CN106612540B

CN106612540B - Downlink synchronization method, user equipment and base station

Info

Publication number: CN106612540B
Application number: CN201510698107.2A
Authority: CN
Inventors: 黄磊; 王艺
Original assignee: Huawei Technologies Co Ltd
Current assignee: XFusion Digital Technologies Co Ltd
Priority date: 2015-10-23
Filing date: 2015-10-23
Publication date: 2020-12-15
Anticipated expiration: 2035-10-23
Also published as: WO2017067436A1; CN106612540A

Abstract

The embodiment of the invention provides a downlink synchronization method, wherein user equipment and a high-frequency base station are in a high-frequency and low-frequency mixed networking system, and the method comprises the following steps: the user equipment receives synchronization information sent by the high-frequency base station, a synchronization radio frame used by the synchronization information comprises at least one special subframe, the special subframe comprises a DLBP, the DLBP comprises Nu subintervals, and each subinterval transmits Nd synchronization signals, wherein Nu and Nd are positive integers larger than 1; and the user equipment carries out synchronization according to the synchronization information. In the embodiment of the invention, the high-frequency base station sends the synchronization information in the special subframe, and the UE completes the synchronization with the high-frequency base station by receiving the synchronization signal in the special subframe, so that the UE can be conveniently and quickly accessed into a high-frequency system, and the power consumption during the access can be saved.

Description

Downlink synchronization method, user equipment and base station

Technical Field

The present invention relates to the field of communications, and in particular, to a method, a user equipment, and a base station for downlink synchronization in a high-frequency and low-frequency hybrid networking system.

Background

With the increasing requirements of data transmission rate, communication quality, etc. for mobile communication nowadays, the existing frequency bands for mobile communication have become very crowded. However, in the millimeter wave band of 6-300GHz, there is still a large amount of spectrum resources that have not been allocated for use. The millimeter wave frequency band is introduced into cellular access communication, and the large bandwidth resource of the millimeter wave frequency band is fully utilized, so that the method is one of important research directions of next generation 5G mobile communication systems.

In the existing research, the high frequency band represented by the millimeter wave frequency band is mainly applied to indoor short-distance communication scenes. In an outdoor scene, the high-frequency section has large road loss and weak barrier penetrating capability due to complex terrain, and has a serious rain attenuation effect at certain frequency points, so that the application of the high-frequency section in the outdoor scene is seriously restricted. However, the high frequency band is short in wavelength, so that a large-scale array antenna is easy to implement, and a beam-forming (beam-forming) technology can be used to bring a large directional antenna gain, so that the high path loss of the antenna can be effectively compensated, and the possibility of applying the high frequency band to medium-long distance transmission in outdoor scenes is provided.

From the current research situation, the higher the frequency band is, the smaller the coverage area is, and the larger the array antenna size available for the base station is. For example, for an E-band system, a cell radius of 25m to 100 m can be covered, and the size of a base station array antenna can reach 1024 antenna array units. For a system in a frequency band below 30GHz, the system can generally cover a cell radius of 50 meters to 200 meters, and the size of the base station array antenna can reach 256 antenna array units. A large-scale array antenna is adopted in a high-frequency system to form a directional beam with high gain, so that high path loss caused by a high frequency band can be overcome, and link coverage is improved. However, directional beams present challenges to the design and transmission of broadcast channels, control channels, synchronization channels, random access channels.

In a conventional Mobile communication System, such as a Universal Mobile Telecommunications System (UMTS) and a Long Term Evolution (LTE) System, the transmission of the channels is realized by receiving and transmitting through an omni-directional antenna. For downlink broadcast channels, downlink control channels and synchronization channels, the base station transmits the channel information once through the omnidirectional antenna, and all user equipment under the coverage of the base station can successfully receive the channel information. For an uplink control channel and a random access channel, the user equipment sends the channel information once, and the base station can successfully receive the channel information through the omnidirectional antenna. However, in a high frequency communication system, due to the limitation of the beam width of the directional beam, a signal transmitted through one directional beam can only cover a small area in a certain direction, and corresponding information cannot be successfully received outside the area. Therefore, to obtain the effect of omni-directional coverage in the existing mobile communication system, it is necessary to traverse all directional beam combinations of the transmitting end and the receiving end. If the transceiving ends all adopt directional beams, the number of the beam combinations is very large, which leads to a sharp increase of high-frequency system overhead.

In a high-Frequency communication system, both a base station and a user equipment can use a large-scale antenna array to perform beamforming, and directional beams (wide beams and narrow beams) with different widths can be formed by adjusting the phase and amplitude of each antenna unit and/or digital weighting vectors on a plurality of Radio Frequency (RF) channels. The beam width of the wide beam is typically more than 2 times the beam width of the narrow beam.

