Beam searching method for 5G NR initial access process
阅读说明：本技术 一种用于5g nr初始接入过程的波束搜索方法 (Beam searching method for 5G NR initial access process ) 是由 林佳培 安文君 张菁菁 夏婷婷 王磊 荣师洁 项维其 于 2018-09-07 设计创作，主要内容包括：本发明公开了一种用于5G NR初始接入过程的波束搜索方法。该方法为：在小区搜索阶段,基站在周期T内扫描M个波束方向并发送同步信号块,用户扫描N个波束中较宽的n个波束方向并检测同步信号块,确定初始波束方向；若n＝N,则将该初始波束方向作为数据传输波束方向；若n＜N,则将初始波束分成<Image he="73" wi="146" file="DDA0001792946590000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>个波束进行扫描,并检测同步信号块,确定数据传输的波束方向；在随机接入阶段,基站在所有可能的物理随机信道位置上检测用户发送的随机接入前导码,若检测成功,则将该信道作为基站与该用户进行数据传输的波束方向。本发明能够使5G NR系统在限定的同步信号块开销下,降低初始接入过程的延迟。(The invention discloses a beam searching method for a 5G NR initial access process. The method comprises the following steps: in a cell searching stage, a base station scans M wave beam directions and sends a synchronous signal block in a period T, and a user scans wider N wave beam directions in N wave beams and detects the synchronous signal block to determine an initial wave beam direction; if N is equal to N, taking the initial beam direction as a data transmission beam direction; if N < N, then divide the initial beam into Scanning each beam, detecting a synchronous signal block, and determining the beam direction of data transmission; in the random access phase, the base station detects random access preambles sent by the user at all possible physical random channel positions, and if the detection is successful, the channel is used as a beam direction for data transmission between the base station and the user. The invention can lead the 5G NR systemThe delay of the initial access procedure is reduced at a defined synchronization signal block overhead.)
1. A beam searching method for a 5G NR initial access process is characterized by comprising the following steps:
(1) the transmission period of a synchronous signal block set is T, and the number of the synchronous signal blocks which are contained in the synchronous signal block set at most is NSSBThe number of wave beams of the base station is M, wherein M is less than or equal to NSSBThe number of beams of the user is N;
(2) in a cell searching stage, in each transmission period T, a base station scans M wave beam directions and sends a synchronous signal block, a user scans N wave beam directions and detects the synchronous signal block, N is less than or equal to N, the size of a search window is T, and after the detection is successful, the wave beam direction with the largest detection energy is selected as an initial wave beam direction;
if N is equal to N, taking the initial beam direction as a data transmission beam direction;
if N is less than N, the initial beam is divided into
(3) in the random access stage, a user sends a random access preamble on a physical random access channel mapped with a detected synchronous signal block, a base station detects on all possible physical random access channels, and after the detection is successful, the channel is used as a beam direction for data transmission between the base station and the user.
2. The beam searching method for 5G NR initial access procedure of claim 1, wherein the base station scans M beam directions and transmits synchronization signal blocks, and the user scans n beam directions and detects the synchronization signal blocks, specifically as follows:
the base station scans the M beams in any order, and the user also scans the n beams in any order.
3. The method of claim 1, wherein the initial beam splitting is performed in a beam search for a 5G NR initial access procedure
in the second cell search stage, the user only needs to scan the direction of the initial beam
4. The beam searching method for 5G NR initial access procedure as claimed in claim 1, wherein the physical random access channel mapped with the detected synchronization signal block in step 4 specifically refers to:
the mapping relation between the synchronous signal blocks and the physical random access channels is determined according to actual requirements, the physical random access channels have a plurality of sending moments in time domains and frequency domains, and the total M synchronous signal blocks of the base station are only associated with a specific number of physical random access channels in an association period.
Technical Field
The invention relates to the technical field of communication, in particular to a beam searching method for a 5G NR initial access process.
Background
In order to support the emerging characteristics of ultra-wide bandwidth, ultra-low delay and the like, a fifth generation mobile communication (5G) New Radio (NR) network introduces a millimeter wave band as one of frequency bands and a beam forming technology. The initial access process is a process of establishing initial link connection between a user and a base station, and comprises a cell search stage and a random access stage, and is a key problem for designing a beamforming cellular system. In the existing cellular mobile communication system, a multi-antenna system mostly adopts a digital beam forming technology, and after an initial access process is successful, a user and a base station realize beam forming according to the calculation of channel state information. In 5G NR, an analog beamforming technology realized by a codebook is introduced at the same time, so that in an initial access stage, a user and a base station must determine a beam direction for data transmission by beam search, and the design of a beam search method needs to consider two performance indexes of initial access delay and system overhead.
