CN114287119A

CN114287119A - DMRS transmission

Info

Publication number: CN114287119A
Application number: CN201980099907.9A
Authority: CN
Inventors: 高毓恺; 王刚
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 2019-08-29
Filing date: 2019-08-29
Publication date: 2022-04-05
Also published as: WO2021035632A1

Abstract

Embodiments of the present disclosure relate to methods, devices, and computer-readable media for DMRS transmission. A method includes selecting, at a network device, a computer-generated (CG) sequence for a downlink channel modulated with a predetermined modulation technique from a plurality of CG sequences each having a predetermined sequence length; generating a DMRS sequence for a downlink channel based on the selected CG sequence; the DMRS sequences are transmitted to the terminal devices over a downlink channel. Embodiments of the present disclosure may provide CG sequences with low PAPR, good autocorrelation performance, and good cross-correlation performance to generate DMRS sequences for channels modulated with various modulation techniques.

Description

DMRS transmission

Technical Field

Embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly, to methods, devices, and computer-storage media for demodulation reference signal (DMRS) transmission.

Background

Generally, prior to transmission of data (including control signaling), a transmitting device may modulate the data to be transmitted. In new radio access (NR), various modulation techniques are supported, such as Binary Phase Shift Keying (BPSK), pi/2-BPSK, Quadrature Phase Shift Keying (QPSK), 8-phase shift keying (8PSK), 16 Quadrature Amplitude Modulation (QAM), 64QAM, and 256 QAM. In a recent discussion of NR above 52.6GHz, it has been agreed that DMRS sequences will be generated using low peak-to-average power ratio (PAPR) sequences.

It has been agreed at present that if the length allocated for the DMRS sequence is equal to or greater than 36, the DMRS sequence will be generated based on the ZC sequence. If the length allocated for the DMRS sequence is 6, 12, 18, or 24, the DMRS sequence will be generated based on a Computer Generated Sequence (CGS). For a channel modulated with pi/2-BPSK (e.g., PUSCH or PUCCH), if the length allocated for the DMRS sequence is equal to or greater than 30, the DMRS sequence for the channel will be generated based on the pseudo-random sequence. If the length allocated for the DMRS sequence is 6, 12, 18, or 24, the DMRS sequence will be generated based on the CGS. For PUSCH modulated with pi/2-BPSK, the DMRS sequence will be generated based on a computer generated QPSK sequence if the length allocated for the DMRS sequence is less than 30. However, CGSs of various lengths for generating DMRS sequences have not been specified for frequency bands exceeding 52.6 GHz.

Disclosure of Invention

In general, example embodiments of the present disclosure provide methods, devices, and computer-storage media for DMRS transmission.

In a first aspect, a method of communication is provided. The method comprises the following steps: selecting, at a network device, a computer-generated (CG) sequence for a downlink channel modulated with a predetermined modulation technique from a plurality of CG sequences each having a predetermined sequence length; generating a DMRS sequence for a downlink channel based on the selected CG sequence; and transmitting the DMRS sequence to the terminal device through a downlink channel.

In a second aspect, a method of communication is provided. The method comprises the following steps: selecting, at a terminal device, a computer-generated (CG) sequence for a downlink channel modulated with a predetermined modulation technique from a plurality of CG sequences each having a predetermined sequence length; determining a DMRS sequence for the downlink channel based on the selected CG sequence; and receiving the DMRS sequence from the network device through a downlink channel.

In a third aspect, a network device is provided. The network device includes a processor and a memory coupled to the processor. The memory stores instructions that, when executed by the processor, cause the network device to perform a method according to the first aspect of the disclosure.

In a fourth aspect, a terminal device is provided. The terminal device includes a processor and a memory coupled to the processor. The memory stores instructions that, when executed by the processor, cause the terminal device to perform a method according to the second aspect of the disclosure.

In a fifth aspect, a computer-readable medium having instructions stored thereon is provided. When executed on at least one processor, the instructions cause the at least one processor to perform a method according to the first or second aspect of the present disclosure.

Other features of the present disclosure will become readily apparent from the following description.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent from the following more detailed description of some embodiments of the present disclosure, as illustrated in the accompanying drawings, in which:

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

fig. 2 illustrates a schematic diagram of a process of DMRS transmission, in accordance with some embodiments of the present disclosure;

fig. 3 illustrates a flow diagram of an example method for determining multiple CG sequences of a particular sequence length in accordance with some embodiments of the present disclosure;

figure 4 illustrates performance of a length 16CG sequence for pi/2-BPSK according to some embodiments of the present disclosure;

fig. 5 illustrates a flowchart of an example method for DMRS transmission, in accordance with some embodiments of the present disclosure;

fig. 6 illustrates a flowchart of an example method for DMRS reception, in accordance with some embodiments of the present disclosure; and

fig. 7 is a simplified block diagram of a device suitable for implementing embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numbers refer to the same or similar elements.

Detailed Description

The principles of the present disclosure will now be described with reference to a few exemplary embodiments. It is understood that these examples are described for illustrative purposes only and to aid those skilled in the art in understanding and practicing the present disclosure, and are not intended to suggest any limitation as to the scope of the present disclosure. The disclosure described herein may be implemented in various ways other than those described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

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. The term "including" and its variants are to be read as open-ended terms, which mean "including, but not limited to". The term "based on" should be read as "based, at least in part, on. The terms "one embodiment" and "an embodiment" should be read as "at least one embodiment". The term "another embodiment" should be read as "at least one other embodiment". The terms "first," "second," and the like may refer to different or the same object. Other definitions, whether explicit or implicit, may be included below.

In some examples, a value, process, or device is referred to as "best," "lowest," "highest," "minimum," "maximum," or the like. It should be appreciated that such descriptions are intended to indicate that a selection may be made among many functional alternatives used, and that such selections need not be better, smaller, higher, or otherwise preferred than other selections.

Fig. 1 illustrates an example communication network 100 in which implementations of the present disclosure may be implemented. Communication network 100 includes network device 110 and terminal devices 120-1, 120-2 … …, and 120-N (where N is a natural number), which may be collectively referred to as "terminal device" 120 or individually as "terminal device" 120. Network 100 may provide one or more cells 102 to serve terminal devices 120. It should be understood that the number of network devices, terminal devices, and/or cells are given for illustrative purposes and do not imply any limitations on the present disclosure. Communication network 100 may include any suitable number of network devices, terminal devices, and/or cells suitable for implementing implementations of the present disclosure.

