CN109391403B

CN109391403B - Method and apparatus for transmission and reception of wireless signals

Info

Publication number: CN109391403B
Application number: CN201710682031.3A
Authority: CN
Inventors: 李栋; 刘勇; T·维尔德斯彻克
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Oyj
Priority date: 2017-08-10
Filing date: 2017-08-10
Publication date: 2021-07-06
Anticipated expiration: 2037-08-10
Also published as: CN109391403A

Abstract

Embodiments of the present disclosure provide methods, apparatuses, and computer program products for wireless signal transmission and reception. A method implemented at a communication device operating in a wireless communication system, comprising: obtaining a plurality of signal sequences corresponding to a plurality of transmit antenna ports of the communication device; mapping the plurality of signal sequences to allocated frequency resources in an interleaved manner with each other; and transmitting the respective signal sequences from the plurality of transmit antenna ports in time units designated for transmission of the signal sequences. With the embodiments of the present disclosure, good diversity gain may be obtained, and/or improved interference suppression performance may be obtained.

Description

Method and apparatus for transmission and reception of wireless signals

Technical Field

The present disclosure relates generally to the field of wireless communications, and in particular to methods, apparatuses and computer program products for transmission and reception of wireless signals.

Background

The statements in this section are intended to facilitate a better understanding of the present disclosure. Accordingly, the contents of this section should be read on this basis and should not be construed as an admission as to which pertains to the prior art or which does not pertain to the prior art.

With the development of wireless communication, a need for device-to-device (D2D) communication has arisen, and one potential extension of D2D communication is to support vehicle-to-any object (V2X) communication. Specifically, the V2X communication may include, for example, vehicle-to-vehicle (V2V) communication, vehicle-to-pedestrian (V2P) communication, and the like. Work Items (WI) for the second phase of the V2X study have been established currently in the third generation partnership (3GPP) and it has been decided to study transmit diversity schemes for V2X transmissions to further improve link quality and reliability over previous versions of single antenna port transmissions, a particular decision can be found in 3GPP conference document RP-170798.

Disclosure of Invention

How to design the transmission scheme for V2X for multiple antenna ports and how to perform detection of receive side association remains an open issue. In embodiments of the present disclosure, a transmission scheme for multiple antenna ports, and an associated reception scheme, are provided. Some embodiments can provide increased diversity gain and/or improved interference suppression/interference cancellation capabilities.

It should be understood that although some embodiments of the present disclosure are described with reference to the communication scenario of V2X, embodiments of the present disclosure are not limited to use in this scenario, but may be more broadly applied to any communication networks, systems, and scenarios in which similar issues exist.

Other features and advantages of embodiments of the present disclosure will be understood from the following description of various embodiments, when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the disclosure.

In a first aspect of the disclosure, a method implemented at a communication device operating in a wireless communication system is provided. The method comprises the following steps: obtaining a plurality of signal sequences corresponding to a plurality of transmit antenna ports of the communication device; mapping the plurality of signal sequences to the allocated frequency resources in an interleaved manner with each other; and transmitting the respective signal sequences from the plurality of transmit antenna ports in time units designated for transmission of the signal sequences.

In one embodiment, the signal sequence may include a demodulation reference signal (DMRS) sequence and/or a data signal sequence.

In another embodiment, obtaining the plurality of signal sequences may include independently generating the plurality of DMRS sequences. In another embodiment, obtaining the plurality of signal sequences may include: generating a parent DMRS sequence; and obtaining a plurality of DMRS sequences by extracting a plurality of signal subsets that do not overlap with each other from the mother DMRS sequence. In a further embodiment, obtaining the plurality of DMRS sequences by extracting a plurality of signal subsets that do not overlap with each other from the parent DMRS sequence may include: extracting an even-numbered signal from the parent DMRS sequence as a first DMRS sequence; and extracting an odd-numbered signal from the parent DMRS sequence as a second DMRS sequence.

In yet another embodiment, obtaining the plurality of signal sequences may include: obtaining a data sequence comprising modulated constellation symbols; and obtaining a plurality of signal sequences by one of: dividing the data sequence into a plurality of parts with equal length which do not overlap with each other to obtain a plurality of signal sequences; performing DFT pre-coding on the data sequence, and dividing the data sequence subjected to DFT pre-coding into a plurality of parts which are not overlapped and have the same length to obtain a plurality of signal sequences; and dividing the data sequence into a plurality of parts which are not overlapped and have the same length, and respectively executing DFT pre-coding on the plurality of parts to obtain a plurality of signal sequences.

In one embodiment, the plurality of signal sequences includes a first signal sequence and a second signal sequence, and mapping the plurality of signal sequences to the allocated frequency resources in an interleaved manner with each other may include: the first signal sequence and the second signal sequence are mapped to subcarriers with even numbers and subcarriers with odd numbers in the frequency resources, respectively. In yet another embodiment, mapping the first signal sequence and the second signal sequence to even-numbered subcarriers and odd-numbered subcarriers, respectively, in the frequency resources may include: extending the first signal sequence to obtain a first component signal sequence such that the 2 nth signal in the first component signal sequence corresponds to the nth signal in the first signal sequence and the remaining signals in the first component signal sequence are 0; extending the second signal sequence to obtain a second component signal sequence such that the 2n +1 signal in the second component signal sequence corresponds to the nth signal in the second signal sequence and the remaining signals in the second component signal sequence are 0; and sequentially mapping the first component signal sequence and the second component signal sequence to subcarriers in the frequency resources, respectively; where n is an integer ranging from 0 to L-1, and L is the length of the first signal sequence and the second signal sequence.

In a second aspect of the disclosure, a method implemented at a communication device operating in a wireless communication system is provided. The method comprises the following steps: receiving signal sequences from a plurality of transmitting antenna ports on the allocated frequency domain resources; the received signal sequence contains information of a plurality of transmitted signal sequences mapped onto non-overlapping subsets of the frequency domain resources, respectively transmitted from the plurality of transmit antenna ports; correlating the received signal sequence with a plurality of local signal sequences in a time domain respectively to obtain a plurality of correlation results; the plurality of local signal sequences respectively correspond to the transmit signal sequences transmitted from the respective transmit antenna ports; obtaining an estimate of the timing offset based on a non-coherent combination of the plurality of correlation results; and performing a timing adjustment on the received signal based on the obtained estimate of the timing offset.

In one embodiment, the method may further include obtaining frequency offset estimation correlation terms for a plurality of local signal sequences; and coherently combining the estimated correlation terms for the frequency offsets in the plurality of local signal sequences to obtain a total frequency offset. In a further embodiment, obtaining a correlation term for frequency offset estimation in a plurality of local signal sequences may comprise: timing adjustment is carried out on the received signal sequence; dividing the timing adjusted signal sequence into a first portion and a second portion; performing the following for each of a plurality of local signal sequences: performing time domain correlation on the first part and the second part and corresponding parts of a local signal sequence in a plurality of local signal sequences respectively to obtain a first correlation result and a second correlation result; and determining a frequency offset estimate for the local signal sequence of the plurality of local signal sequences based on the phase difference between the first correlation result and the second correlation result.