In addition, in a high-frequency communication system, high path loss in a high frequency band needs to be compensated for by high beam gain of an antenna array. The acquisition of high beam gain is based on beam alignment (beam alignment) at both the transmit and receive ends. Once the beams at the two ends of the transceiver are mismatched (mis-aligned), the quality of the received signal will be reduced sharply, and the normal data communication will be interrupted. Therefore, in order to ensure normal data communication in a high-frequency communication system, it is necessary to perform beam training (beam tracking) and beam tracking (beam tracking) periodically or aperiodically so that both transmitting and receiving ends can transmit data using an optimal transmitting and receiving beam pair.

In the prior art, each radio subframe reserves part of resources for transmitting downlink synchronization signals, and is a distributed transmission mode. The user equipment needs to perform combination comparison on the synchronization signals received by a plurality of radio subframes to realize the downlink synchronization of the system. The synchronization method requires a long time, which causes a large overhead and further affects the performance of the system.

Disclosure of Invention

The invention provides a downlink synchronization method in a high-frequency and low-frequency hybrid network, which can save the overhead and improve the performance of a system.

In a first aspect, a downlink synchronization method is provided, which is applied to a high-frequency and low-frequency hybrid networking system, and includes:

the method comprises the steps that user equipment receives synchronous information sent by a high-frequency base station, the synchronous information is carried by a synchronous radio frame, the synchronous radio frame comprises at least one special subframe, the special subframe is used for transmitting synchronous signals, the special subframe comprises a downlink synchronization interval and a beam training interval DLBP, the DLBP comprises Nu subintervals, and Nd synchronous signals are transmitted in each subinterval, wherein Nu and Nd are positive integers larger than 1;

and the user equipment carries out synchronization according to the synchronization information.

Optionally, the synchronization radio frame further includes at least one general subframe, and the general subframe is used for transmitting data.

Therefore, the data is transmitted by the general sub-frame and the synchronous signal is transmitted by the special sub-frame in the synchronous wireless frame, further, the user equipment can perform downlink synchronization according to the compact frame structure, the synchronization overhead is small, the synchronization efficiency of a high-frequency and low-frequency networking system can be improved, and the system performance is improved.

With reference to the first aspect, in a first possible implementation manner of the first aspect, each subinterval includes Nd time slices, and a length of each time slice includes at least two OFDM symbols.

With reference to the first possible implementation manner of the first aspect, in a second possible implementation manner of the first aspect, a first OFDM symbol of the at least two OFDM symbols is used to transmit a primary synchronization signal, and a second OFDM symbol of the at least two OFDM symbols is used to transmit a secondary synchronization signal.

With reference to the second possible implementation manner of the first aspect, in a third possible implementation manner of the first aspect, the second OFDM symbol is used for transmitting a specific sequence of the secondary synchronization signal. Wherein the specific sequence comprises an identification ID of a time slice in which the specific sequence is positioned and an ID of a subinterval in which the specific sequence is positioned.

Alternatively, the ID of the time slice in which the specific sequence is located may be replaced with the ID of the transmission beam. Optionally, the specific sequence may further include an ID of the high frequency base station. In this way, the specific sequence is transmitted in the specific time slice of the specific subinterval, the ue can perform coherent detection on the secondary synchronization signal, and obtain the ID of the time slice in which the specific sequence is located and the ID of the subinterval in which the specific sequence is located, and thus can obtain the position of the OFDM symbol in the special subframe in which the secondary synchronization signal is located, thereby obtaining the radio frame synchronization.

With reference to the first aspect or any one of the foregoing possible implementation manners of the first aspect, in a fourth possible implementation manner of the first aspect, each of the subintervals further includes Nd switching guard intervals SGPs respectively located after the Nd time slices.

With reference to the first aspect or any one of the foregoing possible implementations of the first aspect, in a fifth possible implementation of the first aspect, the Nd synchronization signals are sequentially transmitted by the high-frequency base station using Nd different transmission beams.

With reference to the first aspect or any one of the foregoing possible implementation manners of the first aspect, in a sixth possible implementation manner of the first aspect, the receiving, by the user equipment, synchronization information sent by a high-frequency base station includes: the user equipment receives the synchronization signals on the Nu subintervals respectively using Nu different receiving beams. That is, the user equipment receives Nd synchronization signals over one sub-interval using one reception beam.

With reference to the first aspect or any one of the foregoing possible implementations of the first aspect, in a seventh possible implementation of the first aspect, on a first special subframe in the synchronization information, the high frequency base station transmits the synchronization signal using a first sequence of transmission beams; on a second special subframe in the synchronization information, the high frequency base station transmits the synchronization signal using a second order of transmission beams, wherein the second order is generated by the first order through cyclic shifting.

With reference to the first aspect or any one of the foregoing possible implementations of the first aspect, in an eighth possible implementation of the first aspect, each synchronous radio frame includes a special subframe; the first special subframe is a special subframe in a first synchronous radio frame, and the second special subframe is a special subframe in a second synchronous radio frame; wherein the second synchronization radio frame is a next synchronization radio frame adjacent to the first synchronization radio frame.

