PUSCH allocation of B RBs and given X subbands, the subbands may be divided into floor(B/X) RBs for all subbands except the last subband, which includes B−(X−1)*floor(B/X) RBs. If the difference between floor(B/X) and B−(X−1)*floor(B/X) is greater than a threshold, the UE may apply wideband TPMI and refrain from applying subband TPMI (i.e. re-interpreted TPMI). Otherwise, the UE may apply re-interpreted TPMI. As an example, if the PUSCH allocation is 22 RBs and there are 4 subbands, three subbands may be allocated 5 RBs and the fourth subband would be allocated 7 RB. In such case, if the configured threshold is 3 RBs, the UE may apply re-interpreted TPMI since the difference (e.g. 7 RBs−5 RBs) is less than the threshold (e.g. 3 RBs). Alternatively, if the configured threshold is 1 RB, the UE may apply wideband TPMI and refrain from re-interpreting TPMI since the difference (7 RBs−5 RBs) is greater than the configured threshold (e.g. 1 RB). As a result, an imbalance of power that may result from applying the same split power to different RB allocations in subbands may be prevented.

The number of subbands X may also be configured based on a UE capability message of the UE. The UE capability message may indicate, for example, how many subbands may exist (e.g. based on the number of antennas of the UE), the minimum size of each subband, and the maximum difference in size between any two subbands. For instance, the UE may report a UE capability message indicating the aforementioned subband information to the base station, and the base station may send an RRC message to the UE configuring a number of subbands and/or size of each subband based on the subband information. The UE may then apply re-interpreted TPMI to each subband. Alternatively, the UE may determine a number of subbands and sizes of each subband autonomously, and the UE may report the number of subbands and the sizes of each subband for the base station to reference (e.g. in the UE capability message).

The UE may also apply re-interpreted TPMI when performing inter-slot or intra-slot frequency hopping. In frequency hopping, the bandwidth may generally be split based on a number of hops (e.g. 20 MHz may be split into two bands of 10 MHz each corresponding to one hop). In intra-slot frequency hopping, the bandwidth may also be split based on a number of symbols (e.g. the first hop in the first 10 MHz band may span the first 7 symbols of a single slot, and the second hop in the second 10 MHz band may span the last 7 symbols of the single slot). However, when the ULE receives a TPMI for a frequency range corresponding to one hop (e.g. 10 MHz in the above example), the ULE may re-interpret the TPMI as corresponding to different subbands within the hop. For instance, if the UE receives a TPMI of [0, 1], the UE may split the 10 MHz into different subbands of 5 MHz in which the UE may apply different re-interpreted TPMI (e.g. [1,0] in the first 5 MHz and [0, 1] in the second 5 MHz). Moreover, whenever the UE hops to a next frequency (whether inter-slot or intra-slot), the UE may switch or cycle the antennas transmitting in the different subbands. For example, referring toFIG. 4, if the wireless communication device402is performing frequency hopping and receives a TPMI of [0, 1] (which corresponds to the TPMI bundle: [1, 0] and [0, 1]), Ant0may transmit in the first sub-band of the first hop and Ant1may transmit in the second sub-band of the first hop, while Ant1may transmit in the first sub-band of the second hop and Ant0may transmit in the second sub-band of the second hop. Thus, Antennas0and1may cycle or switch between subbands.

As a result, the UE may apply TPMI re-interpretation and bundling not only for achieving full transmission power for non-coherent antennas with zero precoders as described above, but also for reducing DCI overhead. When the UE receives DCI from the base station scheduling a PUSCH transmission, a certain number of bits may be used for wideband TPMI. For instance, when the UE has two non-coherent antennas as illustrated inFIG. 4, one bit in DCI may indicate to the UE whether to apply TPMI [0, 1] or TPMI [1, 0] when transmitting from its two antennas. The UE may also receive an RRC or MAC-CE configuring different mappings of wideband TPMIs to subband TPMIs. Thus, one bit in DCI may effectively indicate several TPMI for two antennas based on the RRC or MAC-CE mapping configuration. In this way, DCI overhead may be reduced. Therefore, TPMI reinterpretation for different subbands may be used to improve wireless communication in multiple ways (e.g. allowing for full transmission power, reducing DCI overhead, etc.).

FIG. 8illustrates an example communication flow800between a UE802and a base station804that may involve aspects for reinterpreting TPMI for various subbands (thus improving transmission power at the UE, reducing DCI overhead, etc.). The UE802may comprise non-coherent antenna ports, e.g., as described with respect toFIG. 4or partially coherent antenna ports, e.g., as described in connection withFIG. 5.

The UE802may report the UE's capability806to a base station804. That is, the UE802may transmit a report to the base station804that provides UE capability information. The UE capability may provide information on one or more of (1) how many subbands exist, (2) a minimum size of each subband, or (3) a maximum difference in size between any two subbands. Each of these one or more subbands may include a first subband and a second subband.

The base station804may transmit an RRC message808. Accordingly, the UE802may receive the RRC message808. The RRC message may include information for configuring the subbands. Thus, at block810, the UE802may configure at least one of the first subband or the second subband based on the RRC message.

The base station804may transmit a configuration812. Accordingly, the UE802may receive the configuration. The configuration may indicate time-frequency resources associated with the first subband and the second subband. Accordingly, at block814, the UE may configure the first subband and the second subband using the configuration information received.

The base station804may transmit TPMI mapping information816. The UE802may receive the TPMI mapping information816. The TPMI mapping information may indicate a mapping between a received TPMI (e.g. wideband TPMI) and a set of TPMIs (e.g. re-interpreted or subband TPMIs). Accordingly, using the TPMI mapping information, a UE may determine sets of TPMIs from a received TPMI.

The UE802may transmit a scheduling request (SR) for an uplink grant818. The base station804may receive the SR for the uplink grant818. Accordingly, the base station may respond to the SR for the uplink grant. For example, the base station804may transmit a TPMI820associated with a first set of coherent physical antennas and a second set of coherent physical antennas. The UE802may receive the TPMI820associated with the first set of coherent physical antennas and the second set of coherent physical antennas. In an aspect, the base station804may transmit an uplink grant (e.g. DCI) in response to the SR with the PUSCH allocation. The UE802may receive the uplink grant including the PUSCH allocation in response to the SR. The uplink grant may include the received TPMI.

At block822, the UE802may determine a set of TPMIs based on the received TPMI. The set of TPMIs may include at least one TPMI different from the received TPMI. For example, the UE may determine the first TPMI and the second TPMI of the set of TPMIs based on at least one of (1) a pre-specified sequence, (2) a cycled state of the pre-specified sequence, (3) a slot index associated with the transmissions on the first physical antenna and the second physical antenna, (4) a hybrid automatic repeat request (HARQ) ID, or (5) an ID of the UE, as indicated at824.