In a second aspect of the disclosure, a method at a communication device in a wireless communication system is provided. The method comprises the following steps: dividing the allocated frequency domain resources into a plurality of subcarrier groups, wherein each subcarrier group comprises a plurality of continuous subcarriers; for a subcarrier group of the plurality of subcarrier groups, performing the following operations: obtaining a first estimate of interference plus noise using reference signals received on subcarriers having even numbers in a group of subcarriers; performing signal detection with interference suppression on the received data associated with the even-numbered subcarriers based on the first estimation; obtaining a second estimate of interference plus noise using reference signals received on subcarriers having odd numbers in the group of subcarriers; and performing signal detection with interference suppression on the received data associated with the odd-numbered subcarriers based on the second estimate.

In a fourth aspect of the present disclosure, a communication device operating in a wireless communication system is provided. The communication device includes: a signal sequence obtaining unit configured to obtain a plurality of signal sequences corresponding to a plurality of transmission antenna ports of the communication device; a resource mapping unit configured to map the plurality of signal sequences to the allocated frequency resources in an interleaved manner with each other; and a transmitting unit configured to transmit respective signal sequences from the plurality of transmit antenna ports in time units designated for transmission of the signal sequences.

In a fifth aspect of the present disclosure, another communication device operating in a wireless communication system is provided. The communication device includes: a receiving unit configured to receive signal sequences from a plurality of transmit antenna ports on the allocated frequency domain resources; the received signal sequence contains information of a plurality of transmitted signal sequences mapped onto non-overlapping subsets of the frequency domain resources, respectively transmitted from the plurality of transmit antenna ports; a correlation unit configured to correlate the received signal sequence with a plurality of local signal sequences, respectively, in a time domain to obtain a plurality of correlation results; the plurality of local signal sequences respectively correspond to the transmit signal sequences transmitted from the respective transmit antenna ports; a timing offset estimation unit configured to obtain an estimate of a timing offset based on a non-coherent combination of the plurality of correlation results; and a timing adjustment unit configured to perform timing adjustment on the received signal based on the obtained estimate of the timing offset.

In a sixth aspect of the present disclosure, a further communication device in a wireless communication system is provided. The communication device includes: a subcarrier dividing unit configured to divide the allocated frequency domain resources into a plurality of subcarrier groups, each subcarrier group including a plurality of subcarriers in succession; and a signal detection unit configured to perform the following operations for a subcarrier group of the plurality of subcarrier groups: obtaining a first estimate of interference plus noise using reference signals received on subcarriers having even numbers in a group of subcarriers; performing signal detection with interference suppression on the received data associated with the even-numbered subcarriers based on the first estimation; obtaining a second estimate of interference plus noise using reference signals received on subcarriers having odd numbers in the group of subcarriers; and performing signal detection with interference suppression on the received data associated with the odd-numbered subcarriers based on the second estimate.

In a seventh aspect of the present disclosure, an apparatus is provided. The apparatus comprises a processor and a memory containing instructions executable by the processor whereby the apparatus is operative to perform any of the methods described in the first, second, third aspects of the present disclosure.

In an eighth aspect of the present disclosure, there is provided a computer program product comprising instructions which, when executed on one or more processors, cause the one or more processors to perform any of the methods according to the first to third aspects of the present disclosure.

In a ninth aspect of the disclosure, a computer-readable storage medium having embodied thereon a computer program product is provided. The computer program product comprises instructions which, when executed on at least one processor, cause the at least one processor to perform any of the methods according to the first to third aspects of the present disclosure.

Drawings

The above and other aspects, features and benefits of various embodiments of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or equivalent elements. The accompanying drawings are only for the purpose of promoting a better understanding of embodiments of the disclosure, and are not necessarily drawn to scale, wherein:

FIG. 1 illustrates an example communication network in which embodiments of the present disclosure may be implemented;

fig. 2A illustrates an example flow diagram of a method implemented at a communication device operating in a wireless communication system in accordance with an embodiment of this disclosure;

2B-2C illustrate example processes for obtaining multiple data signal sequences corresponding to multiple transmit antenna ports in accordance with embodiments of the present disclosure;

fig. 3A illustrates an example flow diagram of another method implemented at a communication device operating in a wireless communication system in accordance with an embodiment of the present disclosure;

fig. 3B illustrates an example implementation for obtaining frequency offset estimates for a plurality of local signal sequences, in accordance with an embodiment of the present disclosure;

4A-4B illustrate an example flow diagram of another method implemented at a communication device operating in a wireless communication system in accordance with an embodiment of the present disclosure;

fig. 5 illustrates an example flow diagram of yet another method implemented at a communication device operating in a wireless communication system in accordance with an embodiment of the present disclosure; and

fig. 6 shows a simplified block diagram of an apparatus according to an embodiment of the present disclosure.

Detailed Description

Hereinafter, the principle and spirit of the present disclosure will be described with reference to exemplary embodiments. It is understood that all of these examples are given solely to enable those skilled in the art to better understand and further practice the present disclosure, and are not intended to limit the scope of the present disclosure. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. For clarity, some features of the actual implementation described in this specification may be omitted.

References in the specification to "one embodiment," "an example embodiment," etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," comprising, "" has, "" having, "" includes, "" including, "" has, "" having, "" contains, "" containing, "" contains, "" contain a mixture of one or more other features, elements, components, and/or. The term "optional" means that the embodiment or implementation being described is not mandatory, and may be omitted in some cases.

Generally, terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs, unless explicitly defined otherwise.

As used herein, the term "communication network" refers to a network that conforms to any suitable communication standard, such as New Radio (NR), Long Term Evolution (LTE), LTE-advanced (LTE-a), wideband code division multiple access, WCDMA, High Speed Packet Access (HSPA), CDMA2000, time division synchronous code division multiple access (TD-CDMA), and the like. Further, communication between devices in the communication network may be performed according to any suitable communication protocol, including but not limited to global system for mobile communications (GSM), Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), and/or other suitable communication protocols, such as first generation (1G), second generation (2G), 2.5G, 2.75G, 3G, 4G, 4.5G, 5G communication protocols, Wireless Local Area Network (WLAN) standards (such as IEEE 802.11 standards); and/or any other suitable wireless communication standard, and/or any other protocol now known or later developed in the future.

As used herein, the term "network device" refers to a device in a communication network via which a terminal device accesses the network and receives services therefrom. Depending on the terminology and technology employed, a network device may refer to a Base Station (BS), an Access Point (AP), and the like.

