Staggered pilot placement

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be configured to receive a plurality of combined signals. Each combined signal may be on a tone of a plurality of tones. The apparatus may be configured to determine a first pilot signal on a first tone of the plurality of tones. The apparatus may be configured to generate an interference-reduced signal for the first tone by canceling the determined first pilot signal from a first combined signal on the first tone.

BACKGROUND

Field

The present disclosure relates generally to communication systems, and more particularly, to techniques of staggered pilot placement at a user equipment (UE) that may be used to enable interference cancelation at an evolved Node B (eNodeB) or another type of base station.

Background

SUMMARY

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be configured to receive a plurality of combined signals. Each combined signal may be on a tone of a plurality of tones. Each combined signal may include a first symbol of a first plurality of symbols from a first UE and a second symbol of a second plurality of symbols from a second UE. The first plurality of symbols may include at least one first pilot symbol and at least one first data symbol, and the second plurality of symbols may include at least one second pilot symbol and at least one second data symbol. Each of the at least one first pilot symbol may be on a tone that carries one of the at least one second data symbol. The apparatus may be configured to determine a first pilot signal on a first tone of the plurality of tones. The first tone may carry a respective one of the at least one first pilot symbol and a respective one of the at least one second data symbol. The first pilot signal may be determined based on a channel element associated with the first tone and the respective one of the at least one first pilot symbol on the first tone. The apparatus may be configured to generate an interference-reduced signal for the first tone by canceling the determined first pilot signal from a first combined signal on the first tone.

In another aspect, an apparatus is provided. The apparatus may include means for receiving a plurality of combined signals. Each combined signal may be on a tone of a plurality of tones. Each combined signal may include a first symbol of a first plurality of symbols from a first UE and a second symbol of a second plurality of symbols from a second UE. The first plurality of symbols may include at least one first pilot symbol and at least one first data symbol, and the second plurality of symbols may include at least one second pilot symbol and at least one second data symbol. Each of the at least one first pilot symbol may be on a tone that carries one of the at least one second data symbol. The apparatus may include means for determining a first pilot signal on a first tone of the plurality of tones. The first tone may carry a respective one of the at least one first pilot symbol and a respective one of the at least one second data symbol. The first pilot signal may be determined based on a channel element associated with the first tone and the respective one of the at least one first pilot symbol on the first tone. The apparatus may include means for generating an interference-reduced signal for the first tone by canceling the determined first pilot signal from a first combined signal on the first tone. The apparatus may include mean for determining a second pilot signal on a second tone of the plurality of tones. The second tone may carry a respective one of the at least one second pilot symbol and a respective one of the at least one first data symbol. The second pilot signal may be determined based on a second channel element associated with the second tone and the respective one of the at least one second pilot symbol on the second tone. The apparatus may include means for generating a second interference-reduced signal for the second tone by canceling the determined second pilot signal from a second combined signal on the second tone. The apparatus may include means for demodulating the interference-reduced signal, the second interference-reduced signal, and remaining signals on a subset of tones of the plurality of tones to decode the at least one first data symbol and the at least one second data symbol. In an aspect, a first set of periodic pilot signals from the first UE and a second set of periodic pilot signals from the second UE are shifted by a cyclic shift. In another configuration, the apparatus may include means for providing a cyclic shift to the first UE. In another configuration, the apparatus may include means for de-interleaving the plurality of combined signals to determine a first set of pilot signals from the first UE, first and second code blocks from the first UE, a second set of pilot signals from the second UE, and third and fourth code blocks from the second UE. In another aspect, the first set of pilot signals may correspond to a first number tones, and the first number tones may be equal to half a second number of tones in the third code block. In another aspect, the first set of pilot signals from the first UE may overlap with the third code block from the second UE, and the second set of pilot signals from the second UE may overlap with the second code block from the first UE. In another configuration, the apparatus may include means for performing successive decoding after deinterleaving the plurality of combined signals. In another configuration, the means for successive decoding may be configured to decode the third code block by canceling the first set of pilot signals from the third code block, to decode the first code block by canceling the third code block from the first code block, to decode the fourth code block by canceling the first code block from the fourth code block, and to decode the second code block by canceling the fourth code block from the second code block.

In another aspect, a computer-readable medium storing computer executable code is provided. The computer-readable medium may include code to receive a plurality of combined signals. Each combined signal may be on a tone of a plurality of tones. Each combined signal may include a first symbol of a first plurality of symbols from a first UE and a second symbol of a second plurality of symbols from a second UE. The first plurality of symbols may include at least one first pilot symbol and at least one first data symbol, and the second plurality of symbols may include at least one second pilot symbol and at least one second data symbol. Each of the at least one first pilot symbol may be on a tone that carries one of the at least one second data symbol. The computer-readable medium may include code to determine a first pilot signal on a first tone of the plurality of tones. The first tone may carry a respective one of the at least one first pilot symbol and a respective one of the at least one second data symbol. The first pilot signal may be determined based on a channel element associated with the first tone and the respective one of the at least one first pilot symbol on the first tone. The computer-readable medium may include code to generate an interference-reduced signal for the first tone by canceling the determined first pilot signal from a first combined signal on the first tone.