At826, the UE802may determine a transmission (TX) power for transmitting from the first physical antenna and the second physical antenna. For example, the UE802may be preconfigured with a setting for the UE's transmit power. At828, the UE802may determine whether the TX power is less than a TX power threshold (e.g. a PA limit). For example, the UE may compare the determined transmit power to the threshold and select to apply the received TPMI (wideband TPMI) if the TX power is less than the TX power threshold, or to apply the set of TPMI (subband TPMIs) if the TX power meets the TX power threshold.

At830, the UE802may determine a subband size of the first subband and the second subband for transmitting from the first physical antenna and the second physical antenna. For example, the subband size may be set at the UE based on RRC messaging. At832, the UE802may determine whether the subband size is greater than or equal to a threshold. For example, the determined subband size may be compared to the threshold, and the UE may select to apply the received TPMI (wideband TPMI) if the determined subband size is less than the threshold, or to apply the set of TPMI (subband TPMIs) if the subband size is greater than or equal to the threshold.

At834, the UE802may transmit, based on a first TPMI of the set of TPMIs, on a first physical antenna of the first set of coherent physical antennas on a first subband. At836, the UE may transmit, based on a second TPMI of the set of TPMIs, on a second physical antenna of the first set of coherent physical antennas on a second subband different from the first subband. In an aspect, the transmitting based on the set of TPMIs (subband TPMIs) may be based on the TX power meeting a TX power threshold, as determined at828. In an aspect, the transmitting from the first physical antenna and the second physical antenna may alternatively be based on the received TPMI (wideband TPMI) when the subband size is less than the threshold, as determined at832.

At838, the UE802may transmit, subsequently, based on a first TPMI of the set of TPMIs, on a first physical antenna of the first set of coherent physical antennas on a third subband. At840, the UE802may transmit, subsequently, based on a second TPMI of the set of TPMIs, on a second physical antenna of the first set of coherent physical antennas on a fourth subband different from the third subband. The third subband and the fourth subband may both be different from the first subband and the second subband. The subsequent transmissions on the third and fourth subbands may also be concurrent in time with the transmissions on the first subband and the second subband.

FIG. 9illustrates an example900of a wireless communication device902having partial coherent antennas. The wireless communication device902may correspond to the wireless communication device502ofFIG. 5. For example, a first set of antennas904is coherent. Thus, Ant0and Ant1in set904are capable of maintaining a relative phase difference between each other over time. Similarly, a second set of antennas906is coherent, with Ant2and Ant3being capable of maintaining a relative phase difference between each other over time. However, the first set of coherent antennas904is non-coherent to the second set of coherent antennas906. For example, the wireless communication device902may not maintain phase coherence between Ant0in set904and Ant2in set906, and similarly may not maintain phase coherence between Ant1in set904and Ant3in set906. In other words, the wireless communication device902can maintain phase coherence between antennas included in each of two antenna groups (e.g., first antenna set904and second antenna set906), but may not maintain phase coherence between the two antenna groups. Therefore, the wireless communication device902may be described as being capable of achieving partial coherence among antenna ports of the wireless communication device or as having partial coherent antennas. The non-coherent antenna sets may be associated with different precoder values, as shown inFIG. 9. For example, Ant0and Ant1in the first coherent set904may be associated with precoder values of ½ and 0, respectively, while Ant2and Ant3in the second coherent set906may be associated with a precoder value of 0 and ½, respectively. The number of antennas shown inFIG. 9are merely examples, a wireless communication device may include any number of sets of coherent antennas that are non-coherent with each other, whereasFIG. 9only illustrates two sets of coherent antennas. Further, each coherent set may include any number of coherent antennas.

When a UE has multiple antennas, an allocation of RBs to the antennas may be made in the frequency domain. For example, when the UE includes two sets of antennas with each set having two antennas, as illustrated in the example ofFIG. 9, an allocation of RBs to the antennas may be made in the frequency domain. The RBs may be allocated across the antennas based on a TPMI.

The TPMI may be a matrix of multipliers or weights that may be used on an information stream. For example, the multipliers may be estimates of a channel for the particular antenna (or antennas) that the multiplier is to be applied to. The multipliers may impact the power levels used for transmissions on each of the antennas. For example, as illustrated inFIG. 9, Ant0may have a multiplier of 1/√2 and Ant1may have a multiplier of 0. Accordingly, Ant0may transmit at a power level based on some base power multiplied by 1/√2. Ant1may transmit at a power level based on some base power multiplied by 0. Thus, in the example ofFIG. 9, Ant0transmits and Ant1does not transmit during the time when the illustrated TPMI is valid. Similarly, Ant2may transmit at a power level based on some base power multiplied by 0. Ant3may transmit at a power level based on some base power multiplied by ½. Thus, in the example ofFIG. 9, Ant2does not transmit and Ant3does transmit during the time when the illustrated TPMI is valid. The TPMIs may be illustrated using binary whole numbers, e.g., [0,1] and [1,0], rather than the actual multiplier, e.g., 1/√2 and 0. Thus, the TPMI for antenna set904may be indicated as [1,0] rather than [1/√2,0]. Similarly, the TPMI for antenna set906may be indicated as [0,1], rather than [0, 1/√2]. Alternatively, [1/√2, 0] and [0, 1/√2] may be used as valid TPMIs.

When a base station signals a TPMI to a UE (e.g., [0,1] or [1,0]), the TPMI may be interpreted differently. For example, UEs with antennas that may not transmit at full power due to power control may re-interpret TPMI as described above.

In one aspect, a subband may be split. For example, a first subband of the wideband may use one TPMI, e.g., [0,1] or [1,0], and a second subband of the wideband may use another TPMI, e.g., [1,0] or [0,1] respectively. The TPMIs may be opposite to each other, e.g., when the first subband uses [1,0], the second subband may use [0,1]. Similarly, when the first subband uses [0,1], the second subband may use [1,0]. Thus, each TPMI indication may result in the UE transmitting with a different TPMI on separate subbands for uplink communications. For example, assuming two TPMIs may be indicated in DCI (TPMI1 or [0, 1] and TPMI2 or [1, 0]), then when TPMI1 is indicated, the UE applies TPMI in one subband of the PUSCH allocation and TPMI2 in the other subband of the allocation.

By setting up a transmission in a portion of the bandwidth, e.g., a subband, using one TPMI and setting up a second transmission in the other portion of the bandwidth, e.g., another subband, using another TPMI, the UE may transmit across the wideband with full transmit power. For example, the power scaling implemented in power control may result in a calculated transmit power assuming a single subband using a single TPM. Accordingly, the power may be doubled as compared to a single TPMI used across both subbands. Thus, using one TPMI, transmission may be achieved using full power for the subband. Similarly, using the other TPMI, transmission may be achieved using full power for the other subband. Accordingly, one antenna may use full power in one subband and another antenna may use full power for the other subband. Thus, the device may transmit at full power across the two subbands.

