Enhanced PRACH preamble

Abstract

Embodiments of the present disclosure relate to the generation and detection of a physical random access channel (PRACH) preamble. A first device determines a base sequence, a first scrambling sequence for the base sequence, and a second scrambling sequence for the base sequence. The first device generates a random access preamble by applying the first scrambling sequence and the second scrambling sequence to different parts of the base sequence, respectively. The first device transmits the random access preamble to a second device.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to the field of communications, especially in non-terrestrial networks, and specifically to devices, methods, apparatuses, and computer-readable storage media for generating and detecting a physical random access channel (PRACH) preamble. Background Art

[0002] It is difficult for terrestrial networks to provide fifth generation (5G) coverage due to limited resources and infrastructure in remote areas. For this reason, non-terrestrial networks (NTNs) have been introduced. In NTNs, satellites and high altitude platform stations (HAPS) are used to provide connectivity across a wide service area. The main benefit of introducing NTNs is to enable ubiquitous 5G services for terminal devices (e.g., user equipment UE) by extending connectivity in sparsely populated areas where device density is extremely low. In addition, the total cost of NTN deployment can be much lower than the cost of providing permanent infrastructure on land. A new solution, New Radio (NR), has been proposed to support NTN. However, some issues regarding NTN remain unresolved. Summary of the invention

[0003] In general, example embodiments of the present disclosure provide a solution for generating and detecting a PRACH preamble.

[0004] In a first aspect, a first device is provided. The first device includes at least one processor; and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the first device to: determine a base sequence, a first scrambling sequence for the base sequence, and a second scrambling sequence for the base sequence; generate a random access preamble by applying the first scrambling sequence and the second scrambling sequence to different parts of the base sequence, respectively; and transmit the random access preamble to a second device.

[0005] In a second aspect, a second device is provided. The second device includes at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, together with the at least one processor, cause the second device to: determine a first scrambling sequence for a base sequence and a second scrambling sequence for the base sequence; determine a timing metric for estimating a timing offset based on the first scrambling sequence and the second scrambling sequence; and receive a random access preamble from the first device based on the timing metric, the random access preamble being generated by applying the first scrambling sequence and the second scrambling sequence to different parts of the base sequence, respectively.

[0006] In a third aspect, a method is provided. The method includes: determining a base sequence, a first scrambling sequence for the base sequence, and a second scrambling sequence for the base sequence at a first device; generating a random access preamble by applying the first scrambling sequence and the second scrambling sequence to different parts of the base sequence, respectively; and transmitting the random access preamble to a second device.

[0007] In a fourth aspect, a method is provided. The method includes: determining, at a second device, a first scrambling sequence for a base sequence and a second scrambling sequence for the base sequence; determining a timing metric for estimating a timing offset based on the first scrambling sequence and the second scrambling sequence; and receiving a random access preamble from the first device based on the timing metric, the random access preamble being generated by applying the first scrambling sequence and the second scrambling sequence to different portions of the base sequence, respectively.

[0008] In a fifth aspect, an apparatus is provided. The apparatus includes a component for determining a base sequence, a first scrambling sequence for the base sequence, and a second scrambling sequence for the base sequence at a first device; a component for generating a random access preamble by applying the first scrambling sequence and the second scrambling sequence to different parts of the base sequence, respectively; and a component for transmitting the random access preamble to a second device.

[0009] In a sixth aspect, an apparatus is provided. The apparatus includes a component for determining, at a second device, a first scrambling sequence for a base sequence and a second scrambling sequence for the base sequence; a component for determining a timing metric for estimating a timing offset based on the first scrambling sequence and the second scrambling sequence; and a component for receiving a random access preamble from the first device based on the timing metric, the random access preamble being generated by applying the first scrambling sequence and the second scrambling sequence to different portions of the base sequence, respectively.

[0010] In a seventh aspect, a non-transitory computer-readable medium is provided, the non-transitory computer-readable medium comprising program instructions for causing an apparatus to at least perform the method according to the third aspect.

[0011] In an eighth aspect, a non-transitory computer-readable medium is provided, the non-transitory computer-readable medium comprising program instructions for causing an apparatus to at least perform the method according to the fourth aspect.

[0012] It should be understood that the invention summary is not intended to determine the key or essential features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Some example embodiments will now be described with reference to the accompanying drawings, in which:

[0014] Figure 1An example communication system is shown in which embodiments of the present disclosure may be implemented;

[0015] Figure 2A shows a schematic diagram illustrating an example preamble according to some example embodiments of the present disclosure;

[0016] Figure 2B A schematic diagram illustrating another example preamble according to some example embodiments of the present disclosure is shown;

[0017] Figure 3 A flow chart illustrating an example process for transmitting a random access preamble according to some example embodiments of the present disclosure is shown;

[0018] Figure 4A shows simulation results of symbol timing error rate according to some example embodiments of the present disclosure;

[0019] Figure 4B shows simulation results of the error mean of the timing offset according to some example embodiments of the present disclosure;

[0020] Figure 4C shows simulation results of standard deviation of timing offset according to some example embodiments of the present disclosure;

[0021] Figure 5A shows simulation results of symbol timing error rate according to some example embodiments of the present disclosure;

[0022] Figure 5B shows simulation results of the error mean of the timing offset according to some example embodiments of the present disclosure;

[0023] Figure 5C shows simulation results of standard deviation of timing offset according to some example embodiments of the present disclosure;

[0024] Figure 6 shows simulation results of PRACH accurate detection rate according to some example embodiments of the present disclosure;

[0025] Figure 7 A flowchart showing a method according to some example embodiments of the present disclosure is shown;

[0026] Figure 8 A flowchart showing a method according to some example embodiments of the present disclosure is shown;

[0027] Fig. 9 shows a simplified block diagram of a device suitable for implementing an embodiment of the present disclosure; and

[0028] Fig.10 A block diagram of an example computer-readable medium is shown in accordance with some embodiments of the present disclosure.

[0029] Throughout the drawings, the same or similar reference numerals refer to the same or similar elements. DETAILED DESCRIPTION

[0030] The principles of the present disclosure will now be described with reference to some example embodiments. It should be understood that the description of the example embodiments is only for the purpose of illustrating and helping those skilled in the art to understand and implement the present disclosure, and does not represent any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various other ways except for the way described below.

[0031] 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.

[0032] References in this disclosure to "one embodiment," "an embodiment," "an example embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an example embodiment, it is considered to be within the knowledge of those skilled in the art to affect such feature, structure, or characteristic in conjunction with other embodiments (whether or not explicitly described).

[0033] It should be understood that although the terms "first" and "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 element. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of the exemplary embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0034] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the exemplary 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 "comprise", "include", "have", "have", "include" and / or "comprising" when used herein specify the presence of the features, elements and / or components, etc., but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0035] As used in this application, the term "circuitry" may refer to one, more, or all of the following:

[0036] (a) a pure hardware circuit implementation (such as an implementation using only analog and / or digital circuitry), and

[0037] (b) a combination of hardware circuitry and software such as (where applicable):

[0038] (i) a combination of analog and / or digital hardware circuits and software / firmware, and

[0039] (ii) any portion of hardware processor(s) (including digital signal processor(s)), software and memory(s) with software that work together to enable a device (such as a mobile phone or server) to perform various functions, and

[0040] (c) Hardware circuits and / or processor(s), such as microprocessor(s) or portions of microprocessor(s), that require software (e.g., firmware) to operate, but which may not be present when the software is not required for operation.

[0041] This definition of circuitry applies to all uses of the term in this application, including in any claims. As another example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. For example, if applicable to a particular claim element, the term circuitry also covers a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0042] As used herein, the term "communication network" refers to a network that follows any suitable communication standard, such as long term evolution (LTE), advanced LTE (LTE-A), wideband code division multiple access (WCDMA), high speed packet access (HSPA), narrowband Internet of Things (NB-IoT), new radio (NR), etc. In addition, the communication between the terminal equipment and the network equipment in the communication network can be performed according to the communication protocol of any suitable generation, including but not limited to the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, 5G communication protocol, and / or and / or any other protocol currently known or developed in the future. The embodiments of the present disclosure can be applied to various communication systems. In view of the rapid development of communication, there will certainly be communication technologies and systems of future types that can embody the present disclosure. It should not be considered that the scope of the present disclosure is limited to the above-mentioned system.

