阅读说明：本技术 无线通信中的随机接入前导码 (Random access preamble in wireless communications ) 是由 张晨晨 曹伟 杨振 田开波 张楠 于 2019-02-15 设计创作，主要内容包括：用于生成前导码序列的方法、系统和设备,其中多个Zadoff-Chu(ZC)序列基于多个根和每个根的多个循环移位来生成,并被合并以生成前导码序列。一些实施例可被用于预期大传播延迟和/或多普勒运动的无线通信实施例中。(Methods, systems, and devices for generating a preamble sequence, wherein a plurality of Zadoff-chu (zc) sequences are generated based on a plurality of roots and a plurality of cyclic shifts for each root and are combined to generate the preamble sequence. Some embodiments may be used in wireless communication embodiments where large propagation delays and/or doppler motion are expected.)

1. A method of wireless communication, the method comprising:

generating, by a wireless device, a preamble sequence by combining a plurality of Zadoff-Chu (ZC) sequences, wherein the plurality of ZC sequences are based on two or more roots and a cyclically shifted list of each root; and

generating, by the wireless device, a transmission waveform using the preamble sequence.

2. The method of claim 1, wherein generating the preamble sequence by combining the plurality of ZC sequences comprises:

receiving length L, a plurality of roots u₁、u₂、u₃…, and a plurality of sets of circularly shifted lists corresponding to the plurality of roots, wherein each set of circularly shifted lists comprises a plurality of circularly shifted lists;

select the first root u₁And ith cyclic shift list v_1iWherein the first root u₁Is selected from the plurality of roots, and the i-th cyclic shift list v_1iFrom corresponding to the first root u₁A plurality of cyclic shift lists v₁₁、v₁₂、v₁₃…; and

selecting the second root u₂And the jth cyclic shift list v_2jWherein the second root u₂Is selected from the plurality of roots and the jth cyclic shift list v_2jFrom corresponding to said second root u₂A plurality of cyclic shift lists v₂₁、v₂₂、v₂₃….

3. The method of claim 2, wherein the first root u is assigned to₁Of the ith cyclic shift list v_1iComprising N cyclic shift values v_1i1、v_1i2、v_1i3、…、v_1iNCorresponding to said second root u₂Of said jth cyclic shift list v_2jComprising M cyclic shift values v_2j1、v_2j2、v_2j3、…、v_2jM。

4. The method of claim 3, wherein generating the preamble sequence by combining the plurality of ZC sequences comprises:

based on the first root u₁And said ith cyclic shift list v_1i＝{v_li1，v_li2，…，v_liNGenerating a first group of N ZC sequences with the length of L;

based on the second root u₂And said jth cyclic shift list v_2j＝{v_2j1，v_2j2，…，v_2jMGenerating a second set of M ZC sequences with the length of L; and

generating the preamble sequence by combining the first set of N ZC sequences and the second set of M ZC sequences.

5. The method of any of claims 2 to 4, wherein the plurality of roots u₁、u₂、u₃…, and the plurality of sets of cyclic shift lists corresponding to the plurality of roots, collectively uniquely identify a preamble sequence from a plurality of preamble sequences.

6. The method of any of claims 2 to 5, wherein when a cyclic shift is applied to any of the two cyclic shift lists, any two cyclic shift lists in the set of cyclic shift lists do not completely overlap with each other.

7. The method of any of claims 1 to 6, further comprising:

generating a cyclic prefix by pre-appending a part of the preamble sequence, wherein the part is obtained from a tail of the preamble sequence; and

a guard time interval is generated to follow the preamble sequence appended in advance.

8. The method of any one of claims 1 to 7, wherein merging the plurality of ZC sequences comprises concatenating the plurality of ZC sequences.

9. The method of any of claims 1 to 7, wherein merging the plurality of ZC sequences comprises superimposing the plurality of ZC sequences.

10. The method of any of claims 1 to 7, wherein merging the plurality of ZC sequences comprises concatenating and superimposing the plurality of ZC sequences.

11. The method of any of claims 7 to 10, further comprising:

generating a random access preamble signal based on the cyclic prefix, the preamble sequence, and the guard time interval; and

transmitting the random access preamble signal to a wireless node.

12. The method of claim 11, further comprising receiving a timing advance value from the wireless node in response to transmitting the random access preamble signal to the wireless node.

13. A wireless communication apparatus comprising a processor configured to implement the method of any one or more of claims 1-12.