As used herein, the term "terminal device" refers to any device having wireless or wired communication capabilities. Examples of terminal devices include, but are not limited to, User Equipment (UE), personal computers, desktop computers, mobile phones, cellular phones, smart phones, Personal Digital Assistants (PDAs), portable computers, tablets, wearable devices, internet of things (IoT) devices, internet of everything (IoE) devices, Machine Type Communication (MTC) devices, in-vehicle devices for V2X communication (where X means pedestrian, vehicle, or infrastructure/network), or image capture devices such as digital cameras, gaming devices, music storage and playback devices, or internet devices that support wireless or wired internet access and browsing, among others.

As used herein, the term "network device" or "base station" (BS) refers to a device that is capable of providing or hosting a cell or coverage area with which a terminal device may communicate. Examples of network devices include, but are not limited to, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a next generation NodeB (gnb), a Transmission Reception Point (TRP), a Remote Radio Unit (RRU), a Radio Head (RH), a Remote Radio Head (RRH), a low power node such as a femto node, a pico node, and the like.

In one embodiment, terminal device 120 may be connected with a first network device and a second network device (not shown in fig. 1). One of the first network device and the second network device may be a primary node and the other may be a secondary node. The first network device and the second network device may use different Radio Access Technologies (RATs). In one embodiment, the first network device may be a first RAT device and the second network device may be a second RAT device. In one embodiment, the first RAT device is an eNB and the second RAT device is a gNB. Information related to different RATs may be transmitted from at least one of the first network device and the second network device to the terminal device 120. In one embodiment, the first information may be transmitted from the first network device to the terminal device 120 and the second information may be transmitted from the second network device to the terminal device 120 directly or via the first network device. In one embodiment, configuration-related information for terminal device 120 configured by the second network device may be transmitted from the second network device via the first network device. The reconfiguration-related information for the terminal device 120 configured by the second network device may be transmitted from the second network device to the terminal device 120 directly or via the first network device.

In the communication network 100 shown in fig. 1, the network device 110 may transmit data and control information to the terminal device 120, and the terminal device 120 may also transmit data and control information to the network device 110. The link from network device 110 to terminal device 120 is referred to as the Downlink (DL) and the link from terminal device 120 to network device 110 is referred to as the Uplink (UL).

Communications in network 100 may conform to any suitable standard, including but not limited to global system for mobile communications (GSM), Long Term Evolution (LTE), LTE evolution, LTE advanced (LTE-a), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), GSM EDGE Radio Access Network (GERAN), Machine Type Communication (MTC), and so forth. Further, the communication may be performed according to any generational communication protocol currently known or developed in the future. Examples of communication protocols include, but are not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, and fifth generation (5G) communication protocols.

In addition to normal data communications, network device 110 may transmit RSs in a broadcast, multicast, and/or unicast manner in the downlink to one or more of terminal devices 120. Similarly, one or more terminal devices 120 may transmit an RS in the uplink to network device 110. As used herein, "Downlink (DL)" refers to a link from a network device to a terminal device, and "Uplink (UL)" refers to a link from a terminal device to a network device. Examples of RSs may include, but are not limited to, demodulation reference signals (DMRSs), channel state information reference signals (CSI-RSs), Sounding Reference Signals (SRSs), Phase Tracking Reference Signals (PTRSs), fine time and frequency Tracking Reference Signals (TRSs), and so forth.

For example, in the case of DL DMRS transmission, DMRS may be used by terminal device 120 for DL channel demodulation. In general, DMRS is a signal sequence (also referred to as "DMRS sequence") that is known to both network device 110 and terminal device 120. For example, in DL DMRS transmission, DMRS sequences may be generated and transmitted by network device 110 based on certain rules, and terminal device 120 may derive (reduce) DMRS sequences based on the same rules. Similarly, in the case of UL DMRS transmission, DMRS may be used by network device 110 for UL channel demodulation. For example, in UL DMRS transmission, DMRS sequences may be generated and transmitted by terminal device 120 based on certain rules, and network device 110 may derive the DMRS sequences based on the same rules.

In general, prior to transmitting a DMRS sequence, a transmitting device (e.g., terminal device 120 in a UL DMRS transmission or network device 110 in a DL DMRS transmission) may modulate the DMRS sequence to be transmitted. In a recent discussion of NR above 52.6GHz, it has been agreed that DMRS sequences should be generated using low PAPR sequences. It has been agreed at present that if the length allocated for the DMRS sequence is equal to or greater than 36, the DMRS sequence will be generated based on the ZC sequence. If the length allocated for the DMRS sequence is 6, 12, 18, or 24, the DMRS sequence will be generated based on a Computer Generated Sequence (CGS). For a channel modulated with pi/2-BPSK (e.g., PUSCH or PUCCH), if the length allocated for the DMRS sequence is equal to or greater than 30, the DMRS sequence for the channel will be generated based on the pseudo-random sequence. If the length allocated for the DMRS sequence is 6, 12, 18, or 24, the DMRS sequence will be generated based on the CGS. For PUSCH modulated with pi/2-BPSK, the DMRS sequence will be generated based on a computer generated QPSK sequence if the length allocated for the DMRS sequence is less than 30. However, for frequency bands exceeding 52.6GHz, CG sequences of various lengths for generating DMRS sequences have not been specified.

Example embodiments of the present disclosure provide a solution for DMRS transmission. The solution may provide CG sequences of various lengths to generate DMRS sequences for channels modulated with various modulation techniques. A set of candidate CG sequences according to embodiments of the present disclosure may achieve low PAPR, good autocorrelation performance, and good cross-correlation performance.

Fig. 2 illustrates a process 200 for DMRS transmission, in accordance with some embodiments of the present disclosure. The process 200 may involve a first device 201 and a second device 202. In some embodiments, in the scenario of DL DMRS transmission, for example, the first device 201 may be a network device 110 and the second device 202 may be a terminal device 120, as shown in fig. 1. In some embodiments, in the context of UL DMRS transmission, for example, the first device 201 may be a terminal device 120 and the second device 202 may be a network device 110, as shown in fig. 1.