With reference to the first aspect or any one of the foregoing possible implementations of the first aspect, in a ninth possible implementation of the first aspect, each synchronous radio frame includes 2N special subframes; the first special subframe is the 2 i-th special subframe in the 2N special subframes, and the second special subframe is the 2i + 1-th special subframe in the 2N special subframes; wherein N is a positive integer, and i is a positive integer less than or equal to N.

With reference to the first aspect or any one of the foregoing possible implementation manners of the first aspect, in a tenth possible implementation manner of the first aspect, the receiving, by the user equipment, synchronization information sent by a high-frequency base station includes: the user equipment determines the initial position of a synchronous detection window according to a low-frequency signal sent by a low-frequency base station in the system; the user equipment receives Nu groups of synchronization signals respectively from the starting position by using Nu different receiving beams, wherein each group of synchronization signals comprises Nd synchronization signals.

Optionally, the user equipment also receives a low frequency signal transmitted by the low frequency base station. Specifically, the user equipment determines the start position of the synchronization detection window according to a frame structure used by the low-frequency base station to transmit the low-frequency signal. In this way, the user equipment determines the starting point of synchronization with low frequency assistance, making high frequency synchronization more efficient.

With reference to the first aspect or any one of the foregoing possible implementations of the first aspect, in an eleventh possible implementation of the first aspect, the second order is generated by cyclic shifting the first order.

With reference to the first aspect or any one of the foregoing possible implementations of the first aspect, in a twelfth possible implementation of the first aspect, a length of the time slice of the cyclic shift is greater than a high-frequency and low-frequency delay of the system.

Due to the existence of high and low frequency time delay in the system, the user equipment has a synchronization blind area during synchronization. Here, the cyclic shift larger than the high and low frequency delays can ensure that the user equipment receives the synchronization signal originally in the synchronization blind area, so that the user equipment can quickly obtain high-frequency downlink synchronization.

With reference to the first aspect or any one of the foregoing possible implementations of the first aspect, in a thirteenth possible implementation of the first aspect, the special subframe further includes a cyclic suffix CS located after the DLBP, and the CS transmits K synchronization signals, where K is a positive integer smaller than Nd.

With reference to the first aspect or any one of the foregoing possible implementations of the first aspect, in a fourteenth possible implementation of the first aspect, the Nd synchronization signals are sequentially transmitted by the high-frequency base station using Nd transmission beams; the K synchronization signals are sequentially transmitted by the high frequency base station using the first K transmission beams among the Nd transmission beams.

With reference to the first aspect or any one of the foregoing possible implementation manners of the first aspect, in a fifteenth possible implementation manner of the first aspect, the receiving, by the user equipment, synchronization information sent by a high-frequency base station includes: the user equipment determines a first initial position of a first synchronous detection window according to a low-frequency signal sent by a low-frequency base station in the system; the user equipment respectively receives Nu groups of synchronization signals from the first starting position by using Nu different receiving beams, wherein each group of synchronization signals comprises Nd synchronization signals; the user equipment determines a second initial position of a second synchronous detection window according to a low-frequency signal sent by a low-frequency base station in the system and the additional receiving time delay; and the user equipment respectively receives Nu groups of synchronous signals from the second starting position by using Nu different receiving beams, wherein each group of synchronous signals comprises Nd synchronous signals.

With reference to the first aspect or any one of the foregoing possible implementation manners of the first aspect, in a sixteenth possible implementation manner of the first aspect, the second special subframe is a first special subframe located after the first special subframe.

With reference to the first aspect or any one of the foregoing possible implementations of the first aspect, in a seventeenth possible implementation of the first aspect, the additional reception delay is preset in the user equipment. Optionally, the additional receive delay may be preconfigured in the user equipment according to the high and low frequency delays of the system.

With reference to the first aspect or any one of the foregoing possible implementations of the first aspect, in an eighteenth possible implementation of the first aspect, the additional reception delay is obtained by the user equipment from the low frequency base station. Optionally, the low frequency base station may determine the additional receiving delay according to the high and low frequency delays of the system, and send the determined additional receiving delay to the user equipment.

With reference to the first aspect or any one of the foregoing possible implementation manners of the first aspect, in a nineteenth possible implementation manner of the first aspect, the additional receiving delay is obtained by the user equipment through an RRC signaling sent by the low frequency base station. That is, the RRC signaling transmitted by the low frequency base station to the user equipment includes an additional reception delay.

With reference to the first aspect or any one of the foregoing possible implementation manners of the first aspect, in a twentieth possible implementation manner of the first aspect, a length of the additional reception delay is greater than a high-low frequency delay of the system, and a length of a time slice occupied by the CP is greater than or equal to a sum of the high-low frequency delay and the additional reception delay.

Due to the existence of high and low frequency time delay in the system, the user equipment has a synchronization blind area during synchronization. Here, by setting the additional receiving delay greater than the high-low frequency delay and setting the CP greater than the sum of the high-low frequency delay and the additional receiving delay, it can be ensured that the user equipment receives the synchronization signal originally in the synchronization blind area, so that the user equipment can quickly obtain high-frequency downlink synchronization.