In another aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be configured to map, at a first UE, a first set of pilot symbols and a first set of data symbols to a plurality of tones. Each pilot symbol in the first set of pilot symbols may be mapped on a tone that is used by a second UE to carry a data symbol. The apparatus may be configured to provide the first set of pilot symbols and the first set of data symbols for transmission over the plurality of tones.

In another aspect, an apparatus is provided. The apparatus may include means for mapping, at a first UE, a first set of pilot symbols and a first set of data symbols to a plurality of tones. Each pilot symbol in the first set of pilot symbols may be mapped on a tone that is used by a second UE to carry a data symbol. The apparatus may include means for providing the first set of pilot symbols and the first set of data symbols for transmission over the plurality of tones. In another aspect, a data symbol in the first set of data symbols may be mapped on a tone that is used by the second UE to carry a pilot symbol. In another aspect, the first set of pilot symbols may be transmitted on tones shifted by a cyclic shift from a second set of pilot symbols that is concurrently transmitted by the second UE. In another configuration, the apparatus may include means for receiving the cyclic shift for staggering the first set of pilot symbols from a base station. In another aspect, the cyclic shift for staggering the first set of pilot symbols is randomly selected from a set of cyclic shift values based on an identifier associated with the first UE. In another aspect, the first set of data symbols may be associated with a same code block.

DETAILED DESCRIPTION

The E-UTRAN includes the evolved Node B (eNB)106and other eNBs108, and may include a Multicast Coordination Entity (MCE)128. The eNB106provides user and control planes protocol terminations toward the UE102. The eNB106may be connected to the other eNBs108via a backhaul (e.g., an X2 interface). The MCE128allocates time/frequency radio resources for evolved Multimedia Broadcast Multicast Service (MBMS) (eMBMS), and determines the radio configuration (e.g., a modulation and coding scheme (MCS)) for the eMBMS. The MCE128may be a separate entity or part of the eNB106. The eNB106may also be referred to as a base station, a Node B, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), or some other suitable terminology. The eNB106provides an access point to the EPC110for a UE102. Examples of UEs102include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, or any other similar functioning device. The UE102may also 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.

The eNB106is connected to the EPC110. The EPC110may include a Mobility Management Entity (MME)112, a Home Subscriber Server (HSS)120, other MMES114, a Serving Gateway116, a Multimedia Broadcast Multicast Service (MBMS) Gateway124, a Broadcast Multicast Service Center (BM-SC)126, and a Packet Data Network (PDN) Gateway118. The MIME112is the control node that processes the signaling between the UE102and the EPC110. Generally, the MME112provides bearer and connection management. All user IP packets are transferred through the Serving Gateway116, which itself is connected to the PDN Gateway118. The PDN Gateway118provides UE IP address allocation as well as other functions. The PDN Gateway118and the BM-SC126are connected to the IP Services122. The IP Services122may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service (PSS), and/or other IP services. The BM-SC126may provide functions for MBMS user service provisioning and delivery. The BM-SC126may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN), and may be used to schedule and deliver MBMS transmissions. The MBMS Gateway124may be used to distribute MBMS traffic to the eNBs (e.g.,106,108) belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

FIG. 2is a diagram illustrating an example of an access network200in an LTE network architecture. In this example, the access network200is divided into a number of cellular regions (cells)202. One or more lower power class eNBs208may have cellular regions210that overlap with one or more of the cells202. The lower power class eNB208may be a femto cell (e.g., home eNB (HeNB)), pico cell, micro cell, or remote radio head (RRH). The macro eNBs204are each assigned to a respective cell202and are configured to provide an access point to the EPC110for all the UEs206in the cells202. There is no centralized controller in this example of an access network200, but a centralized controller may be used in alternative configurations. The eNBs204are responsible for all radio related functions including radio bearer control, admission control, mobility control, scheduling, security, and connectivity to the serving gateway116. An eNB may support one or multiple (e.g., three) cells (also referred to as a sectors). The term “cell” can refer to the smallest coverage area of an eNB and/or an eNB subsystem serving a particular coverage area. Further, the terms “eNB,” “base station,” and “cell” may be used interchangeably herein.

Channel estimates derived by a channel estimator658from a reference signal or feedback transmitted by the eNB610may be used by the TX processor668to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor668may be provided to different antenna652via separate transmitters654TX. Each transmitter654TX may modulate an RF carrier with a respective spatial stream for transmission.

For Internet-of-everything (IoE) uplink, the number of UEs may be more than the number available time/frequency resources. A time/frequency resource may be the resource in a symbol period on a particular tone (or frequency).

A UE may use resource shared multiple access (RSMA) to share time/frequency resources. In other words, multiple UEs can use the same time/frequency resources to transmit uplink signals to a base station. The base station may perform successive-decoding. In particular, the base station may decode signals from one UE while treating signals from other UEs as noise. The decoded signals may be canceled or subtracted from the received combined signals after decoding.