Thus, in TPMI re-interpretation, a UE may set up a first transmission in one subband using one TPMI and a second transmission in another subband using another TPMI. The UE may receive a first TPMI from the base station (a wideband TPMI). The UE may reinterpret the received TPMI as two different TPMIs (subband TPMIs), e.g., the received TPMI and another TPMI or as two TPMIs distinct from the received TPMI. For example, when an invalid TPMI is received, the invalid TPMI may be interpreted as a set of valid TPMIs.

In an aspect, the TPMI re-interpretation described above may be selectively used by the UE. The TPMI re-interpretation may be selected autonomously by the UE. The UE may select to apply TPMI re-interpretation based on whether the UE reached a per power amplifier (PA) power limit or not. For example, a UE that may be capable of applying TPMI re-interpretation may select not to apply TPMI re-interpretation when the UE is at a cell center, e.g., near a base station. Conversely, the UE may select to apply TPMI re-interpretation when the UE moves to cell edge, e.g., where the UE may need to function at or near full power for a transmission to reach a base station with enough power to be received by the base station.

As described above, a UE may set up a first transmission in one subband using one TPMI and a second transmission in another subband using another TPMI to result in full transmission power, although TPMI re-interpretation may result in other advantages such as DCI overhead reduction. Generally, when a UE is set to transmit at full power, the power may be divided based on power control operation, as described herein. The division of the power may not be an issue when a full power transmission is not being selected. When less than full power is selected by the UE, the power control may ramp up the power until either a target power is reached or full power is reached. When full power is reached, TPMI reinterpretation may be employed. Once the target power is reached, the UE may transmit at that power. Thus, cutting a power level of a transmission in half may generally not be an issue when power may be increased further by the power control. For example, when a UE is close to a base station, the UE may be able to increase the power level based on power control until a target power level to complete transmissions is reached. Conversely, when the UE is far from the base station, the UE may not be able to increase the power level based on power control until the target power level to complete transmissions is reached. For example, power may already be increased to maximum power, but due to reduction of transmission power across different antennas as described above, full power may not be reached. Accordingly, TPMI re-interpretation may be used to address this issue.

TPMI mapping information may include information that indicates a mapping between a received TPMI and a set of TPMIs. A UE may receive TPMI mapping information, for example, through one of a RRC message or a MAC CE from a base station. The set of TPMIs may be determined based on the received TPMI mapping information. The UE may thus be configured with the set of TPMIs based on the RRC message or the MAC CE. The RRC message or MAC CE may indicate how each TPMI indication is mapped into TPMI bundles.

The UE may be configured to split a PUSCH allocation received in an uplink grant in subbands. For example, the UE may be configured with a particular split of the PUSCH allocation in the subbands. Assuming an example PUSCH allocation of 20 PRBs, the 20 PRBs may be split between two subbands as 10 PRBs in a first subband and 10 PRBs in a second subband, 15 PRBs in the first subband and 5 PRBs in the second subband, 5 PRBs in the first subband and 15 PRBs in the second subband, or other combinations of PRBs that add to 20 PRBs total, in various examples. Thus, a UE may receive a signal from a base station including configuration information that indicates resources, such as the number of RBs or specific RBs associated with a first subband and the number of RBs or specific RBs associated with a second subband.

As described herein, a received TPMI may be re-interpreted to a set of TPMIs. When the TPMI is re-interpreted to a set of TPMIs with corresponding subband assignments, an ordering for the TPMIs may be used. For example, when a TPMI such as [0,1] is received, the TPMI ([0,1]) may be re-interpreted as two TPMIs [0,1] and [1,0]. The order that the two TPMIs that are applied to antenna ports may be, for example, pre-specified orders such as [0,1] [1,0] or [1,0] [0,1]. Accordingly, the UE may cycle through the set of TPMIs, applying the TPMIs to corresponding antenna ports using one of the two specified orders (e.g., in a two TPMI example). Furthermore, the pre-specified orders may be changed or cycled.

In another example, for a non-coherent UE with four transmitters, when a PUSCH allocation is 20 PRBs, the PRBs may be split to four groups of 5 PRBs each. Four precoders may be cycled on the four subbands. The four precoders may be cycled on the four subbands using a pre-specified sequence. For example, the four precoders may be [1,0,0,0], [0,1,0,0], [0,0,1,0], [0,0,0,1]). The four precoders may be used on four antenna ports in any order as long as a precoder is not repeated during a given pre-specified sequence. The pre-specified sequence may be determined in advance. In other aspects, the pre-specified sequence may depend on slot index, HARQ ID, or UE ID, some other identifier, or some combination of these. For example, some mathematical function may be performed on slot index, HARQ ID, or UE ID, some other identifier, or some combination of these to generate the precoders. The mathematical function may be any mathematical function that generates a non-repeating sequence (e.g. non-repeating over the sequence, although the sequence itself may repeat). For example, some mathematical function may be used to generate the sequence [1,0,0,0], [0,1,0,0], [0,0,1,0], [0,0,0,1] from slot index, HARQ ID, or UE ID, some other identifier, or some combination of these. The precoders may be applied to antenna ports in that order or any other non-repeating order.

In some instances, a TPMI that was valid for one version of a communication standard may not be valid for another version of the communication standard or a different communication standard on which, for example, a UE may be capable of communicating. Accordingly, a device may receive a TPMI that is not valid. A TPMI that is not valid, i.e., an invalid TPMI, may be reinterpreted to one or more valid TPMI according to TPMI re-interpretation as described above.

Similarly, in some instances, a TPMI that may be valid for UEs with coherent and/or partially coherent antennas may not be valid for a UE with non-coherent antennas. In some instances a TPMI may not be valid for a UE with partially coherent antennas. However, such a TPMI that is valid for coherent antennas (e.g., of a UE with MIMO capability) may in some instances be received by a UE with non-coherent antennas. Accordingly, a device such as a UE with non-coherent antennas may receive a TPMI that is not valid for that device. For example, a UE with UL MIMO capability and non-coherent or partially coherent antennas may receive an invalid TPMI. The invalid TPMI may be reinterpreted to one or more valid TPMI according to TPMI re-interpretation as described above.