With reference to the first aspect or any one of the foregoing possible implementation manners of the first aspect, in a twenty-first possible implementation manner of the first aspect, before the receiving, by the user equipment, synchronization information sent by a high-frequency base station, the method further includes: receiving RRC signaling sent by a low-frequency base station, wherein the RRC signaling comprises: and the frequency point adopted by the high-frequency base station and/or the value of Nd.

The value of Nd is related to the frequency point adopted by the high-frequency base station. Then, if the RRC signaling includes a value of Nd, the user equipment can directly know the value of Nd. If the RRC signaling includes a frequency bin used by the high frequency base station, the user equipment may determine the value of Nd according to the frequency bin.

With reference to the first aspect or any one of the foregoing possible implementation manners of the first aspect, in a twenty-second possible implementation manner of the first aspect, the special subframe further includes a reserved data interval RDP and an uplink and downlink switching guard interval GP.

Alternatively, RDP may be used for uplink data transmission, uplink random access, or the like.

With reference to the first aspect or any one of the foregoing possible implementations of the first aspect, in a twenty-third possible implementation of the first aspect, the synchronous radio frame further includes a general subframe, where the general subframe includes 8 slots with a length of 0.125ms, and the slot includes Ns OFDM symbols, where Ns is a positive integer.

With reference to the first aspect or any one of the foregoing possible implementation manners of the first aspect, in a twenty-fourth possible implementation manner of the first aspect, a cycle of the synchronous radio frame used by the high-frequency base station is a length of M radio frames, where M is a positive integer.

In a second aspect, a downlink synchronization method is provided, which is applied to a high-frequency and low-frequency hybrid networking system, and includes:

the method comprises the steps that a high-frequency base station generates synchronous information, the synchronous information is carried by a synchronous radio frame, the synchronous radio frame comprises at least one special subframe, the special subframe is used for transmitting synchronous signals, the special subframe comprises a downlink synchronization interval and a beam training interval DLBP, the DLBP comprises Nu subintervals, and Nd synchronization signals are transmitted in each subinterval, wherein Nu and Nd are positive integers larger than 1;

and the high-frequency base station sends the synchronization information to user equipment.

Therefore, in the synchronous wireless frame, data is transmitted by the general subframe, synchronous signals are transmitted by the special subframe, and synchronous information sent by the high-frequency base station has a compact frame structure. Furthermore, the user equipment can perform downlink synchronization according to the compact frame structure, the synchronization overhead is low, and therefore the synchronization efficiency of the high-frequency and low-frequency networking system can be improved, and the system performance is improved.

With reference to the second aspect, in a first possible implementation manner of the second aspect, each subinterval includes Nd time slices, and a length of each time slice includes at least two orthogonal frequency division multiplexing OFDM symbols.

With reference to the first possible implementation manner of the second aspect, in a second possible implementation manner of the second aspect, a first OFDM symbol of the at least two OFDM symbols is used for transmitting a primary synchronization signal, and a second OFDM symbol of the at least two OFDM symbols is used for transmitting a secondary synchronization signal.

With reference to the second aspect or any one of the foregoing possible implementations of the second aspect, in a third possible implementation of the second aspect, the second OFDM symbol is used for transmitting a specific sequence of the secondary synchronization signal. Wherein the specific sequence comprises an ID of a time slice in which the specific sequence is positioned and an ID of a subinterval in which the specific sequence is positioned.

With reference to the second aspect or any one of the foregoing possible implementation manners of the second aspect, in a fourth possible implementation manner of the second aspect, each of the subintervals further includes Nd switching guard intervals SGP respectively located after the Nd time slices.

With reference to the second aspect or any one of the foregoing possible implementation manners of the second aspect, in a fifth possible implementation manner of the second aspect, the sending, by the high frequency base station, the synchronization information to the user equipment includes: the high frequency base station transmits the Nd synchronization signals using Nd different transmission beams.

With reference to the second aspect or any one of the foregoing possible implementation manners of the second aspect, in a sixth possible implementation manner of the second aspect, the sending, by the high frequency base station, the synchronization information to the user equipment includes:

on a first special subframe in the synchronization information, the high frequency base station transmits the synchronization signal using a first sequence of transmit beams;

on a second special subframe in the synchronization information, the high frequency base station transmits the synchronization signal using a second sequence of transmit beams.

With reference to the second aspect or any one of the foregoing possible implementations of the second aspect, in a seventh possible implementation of the second aspect, each synchronization radio frame includes one special subframe;

the first special subframe is a special subframe in a first synchronous radio frame, and the second special subframe is a special subframe in a second synchronous radio frame;

wherein the second synchronization radio frame is a next synchronization radio frame adjacent to the first synchronization radio frame.

With reference to the second aspect or any one of the foregoing possible implementations of the second aspect, in an eighth possible implementation of the second aspect, each synchronous radio frame includes 2N special subframes;

the first special subframe is the 2 i-th special subframe in the 2N special subframes, and the second special subframe is the 2i + 1-th special subframe in the 2N special subframes;

wherein N is a positive integer, and i is a positive integer less than or equal to N.