14. A computer program product comprising a computer-readable program medium having stored thereon processor-executable instructions that, when executed by a processor, cause the processor to implement the method of any one or more of claims 1 to 12.

Technical Field

The present application relates generally to wireless communications.

Background

Wireless communication technology is pushing the world to an increasingly interconnected and networked society. In view of the wide service coverage capability, and the reduced vulnerability of space/airborne aircraft to physical attacks and natural disasters, non-terrestrial networks (NTNs) are expected to play an important role in the upcoming fifth generation (5G) New Radio (NR) networks. Non-terrestrial networks will be particularly attractive in areas with no or insufficient service, and will be critical to economically improve the performance of currently limited terrestrial networks in such areas with insufficient service.

Disclosure of Invention

The present application relates to methods, systems, and devices for generating long preamble sequences by concatenating or superimposing two or more short preambles in the time domain.

In one representative aspect, a method of wireless communication is disclosed. The method includes generating or otherwise determining a Zadoff-chu (ZC) sequence based on two or more roots and two or more cyclic shifts for each root, and then generating a long-preamble sequence by combining (concatenating, superimposing, etc.) ZC sequences (short preambles). The generated long preamble sequence is then pre-appended with a cyclic prefix (based on a portion of the preamble sequence tail) and a guard time is added to generate a random access preamble that a wireless device (e.g., a User Equipment (UE)) transmits to a wireless node (e.g., a Base Station (BS)) during a random access procedure (e.g., during an initial network access of the UE). The wireless device selects cyclic shifts for obtaining a ZC sequence from a set of cyclic shift lists corresponding to each root. The cyclic shift list provides a unique signature during random access, wherein the signature pool has a capacity that is easily extended according to the length of the cyclic shift list. By using multiple roots and multiple cyclic shifts, the disclosed techniques enable high frequency and time offset estimation at the receiver, such as may be desirable for non-terrestrial network applications. Furthermore, user detection and corresponding frequency/time offset estimation can be performed on the combined short preamble with relatively low complexity.

In another example aspect, a wireless communications apparatus is disclosed that includes a processor. The processor is configured to implement the above-described method.

In another example aspect, a computer program product is disclosed. The computer program product includes a computer readable medium storing processor executable instructions embodying the above-described method.

The above aspects and other aspects and embodiments thereof are described in more detail in the accompanying drawings, the description and the claims.

Drawings

Fig. 1 illustrates an example of a Base Station (BS) and a User Equipment (UE) in wireless communications, in accordance with some embodiments of the disclosed technology.

Fig. 2 shows an example of a conventional preamble format.

Fig. 3 shows a representative flow diagram illustrating a method for generating a preamble.

Fig. 4 shows an example of a long preamble generated by concatenating a plurality of short preambles.

Fig. 5 shows an example of a long preamble including a cyclic prefix and a guard time.

Fig. 6 shows an example of a long preamble for random access in a satellite communication system.

Fig. 7 illustrates an example set of correlation peaks at a receiver configured to receive a random access preamble.

Fig. 8 shows an example of a long preamble for a system with large frequency offset and small time delay.

Fig. 9 shows an example of an asymmetric long preamble.

Fig. 10 illustrates an example or reordered short preamble.

FIG. 11 shows an example set of roots and a set of circularly shifted lists.

Fig. 12 is a block diagram representation of a portion of an apparatus in accordance with some embodiments of the disclosed technology.

Detailed Description

There is an increasing demand for fourth-generation mobile communication technology (4G, fourth-generation mobile communication technology), long term evolution (LTE, long term evolution), long term evolution Advanced/LTE-a (long term evolution Advanced), and fifth-generation mobile communication technology (5G, fifth-generation mobile communication technology).

In non-terrestrial networks, Low Earth Orbit (LEO) satellite communications have attracted widespread interest in the industry due to their potential to support high bandwidth and low latency communications. However, a fast moving LEO satellite can cause large frequency offsets in the transmitted and received signals. Although the User Equipment (UE) typically performs a coarse frequency offset estimation when detecting the downlink synchronization signal, the residual frequency offset may still be relatively large, which presents new challenges to the random access procedure in the non-terrestrial network. Furthermore, the potential large time offset caused by large propagation delays may exceed the capabilities of conventional random access preambles (e.g., LTE Physical Random Access Channel (PRACH) preambles). Therefore, when used for non-terrestrial random access procedures, it is advantageous to have a random access preamble format that can tolerate large frequency and time offsets.