For example, a TPMI of [1,1] may indicate that the two antenna ports of a UE may be used for transmission. Such a TPMI may be valid for a UE that has two antenna ports which are coherent. Accordingly, both antenna ports may be used for transmissions at the same time. A UE with coherent antennas that receives a TPMI of [1,1] may therefore apply that TPMI to transmissions and transmit on both antenna ports. However, for a UE with two non-coherent antennas which may not transmit at the same time, the TPMI [1,1] may be invalid. Accordingly, transmitting on both non-coherent antenna ports may not be a valid function and the TPMI [1,1] is not a valid TPMI for the UE. The TPMI that is not valid, i.e., the invalid TPMI, may be reinterpreted to one or more valid TPMI (e.g. [0, 1] or [1, 0]) as described above.

Furthermore, when an invalid TPMI is re-interpreted, the TPMI may be re-interpreted as a set of TPMIs, e.g., a TPMI bundle. For example, for a non-coherent UE with two transmitters or two antenna ports, as discussed above, the TPMI [1,1] may not be valid. The TPMI [1,1] generally may not be signaled. For some cases, the TPMI [1,1] may be signaled to enable the sub-band precoding and full transmit power, as described herein, whereas the TPMIs [0,1] and [1,0] still have the same behavior as in some cases.

In an aspect, when a PUSCH allocation is expected to be split into some number of subbands, e.g., X subbands, when the total allocation is smaller than a threshold (e.g., three RBs or another number), the UE may determine not to re-interpret TPMI. For example, for the case when the total allocation is smaller than a threshold, the TPMI that is applied may be the received TPMI. In such case, the UE may not perform TPMI re-interpretation from a received TPMI to a set of TPMIs, since TPMI re-interpretation in cases when the total allocation is smaller than such threshold may result in a high imbalance of RBs transmitted across the antennas. For example, with three RBs used for transmissions, when TPMI re-interpretation occurs, the result may be two TPMIs with one TPMI being used for two RBs on one antenna and another TPMI being used for one RB on another antenna. Accordingly, re-interpretation may result in an imbalance of two RBs to one RB. A one RB imbalance where the total number of RBs is only three may be considered a high imbalance. Accordingly, the imbalance of one RB is a high percentage imbalance when compared to the total RBs and to the RBs used on each antenna port, e.g., one RB imbalance compared to two RBs or one RB over the antenna ports. As the total number of RBs is increased, e.g., 5, 7, 9, etc., the imbalance percentage difference decreases. For example, with nine RBs are split across two antenna ports, an imbalance of one RB may result when the split is 5 RBs and 4 RBs, which may not be considered a high imbalance. In such case, TPMI reinterpretation may still occur.

In another aspect, when the PUSCH allocation is B RBs, and there are X subbands, each TPMI may be applied on floor(B/X) subbands for all except the last one which uses B−(X−1)*floor(B/X). When the difference floor(B/X) minus (B−(X−1)*floor(B/X)) is larger than a threshold, then the UE may determine to apply wideband TPMI and TPMI re-interpretation may not be used. As an example, if the PUSCH allocation is 22 RBs and there are 4 subbands, three subbands may be allocated 5 RBs and the fourth subband may be allocated 7 RB. In such case, if the configured threshold is 1 RB, the UE may apply wideband TPMI and refrain from re-interpreting TPMI since the difference (7 RBs−5 RBs) is larger than the configured threshold (e.g. 1 RB). As a result, an imbalance of power that may result from applying the same split power to different RB allocations in subbands may be prevented.

In some aspects, different UEs may have different capabilities. For example, UEs used on different communication systems may have different capabilities. UE capabilities may vary based on how many subbands may be used, the minimum size of each subband, the maximum difference in the size between any two subbands, and/or other UE capabilities.

FIG. 10Aillustrates an example of intra-slot frequency hopping1000.FIG. 10Billustrates an example of inter-slot frequency hopping1050. A UE may be configured to transmit over multiple, e.g., two, frequency allocations of a PUSCH. The transmissions may be over the span of a sequence of OFDM symbols. Transmitting over multiple frequency allocations of a PUSCH (e.g. over the span of a sequence of OFDM symbols) may be referred to as frequency hopping.

When a UE is configured for frequency hopping, e.g., either intra-slot (FIG. 10A) or inter-slot (FIG. 10B), the antennas used may cycle between the subbands. For example,FIG. 10Aillustrates a first frequency range1002for possible transmissions of antenna01004and antenna11006. Antenna0and/or antenna1, within frequency range1002, may transmit depending on the values in the precoding matrix indicated from re-interpreted TPMI. A second frequency range1008for possible transmissions of antenna01010and antenna11012is illustrated as well inFIG. 10A, but where the ordering of the antennas has changed. Initially, antenna01004was on a higher range of frequencies than antenna11006within the first frequency range1002, while antenna01010is on a lower range of frequencies than antenna11012within the second frequency range1008. However, frequency hopping may not require the changes illustrated in the specific example ofFIG. 10A. Rather, many different combinations of frequency changes over time are possible. Antenna0and/or antenna1, within frequency range1008, may transmit depending on the values in the precoding matrix indicated from re-interpreted TPMI. In an aspect, the first TPMI and the second TPMI may be applied on the first subband and the second subband of frequency range1002respectively as an initial frequency. After a frequency hop, the second TPMI and the first TPMI may be applied on the first and second subband of frequency range1008, respectively.

FIG. 10Billustrates a first frequency range1052for possible transmissions of antenna01054and antenna11056. Antenna0and/or antenna1, within frequency range1052, may transmit depending on the values in the precoding matrix indicated from re-interpreted TPMI. A second frequency range1058for possible transmissions of antenna01060and antenna11062is also illustrated where the ordering of the antennas has changed. Initially, antenna01054was on a higher range of frequencies than antenna11056within the first frequency range1052, while antenna01060is on a lower range of frequencies than antenna11062within the second frequency range1058. However, frequency hopping may not require the changes illustrated in the specific example ofFIG. 10B. Rather, many different combinations of frequency changes over time are possible. Antenna0and/or antenna1, within frequency range1058, may transmit depending on the values in the precoding matrix indicated from re-interpreted TPMI. In an aspect, the first TPMI and the second TPMI may be applied on the first subband and the second subband of frequency range1052respectively as an initial frequency. After a frequency hop, the second TPMI and the first TPMI may be applied on the first and second subband respectively of frequency range1058.

FIG. 11is a flowchart1100of a method of wireless communication. The method may be performed by a UE (e.g., the UE104,350,402,502,802,902; the apparatus1302/1302′; the processing system1414, which may include the memory360and which may be the entire UE350or a component of the UE350, such as the TX processor368, the RX processor356, and/or the controller/processor359). Optional aspects are illustrated in dashed lines. The method allows a UE to perform TPMI re-interpretation of a TPMI received from a base station (e.g. the base station102/180,310,804,1350).