FIG. 7is a diagram700illustrating communication between an eNodeB and two UEs utilizing RSMA. In a first technique, a UE752maps, in a particular symbol period, one or more pilot symbols762, each on a tone770, and maps one or more data symbols766, each on a tone770. Further, a UE753maps, in the same symbol period, one or more pilot symbols763, each on a tone770, and maps one or more data symbols767, each on a tone770. As an example,FIG. 7illustrates 2 pilot symbols762and 6 data symbols766at the UE752and 2 pilot symbols763and 6 data symbols767at the UE753. A pilot symbol762is mapped on the same tone770of a pilot symbol763. A data symbol766is mapped on the same tone770of a data symbol767. Further, the pilot symbols762and the data symbols766are sent to an IFFT component774of the UE752, at which an inverse fast Fourier transform is applied to the pilot symbols762. The IFFT component774sends the generated signals to a parallel-to-serial converter776, which performs a parallel-to-serial conversion to the generated signals. The output from the parallel-to-serial converter776is a time domain signal, which is transmitted to the eNodeB702through an antenna782. Similarly, the pilot symbols763and the data symbols767are sent to an IFFT component775of the UE753. The IFFT component775sends the generated signals to a parallel-to-serial converter777, which generates a time domain signal that is transmitted to the eNodeB702through an antenna783.

The eNodeB702receives the combined time domain signals transmitted from the UE752and the UE753at an antenna712. The received combined signals are sent to a serial-to-parallel converter714for serial-to-parallel conversion. The serial-to-parallel converter714sends the converted combined signal to an FFT component716, at which a Fast Fourier Transform is applied to the converted combined signal to generate a combined signal on each of the tones770. Each combined signal may include a signal derived from a symbol transmitted from the UE752and a signal derived from a symbol transmitted from the UE753. For example, the UE752transmits a pilot symbol762on a first tone770-1to the eNodeB702, and the UE753transmits a pilot symbol763on the first tone770-1to the eNodeB702. Accordingly, the FFT component716outputs on the first tone770-1a combined signal that includes a pilot signal derived from the pilot symbol762and a pilot signal derived from the pilot symbol763. Further, the UE752transmits a data symbol766on a second tone770-2to the eNodeB702, and the UE753transmits a data symbol767on the second tone770-2to the eNodeB702. Accordingly, the FFT component716outputs on the second tone770-2a combined signal that includes a data signal derived from the data symbol766and a data signal derived from the data symbol767.

As described above, upon obtaining the combined signal on a tone770, the eNodeB702may attempt demodulate and decode the pilot signal or the data signal derived from the symbol of one of the UEs752,753while treating the corresponding pilot signal or the corresponding data signal derived from the symbol of the other one of the UEs752,753as noise. It has been observed that the demodulation and decoding accuracy of this technique may not be ideal and may be further improved.

In a second technique, different UEs may be configured to map their respective pilot symbols (e.g., modulated symbols) on different time/frequency resources. As described below, staggered pilot placement may provide non-overlapping pilot placement. In the staggered pilot placement, each UE may shift its periodic pilot placement with a different cyclic shift in frequency. This non-overlapping pilot placement may be exploited in a pilot-aid interference cancellation (PIC) decoder.

FIG. 8is a diagram800illustrating communication between an eNodeB and two UEs. Referring toFIG. 8, a UE852maps one or more pilot symbols862and one or more data symbols866on tones870. The pilot symbols and data symbols may be modulated symbols (e.g., modulated by QPSK, QAM, etc.). Further, each of the pilot symbols862is on a tone that carries one of the data symbols867. A UE853maps one or more pilot symbols863and one or more data symbols867on the tones870. In this disclosure, pi,jdenotes a jthpilot symbol at the ithUE. xi,jdenotes a jthdata symbol at the ithUE. More specifically,FIG. 8shows that, as an example, the UE852maps p1,1, x1,1, x1,2, x1,3, p1,2, x1,4, x1,5, x1,6in that order on 8 tones870. The UE853maps x2,1, p2,1, x2,2, x2,3, x2,4, p2,2, x2,5, x2,6in that order on the same 8 tones870. As shown inFIG. 8, the pilot locations for the UE853may be cyclically shifted from the pilot locations for the UE852. In one aspect, the cyclic shift amount may be signaled and assigned by the eNodeB802. The signaling may be unicasted to individual UEs or broadcasted with a UE identifier, such that each UE may determine a cyclic shift value based on its respective UE identifier. In another aspect, the UE852, for example, may randomly select from among a set of cyclic shift values based on the identifier for the UE852. That is, the cyclic shift value may be a function of the UE identifier.

The pilot symbols862and the data symbols866are processed by an IFFT component874and a parallel-to-serial converter876of the UE852to generate a time domain signal. The pilot symbols863and the data symbols867are processed by an IFFT component875and a parallel-to-serial converter877of the UE853to generate a time domain signal.

An eNodeB802receives the combined signals transmitted from the UE852and the UE853, and the received combined signals are processed by a serial-to-parallel converter814and an FFT component816to generate the combined signal on each of the tones870.

Further, s1,kdenotes the symbol (i.e., a pilot symbol862or a data symbol866) transmitted by the UE852on the kthtone. s2,kdenotes the symbol (i.e., a pilot symbol863or a data symbol867) transmitted by the UE853on the kthtone. ykdenotes the combined signal generated by the FFT component816on the kthtone. A channel matrix for the kthtone is:

The combined signal ykis:

where the noise on the kthtone has been eliminated or ignored. For example, on the first tone870-1and the second tone870-2, the combined signals are:
y1=h1,1p1,1+h2,1x2,1
y2=h1,2x1,1+h2,2p2,1

Subsequently, the FFT component816sends the combined signals to a PIC decoder822.