In some embodiments, multiple CG sequence tables may be configured to the first device 201 and the second device 202 for generating DMRS sequences for channels modulated with a predetermined modulation technique. For example, in the scenario of DL DMRS transmission, the channel may be a Physical Downlink Shared Channel (PDSCH) or a Physical Downlink Control Channel (PDCCH). For example, in the context of UL DMRS transmission, the channel may be a Physical Uplink Shared Channel (PUSCH) or a Physical Uplink Control Channel (PUCCH). In some embodiments, the predetermined modulation technique may comprise any one of: pi/2-BPSK, QPSK and 8 PSK. One of the plurality of CG sequences may include a plurality of CG sequences, each of the plurality of CG sequences having a predetermined sequence length. In some embodiments, the predetermined sequence length may be less than 30. In some embodiments, the predetermined sequence length may include any one of: 5. 7,8,9,10,11,15,16,20,25 and 27.

As shown in fig. 2, in response to a predetermined sequence length being configured to the first device 201, the first device 201 may select 210 a CG sequence for a channel from a corresponding CG sequence list including a plurality of CG sequences each having a configured sequence length. In some embodiments, information regarding CG sequence selection may be preconfigured to the first device 201 and the second device 202. For example, the information may indicate which CG sequence in the corresponding CG sequence list is to be used in a particular slot. Thus, for a particular slot, the first device 201 may determine which CG sequence to use. The first device 201 may generate 220 a DMRS sequence for the channel based on the selected CG sequence and transmit 230 the generated DMRS sequence to the second device 202 over the channel in a particular time slot.

The second device 202 may derive the DMRS sequence based on the same rule. As shown in fig. 2, in response to the configured predetermined sequence length, the second device 202 may select 240 a CG sequence for a channel from a corresponding CG sequence list including a plurality of CG sequences each having the configured sequence length in the same manner as the first device 201. In some embodiments, information regarding CG sequence selection may be preconfigured to the first device 201 and the second device 202. For example, the information may indicate which CG sequence in the corresponding CG sequence list is to be used in a particular slot. As such, the second device 202 may determine which CG sequence the first device 201 will use in a particular time slot based on the configuration information. The second device 202 may determine 250 a DMRS sequence to receive from the first device 201 based on the selected CG sequence. The second device 202 may then receive 230 from the first device 201 a DMRS sequence transmitted through the channel in a particular time slot.

Embodiments of the present disclosure will be described below with reference to a DL channel such as a PDSCH or a PDCCH. It should be understood that this is done for illustrative purposes only and does not imply any limitation on the scope of the disclosure. Embodiments of the present disclosure may also be applicable to uplink channels (such as PUSCH or PUCCH).

In some embodiments, a CG sequence table comprising a plurality of CG sequences used to generate DMRS sequences for a channel may be determined based on at least one of: a predetermined sequence length, a PAPR of a CG sequence, an autocorrelation of a CG sequence, and a cross-correlation of two CG sequences.

Fig. 3 illustrates a flow diagram of an example method 300 for determining a CG sequence table including a plurality of CG sequences having a predetermined sequence length, such as 5,7,8,9,10,11,15,16,20,25, or 27, according to some embodiments of the present disclosure. In some embodiments, the method 300 may be performed at the first device 201 and/or the second device 202 as shown in fig. 2. Alternatively, in other embodiments, method 300 may be performed at another device not shown in fig. 2, and the determined CG sequence table may be preconfigured to first device 201 and second device 202. It should be understood that method 300 may include additional blocks not shown and/or may omit some of the blocks shown, and the scope of the present disclosure is not so limited.

At block 310, a first set of CG sequences may be determined based on a predetermined sequence length.

In some embodiments, the predetermined sequence length may be below 30. For example, the predetermined sequence length may be any of 5,7,8,9,10,11,15,16,20,25, or 27. If the predetermined sequence length is N (where 0< N <30), a binary CG sequence of length N may be represented as 'b (0), b (1), … b (N-1)', where b (m) is 0 or 1, and m e [0, N-1 ]. In some embodiments, if the predetermined sequence length is N (where 0< N <30), the first set of CG sequences may include 2N sequences. For example, if N is equal to 5, the first set of CG sequences may include '00000', '00001' … … '11111'. If N is equal to 8, the first set of CG sequences may include '00000000', '00000001' … … '11111111'. If N is equal to 9, the first set of CG sequences may include '000000000', '000000001' … … '111111111'. If N is equal to 25, the first set of CG sequences may include '0000000000000000000000000', '0000000000000000000000001' … … '1111111111111111111111111'.

At block 320, a second set of CG sequences is selected from the first set of CG sequences such that a PAPR of each CG sequence in the second set of CG sequences is below a first threshold and an autocorrelation of each CG sequence in the second set of CG sequences is below a second threshold.

Let us assume that a binary CG sequence of length N is denoted as 'b (0), b (1),.. b (N-1)'. Taking pi/2-BPSK as an example, in the case of pi/2-BPSK modulation, the above binary CG sequence would be mapped as the sequence Si ═ { d (0), d (1),.. d (N-1) }:

wherein m belongs to [0, N-1 ].

In some embodiments, the sequence Si may be transformed into the sequence Fi by: transform precoding, frequency domain resource mapping and OFDM baseband signal generation. The PAPR of sequence Si may be found by dividing the maximum power in sequence Fi by the average power in sequence Fi.

In some embodiments, the autocorrelation of the sequence Si may be calculated as follows:

in the above formula (1), if N is equal to 8 or 9 or 10 or 16 or 20 or 25 or 27, then α ∈ [ -2, -1,1,2](ii) a If N is equal to 8 or 9 or 10 or 16 or 20 or 25 or 27, then α ∈ 3, -2, -1,1,2,3](ii) a If N is equal to 8 or 9 or 10 or 16 or 20 or 25 or 27, then α ∈ 5, -4, -3, -2, -1,1,2,3,4,5](ii) a And if N is equal to 8 or 9 or 10 or 16 or 20 or 25 or 27, then α ∈ 2, -1,1,2]Or alpha e [ -1,1]. d ((i + α) mod N) × may represent the conjugate of the value d ((i + α) mod N). H may represent the conjugate transpose of the sequence. Qi may denote a sequence obtained by cyclic shifting the sequence Si by α. Qi (Qi)^HIt can represent the conjugate transpose of the sequence obtained by cyclic shifting the sequence Si by α.

In some embodiments, the first threshold and/or the second threshold may be determined based on a predetermined sequence length. In some embodiments, the respective values of the first threshold associated with different sequence lengths may be the same. Alternatively, in some embodiments, the respective values of the first threshold associated with different sequence lengths may be different from each other. In some embodiments, the respective values of the second threshold associated with different sequence lengths may be the same. Alternatively, in some embodiments, the respective values of the second threshold associated with different sequence lengths may be different from each other.