[0043] As used herein, the term "network device" refers to a node in a communication network via which a terminal device accesses the network and receives services from it. A network device may refer to a base station (BS) or an access point (AP), such as a NodeB (NodeB or NB), an evolved NodeB (eNodeB or eNB), a NR NB (also known as a gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, a low power node (such as a femto, a pico), an integrated access backhaul (IAB) node, an NTN or non-terrestrial network device (such as a satellite network device, a low earth orbit (LEO) satellite, a medium earth orbit (MEO) satellite, and a geosynchronous earth orbit (GEO) satellite), an aircraft network device, etc., depending on the terminology and technology applied.

[0044] The term "terminal device" refers to any terminal device that can perform wireless communication. As an example and not limitation, the terminal device may also be referred to as a communication device, a user equipment (UE), a subscriber station (SS), a portable subscriber station, a mobile station (MS) or an access terminal (AT). The terminal device may include, but is not limited to, a mobile phone, a cellular phone, a smart phone, a voice over IP (VoIP) phone, a wireless local loop phone, a tablet computer, a wearable terminal device, a personal digital assistant (PDA), a portable computer, a desktop computer, an image acquisition terminal device such as a digital camera, a game terminal device, a music storage and playback device, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a laptop embedded device (LEE), a laptop mounted device (LME), a USB dongle, a smart device, a wireless client device (CPE), an Internet of Things (IoT) device, a watch or other wearable device, a head mounted display (HMD), a vehicle, a drone, medical equipment and applications (e.g., remote surgery), industrial equipment and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain environments), consumer electronic devices, equipment operating on commercial and / or industrial wireless networks, etc. In the following description, the terms "terminal device", "communication device", "terminal", "user equipment" and "UE" may be used interchangeably.

[0045] Figure 1 An example communication system 100 is shown in which example embodiments of the present disclosure may be implemented. Figure 1 An example NTN network is shown in FIG. The communication system 100 includes a first device 110 and a second device 120 that can communicate with each other. In this example, the first device 110 is shown as a terminal device (specifically a UE), and the second device 120 is shown as an NTN network device serving the terminal device.

[0046] In some NTN scenarios, network equipment (e.g., gNB) will be on Earth communicating with transparent satellites, while in some other NTN scenarios, network equipment will be onboard with regenerative satellites. Figure 1 In the example of , the second device 120 is deployed at a space / airborne platform (e.g., satellite 130), which corresponds to a regenerative satellite. It should be understood that the second device 120 can also be deployed on the earth and communicate with a transparent satellite. In addition, other aircraft can also be used as a space / airborne platform.

[0047] The satellite 130 or the aircraft typically generates several beams over a given area. The footprint of the beam (e.g., beam footprint 102) is typically elliptical. The service link 101 refers to a radio link between the first device 110 and the satellite 130. In addition, although not shown, the first device 110 may also support a radio link with a land-based radio access network (RAN). The feeder link 103 refers to a radio link between the gateway 140 and the satellite 130. The gateway 140 is connected to a data network, such as a core network.

[0048] It should be understood that the number of devices (both the first device and the second device) is for illustration purposes only and does not present any limitation. System 100 may include any suitable number of devices suitable for implementing embodiments of the present disclosure.

[0049] The communication in the communication system 100 can be implemented according to any (multiple) appropriate communication protocols, including but not limited to cellular communication protocols of the first generation (1G), second generation (2G), third generation (3G), fourth generation (4G) and fifth generation (5G), wireless local area network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, and / or any other protocol currently known or developed in the future. In addition, the communication can utilize any appropriate wireless communication technology, including but not limited to: code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplexer (FDD), time division duplexer (TDD), multiple input multiple output (MIMO), orthogonal frequency division multiplexing (OFDM), cyclic prefix orthogonal frequency division multiplexing (CP-OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), and / or any other technology currently known or to be developed in the future.

[0050] In the communication system 100, after the connection is established, the first device 110 and the second device 120 can transmit data and control information to each other. In the case where the first device 110 is a terminal device and the second device 120 is a network device, the link from the second device 120 to the first device 110 is called a downlink (DL), and the link from the first device 110 to the second device 120 is called an uplink (UL). In the DL, the second device 120 is a transmission (TX) device (or transmitter), and the first device 110 is a reception (RX) device (or receiver). In the UL, the first device 110 is a TX device (or transmitter), and the second device 120 is an RX device (or receiver).

[0051] Typically, to communicate with each other, for example, the first device 110 may initiate a random access (RA) procedure to establish or reestablish a connection with the second device 120. During the RA procedure, the first device 110 may transmit a random access preamble (which may also be referred to as a PRACH preamble) to the second device 120.

[0052] As mentioned above, some issues about NTN are still unresolved. Depending on the deployment scenario, the long distance between the network equipment on the NTN platform and the terminal equipment on the surface leads to a large beam footprint, which will cause some problems. For example, the differential delay exceeds the maximum cell coverage supported by the NR preamble format. In addition to delay, high-frequency offset caused by Doppler shift and local oscillator is also a major challenge for the existing NR PRACH preamble format. Therefore, the design of a new PRACH preamble sequence that is robust to frequency offset and time is very important for NTN.

[0053] Several agreements are implemented in terms of DL synchronization, UL frequency compensation, timing advance (TA) adjustment, and PRACH formats and / or sequences. For example, if it is assumed that the timing and frequency offsets are pre-compensated (e.g., if the UE knows the UE's geographical location at the necessary level of accuracy), then the existing PRACH formats and preamble sequences can be reused in the NTN. If pre-compensation of timing and frequency offsets is not performed, it is beneficial to introduce enhanced PRACH formats and / or preamble sequences.

[0054] Existing PRACH preambles utilize Zadoff-Chu (ZC) sequences and include a cyclic prefix (CP), multiple repetitions of the PRACH sequence, and a guard period (GP). These formats are intended to facilitate UL timing estimation, where the UL frequency offset between the terminal device and the network device is assumed to be small after DL synchronization. The small UL frequency offset between the terminal device and the network device in message 1 (Msg 1) of the RA procedure is assumed to be valid in terrestrial networks, where the network device is stationary and the frequency offset is mainly determined by the DL motion of the terminal device.

[0055] Currently, there are two PRACH preamble formats in NR, namely, length L RA =839 long preamble and length L RA =139 short preamble code, as shown in Table 1-1 and Table 1-2.

[0056] Table 1-1 L RA =839 and Δf RA ∈{1.25, 5}kHz preamble format

[0057]

[0058] Table 1-2 L RA =139 and Δf RA =15.2 μ kHz (where μ∈{0, 1, 2, 3}) preamble format

[0059]

[0060] In NTN, the assumption of a small UL frequency offset between the terminal device and the network equipment in Msg 1 is no longer valid due to the high Doppler shift caused by the fast movement of LEO satellites. From Table 1-3, it can be seen that the CP length does not exceed 684.37us, while the maximum differential delay within the beam is 1.6ms in GEO and 0.65ms in LEO, which is much larger than 684.37us or close to this value.

[0061] Table 1-3 Preamble parameters in different formats

[0062]

[0063] In view of the above, the current NR preamble format may not be sufficient for all NTN scenarios. A new PRACH design is needed to resist maximum delay and maximum frequency offset. At least for the case without timing and frequency offset pre-compensation, at least the following options for enhanced PRACH format and / or preamble sequence can be considered: Option 1, a single Zadoff-Chu sequence based on a larger SCS, a number of repetitions; Option 2, a solution based on multiple Zadoff-Chu sequences with different roots; Option 3, Gold / m sequence as a preamble sequence with additional processes, such as modulation and transform precoding; Option 4, a single Zadoff-Chu sequence with a combination of scrambling sequences. However, details about these options have not yet been proposed.