With reference to the second aspect or any one of the foregoing possible implementations of the second aspect, in a ninth possible implementation of the second aspect, the second order is generated by cyclic shifting the first order.

With reference to the second aspect or any one of the foregoing possible implementations of the second aspect, in a tenth possible implementation of the second aspect, a length of the time slice of the cyclic shift is greater than a high-frequency and low-frequency delay of the system.

With reference to the second aspect or any one of the foregoing possible implementations of the second aspect, in an eleventh possible implementation of the second aspect, the special subframe further includes a cyclic suffix CS located after the DLBP, and the CS transmits K synchronization signals, where K is a positive integer smaller than Nd.

With reference to the second aspect or any one of the foregoing possible implementation manners of the second aspect, in a twelfth possible implementation manner of the second aspect, the sending, by the high frequency base station, the synchronization information to the user equipment includes:

the high-frequency base station sequentially transmits the Nd synchronous signals by using Nd transmitting beams;

and the high-frequency base station sequentially transmits the K synchronous signals by using the first K transmitting beams in the Nd transmitting beams.

With reference to the second aspect or any one of the foregoing possible implementation manners of the second aspect, in a thirteenth possible implementation manner of the second aspect, the special subframe further includes a reserved data interval RDP and an uplink and downlink switching guard interval GP.

With reference to the second aspect or any one of the foregoing possible implementation manners of the second aspect, in a fourteenth possible implementation manner of the second aspect, a period of the synchronous radio frame used by the high-frequency base station is a length of M radio frames, where M is a positive integer.

In a third aspect, a user equipment is provided, in a high-low frequency hybrid networking system, and includes:

a receiving unit, configured to receive synchronization information sent by a high-frequency base station, where the synchronization information is carried by a synchronization radio frame, and the synchronization radio frame includes at least one special subframe, and the special subframe is used to transmit a synchronization signal, where the special subframe includes a DLBP, the DLBP includes Nu subintervals, and each subinterval transmits Nd synchronization signals, where Nu and Nd are positive integers greater than 1;

and the processing unit is used for carrying out synchronization according to the synchronization information.

With reference to the third aspect, in a first possible implementation manner of the third aspect, each subinterval includes Nd time slices, and a length of each time slice includes at least two orthogonal frequency division multiplexing OFDM symbols.

With reference to the first possible implementation manner of the third aspect, in a second possible implementation manner of the third aspect, a first OFDM symbol of the at least two OFDM symbols is used to transmit a primary synchronization signal, and a second OFDM symbol of the at least two OFDM symbols is used to transmit a secondary synchronization signal.

With reference to the third aspect or any one of the foregoing possible implementations of the third aspect, in a third possible implementation of the third aspect, the second OFDM symbol is used to transmit a specific sequence of the secondary synchronization signal, where the specific sequence includes an ID of a time slice in which the specific sequence is located and an ID of a subinterval in which the specific sequence is located.

With reference to the third aspect or any one of the foregoing possible implementation manners of the third aspect, in a fourth possible implementation manner of the third aspect, each sub-interval further includes Nd switching guard intervals SGPs respectively located after the Nd time slices.

With reference to the third aspect or any one of the possible implementations of the third aspect, in a fifth possible implementation of the third aspect, the Nd synchronization signals are transmitted by the high-frequency base station using Nd different transmission beams.

With reference to the third aspect or any one of the foregoing possible implementation manners of the third aspect, in a sixth possible implementation manner of the third aspect, the receiving unit is specifically configured to: and respectively receiving the synchronization signals of the Nu subintervals by using Nu different receiving beams.

With reference to the third aspect or any one of the foregoing possible implementations of the third aspect, in a seventh possible implementation of the third aspect, on a first special subframe in the synchronization information, the high frequency base station transmits the synchronization signal using a first sequence of transmission beams; on a second special subframe in the synchronization information, the high frequency base station transmits the synchronization signal using a second sequence of transmit beams.

With reference to the third aspect or any one of the foregoing possible implementations of the third aspect, in an eighth possible implementation of the third aspect, each synchronization radio frame includes one special subframe;

With reference to the third aspect or any one of the foregoing possible implementations of the third aspect, in a ninth possible implementation of the third aspect, each synchronization radio frame includes 2N special subframes;

With reference to the third aspect or any one of the foregoing possible implementation manners of the third aspect, in a tenth possible implementation manner of the third aspect, the receiving unit is specifically configured to:

determining the initial position of a synchronous detection window according to a low-frequency signal sent by a low-frequency base station in the system;

nu groups of synchronization signals are respectively received from the start position using Nu different reception beams, wherein each group of synchronization signals includes Nd synchronization signals.

With reference to the third aspect or any one of the foregoing possible implementations of the third aspect, in an eleventh possible implementation of the third aspect, the second order is generated by the first order through cyclic shifting.