FIG. 9is a diagram900illustrating demodulation and decoding procedures at an eNodeB. The PIC decoder822of the eNodeB802receives the combined signal on each tone870. For a kthtone carrying a pilot symbol from either the UE852or the UE853, the PIC decoder822knows the estimated channel h′i,kand pi,k, where i is 1 or 2 in this example. In an aspect, the PIC decoder822may know the estimated channel h′i,kbased on UE feedback and/or prior transmissions, and pi,kmay be preconfigured. Thus, the PIC decoder822can estimate a pilot signal derived from the pi,k: h′i,kpi,k. The PIC decoder822may cancel the pilot signal h′i,kpi,kfrom the combined signal yk(e.g., i may be 1 and may indicate a pilot symbol from the UE852). The remaining signal of the combined signal is a data signal derived from the data symbol from the other UE on the kthtone. As such, the PIC decoder822may cancel the pilot signals on the tones870. In this way, the noise or interference are reduced for the remaining data signals.

Subsequently, the PIC decoder822sends the remaining signals (e.g., data signals) to a multi-user decoder826. The multi-user decoder826may decode the remaining signals to obtain the information from the data symbols from the UE852and the UE853carried on the tones870. For example, the multi-user decoder826may be a successive interference decoder.

One transmission block (spans over one or multiple OFDM symbol periods) may include pilot tones and multiple code blocks. In an aspect, code blocks may include data symbols or bits but not pilot symbols. In additional to staggered pilot placement, in a third technique, each code block may be allocated as described below to facilitate the successive decoding. In certain configurations, one UE may allocate code blocks in a way such that data symbols on the tones that also carry pilot symbols from another UE belong to the same code block.

FIG. 10is a diagram1000illustrating procedures of mapping pilot symbols and data symbols at a UE. A UE1052has information that the 2ndand the 6thtones1070carry pilot symbols (e.g., p2,1and p2,2) from a UE1053. Thus, an interleaver1090of the UE1052may allocate data symbols derived from information bits of the same code block (e.g., a code block1092) to the 2ndand the 6thtones. Similarly, the UE1053has information that the 1stand the 5thtones1070carry pilot symbols (e.g., p1,1and p1,2) from the UE1052. Thus, an interleaver1091of the UE1053may allocate data symbols derived from information bits of the same code block (e.g., a code block1093) to the 1stand the 5thtones.

FIG. 11is a diagram1100illustrating demodulation and decoding procedures at an eNodeB. An eNodeB1002receives pilot signals1032and data signals1036on the tones1070from the UE1052. The eNodeB1002also receives pilot signals1033and data signals1037on the tones1070from the UE1053. As shown inFIG. 11, the pilot signals1033have been subjected to a different cyclic shift than the pilot signals1032. In an aspect, a cyclic shift may be different from a frequency offset. When a cyclic shift is performed, all of the tones may still be occupied, but the pilot tone locations may be shifted. By contrast, when a frequency offset is performed, certain tones from which the offset begins may be left empty.

Referring toFIG. 11, the eNodeB1002has information that, as described supra, the tones1070carrying the pilot signals1032also carry data signals1037derived from the information bits of the same code block, e.g., the code block1093. Further, the tones1070carrying the pilot signals1033also carry data signals1036derived from the information bits of the same code block, e.g., the code block1092.

Using the second technique described supra, the eNodeB1002may estimate the pilot signals1032and may cancel the pilot signals1032from the combined signals carried on those tones1070carrying the pilot signals1032. The remaining signals on the tones1070carrying the pilot signals1032are data signals1037derived from the code block1093of the UE1053. After a deinterleaving procedure1040, the pilot signals1032from the UE1052overlap with the data signals1037derived from the code block1093of the UE1053. That is, all the pilot signals1032from the UE1052may overlap with the code block1093of the UE1053. As an example, the number of tones carrying the pilot signals1032may be half of the number of tones carrying the data signals1037derived from the code block1093. As such, the eNodeB1002may be able to demodulate and decode all the data signals1037derived from the code block1093more accurately. The eNodeB1002may thus obtain codewords of the code block1093.

Further, as illustrated inFIG. 11, after the deinterleaving procedure1040, the tones1070carrying the data signals1037derived from the code block1093overlap with the tones1070carrying the data signals1036derived from the code block1094. As such, the eNodeB1002may cancel the data signals1037derived the code block1093from the combined signals carried on the overlapping tones. The remaining signals on the overlapping tones are data signals1036derived from the code block1094. In this way, the eNodeB1002may be able to demodulate and decode all the data signals1036derived from the code block1094more accurately. The eNodeB1002may thus obtain codewords of the code block1094.

Similarly to what was described supra, the tones1070carrying the data signals1036derived from the code block1094overlap with the tones1070carrying the data signals1037derived from the code block1095. The eNodeB1002may cancel the data signals1036derived from the code block1094in order to demodulate and decode the data signals1037derived from the code block1095.

Further, the tones1070carrying the data signals1037derived from the code block1095overlap with the tones1070carrying the data signals1036derived from the code block1092. The tones1070carrying the pilot signals1033may also overlap with the tones1070carrying the data signals1036derived from the code block1092. As such, the eNodeB1002may cancel the data signals1037derived from the code block1095and/or the pilot signals1033in order to demodulate and decode the data signals1036derived from the code block1092.