The existing wave beam searching methods include an exhaustive searching method, an iterative searching method, a unilateral searching method and a searching method based on background information. In the 5G NR, a synchronization signal block has a mapping relationship with a physical random access channel, and the maximum delay of a base station detecting its own beam direction is fixed. The exhaustive search method is that a user traverses all the beam directions of the user to perform detection search to find the beam direction for data transmission, and the base station performs search on all possible physical random access channel positions to find the beam direction for data transmission with the user. The iterative search method is that the base station firstly scans the wide beam and carries out the first initial access with the user, after the connection is established, the determined wide beam is subdivided into finer beams to carry out the second initial access, therefore, if the iterative search method is applied to the 5G NR, the initial access delay is larger than the exhaustive search, and the method only considers the situation of a single user and is not suitable for the situation of multiple users. The single-side search method is that the base station firstly transmits an omnidirectional beam, the user traverses all the beam directions of the user to detect the beam direction for data transmission, then the user sends a random access preamble in the detected beam direction, and the base station traverses all the directions to detect, so that the method cannot be applied to the 5G NR. The method comprises the steps that a user obtains the geographical position of the nearest NR base station by utilizing a macro base station and a GPS and performs an initial access process in the direction of a beam aligned with the geographical position, extra delay is introduced when the information of the macro base station and the GPS information are obtained, and the method can only be applied to a line-of-sight scene and is limited in application scene.
Disclosure of Invention
The invention aims to provide a beam searching method for a 5G NR initial access process, which can enable a 5G NR system to reduce the delay of the initial access process under the limited synchronous signal block overhead.
The technical solution for realizing the purpose of the invention is as follows: a beam searching method for a 5G NR initial access process is specifically as follows:
(1) the transmission period of a synchronous signal block set is T, and the number of the synchronous signal blocks which are contained in the synchronous signal block set at most is NSSBThe number of wave beams of the base station is M, wherein M is less than or equal to NSSBThe number of beams of the user is N;
(2) in a cell searching stage, in each transmission period T, a base station scans M wave beam directions and sends a synchronous signal block, a user scans N wave beam directions and detects the synchronous signal block, N is less than or equal to N, the size of a search window is T, and after the detection is successful, the wave beam direction with the largest detection energy is selected as an initial wave beam direction;
if N is equal to N, taking the initial beam direction as a data transmission beam direction;
if N is less than N, the initial beam is divided into
(3) in the random access stage, a user sends a random access preamble on a physical random access channel mapped with a detected synchronous signal block, a base station detects on all possible physical random access channels, and after the detection is successful, the channel is used as a beam direction for data transmission between the base station and the user.
Further, the base station scans M beam directions and sends a synchronization signal block, and the user scans n beam directions and detects the synchronization signal block, which is as follows:
the base station scans the M beams in any order, and the user also scans the n beams in any order.
Further, said splitting the initial beam
in the second cell search stage, the user only needs to scan the direction of the initial beam
Further, the physical random access channel mapped with the detected synchronization signal block in
the mapping relation between the synchronous signal blocks and the physical random access channels is determined according to actual requirements, the physical random access channels have a plurality of sending moments in time domains and frequency domains, and the total M synchronous signal blocks of the base station are only associated with a specific number of physical random access channels in an association period.
The invention is comparable to the prior artCompared with the prior art, the method has the following remarkable advantages: (1) selecting proper N according to the size of N, effectively reducing the detection delay of a cell search stage, thereby reducing the initial access delay; (2) selecting proper N according to the size of N, reducing the total beam scanning times of the user and reducing the energy loss of the user in the initial access stage; (3) the system overhead is
Drawings
Fig. 1 is a flowchart illustrating an initial 5G NR access procedure according to an embodiment of the present invention.
Fig. 2 is a diagram illustrating a beam direction and a synchronization information block mapping of a base station according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of a beam search method for a 5G NR initial access procedure according to the present invention, wherein (a) is a schematic diagram corresponding to a line-of-sight scene, and (b) is a schematic diagram corresponding to a non-line-of-sight scene.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and accompanying drawings.
With reference to fig. 1 to 3, the beam search method for the 5G NR initial access process of the present invention includes the following steps:
(1) the transmission period of a synchronous signal block set is T, and the number of the synchronous signal blocks which are contained in the synchronous signal block set at most is NSSBThe number of wave beams of the base station is M, wherein M is less than or equal to NSSBThe number of beams of the user is N;
(2) in a cell searching stage, in each transmission period T, a base station scans M wave beam directions and sends a synchronous signal block, a user scans N wave beam directions and detects the synchronous signal block, N is less than or equal to N, the size of a search window is T, and after the detection is successful, the wave beam direction with the largest detection energy is selected as an initial wave beam direction;
if N is equal to N, taking the initial beam direction as a data transmission beam direction;
if N is less than N, the method is carried outInitial beam splitting
(3) in the random access stage, a user sends a random access preamble on a physical random access channel mapped with a detected synchronous signal block, a base station detects on all possible physical random access channels, and after the detection is successful, the channel is used as a beam direction for data transmission between the base station and the user.
Further, the base station scans M beam directions and sends a synchronization signal block, and the user scans n beam directions and detects the synchronization signal block, which is as follows:
the base station scans the M beams in any order, and the user also scans the n beams in any order.
Further, said splitting the initial beam
in the second cell search stage, the user only needs to scan the direction of the initial beam
Further, the physical random access channel mapped with the detected synchronization signal block in
the mapping relation between the synchronous signal blocks and the physical random access channels is determined according to actual requirements, the physical random access channels have a plurality of sending moments in time domains and frequency domains, and the total M synchronous signal blocks of the base station are only associated with a specific number of physical random access channels in an association period.
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