[0064] The current PRACH preamble format / parameters are not well suited for NTN because the ambiguity function of the ZC sequence in the delay-Doppler plane has several peaks, resulting in many timing and Doppler ambiguities. Therefore, new primary synchronization signal (PSS) sequence designs, such as the M sequence, have been discussed in NR. For PRACH in NTN, the situation is more difficult because a set of orthogonal sequences needs to be designed to distinguish different terminal devices that transmit simultaneously and have high time / frequency uncertainty relative to terrestrial scenarios. In addition, if cyclically shifted ZC sequences are used, the compound shift caused by the time / frequency ambiguity may cause one sequence to become another, resulting in false detection at the receiver.

[0065] Due to this inherent defect of ZC sequence, some solutions have been proposed, including simply modifying some parameters (e.g., CP size, subcarrier spacing) or repeating the sequence. However, these solutions rarely analyze the problem from the sequence itself and therefore do not show robust performance. In the present disclosure, a new PRACH sequence design adapted to NTN system and a corresponding detection scheme at the receiver are provided.

[0066] In order to design a suitable PRACH preamble format for UL timing estimation and UL frequency estimation, we first need to understand why the existing NR PRACH preamble format based on ZC sequence cannot meet the target. It is well known that the correlation peak of ZC sequence will shift under frequency offset. The offset is a function of root index and frequency offset. The correlation peak usually indicates the start time of the received signal. Therefore, the first thing that should be considered is the sequence design to have robust symbol timing under large frequency shifts in NTN.

[0067] The purpose of symbol timing is to obtain the starting point of the Fast Fourier Transform (FFT) window so that the transmitted data (in this case, the random access preamble) can be correctly demodulated at the receiver. Otherwise, inter-symbol interference (ISI) and inter-channel interference (ICI) will result, resulting in poor detection performance.

[0068] The existing preamble uses more than two OFDM symbols to achieve timing synchronization. For example, the long sequence of format 1 and the short sequences of formats A1 and B1 shown in Table 1-1 have two repeated forms of the same sequence. However, the metric function increases with N cp The length of the preamble is 100 samples, and there is a platform. In order to solve this problem, the preamble is separated from two identical data blocks into four identical data blocks, such as the long sequence of format 2 and the short sequences of formats A2 and B2 shown in Table 1-1. However, the descent curve is not steep enough, which also leads to inaccurate timing estimation. A conjugate symmetric preamble is proposed, which can effectively solve the problem of the steepness of the descent curve. However, there are side lobes outside the main lobe.

[0069] In addition, based on the above agreement, more details on the enhancements to PRACH are provided. For example, for option 2, two alternatives are proposed, such as a single PRACH preamble consisting of two root sequences or multiple preamble transmissions from a single terminal device with different roots. And, details on how to determine the root pair are also provided, such as a complex conjugation rule or an additional rule.

[0070] In the present disclosure, a new PRACH preamble and a corresponding detection scheme are provided. At a transmission device, for example, at a terminal device, the new PRACH preamble is based on a base sequence and at least two scrambling sequences. At least two scrambling sequences having a pseudo-random property are applied to the base sequence to generate a new PRACH preamble. For example, the scrambling sequence can be used as a weighting factor for the base sequence. The base sequence may include multiple root sequences (e.g., ZC sequences) with the same or reversed symbols. At a receiving device, for example, at a network device, a timing metric based on at least two scrambling sequences is used for symbol timing to receive a new PRACH preamble.

[0071] Through the proposed PRACH preamble and detection scheme, the problem of large frequency offset and differential delay between the transmitting device and the receiving device can be overcome, and the timing accuracy can be improved. In this way, an accurate estimation of the timing offset can be achieved to facilitate UL timing estimation, especially in the case of a large UL frequency offset between the transmitting device and the receiving device.

[0072] Some exemplary embodiments of the present disclosure will be described in detail below. In order to better understand the principle of the present invention, firstly, preamble design and detection scheme design are described as examples.

[0073] System Description

[0074] The expressions of the transmitted and received signals are based on the general OFDM signal model of PRACH. At the transmission device, the time-discrete OFDM (such as the PRACH signal) can be expressed as:

[0075]

[0076] where a(k) represents the modulated data (in this case, the random access preamble) or subcarrier symbol on the kth subcarrier. After serial / parallel (S / P) conversion, the transmission duration is extended to T = MT s , where M is the number of repeated symbols, T s is the time length of a symbol, T s =1 / Δf RA . N is the IFFT window size (N ZC ≤N). The length is NCP The cyclic prefix is ​​placed in front of the first symbol.

[0077] At the receiving device, the received signal can be expressed as:

[0078]

[0079] where h l is the channel impulse response of tap l. Integer normalized symbol timing offset θ l and the normalized carrier frequency offset ε are modeled as the delayed signal at the receiving device and the phase offset in the time domain, respectively, and ω(n) is a zero-mean and variance σ n 2 complex Gaussian noise process.

[0080] Preamble design

[0081] As shown in Table 1-1 and Table 1-2, additional preamble formats may be introduced to the existing preamble formats. An additional format called format 4 is given as an example herein. The example format 4 shown in Table 2 is based on the existing long preamble format with an appropriate scaling factor μ.

[0082] Table 2 Example preamble format

[0083]

[0084] Wherein μ∈{0, 4} is used for the first frequency range (eg, FR1); μ∈{5, 6, 7} is used for the second frequency range (eg, FR2).

[0085] Format 4 corresponds to a preamble length of 839 in the frequency domain and 4 repetitions in the time domain. Similar additional preamble formats may be introduced. For example, another additional preamble may be based on an existing short preamble format, for example with 6 repetitions in the time domain.

[0086] The principle of the proposed method is to use two scrambling sequences as weighting factors to ensure that the value of the timing metric function (described in detail below) reaches the maximum value at the correct timing position. Different parts of the random access preamble can be weighted with different scrambling factors. For example, the first and second parts of the preamble are weighted with the first scrambling sequence and the second scrambling sequence respectively.

[0087] The scrambling sequence may have pseudo-random properties. The scrambling sequence may share similar statistical properties with a random signal, but may be generated and processed deterministically.

[0088] Pseudo-noise (PN) sequences are similar to random noise and share similar statistical characteristics. However, unlike true random signals, PN sequences can be generated and processed deterministically. PN sequences can be used in spread spectrum communication systems and secret communication systems. The autocorrelation of a PN sequence is a binary function that has a sharp autocorrelation peak when there is no displacement. Although the cross-correlation properties of PN sequences have not been well described, the cross-correlation properties of m-sequences of the same order (as a typical type of PN sequence) can be viewed as a correlation function between an m-sequence and its sampling sequence, and the calculation of the correlation function is only related to the choice of the sampling factor.

[0089] In view of the above-mentioned properties of the PN sequence, in an exemplary embodiment, two PN sequences can be used as scrambling sequences. The two PN sequences can be two different PN sequences with the same period. By using the PN sequence as the scrambling sequence, the error rate can be reduced, the sudden wide range deviation can be avoided, and the difference of the timing metric value near the correct starting point can be further expanded compared with the existing method.

[0090] An example with two PN sequences G and Q will be described. The two PN sequences G and Q and a binary phase shift keying (BPSK) (±1) conversion sequence can be defined as:

[0091]

[0092]

[0093] As shown in equation (3), the length of each PN sequence is N u / 2. When using format 4, N u The values ​​are shown in Table 2. For example, assuming κ=1, μ=4, then 4*32768*2^(-4) / 2=4096, and the required PN sequence order is 12.

[0094] The PN sequence can be generated using a shift register. For example, the PN sequences G and Q can be generated based on a primitive polynomial. Take the primitive polynomial "fbconnection = [1 0 0 0 0 1 1]" (x^6+x+1) as an example.

[0095] ″fbconnection=[1 0 0 0 0 1 1];%x^6+x+1

[0096] mseq=m_sequence(fbconnection);

[0097] PN1=mseq*2-1; z=[mseq(end)mseq(1:end-1)];

[0098] PN2 = mod(mseq+z, 2)*2-1;

[0099] Here, mseq can be defined as:

[0100] ″function[mseq]=m_sequence(fbconnection);

[0101] n = length(fbconnection);

[0102] N = 2^n-1;

[0103] register=[zeros(1,n-1)1];%The initial state of shift register

[0104] mseq(1) = register(n);

[0105] for i=2:N

[0106] newregister(1)=mod(sum(fbconnection.*register),2);

[0107] for j=2:n,

[0108] newregister(j)=register(j-1);

[0109] end;

[0110] register = newregister;

[0111] mseq(i)=register(n);

[0112] end″

[0113] It should be understood that the above generation example of the m-sequence is for illustrative purposes only and without any limitation. The PN sequence can be generated based on other polynomials, and other schemes for PN sequence generation can be used.