In other words, the efficiency of the PIC decoder822may be further improved by carefully designing interleavers. The PIC decoder822may assume that pilot tones are not aligned, but data bits may be selectively located to improve performance. For example, for the UE1052, the data bits from CB11are located in the tones that correspond to the pilot locations of UE1053. For UE1053, the data bits from CB21may be located in the tones that correspond to the pilot locations of UE1052. That is, all of the pilot locations from UE1052correspond to CB21of the UE1053. Referring toFIG. 11, after deinterleaving, all the pilot locations of the UE1052may overlap with the data bits from CB21of the UE1053, and all the pilot locations of the UE1052may overlap with the data bits from CB11of the UE1052. Based on the foregoing cyclic shifts in frequency and alignments, successive decoding may be performed. For example, the pilot signals1032are canceled from CB21and CB21may be decoded. CB21may be canceled from CB12, and then CB12may be decoded. Then, CB12may be canceled from CB22, and CB22may be decoded. Then, CB22may be canceled from CB11, and CB11may be decoded. In an aspect, the pilot signals1033may be canceled from CB11before CB11is decoded. As shown inFIG. 11, each code block of the UE1053may overlap with at most two code blocks of the UE1052, and vice versa. If the code block from the UE1052overlaps with the pilot signals from the UE1053, the then the code block only overlaps with one other code block of the UE1053, and vice versa. AlthoughFIG. 11illustrates the successive decoding process starting from the pilot signals1032, the decoding process may also begin from the bottom at the pilot signals1033. If the decoding process fails in both directions, then the eNodeB1002may determine that the decoding has failed. Otherwise, if the decoding only fails in one direction, the eNodeB1002may attempt decoding in a different direction. In another aspect, because the CB11has a greater amount of interference canceled (e.g., interference from CB22and from the pilot signals1033), the UE1052may transmit CB22at a higher MCS compared with other code blocks (e.g., CB12). The same may be true of the UE1053for CB21. In other words, UEs may transmit code blocks that overlap with another UE's pilot tone locations at a higher MCS than code blocks that do no overlap with another UE's pilot tone locations.

FIG. 12is a flow chart1200of a method (process) for interference reduction, de-interleaving, and demodulation. The method may be performed by a base station (e.g., the eNodeB802, the eNodeB1002).

At1202, the base station may receive a plurality of combined signals. Each combined signal may be on a tone of a plurality of tones. Each combined signal may include a first symbol of a first plurality of symbols (e.g., modulated symbols) from a first UE and a second symbol of a second plurality of symbols from a second UE. The first plurality of symbols may include at least one first pilot symbol and at least one first data symbol, and the second plurality of symbols may include including at least one second pilot symbol and at least one second data symbol. Each of the at least one first pilot symbol may be on a tone that carries one of the at least one second data symbol, and each of that least one second pilot symbol may be on a tone that carries one of the at least one first data symbol. For example, referring toFIG. 8, the base station may be the eNodeB802. The eNodeB802may receive the combined signals. Each combined signal (e.g., y1) may include a first symbol of a first plurality of symbols from the UE852(the first UE) and a second symbol of a second plurality of symbols from the UE853(the second UE). The first plurality of symbols may include the first pilot symbol p1,1and the first data symbol x1,1. The second plurality of symbols from the UE853may include the second pilot symbol p2,1and the second data symbol x2,1. The first pilot symbol may be on a tone that carries the second data symbol x2,1, and the second pilot symbol p2,1may be on a different tone that carries the first data symbol x1,1.

At1204, the base station may determine a first pilot signal on a first tone of the plurality of tones. The first tone may carry a respective one of the at least one first pilot symbol and a respective one of the at least one second data symbol. The first pilot signal may be determined based on a channel element associated with the first tone and the respective one of the at least one first pilot symbol on the first tone. For example, referring toFIGS. 8 and 9, the eNodeB802may determine the first pilot signal, h′1,1p1,1, on a first tone of the tones870. The first tone may carry the first pilot symbol, p1,1, from the UE852and the second data symbol, x2,1, from the UE853. The pilot signal, h′1,1p1,1, may be determined based on the channel element, h′1,1, associated with the first tone and the respective first pilot symbol p1,1. In an aspect, the channel element may be determined based on received feedback from the UE852that indicates the channel element.

At1206, the base station may generate an interference-reduced signal for the first tone by canceling the determined first pilot signal from a first combined signal on the first tone. For example, referring toFIGS. 8 and 9, the eNodeB802may generate the interference-reduced signal for the first tone, y1−h′1,1p1,1, by canceling the determined first pilot signal, h′1,1p1,1, from the first combined signal, y1, on the first tone.

At1208, the base station may determine a second pilot signal on a second tone of the plurality of tones. The second tone may carry a respective one of the at least one second pilot symbol and a respective one of the at least one first data symbol. The second pilot signal may be determined based on a second channel element associated with the second tone and the respective one of the at least one second pilot symbol on the second tone. For example, referring toFIGS. 8 and 9, the eNodeB802may determine the second pilot signal, h′2,2p2,1, on a second tone of the tones870. The second tone may carry the second pilot symbol, p2,1, from the UE853and the first data symbol, x1,1, from the UE852. The second pilot signal, h′2,2p2,1, may be determined based on the channel element, h′2,2, associated with the second tone and the respective second pilot symbol p2,1.