With reference to the third aspect or any one of the foregoing possible implementations of the third aspect, in a twelfth possible implementation of the third aspect, a length of the time slice of the cyclic shift is greater than a high-frequency and low-frequency delay of the system.

With reference to the third aspect or any one of the foregoing possible implementations of the third aspect, in a thirteenth possible implementation of the third aspect, the special subframe further includes a cyclic suffix CS located after the DLBP, and the CS transmits K synchronization signals, where K is a positive integer smaller than Nd.

With reference to the third aspect or any one of the foregoing possible implementations of the third aspect, in a fourteenth possible implementation of the third aspect, the Nd synchronization signals are sequentially transmitted by the high-frequency base station using Nd transmission beams;

the K synchronization signals are sequentially transmitted by the high frequency base station using the first K transmission beams among the Nd transmission beams.

With reference to the third aspect or any one of the foregoing possible implementation manners of the third aspect, in a fifteenth possible implementation manner of the third aspect, the receiving unit is specifically configured to:

determining a first initial position of a first synchronous detection window according to a low-frequency signal sent by a low-frequency base station in the system;

receiving Nu groups of synchronization signals, respectively, starting from the first start position using Nu different reception beams, wherein each group of synchronization signals comprises Nd synchronization signals;

determining a second initial position of a second synchronous detection window according to a low-frequency signal and additional receiving time delay sent by a low-frequency base station in the system;

nu groups of synchronization signals are respectively received from the second starting position by using Nu different receiving beams, wherein each group of synchronization signals comprises Nd synchronization signals.

With reference to the third aspect or any one of the foregoing possible implementation manners of the third aspect, in a sixteenth possible implementation manner of the third aspect, the second special subframe is a first special subframe located after the first special subframe.

With reference to the third aspect or any one of the foregoing possible implementations of the third aspect, in a seventeenth possible implementation of the third aspect, the additional reception delay is preset in the user equipment.

With reference to the third aspect or any one of the foregoing possible implementation manners of the third aspect, in an eighteenth possible implementation manner of the third aspect, the receiving unit is further configured to acquire the additional receiving delay from the low frequency base station.

With reference to the third aspect or any one of the foregoing possible implementation manners of the third aspect, in a nineteenth possible implementation manner of the third aspect, the receiving unit is specifically configured to acquire the additional receiving delay through a radio resource control RRC signaling sent by the low frequency base station.

With reference to the third aspect or any one of the foregoing possible implementation manners of the third aspect, in a twenty-fifth possible implementation manner of the third aspect, a length of the additional reception delay is greater than a high-low frequency delay of the system, and a length of a time slice occupied by the CP is greater than or equal to a sum of the high-low frequency delay and the additional reception delay.

With reference to the third aspect or any one of the possible implementation manners of the third aspect, in a twenty-first possible implementation manner of the third aspect, the receiving unit is further configured to:

receiving Radio Resource Control (RRC) signaling sent by a low-frequency base station, wherein the RRC signaling comprises:

and the frequency point adopted by the high-frequency base station and/or the value of Nd.

With reference to the third aspect or any one of the foregoing possible implementation manners of the third aspect, in a twenty-second possible implementation manner of the third aspect, the special subframe further includes a reserved data interval RDP and an uplink and downlink switching guard interval GP.

With reference to the third aspect or any one of the foregoing possible implementations of the third aspect, in a twenty-third possible implementation of the third aspect, the synchronous radio frame further includes a general subframe, where the general subframe includes 8 slots with a length of 0.125ms, and the slot includes Ns OFDM symbols, where Ns is a positive integer.

With reference to the third aspect or any one of the foregoing possible implementation manners of the third aspect, in a twenty-fourth possible implementation manner of the third aspect, a cycle of the synchronous radio frame used by the high-frequency base station is a length of M radio frames, where M is a positive integer.

In a fourth aspect, there is provided a high frequency base station comprising:

a generating unit, configured to generate synchronization information, where the synchronization information is carried by a synchronization radio frame, where the synchronization radio frame includes at least one special subframe, and the special subframe is used to transmit a synchronization signal, where the special subframe includes a DLBP, the DLBP includes Nu subintervals, and each subinterval transmits Nd synchronization signals, where Nu and Nd are positive integers greater than 1;

and the sending unit is used for sending the synchronization information to the user equipment.

With reference to the fourth aspect, in a first possible implementation manner of the fourth aspect, each sub-interval includes Nd time slices, and a length of each time slice includes at least two orthogonal frequency division multiplexing OFDM symbols.

With reference to the first possible implementation manner of the fourth aspect, in a second possible implementation manner of the fourth aspect, a first OFDM symbol of the at least two OFDM symbols is used for transmitting a primary synchronization signal, and a second OFDM symbol of the at least two OFDM symbols is used for transmitting a secondary synchronization signal.