In LTE, a Physical Random Access Channel (PRACH) is used to transmit an access request of a User Equipment (UE) to a Base Station (BS). The BS detects the UE and its time delay from the PRACH preamble and then provides Timing Advance (TA) information to the UE. The LTE preamble is constructed based on Zadoff-chu (zc) sequences (length 139 or 839) and cyclic shifts of different lengths. For a given cell, 64 different random access sequences are provided to all UEs. The corresponding root pool and cyclic shift pool (cyclic shift list set) are broadcast to all UEs. The UE randomly selects a root and a cyclic shift to generate its random access preamble signal.

Fig. 1 shows an example of a wireless communication system (e.g., an LTE, 5G, or New Radio (NR) cellular network) including a BS 120 and one or more User Equipments (UEs) 111, 112, and 113. The uplink transmission (131, 132, 133) comprises a random access preamble as described in the present application. The UE may be, for example, a smartphone, a tablet, a mobile computer, a machine-to-machine (M2M) device, a terminal, a mobile device, an internet of things (IoT) device, and/or the like.

The present application uses only examples from the 3GPP New Radio (NR) network architecture and 5G protocol to facilitate understanding, and the disclosed techniques and embodiments may be practiced in other wireless systems using communication protocols other than the 3GPP protocol.

Fig. 2 shows examples of legacy random access preamble formats (e.g., preamble format 0(210), preamble format 1(220), preamble format 2(230), and preamble format 3 (240)). Different random access preamble formats are used for signaling in conventional wireless communication systems (e.g., in the LTE PRACH random access preamble) to support different base station cell sizes. That is, different random access preamble formats (along with different cyclic prefix lengths as described further below) allow users/UEs traveling at different distances from and at different speeds relative to the base station to reliably synchronize with the base station. For example, to extend the coverage of a base station, one or more random access preamble formats (e.g., preamble format 1(220) in fig. 2) may provide a repeating random access preamble sequence (e.g., sequence 222) to form sequence 224. The repeated sequences 222 and 224 may then be combined to form a longer random access preamble sequence. However, this technique for obtaining a longer random access preamble has drawbacks in several respects. For example, conventional preamble formats cannot support a frequency offset greater than subcarrier spacing (SCS) because the correlation peak used by the receiver to detect the random access preamble may be significantly offset due to the frequency offset and it may fall within the detection window of another UE. Therefore, larger cyclic shift lengths are typically used in high speed scenarios where high frequency offsets are expected. A technique other than simple repetition is needed to overcome these and other problems when extending the conventional random access preamble for large time and frequency offsets. Additional benefits of the improved random access preamble format are discussed further below.

Fig. 3 shows a representative flow 300 illustrating a method for generating a preamble, wherein several ZC sequences are generated, grouped into at least two groups, and combined to generate a preamble sequence. Each group includes a plurality of ZC sequences having different cyclic shifts, wherein the ZC sequences in each group have a unique root. At the point of the process at block 310,a User Equipment (UE) receives, from a base station, a length (L), a root { u } and a cyclic shift list { v } of a Zadoff-Chu (ZC) sequence that the UE will use to generate a random access preamble sequence_ri}；u＝{u₁，u₂，u₃，…，u_RIs R roots allowing the UE to generate up to R different root/base ZC sequences, and v_ri(v_ri1，v_ri2，v_ri3…, where r is root and i is list number) is a set of cyclic shift lists corresponding to each root to allow the UE to generate cyclically shifted ZC sequences from each root sequence. For example, for root u₁The UE may receive a cyclic shift list v₁₁，v₁₂，v₁₃… }, wherein v_1i＝(v_1i1，v_1i2…) is a root u₁The ith cyclic shift list of (1); for root u₂The UE may receive a cyclic shift list v₂₁，v₂₂… } in which v_2j＝(v_2j1，v_2j2，v_2j3…) is a root u₂The jth cyclic shift list, and so on. In different embodiments, the circularly shifted lists may have the same or different number of elements, and each root may have a different number of circularly shifted lists.