At1102, the UE may report a UE capability to a base station. The UE capability may indicate at least one of a number of subbands including at least one first subband and at least one second subband, a minimum size for a subband of the at least one first subband and the at least one second subband, or a maximum difference in size between a pair of subbands of the at least one first subband and the at least one second subband. For example,1102may be performed by a report UE capability component of transmission component1314. For example, referring toFIG. 8, the UE802may report the UE's capability806to a base station804. That is, the UE802may transmit a report to the base station804that provides UE capability information on one or more of (1) how many subbands exist, (2) a minimum size of each subband, or (3) a maximum difference in size between any two subbands. Providing the UE capabilities to the base station1350may allow the base station1350to configure the UE with the subbands for TPMI re-interpretation.

At1104, the UE may receive an RRC message. For example,1104may be performed by the RX RRC component of reception component1304. The RRC message may configure the at least one first subband and the at least one second subband. Moreover, the RRC message may indicate how each TPMI indication is mapped into TPMI bundles, e.g., different groups or sets of TPMIs. For example, referring toFIG. 8, the UE802may receive a RRC message808from the base station804including information for configuring the subbands. For instance, the base station may configure the UE with respect to how the PUSCH allocation is to be split in different subbands. For example, if the base station schedules an allocation of PUSCH resources (e.g. in DCI) to the UE of 20 PRBs, the base station may configure the UE to split the PUSCH allocation equally (e.g. 10 PRBs in one subband and 10 PRBs in another subband) or unequally (e.g. 5 PRBs in one subband and 15 PRBs in another subband).

At1106, the UE may configure the at least one first subband and the at least one second subband based on the RRC message. For example,1106may be performed by configuration component1312. Using the RRC message, the UE can determine how each TPMI indication is mapped into TPMI bundles, e.g., groups of TPMIs. The UE may configure at least one of the first subband or the second subband based on the RRC message by determining mapping from the RRC message, and using the mapping to determine a number of needed subbands and selected subbands from available frequency ranges, for example. For instance, referring toFIG. 8, at block810, the UE802may configure at least one of the first subband or the second subband based on the RRC message808. For example, when the UE receives a PUSCH allocation of RBs, the UE may split the subbands among RBs with an equal or near equal distribution. For instance, assuming a PUSCH allocation of B RBs over X subbands, the UE may select as a number of RBs for each subband to be floor(B/X), with any remainder of RBs being in the last subband. Thus, a PUSCH allocation of 20 RBs for a TPMI bundle of 4 TPMIs may be split equally into four subbands of 5 RBs each, while a PUSCH allocation of 22 RBs for the same TPMI bundle may be split into three subbands of 5 RB and one subband of 7 RB.

At1108, the UE may receive a configuration indicating time-frequency resources associated with the first subband and the second subband. For example,1108may be performed by RX configuration component of the reception component1304. The configuration information may include information with respect to how to split the PUSCH allocation in subbands, e.g., for 20 PRBs, splits may include, but are not limited to 10 PRBs and 10 PRBs, 15 PRBs and 5 PRBs, 5 PRBs and 15 PRBs, or other combinations that add to 20 PRBs. For example, referring toFIG. 8, the UE802may receive a configuration812from the base station804indicating time-frequency resources associated with the first subband and the second subband. For instance, the configuration812may include slots and/or symbols and RBs corresponding to the different subbands of a PUSCH allocation for the UE.

At1110, the UE may receive TPMI mapping information indicating a mapping between the received TPMI and the set of TPMIs. For example,1110may be performed by the RX TPMI mapping component of the reception component1304. The TPMI mapping information may be received through one of a RRC message or a MAC-CE. The mapping information may indicate how one or more TPMIs each map to bundles, groups, or sets of TPMIs. For example, referring toFIG. 8, the UE802may receive TPMI mapping information816from the base station804. The TPMI mapping information may indicate a mapping between a received TPMI (e.g. wideband TPMI) and a set of TPMIs (e.g. re-interpreted or subband TPMIs). For instance, referring toFIGS. 4 and 5, the base station may configure the UE with respect to how each TPMI indication (received TPMI) is mapped into TPMI bundles for re-interpretation, e.g., in a RRC message or a MAC-CE. For example, if the UE has two non-coherent antennas such as illustrated inFIG. 4, the UE may be configured via RRC or MAC-CE with a mapping that a received TPMI of [0, 1] may correspond to the following example TPMI bundle: [1, 0] for the first subband and [0, 1] for the second subband. Thus, the UE may re-interpret the TPMI such that it applies [1, 0] for one subband of a PUSCH allocation (e.g. one half of the total bandwidth) and [0, 1] for the other subband of the PUSCH allocation (e.g. the other half of the total bandwidth). In another example, if the UE has two partially coherent sets of non-coherent antennas such as illustrated inFIG. 5(four antennas total), the UE may be configured by the base station with a mapping that a received TPMI of [1, 1, 0, 0] may correspond to the following example TPMI bundle: [1, 0, 1, 0] for a first subband, [0, 1, 0, 1] for a second subband, [0, 1, 1, 0] for a third subband, and [1, 0, 0, 1] for a fourth subband. The number of subbands may be equal to the number of antennas.

FIG. 12is a flowchart1200of a method of wireless communication. The method may be performed by a UE (e.g., the UE104,350,402,502,802,902; the apparatus1302/1302′; the processing system1414, which may include the memory360and which may be the entire UE350or a component of the UE350, such as the TX processor368, the RX processor356, and/or the controller/processor359). Optional aspects are illustrated in dashed lines. The method continues fromFIG. 11in allowing a UE to perform TPMI re-interpretation of a TPMI received from a base station (e.g. the base station102/180,310,804,1350).

At1202, the UE may transmit a SR for an uplink grant. For example,1202may be performed by SR UL grant component of transmission component1314. The SR for the uplink grant may signal the base station to transmit a TPMI, e.g., as part of a response to the SR (e.g. in an uplink grant). The at least one first subband and the at least one second subband may be divisions of a PUSCH resource allocation in the uplink grant. For example, referring toFIG. 8, the UE802may transmit an SR for an uplink grant818, and the base station804may transmit to the UE an uplink grant (e.g. DCI) in response to the SR with the PUSCH allocation. The uplink grant may include the received TPMI820.

At1204, the UE receives a TPMI associated with at least one first antenna and at least one second antenna. The at least one first antenna and the at least one second antenna are non-coherent with each other. For example,1204may be performed by RX TPMI component of the reception component1304. The TPMI may be received in the uplink grant in response to the SR transmitted at1202. The TPMI information may be applied to the antenna configuration of the UE to determine antennas where transmissions will occur. For example, referring toFIG. 8, the UE802may receive a TPMI820from the base station804in response to the SR for the uplink grant818. Moreover, referring toFIGS. 4 and 5, the TPMI may be associated with at least one first antenna (e.g. Ant0inFIG. 4, or Ant0and/or1inFIG. 5) and at least one second antenna (e.g. Ant1inFIG. 4, or Ant2and/or3inFIG. 5) which are non-coherent with each other. For example, with respect toFIG. 4, a received TPMI of [0, 1] may result in Ant0not transmitting and Ant1transmitting at half power across a PUSCH allocation, and with respect toFIG. 5, a received TPMI of [0, 0, 1, 1] may result in Ants0and1not transmitting and Ants2and3transmitting at half power combined across a PUSCH allocation.