At block 330, the second set of CG sequences is divided into a first subset and a second subset. In some embodiments, the first subset may include a predetermined number (e.g., 30 or 60) of CG sequences randomly selected from the second set of CG sequences. The second subset may include the remaining CG sequences in the second set of CG sequences.

At block 340, a first pair of CG sequences associated with the highest cross-correlation is determined from the first subset. In some embodiments, in the case of pi/2-BPSK modulation, two binary CG sequences may be mapped to two sequences, the cross-correlation of which is denoted as Si and Sj. The cross-correlation of the two sequences Si and Sj can be calculated as: si Sj^H. In this way, a first pair of CG sequences in the first subset associated with the highest cross-correlation may be determined.

At block 350, it is determined whether a second pair of CG sequences associated with lower cross-correlation than the first pair of CG sequences is present in a second subset.

In response to determining that the second pair of CG sequences is present in the second subset, at block 360, the first pair of CG sequences in the first subset is replaced with the second pair of CG sequences. Method 300 then returns to block 340.

In response to determining that the second pair of CG sequences is not present in the second subset, at block 370, the CG sequences included in the first subset are determined to be a plurality of CG sequences in the CG sequence table.

In this way, the determined plurality of CG sequences may be associated with low PAPR, good autocorrelation performance, and good cross-correlation performance. For example, for illustrative purposes only, different CG sequence tables associated with different sequence lengths are shown below.

In some embodiments, if the predetermined sequence length is below 30, the DMRS sequence should be generated using CGS. For example, CGS may be modulated with QPSK, 8PSK, or π/2-BPSK.

In some embodiments, sequence B from predetermined sequence Listing T may be composed of a plurality of values B (i) and each B (i) is a binary number, where i is an integer and 0 ≦ i ≦ N-1, where N is the sequence length. That is, in the sequence B, each B (i) may be 0 or 1. Sequence B may be modulated to sequence D using pi/2-BPSK. That is, the value b (i) may be mapped to the complex-valued modulation symbol d (i) according to equation (1) above. In addition, the modulation sequence D may be transformed into the sequence Y by transform precoding. That is, the modulation symbols d (i) can be transformed into the sequence y (k) according to:

wherein k is an integer and is not less than 0 and not more than N-1. Further, the sequence y (k) may be precoded with a precoding matrix, mapped to physical resources, and then generated based on OFDM baseband signal generation according to current 3GPP specification 38.211.

In some embodiments, sequence B should not be included in the predetermined sequence table T, e.g., sequence B consists of the values B (i). In sequence B, B (i) ≦ 0 and i is an integer, where 0 ≦ i ≦ N-1 and N is the sequence length. In some embodiments, sequence B should not be included in the predetermined sequence table T, e.g., sequence B consists of the values B (i). In sequence B, B (i) ≦ 1 and i is an integer, where 0 ≦ i ≦ N-1 and N is the sequence length. In some embodiments, sequence B should not be included in the predetermined sequence table T, e.g., sequence B consists of the values B (i). In the sequence B, the sequence B is,

and 0. ltoreq. i.ltoreq.N-1, where N is the sequence length. In some embodiments, sequence B should not be included in the predetermined sequence table T, e.g., sequence B consists of the values B (i). In the sequence B, the sequence B is,

and 0. ltoreq. i.ltoreq.N-1, where N is the sequence length. In some embodiments, N may be lower than 30. For example, N may be any of {5,7,8,9,10,11,15,16,20,25,27 }.

In some embodiments, in predetermined sequence Listing T, sequence B should not be included, e.g., sequence B consists of the values B (i), where i is an integer and 0 ≦ i ≦ N-1 and where N is the sequence length. In sequence B, the values of B (i) may be the same for all values of i. That is, for all values of i, b (i) has only one value. In some embodiments, in predetermined sequence Listing T, sequence B should not be included, e.g., sequence B consists of the values B (i), where i is an integer and 0 ≦ i ≦ N-1 and where N is the sequence length. In the sequence B, when i is 2 m +1 and 0 m.ltoreq.N/2-1, all values of B (i) are identical. That is, for all values of i 2 m +1 and 0 m N/2-1, b (i) has only one value. In the sequence B, when i is 2 m and 0 m N/2-1, all values of B (i) are the same. That is, for all values of i 2 m and 0 m N/2-1, b (i) has only one value. In some embodiments, in predetermined sequence Listing T, sequence B should not be included, e.g., sequence B consists of the values B (i), where i is an integer and 0 ≦ i ≦ N-1, and where N is the sequence length. In the sequence B, when i is 3 m and 0 m is N/3-1, all values of B (i) are the same. That is, for all values of i 3 m and 0 m N3-1, b (i) has only one value. In the sequence B, when i is 3 m +1 and 0. ltoreq. m.ltoreq.N/3-1, all values of B (i) are identical. That is, for all values of i 3 m +1 and 0 m N3-1, b (i) has only one value. In the sequence B, when i is 3 m +2 and 0. ltoreq. m.ltoreq.N/3-1, all values of B (i) are identical. That is, for all values of i 3 m +2 and 0 m N3-1, b (i) has only one value. In some embodiments, in predetermined sequence Listing T, sequence B should not be included, e.g., sequence B consists of the values B (i), where i is an integer and 0 ≦ i ≦ N-1, and where N is the sequence length. In the sequence B, when i is 4 m and 0 m is N/4-1, all values of B (i) are the same. That is, for all values of i 4 m and 0 m N/4-1, b (i) has only one value. In the sequence B, when i is 4 m +1 and 0. ltoreq. m.ltoreq.N/4-1, all values of B (i) are identical. That is, for all values of i 4 m +1 and 0 m N/4-1, b (i) has only one value. In the sequence B, when i is 4 m +2 and 0. ltoreq. m.ltoreq.N/4-1, all values of B (i) are identical. That is, for all values of i 4 m +2 and 0 m N/4-1, b (i) has only one value. In the sequence B, when i is 4 m +3 and 0. ltoreq. m.ltoreq.N/4-1, all values of B (i) are identical. That is, for all values of i 4 m +3 and 0 m N/4-1, b (i) has only one value. In some embodiments, N may be lower than 30. For example, N may be any of {5,7,8,9,10,11,15,16,20,25,27 }.