At block 320, the UE selects a ZC root (u) from a set of roots u₁) And from corresponding to the selected root u₁Selects the ith cyclic shift list (v) from the set of cyclic shift lists_1i)。

At block 330, the UE selects a ZC root u₂And from corresponding to root u₂Selects the jth cyclic shift list v from the cyclic shift lists_2j。

At block 340, the UE derives a set with root u₁And cyclic shift v_1iIs L. For example, the UE may generate a cyclic shift v_1i1ZC sequence of (1), with cyclic shift v_1i2ZC sequences of (1), etc., wherein the cyclic shifts are obtained from the ith cyclic shift list (e.g., if u is selected)₁Is the first cyclic shift list, then the cyclic shift is v₁₁₁、v₁₁₂、v₁₁₃Etc.).

At block 350, the UE derives with root u₂And cyclic shift v_2jAnother set of length L ZC sequences. For example, the UE generates the quilt v_2j1、v_2j2Cyclically shifted ZC sequences (e.g., if u is selected), …, etc₂Is the first cyclic shift list, then the cyclic shift is v₂₁₁、v₂₁₂、v₂₁₃、v₂₁₄Etc.). In some embodiments, the UE may obtain the predefined ZC sequence from a memory of the UE, such as from a look-up table (LUT) using the selected root and cyclic shift list.

At block 360, the UE combines the ZC sequences generated in blocks 340 and 350 to form a preamble sequence. In some embodiments, the UE concatenates the sequences, while in other embodiments, the UE superimposes the sequences, or combines the concatenation and the superimposition to generate the preamble. The UE may repeat block 320-350 to generate additional ZC sequences for additional roots. In some embodiments, each ZC root uses at least two ZC sequences, and the at least two ZC roots are used to form the preamble sequence. In general, for multiple roots and multiple cyclic shifts for each root, the preamble generated at block 360 may be represented as:wherein the first set of ZC sequences uses corresponds to u₁Has n (and the ith cyclic shift list has n)₁A cyclic shift value); the second set of ZC sequence uses corresponding to u₂Has n (and the jth cyclic shift list has n)₂A cyclic shift value); and the use of the r-th group of ZC sequences corresponds to the root u_rIs not used (and the kth cyclic shift list has n)_rA cyclic shift value). The UE uses the generated preamble sequence to generate a random access preamble waveform that is transmitted to a wireless node (e.g., a base station) as part of a random access procedure (e.g., initial network access for the UE, connection re-establishment, handover, etc.).

In some embodiments, as described further below, forEach circularly shifted list in the set of circularly shifted lists corresponding to the root r is unique. That is, for any cyclic shift s, the ith cyclic shift list of root r does not overlap with the jth cyclic shift list of root r. For example, consider the case where the circularly shifted lists are in increasing order, j ≠ i for any list, and [ (v) for any s_rj1，v_rj2，…)+s)]mod L≠(v_ri1，v_ri2，…)。

Fig. 4 shows an example of a long preamble 400 generated by concatenating several short preambles in the time domain, including preambles 412, 414, 422, and 424. In general, a long preamble such as preamble 400 may be formed by superimposing N in the time domain or by superposition_spA number of short preambles. Each constituent short preamble (e.g., preambles 412, 414, 422, and 424) is generated from a Zadoff-chu (zc) sequence of length L, characterized by a root u and a cyclic shift v. To generate a long preamble, two or more different roots are used to generate a constituent short preamble (i.e., N)_uNot less than 2). The long preamble may be expressed as:whereinNote that for better readability, the list numbers corresponding to the above cyclic shifts have been deleted. That is, as discussed below with respect to FIG. 11, if corresponding to u₁The first group of roots selects the ith circularly shifted list, then the first group can be represented as

In the long preamble 400 depicted in fig. 4, two roots u₁And u₂Is used to compose the short preamble. The first group of short preambles 410 uses root u₁。u₁The root sequence is cyclically shifted to obtain (u)₁，v_1i1，v_1i2，…，v_1iN). For convenience, it is denoted as (u) in the following description₁，v₁₁，v₁₂，…，v_1n) The cyclic shift list index i is omitted. Similarly, the second set of short preambles 420 uses root u₂And the root sequence is cyclically shifted to obtain ((u)₂，v_2j1，v_2j2，…，v_2jm). For convenience, it is denoted as (u) in the following description₂，v₂₁，v₂₂，…，v_2m) The cyclic shift index j is omitted. That is, N + m ═ N_spThe short sequences are concatenated to form the long preamble 400. In some embodiments, different ZC sequences may have different lengths.