At1210, the base station may generate a second interference-reduced signal for the second tone by canceling the determined second pilot signal from a second combined signal on the second tone. For example, referring toFIGS. 8 and 9, the eNodeB802may generated the second interference-reduced signal for the second tone, y2−h′2,2p2,1, by canceling the determined first pilot signal, h′2,2p2,1, from the second combined signal, y2, on the second tone.

At1212, the base station may de-interleave the plurality of combined signals to determine a first set of pilot signals from the first UE, first and second code blocks from the first UE, a second set of pilot signals from the second UE, and third and fourth code blocks from the second UE. For example, referring toFIGS. 8 and 11, the eNodeB802(or the eNodeB1002) may de-interleave the plurality of combined signals (e.g., y1, y2) to determine the pilot signals1032(the first set of pilot signals) from the UE852, the first and second code blocks (CB11and CB12) from the UE852, the pilot signals1033(the second set of pilot signals) from the UE853, and the third and fourth code blocks (CB21and CB22) from the UE853. In an aspect, the eNodeB802may de-interleave by arranging and demodulating the first set of pilot signals in a first portion of the tones, arranging and demodulating the first code block in a second portion of the tones, and arranging and demodulating the second code block in a third set of the tones.

At1214, the base station may perform successive decoding after de-interleaving the plurality of combined signals. In one configuration, the base station may perform successive decoding by decoding the third code block by canceling the first set of pilot signals from the third code block, by decoding the first code block by canceling the third code block from the first code block, by decoding the fourth code block by canceling the first code block from the fourth code block, and by decoding the second code block by canceling the fourth code block from the second code block. For example, referring toFIGS. 8 and 11, the eNodeB802may perform success decoding by decoding CB21by canceling the pilot signals1032from the CB21, by decoding CB12by canceling the corresponding tones in CB21from CB12, by decoding CB22by canceling the corresponding tones from CB12from CB22, and by decoding CB11by canceling the corresponding tones from CB22from CB11. In an aspect, CB11may have corresponding tones canceled from CB22and from the pilot signals1033. As such, compared to other code blocks, CB11may have improved accuracy. In this aspect, CB11may be transmitted with a higher MCS index than other codeblocks.

In an aspect, as shown inFIG. 8, the pilot signals1032from the UE1052are shifted by a cyclic shift as compared to the pilot signals1033from the UE1053. The cyclic shift may be provided (or transmitted) by the eNodeB1002to each of the UEs1052,1053.

FIG. 13is a flow chart1300of a method (process) for mapping pilot symbols and data symbols on multiple tones. The method may be performed by a UE (e.g., the UEs852,853,1052,1053).

At1302, the UE may receive a cyclic shift for staggering pilot symbols from a base station. For example, referring toFIG. 8, the UE may be the UE852. The UE852may receive a cyclic shift for staggering pilot symbols862from the eNodeB802. Alternatively, the UE852may not receive the cyclic shift from the eNodeB802. Instead, the UE852may select the cyclic shift from among a set of cyclic shifts based on an identifier associated with the UE852.

At1304, the UE may map a first set of pilot symbols and a first set of data symbols to a plurality of tones. Each pilot symbol in the first set of pilot symbols being mapped on a tone that is used by a second UE to carry a data symbol. For example, referring toFIG. 8, the UE852may map the pilot symbols p1,1and p1,2and a first set of data symbols x1,1, x1,2, x1,3, x1,4, x1,5, x1,6. The UE852may map the pilot symbols p1,1and p1,2onto tones used by the UE853(the second UE) to carry a data symbol, such as the data symbol x2,1. In an aspect, the UE852may select the tone locations to map the pilot symbols based on a cyclic shift. The UE852may receive the cyclic shift from the eNodeB802or determine the cyclic shift. The UE852may determine which tones are used by other UEs, such as the UE853, to transmit pilot symbols and map data symbols onto those tones.

At1306, the UE may provide the first set of pilot symbols and the first set of data symbols for transmission over the plurality of tones. For example, referring toFIG. 8, the UE852may provide the pilot symbols p1,1and p1,2and a first set of data symbols x1,1, x1,2, x1,3, x1,4, x1,5, x1,6for transmission over the tones by indicating the tones on which the modulated symbols are to be transmitted and placing the tone indication along with the modulated symbols on a bus to be transmitted via a transmitter or a transceiver.