[0114] Now, let's describe the base sequence. Take the case where the base sequence is based on the ZC sequence as an example. The length is N ZC The ZC sequence is defined as:

[0115]

[0116] Where u represents the root sequence index. The root sequence index is in 1≤u≤N ZC An integer in the range -1 and equal to the sequence length NZC Mutually prime.

[0117] The AC sequence defined by equation (4) is in the frequency domain. The root sequence based on the ZC sequence can be defined as:

[0118] x u =IFFT(FFT(X u )) (5)

[0119] The size of the FFT is N ZC , the size of IFFT is N u / 4. In this example, the length of the root sequence is half the length of the scrambling sequence, for example, the PN sequence defined by equation (3).

[0120] Reference now Figure 2A and Figure 2B To illustrate the structure of the base sequence. Figure 2A and Figure 2B In the example of , for illustration purposes, the base sequence is shown as being based on a ZC sequence and the scrambling sequence is shown as a PN sequence.

[0121] The base sequence may include multiple repetitions of the root sequence with reversed sign. Figure 2A A schematic diagram 200 showing an example preamble according to some example embodiments of the present disclosure is shown. A base sequence 210 includes a first portion having two repetitions 201, 202 of a ZC sequence and a second portion having two repetitions 203, 204 of a ZC sequence. The two repetitions 203, 204 of the ZC sequence have opposite signs compared to the two repetitions 201, 202 of the ZC sequence. The repetitions of the root sequence may also be referred to herein as blocks.

[0122] Figure 2A The base sequence 210 in the example has a structure of four cascaded ZC sequences in discrete time. Such a base sequence can be defined as:

[0123]

[0124]

[0125]

[0126]

[0127]

[0128] where x u (i) is defined by equation (5). In the case of using format 4, N u The values ​​are shown in Table 2.

[0129] Alternatively, the base sequence may include multiple repetitions of the root sequence having the same signs. Figure 2B A schematic diagram 250 is shown illustrating another example preamble according to some example embodiments of the present disclosure. The base sequence 260 comprises four repetitions 251, 252, 253, 254 of a ZC sequence, the repetitions having the same sign.

[0130] Figure 2B The base sequence 260 in the example has a structure of four cascaded ZC sequences in discrete time. Such a base sequence can be defined as:

[0131]

[0132]

[0133]

[0134]

[0135]

[0136] where x u (i) is defined by equation (5). In the case of using format 4, N u The values ​​are shown in Table 2. In other words, such a base sequence is determined as a simple repetition of the root sequence.

[0137] The random access preamble can be generated by applying two scrambling sequences to a base sequence (e.g., to different parts of the base sequence). As an example, the scrambling sequence can be used as a weighting factor for the base sequence. Therefore, for the above example, the random access preamble can be defined as the following equation (6):

[0138]

[0139] where ZC(i) is defined by equation (6) or (7), G(i) and It is defined by equation (3).

[0140] Still reference Figure 2A and Figure 2B , Figure 2AThe example preamble shown is generated by applying a PN sequence G 220 to the first two repetitions 201, 202 of the ZC sequence, and applying a PN sequence Q 230 to the last two repetitions 203, 204 of the ZC sequence. This format of the random access preamble utilizes the correlation properties of the four ZC blocks and the PN sequence with the reversed signs of the last two blocks to estimate the PRACH timing offset. The first half of the base sequence 210 can be generated in the same manner as the conventional ZC sequence generation, and the second half of the base sequence 210 can be formed by repeating these samples by symbol conversion. Then, the two PN sequences G and Q are applied as weighting factors to the first and second halves of the base sequence 210, respectively, to generate the random access preamble to be transmitted.

[0141] Similarly, Figure 2B The example preamble shown is generated by applying the PN sequence G 220 to the first two repetitions 251, 252 of the ZC sequence and applying the PN sequence Q 230 to the last two repetitions 253, 254 of the ZC sequence. Figure 2A and Figure 2B Each of the example preambles shown also includes a CP 205. Where format 4 is applicable, the length of the CP 205 is determined by the parameters shown in Table 2. Sure.

[0142] Detection scheme design

[0143] At a receiving device, such as a network device, a timing metric is needed to determine the starting position of the useful part of the PRACH preamble, which may be referred to as PRACH symbol timing. Therefore, the present invention also provides a detection scheme corresponding to the proposed preamble design.

[0144] It is important to note that the PN sequence is used to reduce the difference between two adjacent values ​​of the timing metric, as shown, they share the same sum of product pairs, except for the two product terms. Therefore, in order to expand the difference between two adjacent values ​​of the timing metric and avoid sudden timing offsets and non-robustness at low SNRs, it is necessary to maximize the difference between the two pairs of products.

[0145] For example, the timing metric used at the receiving device may be given by:

[0146]

[0147]

[0148]

[0149] Wherein d represents the starting time when the received signal enters the detection window; y represents the received signal defined by equation (2); G and Q represent the PN sequence defined by equation (3).

[0150] M defined by equation (9) proposed (d) represents the timing metric. P defined by equation (10) proposed (d) represents the cross-correlation metric of the received signal. R defined by equation (11) proposed (d) represents half symbol energy of the received signal.

[0151] As can be seen from (10), the introduction of the PN sequence as a weighting factor ensures that the proposed timing metric reaches its maximum value at the exact timing point which is the starting position of the useful part of the PRACH preamble, while the remaining values ​​at other sample points are quite low compared to the correct position. Therefore, the impact is small and a smaller error rate of PRACH symbol timing can be achieved under large frequency offsets.

[0152] All samples within the PRACH period are used to calculate the half-symbol energy, as shown in equation (11). proposed (d) and R proposed (d) It can be calculated iteratively. The proposed scheme achieves the goal of minimizing the correlation value between two partially correlated blocks and maximizing the different product pairs between two adjacent values. It should be noted that the randomness of the PN sequence can only be eliminated at a perfect timing position. When a long sequence is used, the length of the PN sequence used as a scrambling sequence becomes longer, and therefore the PN sequence is closer to a random signal. Then, the autocorrelation property of the PN sequence (e.g., m-sequence) becomes very sharp in terms of pulse shape, and the system performance can be improved accordingly.

[0153] By using the interval N u / 4 samples, the proposed timing metric defined by equations (9)-(11) takes the form of a sharp pulse shape without large side lobes. As the dual correlation block window slides forward, the same PN sequence including G and Q is introduced into the block, and the PN randomness can be eliminated only when the accurate position of the PRACH timing offset is detected. In this way, the difference between adjacent values ​​of the timing metric function is further amplified. This depends on the structure of the random access preamble code, the properties of the PN sequence and the design of the timing metric function. Computer simulations show that compared with other existing discussed estimators in NTN, the proposed detection scheme has a significant probability of obtaining an accurate estimate of the timing offset as well as a relatively small error mean and SD and an accurate detection rate (to be explained in detail below).

[0154] Example Process

[0155] Some example embodiments of preamble design and corresponding detection schemes have been described above. Figure 3 , Figure 3 An example process 300 for transmitting a random access preamble according to some example embodiments of the present disclosure is shown. For discussion purposes, reference will be made to Figure 1 300. Process 300 may involve Figure 1 A first device 110 and a second device 120 are shown.

[0156] In process 300, the first device 110 determines 305 a base sequence, a first scrambling sequence for the base sequence, and a second scrambling sequence for the base sequence. For example, the first device 110 may generate 306 a first scrambling sequence for the base sequence using equation (6). Figure 2A Alternatively, the first device 110 may use equation (7) to generate the base sequence 210 as shown in FIG. Figure 2B The base sequence is shown as 260. As described above, the scrambling sequence may have a pseudo-random property.

[0157] In some example embodiments, to determine the base sequence, first device 110 may determine a root sequence based on the format of the random access preamble. The root sequence may have a property of zero autocorrelation. First device 110 may generate a base sequence based on the root sequence. The length of the root sequence is less than the length of the base sequence.