The term "terminal device" refers to any terminal device that may have communication capabilities. By way of example, and not limitation, a terminal device may be referred to as a User Equipment (UE), Subscriber Station (SS), portable subscriber station, Mobile Station (MS), or Access Terminal (AT). The terminal devices may include, but are not limited to, mobile phones, cellular phones, smart phones, voice over IP (VoIP) phones, tablet computers, wearable terminal devices, Personal Digital Assistants (PDAs), portable computers, desktop computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEEs), laptop installation devices (LMEs), USB dongles, smart devices, wireless Customer Premises Equipment (CPE), D2D devices, machine-to-machine (M2M) devices, V2X devices, and the like. In the following description, the terms "terminal device", "terminal", "user equipment" and "UE" may be used interchangeably.

A schematic diagram of an example wireless communication system 100 in which embodiments of the present disclosure can be implemented is shown in fig. 1. The wireless communication system 100 may include one or more network devices 101. For example, in this example, network device 101 may be embodied as a base station, e.g., a gNB. It should be understood that the network device 101 may also be embodied in other forms, such as NB, eNB, BTS, BS, or BSs, relay, etc. Network device 101 provides wireless connectivity to a plurality of

terminal devices

111 and 112 within its coverage area.

Terminal devices

111, 112 may communicate with network device 101 via

wireless transport channels

131 or 132 and/or with each other via transport channel 133. It is to be understood that the arrangement of the figures is merely an example, and that the wireless communication system 100 may include more or fewer terminal devices or network devices. Embodiments of the present disclosure may be used for communication between network device 101 and

terminal devices

111 or 112, or for communication between

terminal devices

111 and 112. In one embodiment,

terminal devices

111 and 112 may be in-vehicle wireless devices.

In order to improve communication quality, a transmit diversity scheme may be used at the transmitting side. Existing solutions for transmit diversity include small delay cyclic delay diversity (SD-CDD), Space Time Block Coding (STBC), and Space Frequency Block Coding (SFBC). In SC-CDD, demodulation reference signals (DMRS) for a single antenna port may be directly used, but have a potential drawback in that available diversity gain is limited. In STBC and SFBC, DMRSs for two antenna ports are required, and the DMRSs for two antenna ports may be implemented in a Code Division Multiplexing (CDM) or Frequency Division Multiplexing (FDM) manner. However, the inventors of the present disclosure have discovered that the SFBC/STBC scheme may have significant interference impact on legacy receivers for single antenna port transmissions.

In embodiments of the present disclosure, new methods, apparatus and computer program products are presented to support multiple transmit antenna ports for improving diversity gain and/or interference suppression/cancellation capabilities.

In some embodiments of the present disclosure, transmission is performed using two antenna ports, and DMRS sequences (and/or corresponding data symbol sequences) may be alternately mapped to even-numbered subcarriers and odd-numbered subcarriers in an Orthogonal Frequency Division Multiplexing (OFDM) symbol (and/or data OFDM symbol) used for DMRS transmission, e.g., by a base station, in a bandwidth allocated by the base station. In some embodiments, in one Transmission Time Interval (TTI), some specific OFDM symbols may be configured to be dedicated for DMRS transmission, while other symbols are configured for data transmission, and the allocated subcarriers for transmission are contiguous in the frequency domain. In other embodiments of the present disclosure, a corresponding reception process may be performed on the reception side based on a specific transmission structure of the DMRS sequence (and/or data sequence number sequence), so as to improve synchronization and/or detection performance.

A method 200 implemented at a communication device operating in a wireless communication system is described below in conjunction with fig. 2A. The wireless communication system is, for example, the communication system 100 in fig. 1, and the communication device may be, for example and without limitation, the network device 101 or the

terminal device

111 or 112 shown in fig. 1. For ease of discussion, method 200 will be described below with reference to terminal device 111 and network environment 100 depicted in fig. 1.

As shown in fig. 2A, at block 210, terminal device 111 obtains a plurality of signal sequences corresponding to its plurality of transmit antenna ports. In one embodiment, the method may be used to transmit DMRS, and the plurality of signal sequences corresponding to the plurality of transmit antenna ports is a plurality of DMRS sequences.

In one embodiment, terminal device 111 may independently generate a plurality of DMRS sequences at block 210. For example, each DMRS sequence may be (but is not limited to) a Zadoff Chu sequence defined in LTE release 14 of 3 GPP. This embodiment can guarantee good correlation for each DMRS.

In another embodiment, terminal device 111 may generate only a single mother DMRS sequence and obtain multiple DMRS sequences corresponding to its multiple transmit antenna ports based on the mother DMRS sequence at block 210. For example, terminal device 111 may obtain the plurality of DMRS sequences by extracting a plurality of signal subsets that do not overlap with each other from the mother DMRS sequence. Assume that the mother DMRS sequence is denoted as s₀,s₁,…s₂₃For two antenna ports, the multiple signal subsets (or corresponding DMRS sequences) may be, for example: subset 1 ═ s₀,s₂,s₄,…s₂₂H, subset 2 ═ s₁,s₃,s₅,…s₂₃That is, an even-numbered signal is extracted as a first DMRS sequence and an odd-numbered signal is extracted as a second DMRS sequence from the mother DMRS sequence. In another example, for four antenna ports, the plurality of signal subsets (or corresponding DMRS sequences) may be, for example: subset 1 ═ s₀,s₄,s₈,…s₂₀H, subset 2 ═ s₁,s₅,s₉,…s₂₁H, subset 3 ═ s₂,s₆,s₁₀,…s₂₂And subset 4 ═ s₃,s₇,s₁₁,…s₂₃}。

In another embodiment, the method 200 may additionally or alternatively be used to transmit a data signal sequence, and the plurality of signal sequences corresponding to the plurality of transmit antenna ports may be a plurality of data sequences. An example process for obtaining a plurality of data signal sequences is shown in fig. 2B-2C. As shown in fig. 2B, in this embodiment, terminal device 111 may obtain a mother data sequence { x ] comprising modulated constellation symbols₀,x₁,…,x_M-1And may obtain a plurality of signal sequences corresponding to a plurality of transmit antenna ports based on the mother data sequence by, for example and without limitation, one of the following manners shown in fig. 2C.

Mode A: the mother data sequence is divided into a plurality of parts with equal length, which do not overlap each other, to obtain a plurality of signal sequences. That is, constellation symbols (e.g., QPSK modulation symbols) from a constellation modulation module are directly mapped to a plurality of data symbol sequences. In this case, Discrete Fourier Transform (DFT) precoding is not used.

Mode B: and performing DFT precoding on the mother data sequence, and dividing the DFT precoded mother data sequence into a plurality of parts which are not overlapped with each other and have the same length to obtain a plurality of signal sequences. That is, constellation symbols from the constellation modulation module are first subjected to DFT precoding of length M and then mapped to a plurality of data symbol sequences. In this case, M-point normalized DFT transform is used to realize precoding, where M denotes the number of subcarriers included in the allocated bandwidth.