The preamble formats described above use Nu different roots to overcome the problems discussed above (e.g., conventional random access preambles cannot detect large frequency offsets such as in non-terrestrial networks (e.g., where correlation peaks may shift to detection windows of other users, resulting in erroneous receiver detection results)). In addition, as discussed further below, a combination of peaks (corresponding to the cyclic shift list above) is used to identify a particular user. The use of a long preamble with multiple roots enables high frequency offset estimation at the receiver, which is highly desirable in non-terrestrial network applications, for example.

Cyclic shift list v₁₁，v₁₂，…，v_1nIs a unique signature in the random access procedure. The uniqueness being in the amount of cyclic shift between adjacent sequences in the list, e.g. v₁₂-v₁₁，v₁₃-v₁₂，…，v_1(n-1)-v_1n. Two cyclic shift lists from the same root sequence are identical if they can completely overlap each other by a cyclic shift s of length L. For example, table 1 below shows some examples of identical cyclic shift lists (i.e., given some cyclic shifts s, they overlap completely) and of non-identical cyclic shift lists (i.e., for any cyclic shift s, they do not overlap).

TABLE 1

In the disclosed technique, ZC sequences generated from non-identical cyclic shift lists are concatenated to form a long preamble sequence (e.g., preamble 400 in fig. 3). Furthermore, the mapping between cyclic shifts through any two different roots is typically one-to-one. That is, once the one-to-one mapping is provided, it is passed through the root u₁Selected merge (v)₁₁，v₁₂，…，v_1n) The corresponding circular shift list through the remaining roots will be determined. The pool of signatures (i.e., the cyclic shift list) has an easily expandable capacity based on the length of the cyclic shift list.

Fig. 5 shows an example of a long preamble 500 including a Cyclic Prefix (CP)510 and a guard time 530. A cyclic prefix 510 is pre-appended to the long preamble 400 by taking a portion of the tail of the long preamble signal. A Guard Time (GT)530 is added to the end of the pre-appended long preamble signal.

Fig. 6 illustrates an example of a random access preamble 600 that may be used for random access in a satellite communication system. A satellite communication system may be characterized by a large time delay τ and a large frequency offset fo. The random access preamble 600 includes a Cyclic Prefix (CP)610, a long preamble sequence 620, and a guard time interval 630. In one embodiment, the subcarrier spacing (SCS) Δ f_RAWhich may be 1.25kHz, the ZC sequence length L may be 839, resulting in a duration of 0.8ms for each constituent short preamble (e.g., short preambles 612, 614, 616, 622, 624, 626). For example, if the maximum time delay in a certain Low Earth Orbit (LEO) satellite communication system is 4.4ms, a Cyclic Prefix (CP) may be generated by appending a portion from the end of the long-preamble sequence 620 corresponding to the six ZC preambles before the long-preamble sequence 620.

Fig. 7 illustrates an example set of correlation peaks at a receiver (e.g., a wireless node receiver such as a base station receiver) configured to receive a random access preamble transmitted by a user equipment (e.g., a UE) and to calculate a frequency and time offset. At a Base Station (BS) receiver, the time delay τ 750 may be divided into an integer portion τ_int730 (multiples of 0.8ms for 1.25kHz SCS) and fractional part τ_frac740 (i.e., τ ═ τ)_int+τ_frac). Similarly, the frequency offset fo may be divided into fo ═ k. Δ f_RA+fo_frac. The marker 705 is the zero delay receive time and the length 720 is the length of the Cyclic Prefix (CP). BS receiver superposes section 710 and superposes and uses (u)₁0) and (u)₂0), where "0" represents a cyclic shift of zero, and where the random access preamble is according to two roots u as described above with respect to fig. 6₁And u₂Generation). Same integer frequency offset K.Deltaf_RAThe peak shift is different but determined by two different root bands. In some embodiments, integer time offset τ_int730 may be estimated by using the correlation of a sliding time window and then a fractional time offset τ may be derived_frac740 and a frequency offset fo. As a result, user detection and corresponding frequency/time offset estimation can be performed on the combined short preamble with relatively low complexity. When the time delay is detected as described above, the receiver may transmit a Timing Advance (TA) value to the user equipment.