[0158] As an example, in the case where format 4 is applicable, the first device 110 may first generate a ZC sequence X using equation (4): u , where N ZC is 839. Then, the root sequence x is determined based on the generated ZC sequence using equation (5): u , where N u =4·32768κ·2 -μ It should be noted that due to the characteristics of AC sequences, the root sequence x u It is also a ZC sequence.

[0159] In some example embodiments, the base sequence may be determined by simply repeating the root sequence multiple times. In other words, the base sequence may include multiple repetitions of the root sequence. For example, the base sequence 260 generated using equation (7) may include the root sequence x u Four repetitions of .

[0160] In some example embodiments, the base sequence may be determined by reversing the sign of the root sequence for a portion of the base sequence. In other words, the base sequence may include multiple repetitions of the root sequence, some of which have reversed signs. In such an example embodiment, the first device 110 may determine the first multiple repetitions of the root sequence as the first portion of the base sequence, and determine the second multiple repetitions of the root sequence with reversed signs as the second portion of the base sequence. The first portion and the second portion may be different. In an example embodiment, the number of the first multiple repetitions is the same as the number of the second multiple repetitions.

[0161] for Figure 2A In the example shown, two repetitions 201, 202 of the root sequence constitute the first part, in particular the first half of the base sequence 210. Two repetitions 203, 204 of the root sequence constitute the second part, in particular the second half of the base sequence 210. As described above, such a base sequence can be generated using equation (6).

[0162] To generate the first scrambling sequence and the second scrambling sequence, the first device 110 may determine a first length of the first scrambling sequence and a second length of the second scrambling sequence based on the format of the random access preamble. Then, the first device 110 may generate a first scrambling sequence having a first length and generate a second scrambling sequence having a second length. In some example embodiments, each of the first length and the second length is half the length of the base sequence.

[0163] For example, the lengths of the first scrambling sequence and the second scrambling sequence may be based on the parameter N of the preamble format. u In the case where format 4 is applicable, the first scrambling sequence and the second scrambling sequence may have the same length N u / 2. In the case where the scrambling sequence is based on a PN sequence, the length of each is N u The first scrambling sequence and the second scrambling sequence of / 2 can be generated using a sequence generator based on a shift register as described above. In the case where the scrambling sequence is based on another type of pseudo-random sequence, the length of each is N u The first scrambling sequence and the second scrambling sequence of / 2 may be generated using corresponding sequence generators.

[0164] Still reference Figure 3 , the first device 110 generates 310 a random access preamble by applying the first scrambling sequence and the second scrambling sequence to different parts of the base sequence, respectively. For example, the first scrambling sequence and the second scrambling sequence can be used as weighting factors for different parts of the base sequence. The first device 110 can use equation (8) to generate or determine the random access preamble. Alternatively, the first scrambling sequence and the second scrambling sequence can be applied to the parts of the base sequence that overlap each other.

[0165] The first device 110 transmits 315 a random access preamble to the second device 120. For example, the first device 110 may transmit 315 the random access preamble as Msg 1 in the RA procedure.

[0166] In order to correctly receive the random access preamble, the second device 120 determines 320 a first scrambling sequence and a second scrambling sequence. The scrambling sequence used at the second device 120 may be the same as the scrambling sequence used at the first device 110. Thus, the second device 120 may determine the first scrambling sequence and the second scrambling sequence in a manner similar to that described above with respect to the first device 110. For example, the second device 120 may maintain a sequence generator that is the same as the sequence generator maintained at the first device 110. As an example, the second device 120 may generate the PN sequences G and Q defined by equation (3).

[0167] Then, the second device 120 determines 325 a timing metric for estimating the timing offset based on the first scrambling sequence and the second scrambling sequence. The timing metric can be determined based on a specific format of the random access preamble. The received signal can be divided into multiple parts or multiple sections, for example, how to apply the scrambling sequence to the base sequence according to the requirements of the preamble format. The timing metric can be determined based on the signal received over the multiple parts and the first scrambling sequence and the second scrambling sequence. For example, in the case where format 4 is applicable, the received signal can be divided into two parts.

[0168] In some example embodiments, second device 120 may determine a first cross-correlation of a first portion of the received signal based on the first scrambling sequence and determine a second cross-correlation of a second portion of the received signal based on the second scrambling sequence.The timing metric may then be determined based on the first cross-correlation, the second cross-correlation, and the energy of the received signal.

[0169] For the example timing metrics shown in equations (9)-(11), the term in equation (10) represents the cross-correlation of the first part of the received signal y, which includes the period from d to The sampling points of equation (10) represents the cross-correlation of the second part of the received signal y, which includes to (d+N u -1) sampling point. In addition, the energy of the received signal can be determined as the half-symbol energy defined by equation (11).

[0170] To determine the first mutual correlation, the first portion may be further divided into sub-portions or sub-segments, for example, based on the repetitive nature of the random access preamble. In some example embodiments, the first portion may be divided into a first sub-portion and a second sub-portion. Each of the sampling points in the first sub-portion corresponds to one of the sampling points in the second sub-portion. The first mutual correlation may be determined based on the first scrambling sequence, the sampling points in the first sub-portion, and the corresponding sampling points in the second sub-portion. In such example embodiments, the second mutual correlation may be determined in a similar manner.

[0171] As mentioned above, we can use an interval of N u / 4 samples. For the example cross-correlation shown in equation (10), from d to The sampling points of correspond to the sampling points in the first sub-portion or the first block; arrive The sampling points of correspond to the sampling points in the second sub-part or the second block. The corresponding sampling points in the first block and the second block are spaced N apart. u / 4.

[0172] Still reference Figure 3 , the second device 120 receives the random access preamble from the first device 110 based on the timing metric (e.g., the timing metric defined by equation (9)). For example, when the signal is received, the second device 120 may calculate the value of the timing metric at each time point d. The specific timing point d at which the timing metric reaches the maximum peak value is considered to be the time starting point for demodulating the random access preamble.

[0173] Simulations have been performed to evaluate the proposed timing offset estimator for the proposed PRACH preamble format. The results for PRACH timing are shown in FIG. 4A to FIG. 4C , FIG. 5A to FIG. 5C and Figure 6 shown.

[0174] In the simulation, the symbol length is equal to 4·32768κ·2 -μ , the CP length is 21024κ·2 -μ , the subcarrier spacing (SCS) is 1.25·2 μ KHz, and μ = 4. Assume that the timing offset and carrier frequency offset are θ = 1000 (about 32.56us) and FO = 48kHz. Rayleigh channel models including flat fading channels and frequency selective channels are considered here. The performance is evaluated in terms of symbol timing error rate, error mean (EM) and standard deviation (SD). For the symbol timing error rate, the estimated timing offset The absolute value of the difference from the set value θ is defined as the reference value if This means that the estimated time offset is accurate. is an unbiased estimate of θ, which can be considered as the correct time to detect the start of PRACH. Note that the error mean is the error The arithmetic mean and standard deviation are The square root of the variance, which measures the amount of variation or dispersion about the mean.

[0175] FIG. 4A to FIG. 4C The simulation results of long preamble 839 and SNR under a flat fading channel with FO of 48 kHz at 2 GHz are shown. Figure 4A Results for symbol timing error rate are shown, curve 401 for a single ZC sequence with 2 repetitions, curve 402 for a single ZC sequence with 4 repetitions, curve 403 for the proposed format 4, and curve 404 for multiple ZC sequences with different roots. Figure 4B Shows The results of the error mean are as follows: curve 411 is for a single ZC sequence with 2 repetitions, curve 412 is for a single ZC sequence with 4 repetitions, curve 413 is for the proposed format 4, and curve 414 is for multiple ZC sequences with different roots. Figure 4C Shows SD results, where curve 421 is for a single ZC sequence with 2 repeats, curve 422 is for a single ZC sequence with 4 repeats, curve 423 is for the proposed format 4, and curve 424 is for multiple ZC sequences with different roots.