Mode C: dividing the mother data sequence into a plurality of parts which are not overlapped and have the same length, and respectively executing DFT pre-coding on the parts to obtain the plurality of signal sequences. That is, the constellation symbols from the constellation modulation module are first divided into short sequences, for example, sequences of length M/2, and each DFT precoding of length M/2 is performed. For example, a sub-sequence of odd-numbered symbols and a sub-sequence of even-numbered symbols may be separately performed DFT precoding. The precoded subsequences are mapped to data symbol sequences, respectively. This embodiment will achieve better detection performance with respect to the manner a and the manner B because the peak-to-average ratio (PAPR) of the signal sequence corresponding to each antenna port is effectively controlled.

Note that in the above approaches a-C, we refer to dividing the DFT-precoded or non-DFT-precoded mother data sequence into mutually non-overlapping parts of equal length. The partitioning may be done, for example, but not limited to, in an interleaved manner or in a block-wise manner. As an example of the interleaving manner, even-numbered symbols may be divided into one part and odd-numbered symbols may be divided into another part. As an example of a blocking approach, the first M/2 symbols may be divided into one part, while the last M/2 symbols are the other part. For the case of more than two antenna ports, more than two data signal sequences may be similarly obtained.

As shown in fig. 2, at block 220, terminal apparatus 111 maps the obtained plurality of signal sequences (e.g., DMRS sequences, or data sequences) to the allocated frequency resources in such a manner as to be interleaved with each other. For example, for the case of two antenna ports, the transmitting device obtains a first signal sequence corresponding to a first antenna port and a second signal sequence corresponding to a second antenna port at block 210, and terminal device 111 may map the first signal sequence and the second signal sequence to even-numbered subcarriers and odd-numbered subcarriers, respectively, in the allocated frequency resources at block 220. This example can be seen in fig. 2B. It should be noted that the frequency resource of terminal device 111 may be allocated by a base station (e.g., base station 101 in fig. 1) or may be allocated by itself (e.g., based on channel sensing).

In another example, for the case of four transmit antenna ports, the transmitting device obtains four signal sequences corresponding to the four antenna ports, respectively, at block 210; at block 220, the terminal device 111 may, for example, map the ith signal sequence to a set of subcarriers k satisfying (k mod 4) ═ i (where i ═ 0,1,2,3, mod denotes a modulo operation) in the allocated frequency resources to achieve interleaved mapping. In the present disclosure, signal transmission with such an interleaving scheme mapping is also referred to as comb transmit diversity.

In another embodiment, terminal device 111 may first spread the plurality of signal sequences to a length equal to the number of subcarriers in the allocated frequency resources and then map to the frequency resources at block 220. For example, for the case of two transmit antenna ports, terminal device 111 may expand the first signal sequence to obtain a first component signal sequence such that the 2 nth signal in the first component signal sequence corresponds to the nth signal in the first signal sequence and the remaining signals in the first component signal sequence are 0; and extending the second signal sequence to obtain a second component signal sequence such that the 2n +1 signal in the second component signal sequence corresponds to the nth signal in the second signal sequence and the remaining signals in the second component signal sequence are 0; the first and second component signal sequences are then sequentially mapped to subcarriers in the frequency resource, respectively. Where n is 0,1,2, …, L-1, and L is the length of the first signal sequence and the second signal sequence.

One embodiment for transmitting DMRS sequences is given below. In this embodiment, it is assumed that within one V2X Transmission Time Interval (TTI), some specific OFDM symbols are dedicated for DMRS, while other OFDM symbols are used for data. The subcarriers allocated for transmission are contiguous in the frequency domain, and the allocated transmission bandwidth is represented as M contiguous subcarriers. A DMRS sequence for one OFDM symbol based on a Zadoff Chu sequence may be represented as described in 3GPP technical specification TS 36.211 version 14.0.0:

where n is the index of the symbol in the sequence, mod represents the modulo operation,

indicating the length, n, of the Zadoff Chu sequence used for DMRS_csDenotes a cyclic shift, x, applied to a base sequence_q(n) denotes a Zadoff Chu sequence corresponding to the qth root, and it is expressed as:

wherein

Representing the maximum prime number less than or equal to M. Other parameters can be defined and configured, see, e.g., TS 36.211 v14.0.0. Two component sequences r for two transmit antenna ports obtained based on the DMRS sequences r (n)₁(n) and r₂(n) may be expressed as:

wherein beta is₁And beta₂Is a factor for power setting. The two component sequences are mapped to a first transmit antenna port and a second transmit antenna port, respectively, on the allocated M consecutive subcarriers. Time domain waveform w of the two component DMRS sequences₁(n) And w₂(n) can be obtained by IFFT transformation, i.e.:

w_i＝IFFT(r_i,P),i＝1,2 (3c)

where P denotes the size of the IFFT transform, and can be configured as M ≦ P ≦ N, where N denotes the size of the Fast Fourier Transform (FFT) (or inverse fast Fourier transform IFFT) used for OFDM modulation (or demodulation) of the carrier in the baseband. For example, for a 10MHz carrier in LTE, N is 1024. In case P is larger than M, oversampling will be used. For example, if P ═ 2M, the oversampling ratio is 2.

In block 230, terminal device 111 transmits the respective signal sequences from the plurality of transmit antenna ports in time units designated for transmission of the signal sequences. In one embodiment, the time units designated for transmission of the signal sequence are OFDM symbols dedicated to DMRS, or OFDM symbols dedicated to data.

The method 200 enables the receiving side to more accurately estimate channel state information, e.g., channel estimation, interference plus noise estimation, etc., for each transmitting antenna port and/or enables the receiving side to more accurately detect a signal transmitted from each antenna port, thereby improving detection performance. It should be noted that although the method 200 may be applied to, for example, the transmission of DMRS and data, embodiments of the present disclosure are not limited to using the method for both DMRS and data transmission. For example, in one embodiment, the method 200 may be used to perform transmission of DMRS, while transmission of data may be performed using other, e.g., known techniques (e.g., STBC, SFBC, etc.).

Fig. 3A shows a flow diagram of a method 300 implemented at another communication device operating in a wireless communication system. The wireless communication system may be, for example, but is not limited to, the system 100 in fig. 1, and the communication device may be, for example, any one of the network device 101, the terminal device 111 and the terminal device 112 in fig. 1. For ease of discussion, method 300 will be described below with reference to terminal device 112 and network environment 100 of fig. 1.

As shown in fig. 3A, at block 310, terminal device 112 receives a signal sequence from a plurality of transmit antenna ports of another device (e.g., terminal device 111 in fig. 1) on the allocated frequency domain resources. The received signal sequence includes information of a plurality of transmission signal sequences mapped to non-overlapping subsets of the frequency domain resources, respectively transmitted from a plurality of transmission antenna ports. In one embodiment, the plurality of signal sequences may be DMRS sequences and/or data sequences transmitted by terminal device 111 according to method 200, i.e., terminal device 111 may use comb DMRS transmission diversity and/or comb data transmission diversity.