Fig. 8 shows an example of a preamble 800 for a system with large frequency offset and small time delay. In some embodiments, such as in user equipment embedded or used in an aircraft served by a wireless node (e.g., base station) on a High Altitude Platform (HAP), the propagation delay of signals from the user equipment to the base station may be much lower than in other applications (e.g., ground-based equipment communicating with LEO satellites). However, due to the much higher velocity of the user equipment relative to the BS, the frequency offset caused by doppler spread can be quite large. In these and other such systems, which are prone to large frequency offsets and small time delays, the preamble 800 of fig. 8 may be used, resulting in less resource consumption. For example, ZC sequences 412, 414, 422, and 424 may be superimposed to generate superimposed preamble 820. Further, the preamble 800 may use shorter CPs 810 and GTs 830 (compared to embodiments requiring detection of larger time delays), wherein the shorter CPs and GPs still allow the BS to detect shorter time delays and frequency offsets (as described above with respect to fig. 7).

Fig. 9 shows an example of a preamble 900 including an asymmetric long preamble 920. For example, the preamble 920 may be concatenated with four roots u₁Preambles 612, 614, 616, and 918 and two roots u₂Preambles 622 and 624 (corresponding to the three roots u of fig. 6)₁Preamble and three roots u₂Symmetric preamble structure of the preamble). If the characteristics on the root and cyclic shift lists are as described above, the base station receiver can calculate the time delay and frequency offset according to the description above (with respect to fig. 7).

Fig. 10 shows an example of a preamble 1000 comprising a long preamble 1020, wherein the constituent ZC sequence groups 612, 624, 616, 626, 614, 622 are concatenated or superimposed in a different order than the example of fig. 6. For example, in FIG. 10, each stub u₁Preamble followed by short root u in an alternating manner₂Preamble (root u)₁After the preamble 612 is the root u₂Preamble 624, root u₂Preamble 624 is followed by root u₁A preamble 616, etc.). In contrast, in FIG. 6, the root u₁The preambles (preambles 612, 614, and 616) are grouped together and followed by a set of roots u₂A preamble (preambles 622, 624, and 626). That is, the order of the short preambles does not affect the calculation of the frequency offset and time delay (as described above with respect to fig. 7).

FIG. 11 shows a root (e.g., root u)₁ 1110、u₂1120 and u_r1150) An example set of (1); a set of circularly shifted lists corresponding to a root (e.g., corresponding to root u)₁1110 corresponding to root u₂1120 circularly shifted list set 1122, and corresponding root u_rSet 1152 of cyclic shift lists of 1150). Each set of circularly shifted lists contains several circularly shifted lists. For example, circularly shifted list set 1112 includes circularly shifted list v₁₁ 1114、v₁₂ 1116、…、v_1i1118. …, etc. Ith cyclic shift list v corresponding to the r-th root_ri1154 contains M elements v_ri1、v_ri2、v_ri3、…、v_riMWherein each element corresponds to a cyclic shift value.

Some example embodiments may be described using the following clauses.

Clause 1. A wireless device generates a preamble sequence by combining a plurality of Zadoff-chu (zc) sequences. The plurality of ZC sequences are based on two or more roots and a cyclic shift of each root. The wireless device (e.g., UE) may then generate a transmission waveform using the preamble sequence and transmit it to a wireless node (e.g., BS). The merging may be a concatenation, an overlay, or a concatenation and overlay merging.

Clause 2. To generate the preamble sequence, the UE receives a length L, a number of roots u₁、u₂、u₃…, and a plurality of sets of circularly shifted lists corresponding to the plurality of roots. Each set of circularly shifted lists comprises a plurality of circularly shifted lists. It may then select the first root u₁And ith cyclic shift list v_1iWherein the first root u₁Selected from a plurality of roots, and the ith circularly shifted list v_1iFrom corresponding to the first root u₁A plurality of cyclic shift lists v₁₁、v₁₂、v₁₃…; and a second root u₂And the jth cyclic shift list v_2jWherein the second root u₂Selected from a plurality of roots and the jth circularly shifted list v_2jFrom corresponding to the second root u₂A plurality of cyclic shift lists v₂₁、v₂₂、v₂₃…; for the r root u_rAnd the kth cyclic shift list v_2kAnd so on. Corresponding to the first root u₁Of the ith cyclic shift list v_1iComprising N cyclic shift values v_1i1、v_1i2、v_1i3、…、v_1iNAnd corresponds to the second root u₂Of the jth cyclic shift list v_2jComprising M cyclic shift values v_2j1、v_2j2、v_2j3、…、v_2jM. The UE may then be based on the first root u₁And ith cyclic shift list v_1i＝{v_li1，v_li2，…，v_liNGenerating a first group of N ZC sequences with the length of L; based on the second root u₂And the jth cyclic shift list v_2j＝{v_2j1，v_2j2，…，v_2jMGenerating a second set of M ZC sequences with the length of L; and generating a preamble sequence by combining the first set of N ZC sequences and the second set of M ZC sequences.