FIG. 14is a conceptual data flow diagram1400illustrating the data flow between different means/components in an exemplary apparatus1402. The apparatus may be an eNB. The apparatus includes a reception component1404, a deinterleaver component1406, a decoding component1408, and a transmission component1410. The reception component1404may be configured to receive a plurality of combined signals. Each combined signal may be on a tone of a plurality of tones. Each combined signal may include a first symbol of a first plurality of symbols from a first UE and a second symbol of a second plurality of symbols from a second UE. The first plurality of symbols may include at least one first pilot symbol and at least one first data symbol. The second plurality of symbols may include at least one second pilot symbol and at least one second data symbol. Each of the at least one first pilot symbol may be on a tone that carries one of the at least one second data symbol. The deinterleaver component1406may be configured to determine a first pilot signal on a first tone of the plurality of tones. The first tone may carry a respective one of the at least one first pilot symbol and a respective one of the at least one second data symbol. The first pilot signal may be determined based on a channel element associated with the first tone and the respective one of the at least one first pilot symbol on the first tone. The decoding component1408may be configured to generate an interference-reduced signal for the first tone by canceling the determined first pilot signal from a first combined signal on the first tone. In another configuration, the deinterleaver component1406may be configured to determine a second pilot signal on a second tone of the plurality of tones. The second tone may carry a respective one of the at least one second pilot symbol and a respective one of the at least one first data symbol. The second pilot signal may be determined based on a second channel element associated with the second tone and the respective one of the at least one second pilot symbol on the second tone. The decoding component1408may be configured to generate a second interference-reduced signal for the second tone by canceling the determined second pilot signal from a second combined signal on the second tone. In an aspect, a first set of periodic pilot signals from the first UE and a second set of periodic pilot signals from the second UE are shifted by a cyclic shift. In another aspect, the transmission component1410may be configured to provide a cyclic shift to the first UE. In another configuration, the deinterleaver component1406may be configured to deinterleave the plurality of combined signals to determine a first set of pilot signals from the first UE, first and second code blocks from the first UE, a second set of pilot signals from the second UE, and third and fourth code blocks from the second UE. In an aspect, the first set of pilot signals may correspond to a first number tones. The first number tones may be equal to half a second number of tones in the third code block. In another aspect, the first set of pilot signals from the first UE may overlap with the third code block from the second UE, and the second set of pilot signals from the second UE may overlap with the second code block from the first UE. In another configuration, the decoding component1408may be configured to perform successive decoding after deinterleaving the plurality of combined signals. In another configuration, the decoding component1408may be configured to perform successive decoding by decoding the third code block by canceling the first set of pilot signals from the third code block, by decoding the first code block by canceling the third code block from the first code block, by decoding the fourth code block by canceling the first code block from the fourth code block, and by decoding the second code block by canceling the fourth code block from the second code block.

FIG. 15is a diagram1500illustrating an example of a hardware implementation for an apparatus1402′ employing a processing system1514. The processing system1514may be implemented with a bus architecture, represented generally by the bus1524. The bus1524may include any number of interconnecting buses and bridges depending on the specific application of the processing system1514and the overall design constraints. The bus1524links together various circuits including one or more processors and/or hardware components, represented by the processor1504, the components1404,1406,1408,1410, and the computer-readable medium/memory1506. The bus1524may 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 system1514may be coupled to a transceiver1510. The transceiver1510is coupled to one or more antennas1520. The transceiver1510provides a means for communicating with various other apparatus over a transmission medium. The transceiver1510receives a signal from the one or more antennas1520, extracts information from the received signal, and provides the extracted information to the processing system1514, specifically the reception component1404. In addition, the transceiver1510receives information from the processing system1514, specifically the transmission component1410, and based on the received information, generates a signal to be applied to the one or more antennas1520. The processing system1514includes a processor1504coupled to a computer-readable medium/memory1506. The processor1504is responsible for general processing, including the execution of software stored on the computer-readable medium/memory1506. The software, when executed by the processor1504, causes the processing system1514to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory1506may also be used for storing data that is manipulated by the processor1504when executing software. The processing system1514further includes at least one of the components1404,1406,1408,1410. The components may be software components running in the processor1504, resident/stored in the computer readable medium/memory1506, one or more hardware components coupled to the processor1504, or some combination thereof. The processing system1514may be a component of the eNB310and may include the memory376and/or at least one of the TX processor316, the RX processor370, and the controller/processor375.

In one configuration, the apparatus1402/1402′ for wireless communication includes means for receiving a plurality of combined signals. Each combined signal may be on a tone of a plurality of tones. Each combined signal may include a first symbol of a first plurality of symbols from a first UE and a second symbol of a second plurality of symbols from a second UE. The first plurality of symbols may include at least one first pilot symbol and at least one first data symbol. The second plurality of symbols may include at least one second pilot symbol and at least one second data symbol. Each of the at least one first pilot symbol may be on a tone that carries one of the at least one second data symbol. The apparatus may include means for determining a first pilot signal on a first tone of the plurality of tones. The first tone may carry a respective one of the at least one first pilot symbol and a respective one of the at least one second data symbol. The first pilot signal may be determined based on a channel element associated with the first tone and the respective one of the at least one first pilot symbol on the first tone. The apparatus may include means for generating an interference-reduced signal for the first tone by canceling the determined first pilot signal from a first combined signal on the first tone. In another configuration, the apparatus may include means for determining a second pilot signal on a second tone of the plurality of tones. The second tone may carry a respective one of the at least one second pilot symbol and a respective one of the at least one first data symbol. The second pilot signal may be determined based on a second channel element associated with the second tone and the respective one of the at least one second pilot symbol on the second tone. The apparatus may include means for generating a second interference-reduced signal for the second tone by canceling the determined second pilot signal from a second combined signal on the second tone. In an aspect, a first set of periodic pilot signals from the first UE and a second set of periodic pilot signals from the second UE are shifted by a cyclic shift. In another aspect, the apparatus may include means for providing a cyclic shift to the first UE (e.g., a bus interface, a transmitter, and/or transceiver). In another configuration, the apparatus may include means for deinterleaving the plurality of combined signals to determine a first set of pilot signals from the first UE, first and second code blocks from the first UE, a second set of pilot signals from the second UE, and third and fourth code blocks from the second UE. In an aspect, the first set of pilot signals may correspond to a first number tones. The first number tones may be equal to half a second number of tones in the third code block. In another aspect, the first set of pilot signals from the first UE may overlap with the third code block from the second UE, and the second set of pilot signals from the second UE may overlap with the second code block from the first UE. In another configuration, the apparatus may include means for performing successive decoding after deinterleaving the plurality of combined signals. In another configuration, the means for performing successive decoding may be configured to decode the third code block by canceling the first set of pilot signals from the third code block, to decode the first code block by canceling the third code block from the first code block, to decode the fourth code block by canceling the first code block from the fourth code block, and to decode the second code block by canceling the fourth code block from the second code block. The aforementioned means may be one or more of the aforementioned components of the apparatus1402and/or the processing system1514of the apparatus1402′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system1514may include the TX Processor316, the RX Processor370, and the controller/processor375. As such, in one configuration, the aforementioned means may be the TX Processor316, the RX Processor370, and the controller/processor375configured to perform the functions recited by the aforementioned means.