In another embodiment, in case of receiving signals from two antenna ports, two signal sequences transmitted from two transmit antenna ports may be mapped at transmit side to a first subset consisting of even-numbered subcarriers in the frequency domain resource and a second subset consisting of odd-numbered subcarriers in the frequency domain resource, respectively.

In yet another embodiment, in case of receiving signals from four antenna ports, four non-overlapping subsets a of the frequency domain resources_iI ═ 0,1,2, and 3 may include subcarriers k satisfying (k mod 4) ═ i in the frequency resources, respectively.

At block 320, terminal device 112 correlates the received signal sequence with a plurality of local signal sequences, respectively, in the time domain to obtain a plurality of correlation results. The plurality of local signal sequences respectively correspond to transmission signal sequences transmitted from the respective transmission antenna ports. For example, the local signal sequence may be as shown in equation (3 c).

At block 330, terminal device 112 obtains an estimate of the timing offset based on a non-coherent combination of the multiple correlation results. Non-coherent combining means that the phase information of the components is not taken into account in the combining.

By way of example embodiment and not limitation, assuming that the signal sequence received by terminal device 112 at block 310 is a DMRS sequence, and that the received DMRS sequence is denoted at baseband as y (N), N ═ 0,1, …, N-1, the timing and frequency synchronization process may (but is not limited to) proceed as follows.

Action 1: converting the received DMRS signal y (N) of length N into a signal y' (N) of length P. Specifically, to achieve this operation, the received signal y (n) may be converted to the frequency domain, from which a DMRS sequence having a length M on the allocated subcarriers is extracted, on which P-point IFFT is performed to return to the time domain, thereby obtaining a sequence y' (n) having a length P. The received signal y (n) is a combined signal obtained by channel-transmitting a plurality of signal sequences transmitted from a plurality of antenna ports by the transmitting end, and thus contains information of the plurality of signal sequences transmitted from the plurality of antenna ports by the transmitting end.

And action 2: estimating a timing offset Δ in a received DMRS sequence y' (n)_t. For example, it can be calculated according to the following equation (4):

i.e. will be_tK is set to maximize the value in the upper brackets. Where q is a positive integer, and may be configured, for example, to 1 or 2. The operator conj (·) indicates that a conjugate operation is performed on the input complex-valued number. As can be seen from the operation of equation (4), in this example, DMRS corresponds to two components (i.e., to respective local signal sequences w)_iCorresponding) correlation results are combined non-coherently. In other embodiments, a non-coherent combination different from that shown in equation (4) may also be used. The incoherent combination can eliminate phase difference caused by channels corresponding to different transmitting antenna ports and improve the precision of timing estimation.

In block 340, the terminal device performs a timing adjustment on the received signal based on the obtained estimate of the timing offset. For example, terminal device 112 may perform timing compensation for the received signal based on the estimate of the timing offset.

In certain embodiments, the method 300 may optionally further comprise operations for frequency synchronization. For example, at block 350, terminal device 112 may obtain frequency offset estimate correlation terms for the plurality of local signal sequences, i.e., obtain information indicative of, or otherwise related to, frequency offset estimates for the plurality of local signal sequences. Embodiments of the present disclosure are not limited to implementing the frequency offset estimation correlation term in any particular manner. An example implementation of block 350 is shown in fig. 3B for illustrative purposes only.

In this example, terminal device 112 makes timing adjustments to the received signal sequence at block 351; and at block 352, the timing adjusted signal sequence is divided into a first portion and a second portion. Based on the timing-adjusted signal sequences, the terminal device 112 targets each local signal sequence w of the plurality of local signal sequences_iThe operations of block 353-354 are performed to obtain the local signal sequence w for the plurality of local signal sequences_iIs estimated.

Specifically, at block 353, the terminal device 112 combines the first and second portions of the timing adjusted signal sequence with a local signal sequence w of the plurality of local signal sequences, respectively_iPerforms time domain correlation on the corresponding parts to obtain a first correlation result and a second correlation result. At block 354, the terminal device 112 determines a local signal sequence w for the plurality of local signal sequences based on the phase difference between the first correlation result and the second correlation result_iFrequency offset estimation of (2). The

operations

353 and 354 may be performed sequentially in a loop or in parallel for a plurality of local signal sequences, and embodiments of the present disclosure are not limited to a specific execution order. This embodiment enables more accurate frequency estimates for a particular sequence to be obtained using the phase differences within each sequence.

Returning to fig. 3A, in some embodiments, optionally at block 360, terminal device 112 coherently combines estimated correlation terms for frequency offsets in multiple local signal sequences to obtain an overall frequency offset. This total frequency offset enables accurate frequency synchronization to be performed.

By way of example and not limitation, assume that the timing offset Δ has been estimated based on the received DMRS signal y' (n)_tThen frequency shift Δ_fCan be obtained according to the following formulae (5a-5 b):

Δ_f＝(∠(C_hs))/(-π) (5a)

wherein the content of the first and second substances,

where operation < is indicative of the angle at which the input complex value is calculated, in radians, and conj is indicative of the conjugate operation. Note that in this example, the estimated frequency offset is normalized by the sub-carrier spacing. In addition, it can be found from the above operations that, in this example, terminal device 112 first performs half-symbol correlation between the received DMRS signal and the local component DMRS signal, i.e., performs correlation operation with half sequence of length P/2; multiplying the correlation result of the first half symbol by the correlation result of the second half symbol, the result of the multiplication being referred to herein as a multiplication combination; after that, the multiplicative combinations corresponding to the two local component DMRS sequences are directly added and based on this, an estimate of the frequency offset can be obtained. Half-symbol correlation and coherent combination thereof can improve the estimation accuracy of the frequency offset. In another embodiment, other coherent combining approaches than this example may be utilized.

Based on the obtained estimation of the time and/or frequency offset, timing and/or frequency compensation can be performed, as well as subsequent channel estimation and data detection. That is, the method 300 may be used in conjunction with any known synchronization method for which time and/or frequency offset estimates are provided as inputs. These specific synchronization operations may be performed according to any known method, and thus, the present disclosure will not be described in detail herein.

In some embodiments, time/frequency synchronization may be implemented based on DMRS signals in a V2X transmission to combat timing/frequency offsets that may exist between both the transmitter and receiver. The timing/frequency offset may be estimated, for example, using a particular DMRS in accordance with the method 300 described above. The timing and frequency offset may be performed based on the results of the timing/frequency offset estimation. As described in connection with method 300, in timing synchronization, two local component DMRS sequences may be used to calculate correlation with a received DMRS signal, respectively, and a combined correlation result may be obtained by non-coherent combination of the two correlation results. Based on the combined correlation results, the largest correlation instant can be found, which indicates the timing offset information. Frequency synchronization may be further performed based on timing synchronization. As described in connection with method 300, in frequency synchronization, half-symbol based correlations may be calculated using two local DMRS sequences, respectively, and two correlation results corresponding to a first half of the symbols and a second half of the symbols are used to calculate a multiplied combination result. The combined result of the multiplication contains information of the frequency offset. The combined results of the two multiplications, which respectively correspond to the two local DMRS sequences, may be coherently added to obtain an estimate of the frequency offset.