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence)B_pBy a value of b_p(i) Composition) of another sequence B_qCannot be included in a predetermined sequence table T, in which the sequence B_qIs prepared by mixing the sequence B_pA sequence obtained by cyclic shift α. For example, the sequence B_qBy a value of b_q(i) And (4) forming. In the sequence B_qIn (b)_q(i)＝b_p((i + α) mod N), where i is an integer and 0 ≦ i ≦ N-1, and where N is the sequence length. In some embodiments, N may be lower than 30. For example, N may be any of {5,7,8,9,10,11,15,16,20,25,27 }. In some embodiments, α can be any of { -5, -4, -3, -2, -1,1,2,3,4,5 }. In some embodiments, the possible values of α may be different for different values of N. For example, if N is equal to 8 or 9, then α can be any of { -2, -1,1,2 }. As another example, if N is equal to 16 or 20, then α can be any of { -3, -2, -1,1,2,3 }. As another example, if N is equal to 25 or 27, then α can be any of { -3, -1,1,3 }. As another example, if N is equal to 27, then α can be any of { -5, -4, -3, -2, -1,1,2,3,4,5 }.

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence B)_pBy a value of b_p(i) Composition of each b_p(i) May be 0 or 1), then another sequence B_qCannot be included in a predetermined sequence table T, in which the sequence B_qAnd sequence B_pHave a certain relationship. For example, the sequence B_qBy a value of b_q(i) And (4) forming. In the sequence B_qIn (b)_q(i)＝(b_p(i) +1) mod2, where i is an integer and 0 ≦ i ≦ N-1, and where N is the sequence length. For example, N may be any of {5,7,8,9,10,11,15,16,20,25,27 }.

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence B)_pBy a value of b_p(i) Composition of each b_p(i) May be 0 or 1), then another sequence B_qCannot be included in a predetermined sequence table T, in which the sequence B_qAnd sequence B_pHave a certain relationship. Example (b)E.g., sequence B_qBy a value of b_q(i) And (4) forming. In the sequence B_qIn (1),

wherein 0 ≦ i ≦ N-1 and N is the sequence length. Alternatively, in some embodiments, in sequence B_qIn (1),

wherein m is 0. ltoreq. N/2-1 and i is 0. ltoreq. N-1, and wherein N is the sequence length. For example, N may be any of {5,7,8,9,10,11,15,16,20,25,27 }.

In some embodiments, in the predetermined sequence table T, if a sequence B is included_p(e.g., sequence B)_pBy a value of b_p(i) Composition of each b_p(i) May be 0 or 1), then another sequence B_qCannot be included in a predetermined sequence table T, in which the sequence B_qAnd sequence B_pHave a certain relationship. For example, the sequence B_qBy a value of b_q(i) And (4) forming. In the sequence B_qIn (1),

wherein 0 ≦ i ≦ N-1 and wherein N is the sequence length. Alternatively, in the sequence B_qIn (1),

wherein 0. ltoreq. m.ltoreq.N/2-1 and 0. ltoreq. i.ltoreq.N-1 and wherein N is the sequence length. For example, N may be any of {5,7,8,9,10,11,15,16,20,25,27 }.

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence B)_pBy a value of b_p(i) Composition of each b_p(i) May be 0 or 1), then another sequence B_qCannot be included in a predetermined sequence table T, in which the sequence B_qAnd sequence B_pThere is a relationship. For example, the sequence B_qBy a value of b_q(i) And (4) forming. In the sequence B_qIn (1),

where N is the sequence length. For example, N may be any of {5,7,8,9,10,11,15,16,20,25,27 }.

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence B)_pBy a value of b_p(i) Composition of each b_p(i) May be 0 or 1), then another sequence B_qCannot be included in a predetermined sequence table T, in which the sequence B_qAnd sequence B_pHave a certain relationship. For example, the sequence B_qBy a value of b_q(i) And (4) forming. In the sequence B_qIn (1),

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence B)_pBy a value of b_p(i) Composition of each b_p(i) May be 0 or 1), other sequences B_q1And B_q2And B_q3Cannot be included in a predetermined sequence table T, in which the sequence B_q1、B_q2And B_q3Are all related to sequence B_pHave a certain relationship. For example, the sequence B_q1By a value of b_q1(i) And (4) forming. In the sequence B_q1In (1),

where N is the sequence length. Furthermore, in the sequence B_q2In (1),

where N is the sequence length. Furthermore, in the sequence B_q3In (1),

where N is the sequence length. Furthermore, in the sequence B_q2In (1),

where N is the sequence length. Furthermore, in the sequence B_q3In (1),

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence B)_pBy a value of b_p(i) Composition of each b_p(i) May be 0 or 1), other sequences B_q1And B_q2And B_q3Cannot be included in a predetermined sequence table T, in which the sequence B_q1、B_q2And B_q3All are in harmony withSequence B_pHave a certain relationship. For example, the sequence B_q1By a value of b_q1(i) And (4) forming. In the sequence B_q1In (1),

wherein m is 0. ltoreq. N/4-1 and i is 0. ltoreq. N-1, where N is the sequence length. Furthermore, in the sequence B_q2In (1),

wherein m is 0. ltoreq. N/4-1 and i is 0. ltoreq. N-1, where N is the sequence length. Furthermore, in the sequence B_q3In (1),

wherein m is 0. ltoreq. N/4-1 and i is 0. ltoreq. N-1, where N is the sequence length. For example, N may be any of {5,7,8,9,10,11,15,16,20,25,27 }.

In some embodiments, sequence B from predetermined sequence Listing T may consist of a plurality of values B (i) and each B (i) may be any of { -3, -1,1,3}, where i is an integer and 0 ≦ i ≦ N-1, and where N is the sequence length. Sequence B may be modulated (e.g., with QPSK) to sequence D. That is, the value b (i) may be mapped to a complex-valued modulation symbol d (i) according to:

d(i)＝e^j*b(i)π/4 (4)

in addition, the modulation sequence D may be transformed into the sequence Y by transform precoding. That is, the modulation symbol d (i) may be transformed into the sequence y (k) according to the above equation (3). Further, the sequence y (k) may be precoded with a precoding matrix, mapped to physical resources, and then generated based on OFDM baseband signal generation according to current 3GPP specification 38.211.

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence B)_pBy a value of b_p(i) In which b is_p(i) May be any of { -3, -1,1,3 }), then another sequence B_qCannot be included in the predetermined sequence table T. For example, the sequence B_qCan be represented by the value b_q(i) Is composed of, and

where i is an integer and 0. ltoreq. i.ltoreq.N-1, where N is the sequence length. For example, N may be {5,7,8,9,10,11,15,16,20,25,27 }.