At1206, the UE determines a set of TPMIs based on the received TPMI. The set of TPMIs include at least one TPMI different from the received TPMI. For example,1206may be performed by determine set of TPMI component1306. For example, the set of TPMIs may be determined based on at least one of a pre-specified sequence, a cycled state of the pre-specified sequence, a slot index, a HARQ ID, or an ID of the UE. The set of TPMIs may be determined based on the received mapping information at1110. For example, the set of TPMIs may be determined by applying a received TPMI to a mapping of a received TPMI to a set of TPMIs and determining the set of TPMIs from the mapping. For instance, referring toFIG. 8, at block822, the UE802may determine a set of TPMIs based on the received TPMI. In on example, the set of TPMIs may be determined based on TPMI mapping information816. For instance, referring toFIG. 4, the UE may determine from the mapping that a received TPMI of [0, 1] may correspond to the following example TPMI bundle: [1, 0] for the first subband and [0, 1] for the second subband. Similarly, referring toFIG. 5, the UE may determine from the mapping that a received TPMI of [1, 1, 0, 0] may correspond to the following example TPMI bundle: [1, 0, 1, 0] for a first subband, [0, 1, 0, 1] for a second subband, [0, 1, 1, 0] for a third subband, and [1, 0, 0, 1] for a fourth subband. Moreover, referring back toFIG. 8, in another example, the UE802may determine the first TPMI and the second TPMI of the set of TPMIs based on at least one of (1) a pre-specified sequence, (2) a cycled state of the pre-specified sequence, (3) a slot index associated with the transmissions on the first physical antenna and the second physical antenna, (4) a HARQ ID, or (5) an ID of the UE, as indicated at824.

At1208, the UE may determine a combined Tx power for transmitting from the at least one first antenna and the at least one second antenna. For example,1208may be performed by the TX power component of the determination component1310. The TX power may be determined by, for example, receiving or reading a TX power setting and using the reported result for further processing, e.g., at1210. For example, referring toFIG. 8, at826, the UE802may determine a Tx power for transmitting from a first physical antenna and a second physical antenna. For example, the UE802may be preconfigured with a setting for the UE's transmit power.

At1210, the UE may determine whether the combined Tx power meets a TX power threshold. For example,1210may be performed by TX power threshold component of the determination component1310. For example, the UE may get the result at1208and compare the result to the threshold. The UE may transmit from the at least one first antenna based on the first TPMI, and from the at least one second antenna based on the second TPMI, when the combined Tx power meets the Tx power threshold. Alternatively, the UE may transmit from the at least one first antenna and the at least one second antenna based on the received TPMI when the combined Tx power does not meet the Tx power threshold. For example, referring toFIG. 8, at828, the UE802may determine whether the TX power is less than a TX power threshold (e.g. a PA limit). For example, the UE may compare the determined transmit power to the threshold and select to apply the received (wideband) TPMI if the TX power is less than the TX power threshold, or to apply the set of (subband) TPMI if the TX power meets the TX power threshold. Moreover, referring toFIGS. 4 and 5, if the UE has non-coherent antennas or partially coherent antennas, the UE may determine whether to re-interpret a received TPMI or not based on a location of the UE. For instance, if the UE is located near a base station at the center of the cell, the UE may be below the PA limit and determine not to re-interpret TPMI, while if the UE is at a cell edge, the UE may have reached the PA limit and may determine to re-interpret TPMI.

At1216, the UE may determine a size of each subband of the at least one first subband and the at least one second subband. For example,1216may be performed by the subband size component of the determination component1310. For example, subband size may be based on determining available frequency ranges and applying the number of subbands needed to the frequencies available for use as subbands. For instance, referring toFIG. 8, at830, the UE802may determine a subband size of the first subband and the second subband for transmitting from the first physical antenna and the second physical antenna. For example, the subband size may be set at the UE based on RRC messaging. For instance, if the base station schedules an allocation of PUSCH resources (e.g. in DCI) to the UE of 20 PRBs, the base station may configure the UE to split the PUSCH allocation equally (e.g. 10 PRBs in one subband and 10 PRBs in another subband) or unequally (e.g. 5 PRBs in one subband and 15 PRBs in another subband). In another example, the UE may determine the size of each subband based on a number of TPMIs in a TPMI bundle or a number of antennas of the UE. The subbands may also be split among RBs with an equal or near equal distribution. For example, assuming a PUSCH allocation of B RBs over X subbands, the number of RBs for each subband may be floor(B/X), with any remainder of RBs being in the last subband. Thus, a PUSCH allocation of 20 RBs for a TPMI bundle of 4 TPMIs may be split equally into four subbands of 5 RBs each, while a PUSCH allocation of 22 RBs for the same TPMI bundle may be split into three subbands of 5 RB and one subband of 7 RB.

At1218, the UE may determine whether the size of each subband is greater than or equal to a threshold. For example,1218may be performed by the subband size threshold component of the determination component1310. The UE may transmit from the at least one first antenna based on the first TPMI and from the at least one second antenna based on the second TPMI when the size of each subband is greater than or equal to the threshold. Alternatively, the UE may transmit from the at least one first antenna and from the at least one second antenna based on the received TPMI when the size of one or more of the at least one first subband and the at least one second subband is less than the threshold. For example, referring toFIG. 8, at832, the UE802may determine whether the subband size is greater than or equal to a threshold. For example, the determined subband size may be compared to the threshold, and the UE may select to apply the received TPMI (wideband TPMI) if the determined subband size is less than the threshold, or to apply the set of TPMI (subband TPMIs) if the subband size is greater than or equal to the threshold.

In another example, when the total size of all subbands is smaller than a threshold (e.g. 3 RBs), or when the difference in size between two subbands is greater than the threshold, the UE may refrain from re-interpreting TPMI and instead use the received TPMI for all subbands in order to prevent a high imbalance across the antennas. As an example, if the PUSCH allocation is 22 RBs and there are 4 subbands, three subbands may be allocated 5 RBs and the fourth subband would be allocated 7 RB. In such case, if the configured threshold is 3 RBs, the UE may apply re-interpreted TPMI since the difference (e.g. 7 RBs−5 RBs) is less than the threshold (e.g. 3 RBs). Alternatively, if the configured threshold is 1 RB, the UE may apply wideband TPMI and refrain from re-interpreting TPMI since the difference (7 RBs−5 RBs) is greater than the configured threshold (e.g. 1 RB).