With reference to the second possible implementation manner of the fourth aspect, in a third possible implementation manner of the fourth aspect, the second OFDM symbol is used to transmit a specific sequence of the secondary synchronization signal, where the specific sequence includes an ID of a time slice in which the specific sequence is located and an ID of a subinterval in which the specific sequence is located.

With reference to the fourth aspect or any one of the foregoing possible implementation manners of the fourth aspect, in a fourth possible implementation manner of the fourth aspect, each sub-interval further includes Nd switching guard intervals SGP respectively located after the Nd time slices.

With reference to the fourth aspect or any one of the foregoing possible implementation manners of the fourth aspect, in a fifth possible implementation manner of the fourth aspect, the sending unit is specifically configured to: the Nd synchronization signals are transmitted using Nd different transmit beams.

With reference to the fourth aspect or any one of the foregoing possible implementation manners of the fourth aspect, in a sixth possible implementation manner of the fourth aspect, the sending unit is specifically configured to:

transmitting the synchronization signal using a first order of transmit beams on a first special subframe in the synchronization information;

transmitting the synchronization signal using a second order of transmit beams on a second special subframe in the synchronization information.

With reference to the fourth aspect or any one of the foregoing possible implementations of the fourth aspect, in a seventh possible implementation of the fourth aspect, each synchronization radio frame includes one special subframe;

With reference to the fourth aspect or any one of the foregoing possible implementations of the fourth aspect, in an eighth possible implementation of the fourth aspect, each synchronization radio frame includes 2N special subframes;

With reference to the fourth aspect or any one of the possible implementations of the fourth aspect, in a ninth possible implementation of the fourth aspect, the second order is generated by cyclic shifting the first order.

With reference to the fourth aspect or any one of the foregoing possible implementations of the fourth aspect, in a tenth possible implementation of the fourth aspect, a length of the time slice of the cyclic shift is greater than a high-low frequency delay of the system.

With reference to the fourth aspect or any one of the foregoing possible implementations of the fourth aspect, in an eleventh possible implementation of the fourth aspect, the special subframe further includes a cyclic suffix CS located after the DLBP, and the CS transmits K synchronization signals, where K is a positive integer smaller than Nd.

With reference to the fourth aspect or any one of the foregoing possible implementation manners of the fourth aspect, in a twelfth possible implementation manner of the fourth aspect, the sending unit is specifically configured to: sequentially transmitting the Nd synchronization signals by using Nd transmission beams; sequentially transmitting the K synchronization signals using first K of the Nd transmit beams.

With reference to the fourth aspect or any one of the foregoing possible implementation manners of the fourth aspect, in a thirteenth possible implementation manner of the fourth aspect, the special subframe further includes a reserved data interval RDP and an uplink and downlink switching guard interval GP.

With reference to the fourth aspect or any one of the foregoing possible implementation manners of the fourth aspect, in a fourteenth possible implementation manner of the fourth aspect, a cycle of the synchronous radio frame used by the high-frequency base station is a length of M radio frames, where M is a positive integer.

In a fifth aspect, a user equipment is provided that includes a processor, a transceiver, and a memory. The transceiver is configured to receive synchronization information sent by the high-frequency base station, where a synchronization radio frame carrying the synchronization information includes at least one special subframe, and the special subframe is used to transmit a synchronization signal, where the special subframe includes a DLBP, the DLBP includes Nu subintervals, and each subinterval transmits Nd synchronization signals, where Nu and Nd are positive integers greater than 1. The processor is used for carrying out synchronization according to the synchronization information.

Alternatively, the transceiver in the fifth aspect may be implemented by a receiver.

In a sixth aspect, a high frequency base station is provided that includes a processor, a transceiver, and a memory. The processor is configured to generate synchronization information, where a synchronization radio frame carrying the synchronization information includes at least one special subframe, where the special subframe includes a DLBP, the DLBP includes Nu subintervals, and each subinterval transmits Nd synchronization signals, where Nu and Nd are positive integers greater than 1. The transceiver is used for sending the synchronization information to the user equipment.

Alternatively, the transceiver in the sixth aspect may be implemented by a transmitter.

In a seventh aspect, a computer program product is provided, the computer program product comprising: computer program code for causing a user equipment to perform the above first aspect and any of its various implementations as a method of downlink synchronization when said computer program code is run by a receiving unit, a processing unit or a transceiver, a processor of said user equipment.

In an eighth aspect, there is provided a computer program product comprising: computer program code which, when run by a generating unit, a transmitting unit or a transceiver, a processor of a high frequency base station, causes the high frequency base station to perform the above-mentioned second aspect, and any of its various implementations, a method of downlink synchronization.

In a ninth aspect, a computer-readable storage medium is provided, where the computer-readable storage medium stores a program, and the program enables a user equipment to execute the method for downlink synchronization in the first aspect and any one of its various implementations.

In a tenth aspect, there is provided a computer-readable storage medium storing a program for causing a high frequency base station to execute the method for downlink synchronization of the second aspect described above and any of its various implementations.