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence B)_pBy a value of b_p(i) In which b is_p(i) May be any of { -3, -1,1,3 }), then another sequence B_qCannot be included in the predetermined sequence table T. For example, the sequence B_qCan be represented by the value b_q(i) Wherein if i is 2 m +1, then

And if i is 2 m, then b_q(i)＝b_p(i) In a manner similar to that described above. Furthermore, 0. ltoreq. m.ltoreq.N/2-1 and 0. ltoreq. i.ltoreq.N-1, where N is the sequence length. For example, N may be any of {5,7,8,9,10,11,15,16,20,25,27 }.

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence B)_pBy a value of b_p(i) In which b is_p(i) May be any of { -3, -1,1,3 }), then another sequence B_qCannot be included in the predetermined sequence table T. For example, the sequence B_qCan be represented by the value b_q(i) Wherein if i is 2 m, then

And if i is 2 m +1, then b_q(i)＝b_p(i) In a manner similar to that described above. Furthermore, 0. ltoreq. m.ltoreq.N/2-1 and 0. ltoreq. i.ltoreq.N-1, where N is the sequence length. For example, N may be any of {5,7,8,9,10,11,15,16,20,25,27 }.

In some embodiments, sequence B from predetermined sequence Listing T may consist of a plurality of values B (i) and each B (i) may be any of { -7, -5, -3, -1,1,3,5,7}, where i is an integer and 0 ≦ i ≦ N-1, and where N is the sequence length. Sequence B may be modulated (e.g., with QPSK) to sequence D. That is, the value b (i) may be mapped to a complex-valued modulation symbol d (i) according to:

d(i)＝e^j*b(i)π/8 (5)

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence B)_pBy a value of b_p(i) In which b is_p(i) May be any one of { -7, -5, -3, -1,1,3,5,7 }), then another sequence B)_qCannot be included in the predetermined sequence table T. For example, the sequence B_qCan be represented by the value b_q(i) Is composed of, and

where i is an integer and 0. ltoreq. i.ltoreq.N-1, where N is the sequence length. For example, N may be any of {5,7,8,9,10,11,15,16,20,25,27 }.

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence B)_pBy a value of b_p(i) In which b is_p(i) May be any one of { -7, -5, -3, -1,1,3,5,7 }), then another sequence B)_qCannot be included in the predetermined sequence table T. For example, the sequence B_qCan be represented by the value b_q(i) Wherein if i is 2 m +1, then

In some embodiments, in the predetermined sequence table T, if a sequence B_pIs included (e.g., sequence B)_pBy a value of b_p(i) In which b is_p(i) May be any one of { -7, -5, -3, -1,1,3,5,7 }), then another sequence B)_qCannot be included in the predetermined sequence table T. For example, the sequence B_qCan be represented by the value b_q(i) Group ofWherein if i is 2 m, then b_q(i)＝

And if i is 2 m +1, then b_q(i)＝b_p(i) In that respect Furthermore, 0. ltoreq. m.ltoreq.N/2-1 and 0. ltoreq. i.ltoreq.N-1, where N is the sequence length. For example, N may be any of {5,7,8,9,10,11,15,16,20,25,27 }.

In some embodiments, for 2 symbols, one Control Channel Element (CCE) may occupy 3 Physical Resource Blocks (PRBs) in the frequency domain. In this case, if a DMRS transmission occupies 3 Resource Elements (REs) in one PRB, a length-9 CGS may be required to generate the DMRS sequence. In some embodiments, if a Reference Signal (RS) transmission occupies 3 REs in one PRB, and if the RS transmission occupies 3 PRBs, a length 9 CGS may be required to generate the RS sequence. In some embodiments, a length 9 CGS may be modulated with one of: QPSK, 8PSK or pi/2-BPSK.

In some embodiments, if the sequence length is 9 and the modulation technique is pi/2-BPSK, the predetermined sequence table may include at least one of the CGSs shown in table 1-1:

tables 1 to 1: CG sequence of length 9 (pi/2-BPSK)

In some embodiments, if the sequence length is 9 and the modulation technique is QPSK, the predetermined sequence table may include at least one of the CGSs shown in tables 1-2:

tables 1 to 2: CG sequence of length 9 (QPSK)

In some embodiments, for 2 symbols, one Control Channel Element (CCE) may occupy 2 PRBs in the frequency domain. In this case, if a DMRS transmission occupies 4 REs in one PRB, a length-8 CGS may be needed to generate the DMRS sequence. In some embodiments, if an RS transmission occupies 4 REs in one PRB and an RS transmission occupies 2 RBs, a length-8 CGS may be needed to generate an RS sequence. For example, a CGS of length 8 may be modulated with one of: QPSK, 8PSK or pi/2-BPSK.

In some embodiments, if the sequence length is 8 and the modulation technique is pi/2-BPSK, the predetermined sequence table may include at least one of the CGSs shown in table 2-1:

table 2-1: CG sequence of length 8 (pi/2-BPSK)

Alternatively, in some embodiments, if the sequence length is 8 and the modulation technique is QPSK, the predetermined sequence table may include at least one of the CGSs shown in table 2-2:

tables 2 to 2: CG sequence (QPSK) of length 8

In some embodiments, a length 7 CGS may be required to generate the DMRS sequence. For example, a CGS of length 7 may be modulated with one of: QPSK, 8PSK or pi/2-BPSK. In some embodiments, if the sequence length is 7 and the modulation technique is QPSK, the predetermined sequence table may include at least one of CGSs shown in table 3-1:

table 3-1: CG sequence of length 7 (QPSK)

In some embodiments, a length-10 CGS may be required to generate the DMRS sequence. For example, a CGS of length 10 may be modulated with one of: QPSK or pi/2-BPSK. In some embodiments, if the sequence length is 10 and the modulation technique is QPSK, the predetermined sequence table may include at least one of CGSs shown in table 4-1:

table 4-1: CG sequence of length 10 (QPSK)

In some embodiments, a length-11 CGS may be required to generate the DMRS sequence. For example, a CGS of length 11 may be modulated with one of: QPSK or pi/2-BPSK. In some embodiments, if the sequence length is 11 and the modulation technique is QPSK, the predetermined sequence table may include at least one of CGSs shown in table 5-1:

table 5-1: CG sequence of length 11 (QPSK)

In some embodiments, a length 16 CGS may be required to generate the DMRS sequence. For example, a length 16 CGS may be modulated with one of: QPSK or pi/2-BPSK.