It should be noted that although some embodiments are described in connection with transmission and reception of DMRS sequences, the principles of the present disclosure are not so limited and may also be used for transmission and reception of other reference signals, pilots, etc. and related detection.

A method 400 at another communication device in a wireless communication system is shown in fig. 4A. The communication system may be, for example, the system 100 in fig. 1, and the communication device may be any one of the network device 101, the terminal device 111, and the terminal device 112. For ease of discussion, the following description will take the terminal device 112 as an example.

In this method 400, to improve signal detection accuracy in view of frequency selectivity of a channel, a terminal device divides allocated frequency domain resources into a plurality of subcarrier groups to perform signal detection for each subcarrier group at block 410. Each subcarrier group includes a plurality of subcarriers in succession. For example, each subcarrier group may be one physical resource block defined in LTE of 3GPP, thereby including 12 subcarriers. In another embodiment, the size of the subcarrier group may be appropriately configured according to channel characteristics.

At block 420, terminal device 112 performs the operations at blocks 421 and 424 shown in fig. 4B for the subcarrier group of the plurality of subcarrier groups for signal detection. Specifically, at block 421, terminal device 112 obtains a first estimate of interference plus noise using reference signals received on subcarriers having even numbers in the group of subcarriers; at block 422, terminal device 112 performs signal detection with interference suppression on the received data associated with the subcarriers having even numbers based on the first estimate; at block 423, terminal device 112 obtains a second estimate of interference plus noise using the reference signals received on the odd-numbered subcarriers in the group of subcarriers; and at block 424, the terminal device 112 performs signal detection with interference suppression on the received data associated with the odd-numbered subcarriers based on the second estimate. It should be noted that 421-424 may be performed in any suitable order. For example, the first and second estimates may be obtained in parallel or sequentially, and block 423 may be performed after obtaining the first estimate or after obtaining both the first and second estimates.

Additionally, embodiments of the present disclosure are not limited to any particular form of first and second estimates. For example only, in some embodiments, the first estimate and the second estimate may be interference-plus-noise covariance matrices corresponding to even-numbered subcarriers and odd-numbered subcarriers, respectively.

Alternatively or additionally, in one embodiment, the signal detection with interference suppression performed in

blocks

420, 422, 424 may include performing Minimum Mean Square Error (MMSE) -based signal detection. However, in another embodiment, other interference-suppressed signal detection algorithms may be used by the terminal device 112.

In some embodiments, method 400 optionally further includes block 430 where terminal device 112 performs data recovery based on the results of the signal detection in the plurality of subcarrier groups. This operation may be performed based on any known technique. For example, the data recovery operation may include one or more of an inverse operation corresponding to transform precoding, constellation demodulation, channel decoding, and the like, depending on processing at the transmitting end.

A flow of a method 500 for signal detection is shown in fig. 5. The method 500 may be viewed as an example implementation of the method 400. In the example of fig. 5, it is assumed that the transmitting end uses the comb data transmission diversity and the comb DMRS transmission diversity described in connection with the method 200.

For example, the sender may perform data transmission according to the comb data structure shown in fig. 2B-2C. That is, the constellation symbol sequence (e.g., QPSK symbol) output from the constellation modulation module is first transform-coded. The transform coding may include, for example, but not limited to, no precoding, M-point DFT based precoding, and M/2/point DFT based precoding. Note that DFT precoding may be based on a normalized DFT transform. After transform precoding, the precoded symbol sequence is alternately mapped to two transmit antenna ports (e.g., in a comb fashion), as shown in fig. 2B.

With respect to the comb DMRS configuration, in this embodiment, for example, but not limited to, two separate DMRS sequences of length M/2 may be generated first (e.g., using equations (1) - (2)). The two separate DMRS sequences may be denoted as r_e(n) and r_o(n), n is 0,1, …, M/2-1. Then, the total DMRS sequence may be obtained by interleaving the two separate DMRS sequences of length M/2, as follows:

the two component DMRS sequences r may then be obtained, e.g., according to equations (3a-3b)₁(n) and r₂(n), n is 0,1, …, M-1. Alternatively, two component DMRS sequences r₁(n) and r₂(n) may also be represented by the formula_e(n) and r_o(n) direct zero insertion extension. The two component DMRS sequences will be mapped to a first transmit antenna port and a second transmit antenna port on the allocated M consecutive subcarriers, respectively.

Note that the synchronization procedure described above with reference to method 300 may be performed with comb DMRS transmission diversity, however in this embodiment, the detection of comb data transmission diversity and the interference suppression/cancellation scheme based on joint comb data transmission and comb DMRS structure are not limited to simultaneous synchronization using method 300. That is, method 500 need not be used with method 300.

In this embodiment, for simplicity, it is assumed that within one V2X Transmission Time Interval (TTI), some specific OFDM symbols are dedicated to DMRS, while the remaining OFDM symbols are used for data, and the allocated subcarriers for transmission are contiguous in the frequency domain.

As shown in fig. 5, terminal device 112 obtains channel estimates for multiple antenna ports at block 510; interference plus noise on DMRS subcarriers is estimated at block 520. For example, terminal device 112 may obtain an estimate of the total interference and noise by subtracting the estimate of the useful DMRS signal and associated channel coefficients from the received DMRS signal (including the useful DMRS signal and the interference and noise on the DMRS). Embodiments of the present disclosure are not limited to obtaining the interference plus noise estimate in any particular manner.

At block 530, terminal device 112 divides the allocated M subcarriers into G groups of subchannels. Each subchannel contains consecutive subcarriers, e.g. the number of carriers contained in one PRB (12 in LTE terminology). And the subchannel index is initialized to 0 at block 530.

In this example, terminal device 112 performs the operations of

block

540 and 570 for each subchannel for data detection with interference suppression. Specifically, at block 540, terminal device 112 estimates a first covariance matrix of interference-plus-noise on even-numbered DMRS subcarriers; at block 550, terminal device 112 performs, e.g., MMSE detection for data on even-numbered subcarriers based on the received data signal, the estimated channel coefficients, and the estimated first covariance matrix. Similarly, at block 560, terminal device 112 estimates a second covariance matrix of interference plus noise on the odd-numbered DMRS subcarriers, and at block 570, MMSE detection, for example, is performed for data on the odd-numbered subcarriers based on the received data signal, the estimated channel coefficients, and the estimated second covariance matrix.