Clause 3. A plurality of roots u₁、u₂、u₃…, and a plurality of sets of cyclic shift lists corresponding to the plurality of roots, collectively uniquely identify a preamble sequence from among the plurality of preamble sequences.

Clause 4. When a cyclic shift is applied to either of the two cyclic shift lists, any two cyclic shift lists in the set of cyclic shift lists do not completely overlap with each other.

Clause 5. The UE may generate a Cyclic Prefix (CP) by pre-appending a portion of a preamble sequence, which is obtained from a tail of the preamble sequence. The UE may also generate a guard time interval (GT) to follow the pre-appended preamble sequence. The CP, preamble sequence, GT together define the preamble (e.g., PRACH preamble) that the UE sends to the BS. The BS may transmit a timing advance value to the UE in response to receiving the random access preamble signal.

A wireless device (e.g., UE) or a wireless node (e.g., base station) may include a processor configured to implement a method as described in any one or more of the clauses above. Further, the UE or base station may include a computer program product comprising a computer readable program medium having stored thereon processor executable instructions that, when executed by a processor, cause the processor to implement a method according to any one or more of the clauses described above.

Fig. 12 is a block diagram representation of a portion of an apparatus in accordance with some embodiments of the disclosed technology. The apparatus 1205, such as a base station or wireless device (or UE), may include processor electronics 1210, such as a microprocessor, that implements one or more of the techniques presented herein. The apparatus 1205 may include transceiver electronics 1215 to transmit and/or receive wireless signals over one or more communication interfaces, such as one or more antennas 1220. The apparatus 1205 may include other communication interfaces for transmitting and receiving data. The apparatus 1205 may include one or more memories (not explicitly shown) configured to store information such as data and/or instructions. In some implementations, the processor electronics 1210 may include at least a portion of the transceiver electronics 1215. In some embodiments, at least some of the disclosed techniques, modules, or functions are implemented using an apparatus 1205.

The specification and drawings are to be regarded in an illustrative manner, with illustrative meaning exemplary, and not restrictive of the preferred embodiments, unless otherwise specified. As used herein, the use of "or" is intended to include "and/or" unless the context clearly indicates otherwise.

Some embodiments described herein are described in the general context of methods or processes, which may be implemented in one embodiment by a computer program product, embodied in a computer-readable medium, including computer-executable instructions, such as program code, executed by computers in networked environments. Computer-readable media may include removable and non-removable storage devices including, but not limited to, read-only memory (ROM), random-access memory (RAM), Compact Disks (CDs), Digital Versatile Disks (DVDs), and the like. Accordingly, the computer readable medium may include a non-transitory storage medium. Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-or processor-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

Some embodiments disclosed may be implemented as a device or module using hardware circuitry, software, or a combination thereof. For example, a hardware circuit implementation may include discrete analog and/or digital components that are integrated as part of a printed circuit board, for example. Alternatively, or in addition, the disclosed components or modules may be implemented as Application Specific Integrated Circuit (ASIC) and/or Field Programmable Gate Array (FPGA) devices. Some embodiments may additionally or alternatively include a Digital Signal Processor (DSP), which is a special purpose microprocessor having an architecture optimized for the operational needs of the digital signal processing associated with the disclosed functionality of the present application. Similarly, the various components or sub-components within each module may be implemented in software, hardware, or firmware. Connections between modules and/or components within modules may be provided using any of a variety of connection methods and media known in the art, including, but not limited to, communications over the internet, wired, or wireless networks using an appropriate protocol.

While this application contains many specifics, these should not be construed as limitations on the scope of the claimed invention or of what may be claimed, but rather as descriptions of features specific to particular embodiments. Certain features that are described in this application 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. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a described combination can in some cases be excised from the combination, and the combination may be directed to a subcombination or variation of a subcombination. Similarly, while operations are depicted in the drawings 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.

Only some embodiments and examples are described and other embodiments, enhancements and variations can be made based on what is described and illustrated in this disclosure.