In some embodiments, if the sequence length is 16 and the modulation technique is pi/2-BPSK, the predetermined sequence table may include at least one of the CGSs shown in table 6-1:

table 6-1: CG sequence of length 16 (pi/2-BPSK)

Fig. 4 shows the performance of the CG sequences in table 6-1. For example, the autocorrelation performance of the CG sequence in table 6-1 is shown in a Cumulative Distribution Function (CDF) curve 410 in fig. 4, where the horizontal axis may represent autocorrelation values and the vertical axis may represent cumulative distribution probabilities. The PAPR performance of the CG sequence in table 6-1 is shown in table 420 in fig. 4.

Alternatively, in some embodiments, if the sequence length is 16 and the modulation technique is QPSK, the predetermined sequence table may include at least one of the CGSs shown in table 6-2:

table 6-2: CG sequence of length 16 (QPSK)

In some embodiments, a length-20 CGS may be required to generate the DMRS sequence. For example, a length-20 CGS may be modulated with one of: QPSK or pi/2-BPSK. In some embodiments, if the sequence length is 20 and the modulation technique is pi/2-BPSK, the predetermined sequence table may include at least one of the CGSs shown in table 7-1:

table 7-1: CG sequence of length 20 (pi/2-BPSK)

In some embodiments, RS transmission may occupy 3 REs within one PRB, and de-RS transmission may occupy 9 RBs. In some embodiments, a length 27 CGS may be required to generate the DMRS sequence in this case. For example, a CGS of length 27 may be modulated with one of: QPSK or pi/2-BPSK. In some embodiments, if the sequence length is 27 and the modulation technique is pi/2-BPSK, the predetermined sequence table may include at least one of the CGSs shown in table 8-1:

table 8-1: CG sequence of length 27 (pi/2-BPSK)

Fig. 5 illustrates a flowchart of an example method 500 for DMRS transmission, in accordance with some embodiments of the present disclosure. Method 500 may be implemented at network device 110 as shown in fig. 1. It should be understood that method 500 may include additional blocks not shown and/or may omit some of the blocks shown, and the scope of the present disclosure is not limited in this respect.

At block 510, the network device 110 selects a CG sequence for a downlink channel modulated with a predetermined modulation technique from a plurality of CG sequences each having a predetermined sequence length.

At block 520, the network device 110 generates a DMRS sequence for the downlink channel based on the selected CG sequence.

At block 530, network device 110 transmits the DMRS sequence to the terminal device over the downlink channel.

In some embodiments, the downlink channel may include any one of a PDSCH and a PDCCH.

In some embodiments, the predetermined modulation technique may include any one of: pi/2-BPSK, QPSK and 8 PSK.

In some embodiments, the predetermined sequence length may be below 30.

In some embodiments, the predetermined sequence length may include any one of: 5. 7,8,9,10,11,15,16,20,25 and 27.

In some embodiments, network device 110 may determine the plurality of CG sequences based on at least one of: a predetermined sequence length, a PAPR of a CG sequence, an autocorrelation of a CG sequence, and a cross-correlation of two CG sequences.

In some embodiments, network device 110 may determine the plurality of CG sequences by: determining a first set of CG sequences based on a predetermined sequence length; selecting a second set of CG sequences from the first set of CG sequences such that a PAPR of each CG sequence in the second set of CG sequences is below a first threshold and an autocorrelation of each CG sequence in the second set of CG sequences is below a second threshold; and selecting a plurality of CG sequences from the second set of CG sequences.

In some embodiments, network device 110 may select multiple CG sequences from the second set of CG sequences by: dividing a second set of CG sequences into a first subset and a second subset; iteratively performing at least one of: determining, from the first subset, a first pair of CG sequences associated with a highest cross-correlation among the first subset, determining whether a second pair of CG sequences associated with a cross-correlation lower than the highest cross-correlation is present in the second subset, and in response to determining that the second pair of CG sequences is present in the second subset, replacing the first pair of CG sequences in the first subset with the second pair of CG sequences; and determining a plurality of CG sequences based on the first subset.

Fig. 6 illustrates a flowchart of an example method 600 for DMRS reception, in accordance with some embodiments of the present disclosure. Method 600 may be implemented at terminal device 120 as shown in fig. 1. It should be understood that method 600 may include additional blocks not shown and/or may omit some of the blocks shown, and the scope of the present disclosure is not so limited.

At block 610, terminal device 110 selects a CG sequence for a downlink channel modulated with a predetermined modulation technique from a plurality of CG sequences each having a predetermined sequence length.

At block 620, the terminal device 120 determines a DMRS sequence for the downlink channel based on the selected CG sequence.

At block 630, the terminal device 120 receives a DMRS sequence from the network device over the downlink channel.

In some embodiments, the predetermined sequence length may be below 30.

In some embodiments, the terminal device 120 may determine the plurality of CG sequences based on at least one of: a predetermined sequence length, a PAPR of a CG sequence, an autocorrelation of a CG sequence, and a cross-correlation of two CG sequences.

In some embodiments, the terminal device 120 may determine the plurality of CG sequences by: determining a first set of CG sequences based on a predetermined sequence length; selecting a second set of CG sequences from the first set of CG sequences such that a PAPR of each CG sequence in the second set of CG sequences is below a first threshold and an autocorrelation of each CG sequence in the second set of CG sequences is below a second threshold; and selecting a plurality of CG sequences from the second set of CG sequences.

In some embodiments, the terminal device 120 may select multiple CG sequences from the second set of CG sequences by: dividing a second set of CG sequences into a first subset and a second subset; iteratively performing at least one of: determining, from the first subset, a first pair of CG sequences associated with a highest cross-correlation among the first subset, determining whether a second pair of CG sequences associated with a cross-correlation lower than the highest cross-correlation is present in the second subset, and in response to determining that the second pair of CG sequences is present in the second subset, replacing the first pair of CG sequences in the first subset with the second pair of CG sequences; and determining a plurality of CG sequences based on the first subset.

Fig. 7 is a simplified block diagram of a device 700 suitable for implementing embodiments of the present disclosure. Device 700 may be considered a further example implementation of network device 110 or terminal device 120 as shown in fig. 1. Accordingly, device 700 may be implemented at or as at least a portion of network device 110 or terminal device 120.