The terminal device increments the index of the subcarrier group by 1 in block 580 and determines whether it has finished performing for all subcarrier groups in block 590. If there are more subcarrier groups unprocessed, return to block 540 and continue execution; otherwise proceed to block 591. In block 591, the terminal device may perform other processing based on the data monitoring results, such as inverse operation corresponding to transform precoding, constellation demodulation, and channel decoding.

Although in the example of fig. 5, the detection is performed in a loop for each of the plurality of subcarrier groups, it should be understood that embodiments of the present disclosure are not limited thereto. For example, in another embodiment, signal detection for multiple subcarrier groups may be performed in parallel.

In a V2X transmission, transmission collisions sometimes occur, i.e., different transmitters select the same transmission resource (e.g., the same time/frequency resource). In this case, the receiver may use interference suppression/interference cancellation as described in connection with method 400-500 to improve detection performance for all potential transmitters. For example, in some embodiments, a simple interference suppression/cancellation scheme may be implemented with an estimate of the DMRS based covariance matrix. In some embodiments, it is assumed that channel estimates for both transmit ports have been obtained prior to data detection. The allocated subcarriers are divided into a plurality of subcarrier groups. Each group containing an appropriate number of adjacent subcarriers. For example, each group may contain 12 subcarriers. In this case, one subcarrier group corresponds to one Physical Resource Block (PRB) to which LTE belongs. Data detection will be performed for each subcarrier group. Specifically, as described in connection with method 400-500, the covariance matrices of noise plus interference on even-numbered subcarriers and odd-numbered subcarriers at the plurality of receive antennas may be estimated separately for each subcarrier group. This may be done, for example, using the received DMRS signal, the estimated channel, and the original DMRS sequence. With the two covariance matrices, corresponding data detection (e.g., using a Minimum Mean Square Error (MMSE) algorithm) on even-numbered subcarriers and on odd-numbered subcarriers, respectively, can be performed.

Embodiments of the present disclosure have numerous advantages. In one aspect, good diversity gain can be achieved using the method 200. On the other hand, signal detection performance may be improved using either method 400 or 500. In yet another aspect, a receiver can obtain improved interference cancellation when an interferer uses a transmission scheme as described in method 200.

An aspect of the present disclosure also provides a communication device in a wireless communication network (e.g., the communication network 100 shown in fig. 1). The communication device may be, for example, any one of the network device 101 and the

terminal device

111 and 112 shown in fig. 1.

In one embodiment, a communication device includes a signal sequence obtaining unit, a resource mapping unit, and a transmitting unit. The signal sequence obtaining unit is configured to obtain a plurality of signal sequences corresponding to a plurality of transmit antenna ports of the communication device. The resource mapping unit is configured to map the plurality of signal sequences to the allocated frequency resources in an interleaved manner with each other. The transmitting unit is configured to transmit the respective signal sequences from the plurality of transmit antenna ports in time units designated for transmission of the signal sequences.

In one embodiment, the communication device may perform the method 200 described in conjunction with fig. 2A-2C, and the operations of signal sequence obtaining, resource mapping, and transmitting described in conjunction with the method 200 are also applicable here and will not be described again.

In another embodiment, another communication device is provided. The communication device includes a receiving unit, a correlation unit, a timing offset estimation unit, and a timing adjustment unit. The receiving unit is configured to receive signal sequences from a plurality of transmit antenna ports of another device on the allocated frequency domain resources. The received signal sequence contains information of a plurality of transmitted signal sequences mapped onto non-overlapping subsets of the frequency domain resources, respectively transmitted from the plurality of transmit antenna ports. The correlation unit is configured to correlate the received signal sequence with a plurality of local signal sequences, respectively, in the time domain to obtain a plurality of correlation results. The plurality of local signal sequences respectively correspond to the transmission signal sequences transmitted from the respective transmission antenna ports. The timing offset estimation unit is configured to obtain an estimate of the timing offset based on a non-coherent combination of the plurality of correlation results. The timing adjustment unit is configured to perform a timing adjustment on the received signal based on the obtained estimate of the timing offset.

In a further embodiment, the communication device may further comprise a frequency offset estimation unit configured to obtain frequency offset estimation correlation terms for the plurality of local signal sequences; and coherently combining the frequency offset estimate correlation terms for the plurality of local signal sequences to obtain a total frequency offset.

In one embodiment, the communication device may perform the method 300 described in conjunction with fig. 3, and the operations of signal reception and timing/frequency offset estimation described in conjunction with the method 300 are also applicable here and will not be described in detail.

In yet another embodiment, another communication device is provided that alternatively or additionally includes a subcarrier dividing unit and a signal detection unit. The subcarrier dividing unit is configured to divide the allocated frequency domain resources into a plurality of subcarrier groups, wherein each subcarrier group includes a plurality of subcarriers in succession. The signal detection unit is configured to perform signal detection for a subcarrier group of the plurality of subcarrier groups. In one embodiment, the signal detection unit may include a first estimation unit, a first detection unit, a second estimation unit, and a second detection unit. The first estimation unit is configured to obtain a first estimate of interference plus noise using reference signals received on subcarriers having even numbers in the group of subcarriers. The first detection unit is configured to perform signal detection with interference suppression on the received data associated with the subcarriers having even numbers based on the first estimation. The second estimation unit is configured to obtain a second estimate of interference plus noise using reference signals received on odd-numbered subcarriers of the group of subcarriers. The second detection unit is configured to perform signal detection with interference suppression on the received data associated with the odd-numbered subcarriers based on a second estimation.

In one embodiment, the communication device may perform the methods 400 or 500 described in conjunction with fig. 4-5, and therefore the operations related to signal detection described in conjunction with the methods 400 and 500 are equally applicable here and will not be described in detail.

Fig. 6 illustrates a simplified block diagram of an apparatus 600 that may be implemented in or as a communication device (e.g., network device 101 or terminal devices 11-112 shown in fig. 1).

The apparatus 600 may include one or more processors 610, such as a Data Processor (DP), and one or more memories 620 coupled to the processors 610. The apparatus 600 may also include one or more transmitter/receivers 640 coupled to the processor 610. The memory 620 may be a non-transitory machine-readable storage medium and it may store a program or computer program product 630. The computer program (product) 630 may include instructions that, when executed on the associated processor 610, enable the apparatus 600 to operate in accordance with embodiments of the disclosure (e.g., perform the

methods

300, 400, or 500). The combination of one or more processors 610 and one or more memories 620 may form a processing component 650 suitable for implementing various embodiments of the present disclosure.

Various embodiments of the disclosure may be implemented by a computer program or computer program product executable by processor 610, software, firmware, hardware, or combinations thereof.

The memory 620 may be of any type suitable to the local technical environment, and may be implemented using any suitable data storage technology, such as semiconductor-based memory terminal devices, magnetic memory terminal devices and systems, optical memory terminal devices and systems, fixed memory and removable memory, as non-limiting examples.

The processor 610 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, Digital Signal Processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples.