[0176] like Figure 4A As shown in Figure 2, the proposed format performs better than other formats, especially at low SNR, because in addition to the correct position, the impact of side peaks is further reduced. The EM and SD performances are shown in Figure 2, respectively. Figure 4B and Figure 4C The results show that the proposed format performs the same as a single ZC sequence with 4 repetitions and multiple ZC sequences with different roots when the SNR is greater than -12dB, but outperforms the other formats when the SNR is less than -12dB.

[0177] FIG. 5A to FIG. 5C The simulation results of long preamble 839 and SNR in a frequency selective fading channel with 48kHz FO at 2GHz are shown. All channels contain 6 Rayleigh fading taps (L=5) with exponential energy decay curves. The channel response is generated using a complex Gaussian random variable with zero mean and unit variance, which satisfies that the sum of the power of each normalized path amplitude is equal to ∑ l |h l | 2 =1. Figure 5AResults for symbol timing error rate are shown, curve 501 for a single ZC sequence with 2 repetitions, curve 502 for a single ZC sequence with 4 repetitions, curve 503 for the proposed format 4, and curve 504 for multiple ZC sequences with different roots. Figure 5B Shows The results of the error mean are shown in FIG. 5 , where curve 511 is for a single ZC sequence with 2 repetitions, curve 512 is for a single ZC sequence with 4 repetitions, curve 513 is for the proposed format 4, and curve 514 is for multiple ZC sequences with different roots. Figure 5C Shows Curve 521 is for a single ZC sequence with 2 repeats, curve 522 is for a single ZC sequence with 4 repeats, curve 523 is for the proposed format 4, and curve 524 is for multiple ZC sequences with different roots.

[0178] like Figure 5A As shown in Figure 2, it can be seen that the proposed format still shows good performance in terms of symbol timing error rate. In terms of EM and SD, the proposed format has similar performance to the case of a single ZC sequence with 4 repetitions, but outperforms other formats such as Figure 5B and Figure 5C shown.

[0179] As described above, through the proposed PRACH format and detection scheme, accurate timing offset can be achieved to facilitate UL timing estimation in the presence of large UL frequency offsets between the terminal device and the network equipment. Note that even if the maximum differential delay in LEO cannot be accommodated by the longest CP in the existing PRACH format, multiple timing assumptions can be used to detect it with high complexity. The most important thing in the proposed solution is the ability to handle the large differential delay problem when large Doppler frequency shifts in the PRACH receiver (e.g., gNB).

[0180] The PRACH detection rate is also evaluated. Figure 6 The simulation results of the proposed long preamble 839 format 4 PRACH accurate detection rate and SNR at 2GHz with FO of 48kHz are shown, curve 601 is for a single ZC sequence with 2 repetitions, curve 602 is for a single ZC sequence with 4 repetitions, curve 603 is for the proposed format 4, and curve 604 is for multiple ZC sequences with different roots. Figure 6 It can be seen that a receiving device (eg, network equipment) is able to have a 99% PRACH accurate detection rate at an SNR point around -9dB by using the proposed format 4, which is better than other existing formats under discussion in 3GPP.

[0181] Table 3 shows the parameters used for link level PRACH simulation.

[0182] Table 3 Link-level simulation assumptions for PRACH evaluation

[0183]

[0184]

[0185] It should be noted that the simulation results of the proposed format are based specifically on Figure 2A The example shown is Figure 2B As shown, the simulation results of the random access preamble including only 4 repetitions of the ZC sequence show that the Figure 2A Poor performance, but better performance than other options.

[0186] In the present disclosure, a novel preamble-based symbol timing synchronizer has been proposed for NTN to improve timing accuracy. By exploiting the special properties of scrambling sequences (e.g., PN sequences), a new PRACH format can be designed using two different scrambling sequences with the same period as weighting factors. A corresponding novel PRACH detection scheme is also provided to ensure that the timing metric function has a pulse-like shape at the correct timing position.

[0187] The novel PRACH format and detection scheme are robust to large FO and show good properties, especially under low SNR assumptions. Computer simulations show that the proposed solution achieves accurate timing offset estimation with smaller EM and SD and higher PRACH detection rate compared to the current solution in 3GPP NTN discussion. It should be understood that although the proposed enhanced PRACH preamble solution is discussed for NTN scenarios, the embodiments of the present disclosure are also applicable to TN scenarios.

[0188] Reference Figures 7 and 8 More details of example embodiments according to the present disclosure are described.

[0189] Figure 7 1 shows a flow chart of an example method 700 according to some example embodiments of the present disclosure. The method 700 may be performed as follows: Figure 1 For the purpose of discussion, reference will be made to Figure 1 Method 700 is described.

[0190] At block 710, the first device 110 determines a base sequence, a first scrambling sequence for the base sequence, and a second scrambling sequence for the base sequence. At block 720, the first device 110 generates a random access preamble by applying the first scrambling sequence and the second scrambling sequence to different parts of the base sequence, respectively. At block 730, the first device 110 transmits the random access preamble to the second device 120.

[0191] In some example embodiments, determining the base sequence includes: determining a root sequence based on a format of the random access preamble, the root sequence having a property of zero autocorrelation; and generating the base sequence based on the root sequence, the length of the root sequence being less than the length of the base sequence.

[0192] In some example embodiments, generating a base sequence based on a root sequence includes: determining a first plurality of repetitions of the root sequence as a first portion of the base sequence; and determining a second plurality of repetitions of the root sequence with a reversed sign as a second portion of the base sequence.

[0193] In some example embodiments, the number of the first plurality of repetitions is the same as the number of the second plurality of repetitions.

[0194] In some example embodiments, determining the first scrambling sequence and the second scrambling sequence includes: determining a first length of the first scrambling sequence and a second length of the second scrambling sequence based on a format of the random access preamble; generating the first scrambling sequence having the first length; and generating the second scrambling sequence having the second length.

[0195] In some example embodiments, each of the first length and the second length is half the length of the base sequence.

[0196] In some example embodiments, the base sequence is based on a Zadoff-Chu sequence, and the first scrambling sequence and the second scrambling sequence are based on a pseudo noise sequence.

[0197] In some example embodiments, the first device 110 comprises a terminal device, and the second device 120 comprises a network device.

[0198] Figure 8 800 according to some example embodiments of the present disclosure. Figure 1 The second device 120 is shown as being implemented. For the purpose of discussion, reference will be made to Figure 1 Method 800 is described.

[0199] At block 810, the second device 120 determines a first scrambling sequence for a base sequence and a second scrambling sequence for the base sequence. At block 820, the second device 120 determines a timing metric for estimating a timing offset based on the first scrambling sequence and the second scrambling sequence. At block 830, the second device 120 receives a random access preamble from the first device 110 based on the timing metric. The random access preamble is generated by applying the first scrambling sequence and the second scrambling sequence to different portions of the base sequence, respectively.

[0200] In some example embodiments, determining the timing metric includes determining a first mutual correlation of a first portion of the received signal based on the first scrambling sequence; determining a second mutual correlation of a second portion of the received signal based on the second scrambling sequence; and determining the timing metric based on the first mutual correlation, the second mutual correlation, and an energy of the received signal.

[0201] In some example embodiments, generating a base sequence based on a root sequence includes: determining a first plurality of repetitions of the root sequence as a first portion of the base sequence; and determining a second plurality of repetitions of the root sequence with a reversed sign as a second portion of the base sequence.

[0202] In some example embodiments, the number of the first plurality of repetitions is the same as the number of the second plurality of repetitions.

[0203] In some example embodiments, determining the first scrambling sequence and the second scrambling sequence includes: determining a first length of the first scrambling sequence and a second length of the second scrambling sequence based on a format of the random access preamble; generating the first scrambling sequence having the first length; and generating the second scrambling sequence having the second length.

[0204] In some example embodiments, each of the first length and the second length is half the length of the base sequence.

[0205] In some example embodiments, the base sequence is based on a Zadoff-Chu sequence, and the first scrambling sequence and the second scrambling sequence are based on a pseudo noise sequence.

[0206] In some example embodiments, the first device 110 comprises a terminal device, and the second device 120 comprises a network device.

[0207] In some example embodiments, a device capable of executing method 700 may include a component for executing the corresponding steps of method 700. The component may be implemented in any suitable form. For example, the component may be implemented by a circuit system or a software module.