Where optional steps1208,1210,1216, and1218are skipped, then as indicated by1212, the UE may proceed directly to step1224below. Otherwise, if the UE performs steps1208and1210, then at1214, the UE may determine whether to transmit from the at least one first antenna based on the first TPMI and from the at least one second antenna based on the second TPMI, or alternatively based on the received TPMI, based on the combined Tx power as described above. Similarly, if the UE performs steps1216and1218, then at1220, the UE may determine whether to transmit from the at least one first antenna based on the first TPMI and from the at least one second antenna based on the second TPMI, or alternatively based on the received TPMI, based on the subband size as described above. In certain cases, at1222, the process may restart from1202for instances where the transmissions using TPMI re-interpretation are not used (e.g. when the UE decides to transmit based on the received TPMI rather than the set of TPMIs). Alternatively, various transmissions may be made without using TPMI re-interpretation.

At1224, the UE transmits, based on a first TPMI of the set of TPMIs, from the at least one first antenna within the at least one first subband. For example,1224may be performed by the TX first subband component of the transmission component1314. Moreover, at1226the UE transmits, based on a second TPMI of the set of TPMIs, from the at least one second antenna within the at least one second subband different from the at least one first subband. For example,1226may be performed by the TX second subband component of the transmission component1314. For instance, referring toFIG. 8, at834, the UE802may transmit, based on a first TPMI of the set of TPMIs, on a first physical antenna of the first set of coherent physical antennas on a first subband, and at836, the UE may transmit, based on a second TPMI of the set of TPMIs, on a second physical antenna of the second set of coherent physical antennas on a second subband different from the first subband. For example, referring toFIG. 4, if the UE receives a TPMI of [0, 1], the UE may re-interpret the TPMI as [1, 0] for the first subband and [0, 1] for the second subband of the PUSCH allocation. Thus, the UE may have Ant1transmit at half power across the first subband, and Ant0transmit at half power across the second subband, such that full power is transmitted in combination across both subbands.

The at least one first antenna and the at least one second antenna may be switched between the at least one first subband and the at least one second subband during frequency hopping. For example, when the UE receives a TPMI for a frequency range corresponding to one hop (e.g. 10 MHz), the UE may re-interpret the TPMI as corresponding to different subbands of the hop, as described above with respect toFIGS. 10A and 10B. For instance, if the UE receives a TPMI of [0, 1], the UE may split the 10 MHz into different subbands of 5 MHz in which the UE may apply different re-interpreted TPMI (e.g. [1,0] in the first 5 MHz and [0, 1] in the second 5 MHz). Moreover, whenever the UE hops to a next frequency (including inter-slot or intra-slot), the UE may switch or cycle the antennas transmitting in the different subbands. For example, referring toFIG. 4, if the wireless communication device402is performing frequency hopping and receives a TPMI of [0, 1] (which corresponds to the TPMI bundle: [1, 0] and [0, 1]), Ant0may transmit in the first sub-band of the first hop, Ant1may transmit in the second sub-band of the first hop, Ant1may transmit in the first sub-band of the second hop, and Ant0may transmit in the second sub-band of the second hop.

The at least one first antenna may comprise a first set of coherent antennas and the at least one second antenna may comprise a second set of coherent antennas. Thus, at1228, the UE may transmit subsequently, based on a first TPMI of the set of TPMIs, from the at least one first antenna on a third subband. For example,1228may be performed by the TX third subband component of the transmission component1314. Moreover, at1230, the UE may transmit subsequently, based on a second TPMI of the set of TPMIs, from the at least one second antenna on a fourth subband. For example,1230may be performed by the TX fourth subband component of the transmission component1314. For instance, referring toFIG. 8, at838, the UE802may transmit based on a first TPMI of the set of TPMIs, on a first physical antenna of the first set of coherent physical antennas on a third subband, and at840, the UE802may transmit, based on a second TPMI of the set of TPMIs, on a second physical antenna of the second set of coherent physical antennas on a fourth subband different from the third subband. For instance, referring toFIG. 5, Ant0and1may be part of a first set of coherent physical antennas, and Ant2and3may be part of a second set of coherent physical antennas, with each of the four antennas respectively transmitting on its own subband based on re-interpreted TPMIs.

One or more of the transmissions1224,1226,1228,1230may be based on the received TPMI on the first physical antenna and the second physical antenna when the size of at least one of the subbands is less than a threshold and/or when the combined Tx power is less than a Tx power threshold. Using the set of TPMIs for the transmissions1224,1226,1228,1230may be referred to as TPMI re-interpretation.

FIG. 13is a conceptual data flow diagram1300illustrating the data flow between different means/components in an example apparatus1302. The apparatus may be a UE. The apparatus includes a reception component1304that receives transmissions from a base station1350, e.g., as described in connection with1104,1108,1110ofFIG. 11 and/or 1204ofFIG. 12. The apparatus includes a determine set of TPMI component1306that determines a set of TPMIs based on a received TPMI, e.g., as described in connection with1206ofFIG. 12. The determination of the TPMI may be based on at least one of a pre-specified sequence, a cycled state of the pre-specified sequence, a slot index associated with the transmissions from the at least one first antenna and the at least one second antenna, a HARQ ID, or an ID of the UE. The apparatus includes a determination component1310that processes information and makes determinations, e.g., as described in connection with1208,1210,1216,1218ofFIG. 12. The apparatus includes a configuration component1312that configures the at least one of the first subband or the second subband based on a RRC message, e.g., as described in connection with1106ofFIG. 11. The apparatus includes a transmission component1314that transmits signals, i.e., uplink transmissions to base station1350, e.g., as described in connection with1102ofFIG. 11 and/or 1202, 1224, 1226, 1228, 1230ofFIG. 12.

The reception component1304that receives transmissions from the base station1350may include sub-components, such as a RX TPMI component that receives a TPMI associated with at least one first antenna and at least one second antenna, e.g., as described in connection with1204, a RX response component that receives an uplink grant in response to a transmitted SR request, e.g., as described in connection with1202, a RX TPMI mapping component that receives TPMI mapping information indicating a mapping between a received TPMI and a set of TPMIs, e.g., as described in connection with1110, a RX configuration component that receives a configuration indicating time-frequency resources associated with the at least one first and second subband, e.g., as described in connection with1108, and/or a RX RRC component that receives an RRC message configuring at least one first subband or second subband, e.g., as described in connection with1104.