Although some of the above description has been made in the context of the communication system shown in fig. 1, this should not be construed as limiting the spirit and scope of the present disclosure. The principles and concepts of the present disclosure may be more generally applicable to other scenarios.

Furthermore, the present disclosure may also provide a computer-readable storage medium, such as a memory containing a computer program or computer program product as described above, including a machine-readable medium and a machine-readable transmission medium. The machine-readable medium may also be referred to as a computer-readable medium and may include a machine-readable storage medium, such as a magnetic disk, magnetic tape, optical disk, phase change memory, or electronic memory terminal device, such as Random Access Memory (RAM), Read Only Memory (ROM), flash memory device, CD-ROM, DVD, Blu-ray disk, etc. A machine-readable transmission medium may also be referred to as a carrier and may include, for example, electrical, optical, radio, acoustic, or other form of propagated signals, such as carrier waves, infrared signals, etc.

The techniques described herein may be implemented by various means, such that a device implementing one or more functions of the corresponding device described with the embodiments includes not only prior art means, but also means for implementing one or more functions of the corresponding device described with the embodiments, and it may include separate means for each separate function or means that may be configured to perform two or more functions. For example, these techniques may be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or a combination thereof. For firmware or software, implementation can be through modules (e.g., procedures, functions, and so on) that perform the functions described herein.

Example embodiments herein are described above with reference to block diagrams and flowchart illustrations of methods and apparatus. It should be understood that each block of the block diagrams and flowchart illustrations, and combinations of blocks in the block diagrams and flowchart illustrations, respectively, can be implemented by various means including hardware, software, firmware, and combinations thereof. For example, in one embodiment, each block of the block diagrams and flowchart illustrations, and combinations of blocks in the block diagrams and flowchart illustrations, can be implemented by a computer program or computer program product comprising computer program instructions. These computer program instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions which execute on the computer or other programmable data processing apparatus create means for implementing the functions specified in the flowchart block or blocks.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking and parallel processing may be advantageous. Likewise, although several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the subject matter described herein, but rather as descriptions of features specific to particular embodiments. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

It is obvious to a person skilled in the art that with the advancement of technology, the inventive concept may be implemented in various ways. The above-described embodiments are given for the purpose of illustration and not limitation of the present disclosure, and it is to be understood that modifications and variations may be made without departing from the spirit and scope of the present disclosure as readily understood by those skilled in the art. Such modifications and variations are considered to be within the scope of the disclosure and the appended claims. The scope of the disclosure is defined by the appended claims.

Claims

1. A method implemented at a communication device operating in a wireless communication system, comprising:

obtaining a plurality of signal sequences corresponding to a plurality of transmit antenna ports of the communication device;

mapping the plurality of signal sequences to the allocated frequency resources in an interleaved manner with each other, wherein the plurality of signal sequences includes a first signal sequence and a second signal sequence, and mapping the plurality of signal sequences to the allocated frequency resources in an interleaved manner with each other includes: mapping the first signal sequence and the second signal sequence to subcarriers with even numbers and subcarriers with odd numbers in the frequency resources, respectively; and

transmitting the respective signal sequences from the plurality of transmit antenna ports in time units designated for transmission of the signal sequences.

2. The method according to claim 1, wherein the signal sequences comprise demodulation reference signal, DMRS, sequences and/or data signal sequences.

3. The method of claim 1, wherein obtaining the plurality of signal sequences comprises:

a plurality of DMRS sequences are independently generated.

4. The method of claim 1, wherein obtaining the plurality of signal sequences comprises:

generating a parent DMRS sequence; and

obtaining a plurality of DMRS sequences by extracting a plurality of signal subsets that do not overlap with each other from the parent DMRS sequence.

5. The method of claim 4, wherein obtaining the plurality of DMRS sequences by extracting a plurality of signal subsets that do not overlap with each other from the parent DMRS sequence comprises:

extracting an even-numbered signal from the parent DMRS sequence as a first DMRS sequence; and

and extracting odd-numbered signals from the parent DMRS sequence as a second DMRS sequence.

6. The method of claim 1, wherein obtaining the plurality of signal sequences comprises:

obtaining a data sequence comprising modulated constellation symbols; and

obtaining the plurality of signal sequences by one of:

dividing the data sequence into a plurality of parts with equal length, which do not overlap with each other, to obtain a plurality of signal sequences;

performing Discrete Fourier Transform (DFT) precoding on the data sequence, and dividing the DFT precoded data sequence into a plurality of non-overlapping parts with equal length to obtain a plurality of signal sequences; and

dividing the data sequence into a plurality of parts which are not overlapped and have the same length, and respectively executing DFT precoding on the parts to obtain the plurality of signal sequences.

7. The method of claim 1, wherein mapping the first and second signal sequences to even-numbered subcarriers and odd-numbered subcarriers, respectively, in the frequency resources comprises:

extending the first signal sequence to obtain a first component signal sequence such that the 2 nth signal in the first component signal sequence corresponds to the nth signal in the first signal sequence and the remaining signals in the first component signal sequence are 0;

expanding the second signal sequence to obtain a second component signal sequence such that a 2n +1 signal in the second component signal sequence corresponds to an nth signal in the second signal sequence and the remaining signals in the second component signal sequence are 0; and

sequentially mapping the first and second component signal sequences to subcarriers in the frequency resources, respectively;

wherein n is an integer ranging from 0 to L-1, and L is the length of the first signal sequence and the second signal sequence.

8. A method at a communication device in a wireless communication system, comprising:

dividing the allocated frequency domain resources into a plurality of subcarrier groups, wherein each subcarrier group comprises a plurality of continuous subcarriers;

for a subcarrier group of the plurality of subcarrier groups, performing the following operations:

obtaining a first estimate of interference plus noise using reference signals received on subcarriers having even numbers in the group of subcarriers;

performing signal detection with interference suppression on the received data associated with the subcarriers having even numbers based on the first estimate;

obtaining a second estimate of interference plus noise using reference signals received on subcarriers having odd numbers in the group of subcarriers; and

performing signal detection with interference suppression on the received data associated with the odd-numbered subcarriers based on the second estimate.

9. The method of claim 8, wherein the first and second estimates are interference-plus-noise covariance matrices corresponding to even-numbered subcarriers and odd-numbered subcarriers, respectively.

10. The method of claim 9, wherein performing signal detection with interference suppression comprises performing minimum mean square error, MMSE, based signal detection.

11. The method of claim 8, further comprising:

performing data recovery based on a result of the signal detection in the plurality of subcarrier groups.

12. An electronic device comprising a processor and a memory, the memory containing instructions executable by the processor whereby the device is operative to perform the method of any one of claims 1 to 7.

13. An electronic device comprising a processor and a memory, the memory containing instructions executable by the processor whereby the device is operative to perform the method of any of claims 8 to 11.

14. A computer-readable storage medium having embodied thereon a computer program product comprising instructions that, when executed on at least one processor, cause the at least one processor to perform the method according to any one of claims 8 to 11.