[0208] In some example embodiments, the apparatus includes means for determining, at a first device, a base sequence, a first scrambling sequence for the base sequence, and a second scrambling sequence for the base sequence; means for generating a random access preamble by applying the first scrambling sequence and the second scrambling sequence to different portions of the base sequence, respectively; and means for transmitting the random access preamble to a second device.

[0209] In some example embodiments, the means for determining the base sequence includes: means for determining a root sequence based on a format of the random access preamble, the root sequence having a property of zero autocorrelation; and means for generating the base sequence based on the root sequence, the length of the root sequence being less than the length of the base sequence.

[0210] In some example embodiments, means for generating a base sequence based on a root sequence includes means for determining a first plurality of repetitions of the root sequence as a first portion of the base sequence; and means for determining a second plurality of repetitions of the root sequence with a reversed sign as a second portion of the base sequence.

[0211] In some example embodiments, the number of the first plurality of repetitions is the same as the number of the second plurality of repetitions.

[0212] In some example embodiments, the means for determining the first scrambling sequence and the second scrambling sequence includes: means for determining a first length of the first scrambling sequence and a second length of the second scrambling sequence based on a format of the random access preamble; means for generating the first scrambling sequence having the first length; and means for generating the second scrambling sequence having the second length.

[0213] In some example embodiments, each of the first length and the second length is half the length of the base sequence.

[0214] In some example embodiments, the base sequence is based on a Zadoff-Chu sequence, and the first scrambling sequence and the second scrambling sequence are based on a pseudo noise sequence.

[0215] In some example embodiments, the first device comprises a terminal device and the second device comprises a network device.

[0216] In some example embodiments, a device capable of executing method 800 may include a component for executing the corresponding steps of method 800. The component may be implemented in any suitable form. For example, the component may be implemented by a circuit system or a software module.

[0217] In some example embodiments, the apparatus includes means for determining, at a second device, a first scrambling sequence for a base sequence and a second scrambling sequence for the base sequence; means for determining a timing metric for estimating a timing offset based on the first scrambling sequence and the second scrambling sequence; and means for receiving a random access preamble from the first device based on the timing metric, the random access preamble being generated by applying the first scrambling sequence and the second scrambling sequence to different portions of the base sequence, respectively.

[0218] In some example embodiments, means for determining a timing metric includes means for determining a first cross-correlation of a first portion of a received signal based on a first scrambling sequence; means for determining a second cross-correlation of a second portion of the received signal based on a second scrambling sequence; and means for determining the timing metric based on the first cross-correlation, the second cross-correlation, and an energy of the received signal.

[0219] In some example embodiments, means for generating a base sequence based on a root sequence includes means for determining a first plurality of repetitions of the root sequence as a first portion of the base sequence; and means for determining a second plurality of repetitions of the root sequence with a reversed sign as a second portion of the base sequence.

[0220] In some example embodiments, the number of the first plurality of repetitions is the same as the number of the second plurality of repetitions.

[0221] In some example embodiments, the means for determining the first scrambling sequence and the second scrambling sequence includes: means for determining a first length of the first scrambling sequence and a second length of the second scrambling sequence based on a format of a random access preamble; means for generating the first scrambling sequence having a first length; and means for generating the second scrambling sequence having a second length.

[0222] In some example embodiments, each of the first length and the second length is half the length of the base sequence.

[0223] In some example embodiments, the base sequence is based on a Zadoff-Chu sequence, and the first scrambling sequence and the second scrambling sequence are based on a pseudo noise sequence.

[0224] In some example embodiments, the first device comprises a terminal device and the second device comprises a network device.

[0225] Fig. 9 900 is a simplified block diagram of a device suitable for implementing an embodiment of the present disclosure. The device 900 may be provided to implement a communication device, such as Figure 1The first device 110 or the second device 120 is shown. As shown in the figure, the device 900 includes one or more processors 910, one or more memories 920 coupled to the processor 910, and one or more communication modules 940 coupled to the processor 910.

[0226] The communication module 940 is used for two-way communication. The communication module 940 has at least one antenna to facilitate communication. The communication interface may represent any interface necessary to communicate with other network elements.

[0227] Processor 910 may be of any type suitable for the local technology network, and may include, as non-limiting examples, one or more of a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. Device 900 may have multiple processors, such as application specific integrated circuit chips that are time slaved to a clock synchronized with a main processor.

[0228] The memory 920 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 924, electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disk (CD), digital video disk (DVD), and other magnetic storage and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 922 and other volatile memories that do not persist during power outages.

[0229] The computer program 930 includes computer executable instructions executed by the associated processor 910. The program 930 may be stored in the ROM 920. The processor 910 may perform any suitable actions and processes by loading the program 930 into the RAM 920.

[0230] The embodiments of the present disclosure may be implemented by a program 930, so that the device 900 may execute the Figures 7 and 8 Any process of the present disclosure discussed. The embodiments of the present disclosure may also be implemented by hardware or a combination of software and hardware.

[0231] In some embodiments, the program 930 may be tangibly embodied in a computer-readable medium, which may be included in the device 900 (such as memory 920) or other storage devices accessible to the device 900. The device 900 may load the program 930 from the computer-readable medium to the RAM 922 for execution. The computer-readable medium may include any type of tangible non-volatile memory, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. Fig.10An example of a computer readable medium 1000 in the form of a CD or DVD is shown. The computer readable medium has a program 930 stored thereon.

[0232] Generally, various embodiments of the present disclosure may be implemented using hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects may be implemented using hardware, while other aspects may be implemented using firmware or software that may be executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flow charts, or using some other graphical representations, it should be understood that, as non-limiting examples, the blocks, devices, systems, techniques, or methods described herein may be implemented using hardware, software, firmware, dedicated circuits or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof.

[0233] 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 instructions included in a program module, which are executed in a device on a target real or virtual processor to perform the above referenced Figure 7-Figure 8 Method 600, 700 or 800 described herein. Typically, a program module includes a routine, program, library, object, class, component, data structure, etc. that performs a specific task or implements a specific abstract data type. In various embodiments, the functions of the program modules can be combined or split between program modules as needed. The machine executable instructions of the program modules can be executed in a local or distributed device. In a distributed device, the program modules can be located in both local and remote storage media.

[0234] The program code for executing the method of the present disclosure can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device so that the program code enables the function / operation specified in the flow chart and / or block diagram to be realized when executed by the processor or controller. The program code can be executed completely on the machine, partially on the machine, as an independent software package, partially on the machine and partially on a remote machine, or completely on a remote machine or server.

[0235] In the context of the present disclosure, computer program codes or related data may be carried by any suitable carrier to enable a device, apparatus or processor to perform various processes and operations as described above. Examples of carriers include signals, computer readable media, etc.

[0236] The computer readable medium can be a computer readable signal medium or a computer readable storage medium. The computer readable medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. A more specific example of a computer readable storage medium will include an electrical connection with one or more wires, a portable computer floppy disk, 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 disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0237] In addition, although the operations are described in a particular order, this should not be understood as requiring such operations to be performed in the particular order shown or in order or performing all the operations shown to obtain the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be interpreted as limitations on the scope of the present disclosure, but rather descriptions of features that may be specific to a particular embodiment. Certain features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0238] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it should be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Instead, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A first device for communication, comprising: at least one processor; as well as at least one memory including computer program code; The at least one memory and the computer program code are configured to, with the at least one processor, cause the first device to at least: Determine a base sequence, a first scrambling sequence for the base sequence, and a second scrambling sequence for the base sequence, wherein determining the base sequence comprises: determining a root sequence based on a format of the random access preamble, the root sequence having a property of zero autocorrelation; and The base sequence is generated based on the root sequence, wherein the length of the root sequence is less than the length of the base sequence; wherein determining the first scrambling sequence for the base sequence and the second scrambling sequence for the base sequence comprises: determining a first length of the first scrambling sequence and a second length of the second scrambling sequence based on a format of the random access preamble; generating the first scrambling sequence having the first length; and generating the second scrambling sequence having the second length; generating the random access preamble by applying the first scrambling sequence and the second scrambling sequence to different parts of the base sequence, respectively; and The random access preamble is transmitted to the second device.