As shown, device 700 includes a processor 710, a memory 720 coupled to processor 710, a suitable Transmitter (TX) and Receiver (RX)740 coupled to processor 710, and a communication interface coupled to TX/RX 740. The memory 710 stores at least a portion of the program 730. TX/RX 740 is used for bi-directional communication. TX/RX 740 has at least one antenna to facilitate communication, but in practice the access node referred to in this application may have several antennas. The communication interface may represent any interface required for communication with other network elements, such as an X2 interface for bidirectional communication between enbs, an S1 interface for communication between a Mobile Management Entity (MME)/serving gateway (S-GW) and an eNB, a Un interface for communication between an eNB and a Relay Node (RN), or a Uu interface for communication between an eNB and a terminal device.

The program 730 is assumed to include program instructions that, when executed by the associated processor 710, enable the device 700 to operate in accordance with embodiments of the present disclosure, as discussed herein with reference to fig. 1-6. Embodiments herein may be implemented by computer software executable by the processor 710 of the device 700, or by hardware, or by a combination of software and hardware. The processor 710 may be configured to implement various embodiments of the present disclosure. Further, the combination of processor 710 and memory 720 may form a processing component 750 suitable for implementing various embodiments of the present disclosure.

The memory 720 may be of any type suitable to the local technology network and may be implemented using any suitable data storage technology, such as non-transitory computer-readable storage media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. Although only one memory 720 is shown in device 700, there may be several physically separate memory modules in device 700. The processor 710 may be of any type suitable to the local technology network, 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. Device 700 may have multiple processors, such as an application specific integrated circuit chip that is time dependent from a clock synchronized to the main processor.

In general, the various embodiments of the disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of the embodiments of the disclosure are illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, executed in a device on a target real or virtual processor to perform the processes or methods described above with reference to fig. 5-6. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or split between program modules as desired. Machine-executable instructions of program modules may be executed within a local device or within a distributed device. In a distributed facility, program modules may be located in both local and remote memory storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowchart and/or block diagram to be performed. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

The program code described above may be embodied on a machine-readable medium, which may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of machine-readable storage media would include: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are described 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 scenarios, multitasking and parallel processing may be advantageous. Likewise, while the above discussion contains several specific implementation details, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described 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.

Although the disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A method of communication, comprising:

selecting, at a network device, a computer-generated (CG) sequence for a downlink channel modulated using a predetermined modulation technique from a plurality of CG sequences each having a predetermined sequence length;

generating a demodulation reference signal (DMRS) sequence for the downlink channel based on the selected CG sequence; and

and transmitting the DMRS sequence to a terminal device through the downlink channel.

2. The method of claim 1, wherein the downlink channel comprises any one of a Physical Downlink Shared Channel (PDSCH) and a Physical Downlink Control Channel (PDCCH).

3. The method of claim 1, wherein the predetermined modulation technique comprises any one of: pi/2-binary phase shift keying (pi/2-BPSK), Quadrature Phase Shift Keying (QPSK), and 8-phase shift keying (8 PSK).

4. The method of claim 1, wherein the predetermined sequence length is below 30.

5. The method of claim 1, wherein the predetermined sequence length comprises any one of: 5. 7,8,9,10,11,15,16,20,25 and 27.

6. The method of claim 1, further comprising:

determining the plurality of CG sequences based on at least one of:

the length of the predetermined sequence is such that,

peak-to-average power ratio (PAPR) of a CG sequence,

autocorrelation of a CG sequence, and

cross-correlation of two CG sequences.

7. The method of claim 6, wherein determining the plurality of CG sequences comprises:

determining a first set of CG sequences based on the predetermined sequence length;

selecting a second set of CG sequences from the first set of CG sequences such that the PAPR of each CG sequence in the second set of CG sequences is below a first threshold and the autocorrelation of each CG sequence in the second set of CG sequences is below a second threshold; and

selecting the plurality of CG sequences from the second set of CG sequences.

8. The method of claim 7, wherein selecting the plurality of CG sequences from the second set of CG sequences comprises:

dividing the second set of CG sequences into a first subset and a second subset;

iteratively performing at least one of:

determining a first pair of CG sequences from the first subset that is associated with a highest cross-correlation among the first subset,

determining whether a second pair of CG sequences associated with a cross-correlation lower than the highest cross-correlation exists in the second subset, and

in response to determining that the second pair of CG sequences is present in the second subset, replacing the first pair of CG sequences in the first subset with the second pair of CG sequences; and

determining the plurality of CG sequences based on the first subset.

9. A method of communication, comprising:

selecting, at a terminal device, a computer-generated (CG) sequence for a downlink channel modulated with a predetermined modulation technique from a plurality of CG sequences each having a predetermined sequence length;

determining a demodulation reference signal (DMRS) sequence for the downlink channel based on the selected CG sequence; and

receiving the DMRS sequence from a network device over the downlink channel.

10. The method of claim 9, wherein the downlink channel comprises any one of a Physical Downlink Shared Channel (PDSCH) and a Physical Downlink Control Channel (PDCCH).

11. The method of claim 9, wherein the predetermined modulation technique comprises any one of: pi/2-binary phase shift keying (pi/2-BPSK), Quadrature Phase Shift Keying (QPSK), and 8-phase shift keying (8 PSK).

12. The method of claim 9, wherein the predetermined sequence length is below 30.

13. The method of claim 9, wherein the predetermined sequence length comprises any one of: 5. 7,8,9,10,11,15,16,20,25 and 27.

14. The method of claim 9, further comprising:

determining the plurality of CG sequences based on at least one of:

the length of the predetermined sequence is such that,

peak-to-average power ratio (PAPR) of a CG sequence,

autocorrelation of a CG sequence, and

cross-correlation of two CG sequences.

15. The method of claim 14, wherein determining the plurality of CG sequences comprises:

determining a first set of CG sequences based on the predetermined length;

selecting the plurality of CG sequences from the second set of CG sequences.

16. The method of claim 15, wherein selecting the plurality of CG sequences from the second set of CG sequences comprises:

iteratively performing at least one of:

determining the plurality of CG sequences based on the first subset.

17. A network device, comprising:

a processor; and

a memory coupled with the processor and having instructions stored thereon that, when executed by the processor, cause the network device to perform the method of any of claims 1-8.

18. A terminal device, comprising:

a processor; and

a memory coupled with the processor and having instructions stored thereon that, when executed by the processor, cause the terminal device to perform the method of any of claims 9-16.

19. A computer-readable medium having stored thereon 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 1 to 8.

20. A computer-readable medium having stored thereon 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 9 to 16.