FIG. 16is a conceptual data flow diagram1600illustrating the data flow between different means/components in an exemplary apparatus1602. The apparatus may be a UE. The apparatus includes a reception component1604, a modulation component1606, an interleaver component1608, and a transmission component1610. A modulation component1606may be configured to map information (e.g., data and pilot information) onto data symbols or pilot symbols using QPSK, QAM, or other modulation techniques. The interleaver component1608may be configured to map, at a first UE, a first set of pilot symbols and a first set of data symbols to a plurality of tones. Each pilot symbol in the first set of pilot symbols may be mapped on a tone that is used by a second UE to carry a data symbol. The transmission component1610may be configured to provide the mapped first set of pilot symbols and the mapped first set of data symbols for transmission over the plurality of tones. In an aspect, a data symbol in the first set of data symbols is mapped on a tone that is used by the second UE to carry a pilot symbol. In another aspect, the first set of pilot symbols may be transmitted on tones shifted by a cyclic shift from a second set of pilot symbols that is concurrently transmitted by the second UE. In another configuration, the reception component1604may be configured to receive the cyclic shift for staggering the first set of pilot symbols from a base station. In another aspect, the cyclic shift for staggering the first set of pilot symbols may be randomly selected from a set of cyclic shift values based on an identifier associated with the first UE. In another aspect, the first set of data symbols may be associated with a same code block.

FIG. 17is a diagram1700illustrating an example of a hardware implementation for an apparatus1602′ employing a processing system1714. The processing system1714may be implemented with a bus architecture, represented generally by the bus1724. The bus1724may include any number of interconnecting buses and bridges depending on the specific application of the processing system1714and the overall design constraints. The bus1724links together various circuits including one or more processors and/or hardware components, represented by the processor1704, the components1604,1606,1608,1610and the computer-readable medium/memory1706. The bus1724may 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 system1714may be coupled to a transceiver1710. The transceiver1710is coupled to one or more antennas1720. The transceiver1710provides a means for communicating with various other apparatus over a transmission medium. The transceiver1710receives a signal from the one or more antennas1720, extracts information from the received signal, and provides the extracted information to the processing system1714, specifically the reception component1604. In addition, the transceiver1710receives information from the processing system1714, specifically the transmission component1610, and based on the received information, generates a signal to be applied to the one or more antennas1720. The processing system1714includes a processor1704coupled to a computer-readable medium/memory1706. The processor1704is responsible for general processing, including the execution of software stored on the computer-readable medium/memory1706. The software, when executed by the processor1704, causes the processing system1714to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory1706may also be used for storing data that is manipulated by the processor1704when executing software. The processing system1714further includes at least one of the components1604,1606,1608,1610. The components may be software components running in the processor1704, resident/stored in the computer readable medium/memory1706, one or more hardware components coupled to the processor1704, or some combination thereof. The processing system1714may 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.

In one configuration, the apparatus1602/1602′ for wireless communication includes means for mapping, at a first UE, a first set of pilot symbols and a first set of data symbols to a plurality of tones. Each pilot symbol in the first set of pilot symbols may be mapped on a tone that is used by a second UE to carry a data symbol. The apparatus may include means for providing the mapped first set of pilot symbols and the mapped first set of data symbols for transmission over the plurality of tones. In an aspect, a data symbol in the first set of data symbols is mapped on a tone that is used by the second UE to carry a pilot symbol. In another aspect, the first set of pilot symbols may be transmitted on tones shifted by a cyclic shift from a second set of pilot symbols that is concurrently transmitted by the second UE. In another configuration, the apparatus may include means for receiving the cyclic shift for staggering the first set of pilot symbols from a base station. In another aspect, the cyclic shift for staggering the first set of pilot symbols may be randomly selected from a set of cyclic shift values based on an identifier associated with the first UE. In another aspect, the first set of data symbols may be associated with a same code block.

The aforementioned means may be one or more of the aforementioned components of the apparatus1602and/or the processing system1714of the apparatus1602′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system1714may 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.