2. The first device according to claim 1, wherein generating the base sequence based on the root sequence comprises: determining a first plurality of repetitions of the root sequence as a first portion of the base sequence; as well as A second plurality of repetitions of the root sequence having a reversed sign is determined as a second portion of the base sequence. 3 . The first device of claim 2 , wherein the number of the first plurality of repetitions is the same as the number of the second plurality of repetitions. 4 . The first device according to claim 1 , wherein each of the first length and the second length is half of a length of the base sequence.

5. The first device of claim 1, wherein the base sequence is based on a Zadoff-Chu sequence, and the first scrambling sequence and the second scrambling sequence are based on a pseudo noise sequence. 6 . The first device according to claim 1 , wherein the first device comprises a terminal device, and the second device comprises a network device.

7. A second device for communication, comprising: at least one processor; as well as at least one memory including computer program code; The at least one memory and the computer program code are configured to, with the at least one processor, cause the second device to at least: Determine a first scrambling sequence for a base sequence and a second scrambling sequence for the base sequence, wherein the base sequence is determined in the following manner: Determining a root sequence based on a format of a random access preamble, wherein the root sequence has a property of zero autocorrelation; as well as generating the base sequence based on the root sequence, wherein the length of the root sequence is less than the length of the base sequence; Wherein determining the first scrambling sequence for the base sequence and the second scrambling sequence for the base sequence comprises: determining a first length of the first scrambling sequence and a second length of the second scrambling sequence based on a format of the random access preamble; generating the first scrambling sequence having the first length; and generating the second scrambling sequence having the second length; determining a timing metric for estimating a timing offset based on the first scrambling sequence and the second scrambling sequence; and The random access preamble is received from a first device based on the timing metric, the random access preamble being generated by applying the first scrambling sequence and the second scrambling sequence to different portions of the base sequence, respectively.

8. The second device of claim 7, wherein the second device is caused to determine the timing metric by: determining a first cross-correlation of a first portion of a received signal based on the first scrambling sequence; determining a second cross-correlation of a second portion of the received signal based on the second scrambling sequence; as well as The timing metric is determined based on the first cross-correlation, the second cross-correlation, and an energy of the received signal.

9. The second device of claim 8, wherein determining the first cross-correlation comprises: dividing the first portion into a first sub-portion and a second sub-portion, each of the sampling points in the first sub-portion corresponding to one of the sampling points in the second sub-portion; as well as The first cross-correlation is determined based on the first scrambling sequence, the sampling points in the first sub-portion, and the corresponding sampling points in the second sub-portion.

10. The second device of claim 7, wherein the base sequence is based on a Zadoff-Chu sequence, and the first scrambling sequence and the second scrambling sequence are based on a pseudo noise sequence.

11. The second device according to claim 7, wherein the first device comprises a terminal device, and the second device comprises a network device.

12. A method for communication, comprising: Determining, at a first device, a base sequence, a first scrambling sequence for the base sequence, and a second scrambling sequence for the base sequence, wherein determining the base sequence comprises: determining a root sequence based on a format of the random access preamble, the root sequence having a property of zero autocorrelation; and The base sequence is generated based on the root sequence, wherein the length of the root sequence is less than the length of the base sequence; wherein determining the first scrambling sequence for the base sequence and the second scrambling sequence for the base sequence comprises: determining a first length of the first scrambling sequence and a second length of the second scrambling sequence based on a format of the random access preamble; generating the first scrambling sequence having the first length; and generating the second scrambling sequence having the second length; generating the random access preamble by applying the first scrambling sequence and the second scrambling sequence to different parts of the base sequence, respectively; and The random access preamble is transmitted to the second device.

13. The method according to claim 12, wherein generating the base sequence based on the root sequence comprises: determining a first plurality of repetitions of the root sequence as a first portion of the base sequence; as well as A second plurality of repetitions of the root sequence having a reversed sign is determined as a second portion of the base sequence. The method of claim 13 , wherein the number of the first plurality of repetitions is the same as the number of the second plurality of repetitions.

15. The method of claim 12, wherein each of the first length and the second length is half the length of the base sequence.

16. The method of claim 12, wherein the base sequence is based on a Zadoff-Chu sequence, and the first scrambling sequence and the second scrambling sequence are based on a pseudo noise sequence.

17. The method of claim 12, wherein the first device comprises a terminal device, and the second device comprises a network device.

18. A method for communication, comprising: A first scrambling sequence for a base sequence and a second scrambling sequence for the base sequence are determined at a second device, wherein the base sequence is determined by: Determining a root sequence based on a format of a random access preamble, wherein the root sequence has a property of zero autocorrelation; as well as generating the base sequence based on the root sequence, wherein the length of the root sequence is less than the length of the base sequence; Wherein determining the first scrambling sequence for the base sequence and the second scrambling sequence for the base sequence comprises: determining a first length of the first scrambling sequence and a second length of the second scrambling sequence based on a format of the random access preamble; generating the first scrambling sequence having the first length; and generating the second scrambling sequence having the second length; determining a timing metric for estimating a timing offset based on the first scrambling sequence and the second scrambling sequence; and The random access preamble is received from a first device based on the timing metric, the random access preamble being generated by applying the first scrambling sequence and the second scrambling sequence to different portions of the base sequence, respectively.

19. The method of claim 18, wherein determining the timing metric comprises: determining a first cross-correlation of a first portion of a received signal based on the first scrambling sequence; determining a second cross-correlation of a second portion of the received signal based on the second scrambling sequence; as well as The timing metric is determined based on the first cross-correlation, the second cross-correlation, and an energy of the received signal.

20. The method of claim 19, wherein determining the first cross-correlation comprises: dividing the first portion into a first sub-portion and a second sub-portion, each of the sampling points in the first sub-portion corresponding to one of the sampling points in the second sub-portion; as well as The first cross-correlation is determined based on the first scrambling sequence, the sampling points in the first sub-portion, and the corresponding sampling points in the second sub-portion.

21. The method of claim 18, wherein the base sequence is based on a Zadoff-Chu sequence, and the first scrambling sequence and the second scrambling sequence are based on a pseudo noise sequence.

22. The method of claim 18, wherein the first device comprises a terminal device and the second device comprises a network device.

23. An apparatus for communication, comprising: Means for determining, at a first device, a base sequence, a first scrambling sequence for the base sequence, and a second scrambling sequence for the base sequence, wherein determining the base sequence comprises: determining a root sequence based on a format of the random access preamble, the root sequence having a property of zero autocorrelation; and The base sequence is generated based on the root sequence, wherein the length of the root sequence is less than the length of the base sequence; wherein determining the first scrambling sequence for the base sequence and the second scrambling sequence for the base sequence comprises: determining a first length of the first scrambling sequence and a second length of the second scrambling sequence based on a format of the random access preamble; generating the first scrambling sequence having the first length; and generating the second scrambling sequence having the second length; means for generating the random access preamble by applying the first scrambling sequence and the second scrambling sequence to different parts of the base sequence, respectively; and Means for transmitting the random access preamble to a second device.

24. An apparatus for communication, comprising: Means for determining, at a second device, a first scrambling sequence for a base sequence and a second scrambling sequence for the base sequence, wherein the base sequence is determined by: Determining a root sequence based on a format of a random access preamble, wherein the root sequence has a property of zero autocorrelation; as well as generating the base sequence based on the root sequence, wherein the length of the root sequence is less than the length of the base sequence; Wherein determining the first scrambling sequence and the second scrambling sequence for determining the base sequence at the second device comprises: determining a first length of the first scrambling sequence and a second length of the second scrambling sequence based on a format of the random access preamble; generating the first scrambling sequence having the first length; and generating the second scrambling sequence having the second length; means for determining a timing metric for estimating a timing offset based on the first scrambling sequence and the second scrambling sequence; and means for receiving the random access preamble from a first device based on the timing metric, the random access preamble being generated by applying the first scrambling sequence and the second scrambling sequence to different portions of the base sequence, respectively.

25. A non-transitory computer-readable medium comprising program instructions for causing an apparatus to at least perform the method according to any one of claims 12 to 17.

26. A non-transitory computer readable medium comprising program instructions for causing an apparatus to at least perform the method according to any one of claims 18 to 22.

Images