The determination component1310that processes information and makes determinations may include sub-components, such as a TX power component that determines a combined Tx power for transmitting from the at least one first and second antennas, e.g., as described in connection with1208, a TX power threshold component that determines whether the combined Tx power meets a Tx power threshold, e.g., as described in connection with1210, a subband size component that determines a size of each subband of the at least one first and second subband, e.g., as described in connection with1216, and/or a subband size threshold component that determines whether the size of each subband is greater than or equal to a threshold, e.g., as described in connection with1218.

The transmission component1314that transmits signals, i.e., uplink transmissions, may include sub-components, such as a SR UL grant component that transmits a SR for an uplink grant, e.g., as described in connection with1202, a report UE capability component that reports a UE capability to a base station, e.g., as described in connection with1102, a TX first subband component that transmits based on a first TPMI from at least one first antenna within at least one first subband, e.g., as described in connection with1224, a TX second subband component that transmits based on a second TPMI from at least one second antenna within at least one second subband, e.g., as described in connection with1226, a TX third subband component that transmits subsequently from the at least one first antenna on a third subband, e.g., as described in connection with1228, and/or a Tx fourth subband component that transmits subsequently from the at least one second antenna on a fourth subband, e.g., as described in connection with1230.

FIG. 14is a diagram1400illustrating an example of a hardware implementation for an apparatus1302′ employing a processing system1414. The processing system1414may be implemented with a bus architecture, represented generally by the bus1424. The bus1424may include any number of interconnecting buses and bridges depending on the specific application of the processing system1414and the overall design constraints. The bus1424links together various circuits including one or more processors and/or hardware components, represented by the processor1404, the components1304(and subcomponents),1306,1310(and subcomponents),1312,1314(and subcomponents), and the computer-readable medium/memory1406. The bus1424may 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.

The processing system1414may be coupled to a transceiver1410. The transceiver1410is coupled to one or more antennas1420. The transceiver1410provides a means for communicating with various other apparatus over a transmission medium. The transceiver1410receives a signal from the one or more antennas1420, extracts information from the received signal, and provides the extracted information to the processing system1414, specifically the reception component1304. In addition, the transceiver1410receives information from the processing system1414, specifically the transmission component1314, and based on the received information, generates a signal to be applied to the one or more antennas1420. The processing system1414includes a processor1404coupled to a computer-readable medium/memory1406. The processor1404is responsible for general processing, including the execution of software stored on the computer-readable medium/memory1406. The software, when executed by the processor1404, causes the processing system1414to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory1406may also be used for storing data that is manipulated by the processor1404when executing software. The processing system1414further includes at least one of the components1304(and subcomponents),1306,1310(and subcomponents),1312,1314(and subcomponents). The components may be software components running in the processor1404, resident/stored in the computer readable medium/memory1406, one or more hardware components coupled to the processor1404, or some combination thereof. The processing system1414may be a component of the UE350and may include the memory360and/or at least one of the TX processor368, the RX processor356, and the controller/processor359. Alternatively, the processing system1414may be the entire UE (e.g., see350ofFIG. 3).

In one configuration, the apparatus1302/1302′ for wireless communication includes means for receiving a TPMI associated with at least one first antenna and at least one second antenna, the at least one first antenna and the at least one second antenna being non-coherent with each other; means for determining a set of TPMIs based on the received TPMI, the set of TPMIs including at least one TPMI different from the received TPMI; means for transmitting, based on a first TPMI of the set of TPMIs, from the at least one first antenna within at least one first subband; and means for transmitting, based on a second TPMI of the set of TPMIs, from the at least one second antenna within at least one second subband different from the at least one first subband.

In one configuration, the apparatus may include means for transmitting a SR for an uplink grant, where the TPMI is received in the uplink grant in response to the SR.

In one configuration, the at least one first antenna may comprise a first set of coherent antennas and the at least one second antenna comprises a second set of coherent antennas.

In one configuration, the at least one first subband and the at least one second subband may be divisions of a Physical Uplink Shared Channel (PUSCH) resource allocation.

In one configuration, the apparatus may include means for determining a combined transmission (Tx) power for transmitting from the at least one first antenna and the at least one second antenna; and means for determining whether the combined Tx power meets a Tx power threshold, wherein the transmitting from the at least one first antenna may be based on the first TPMI and the transmitting from the at least one second antenna may be based on the second TPMI when the combined Tx power meets the Tx power threshold.

In one configuration, the transmitting from the at least one first antenna and the transmitting from the at least one second antenna may be based on the received TPMI when the combined Tx power does not meet the Tx power threshold.

In one configuration, the apparatus may include means for receiving TPMI mapping information indicating a mapping between the received TPMI and the set of TPMIs, wherein the set of TPMIs is determined based on the received TPMI mapping information.

In one configuration, the TPMI mapping information may be received through one of a RRC message or a MAC-CE.

In one configuration, the apparatus may include means for receiving a RRC message configuring the at least one first subband and the at least one second subband.

In one configuration, the set of TPMIs may be determined based on at least one of a pre-specified sequence, a cycled state of the pre-specified sequence, a slot index, a HARQ identifier (ID), or an ID of the UE.

In one configuration, the apparatus may include means for reporting a UE capability to a base station, wherein the UE capability indicates at least one of: a number of subbands including the at least one first subband and the at least one second subband; a minimum size for a subband of the at least one first subband and the at least one second subband; or a maximum difference in size between a pair of subbands of the at least one first subband and the at least one second subband.

In one configuration, the apparatus may include means for determining a size of each subband of the at least one first subband and the at least one second subband; and means for determining whether the size of each subband is greater than or equal to a threshold, wherein the transmitting from the at least one first antenna is based on the first TPMI and the transmitting from the at least one second antenna is based on the second TPMI when the size of each subband is greater than or equal to the threshold.

In one configuration, the transmitting from the at least one first antenna and the transmitting from the at least one second antenna may be based on the received TPMI when the size of one or more of the at least one first subband and the at least one second subband is less than the threshold.

In one configuration, the at least one first antenna and the at least one second antenna may be switched between the at least one first subband and the at least one second subband during frequency hopping.

The aforementioned means may be one or more of the aforementioned components of the apparatus1302and/or the processing system1414of the apparatus1302′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system1414may include the TX Processor368, the RX Processor356, and the controller/processor359. As such, in one configuration, the aforementioned means may be the TX Processor368, the RX Processor356, and the controller/processor359configured to perform the functions recited by the aforementioned means.

Accordingly, the present disclosure allows UEs to re-interpret TPMI as a set of TPMIs, thereby improving transmission power and reducing DCI overhead. For example, the set of TPMIs may result in, e.g., two half power transmissions with one transmission on each of two subbands. The two ½ power transmissions on the separate two subbands result in a full power transmission, i.e., ½+½. Allowing the UE to transmit at full power may provide for better performance, e.g., when a UE is at a cell edge. When the UE is not on the cell edge, the UE may disable TPMI reinterpretation.