In the invention, the high-frequency base station sends the synchronous information in the special subframe, and the UE completes the synchronization with the high-frequency base station by receiving the synchronous signal in the special subframe, thereby being beneficial to the UE to quickly access a high-frequency system and saving the power consumption during the access.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive labor.

Fig. 1 is a schematic scene diagram of a high-low frequency hybrid networking system according to an embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a synchronous radio frame according to an embodiment of the present invention.

Fig. 3 is a diagram illustrating a frame structure used by the high frequency base station according to an embodiment of the present invention.

Fig. 4 is a schematic structural diagram of a special subframe according to an embodiment of the present invention.

Fig. 5 is another structural diagram of a special subframe according to an embodiment of the present invention.

Fig. 6 is another structural diagram of a special subframe according to an embodiment of the present invention.

Fig. 7 is another structural diagram of a special subframe according to an embodiment of the present invention.

Fig. 8 is a schematic structural diagram of DLBP according to an embodiment of the present invention.

Fig. 9 is a schematic structural diagram of a subinterval of DLBP according to an embodiment of the present invention.

Fig. 10 is another structural diagram of a special subframe according to an embodiment of the present invention.

Fig. 11 is a diagram illustrating a receiving beam used by a UE according to an embodiment of the present invention.

Fig. 12 is a diagram of a sync detection window according to an embodiment of the present invention.

Fig. 13 is another schematic diagram of a sync detection window according to an embodiment of the present invention.

Fig. 14 is another diagram of a receiving beam used by the UE according to an embodiment of the present invention.

Fig. 15 is a schematic diagram of a transmission beam used by the high frequency base station of the embodiment of the present invention.

Fig. 16 is another schematic diagram of a transmission beam used by the high frequency base station of the embodiment of the present invention.

Fig. 17 is another schematic diagram of a transmission beam used by the high frequency base station of the embodiment of the present invention.

Fig. 18 is a diagram illustrating a UE receiving a synchronization signal in a special subframe according to an embodiment of the present invention.

Fig. 19 is another diagram illustrating a UE receiving a synchronization signal in another special subframe according to an embodiment of the present invention.

Fig. 20 is another schematic diagram of a transmission beam used by the high frequency base station of the embodiment of the present invention.

Fig. 21 is another schematic diagram of a transmission beam used by the high frequency base station of the embodiment of the present invention.

FIG. 22 is another illustration of a sync detection window according to an embodiment of the invention.

Fig. 23 is a diagram illustrating a UE receiving a synchronization signal in a special subframe according to an embodiment of the present invention.

Fig. 24 is another diagram illustrating a UE receiving a synchronization signal in another special subframe according to an embodiment of the present invention.

Fig. 25 is a flowchart of a method of downlink synchronization according to an embodiment of the present invention.

Fig. 26 is a flowchart of a method of downlink synchronization according to another embodiment of the present invention.

Fig. 27 is a block diagram of a user equipment according to an embodiment of the present invention.

Fig. 28 is a block diagram of a user equipment according to another embodiment of the present invention.

Fig. 29 is a block diagram of a high frequency base station according to an embodiment of the present invention.

Fig. 30 is a block diagram of a high frequency base station according to another embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In this embodiment of the present invention, the Base Station may be a Base Transceiver Station (BTS) in a Global System for Mobile communications (GSM) System or a Code Division Multiple Access (CDMA) System, may also be a Base Station (NodeB) in a Wideband Code Division Multiple Access (WCDMA) System, may also be an evolved Node B (eNB) or eNodeB in an LTE System, or may also be a Base Station device or a small Base Station device in a future 5G network, and the present invention is not limited to this.

In the embodiment of the present invention, a User Equipment (UE) may communicate with one or more Core networks (Core networks) through a Radio Access Network (RAN), and the UE may be referred to as an Access terminal, a terminal device, a subscriber unit, a subscriber station, a mobile station, a remote terminal, a mobile device, a User terminal, a wireless communication device, a User agent, or a User Equipment. The UE may be a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device with Wireless communication capability, a computing device or other processing device connected to a Wireless modem, a vehicle mounted device, a wearable device, a terminal device in a future 5G network, and so on.

FIG. 1 is a schematic diagram of an application scenario of one embodiment of the present invention. In fig. 1, a high-low frequency hybrid networking system is shown, which includes a low frequency base station 11, a high frequency base station 12 and a UE 13.

In the embodiment of the present invention, the frequency band of the low frequency base station 11 is lower than the frequency band of the high frequency base station 12. The frequency band used by the low frequency base station 11 may be a low frequency band below 6GHz, such as 2GHz and 5 GHz. The frequency band used by the high frequency base station 12 may be a high frequency band represented by a millimeter wave frequency band (i.e. above 6 GHz), for example, the frequency point used by the high frequency base station 12 may be 72GHz, 28GHz, or 14 GHz.

The low frequency base station 11 covers an area with a large range, and the high frequency base station 12 performs hot spot coverage in the coverage area of the low frequency base station to improve the capacity of a hot spot area. The UE13 is typically equipped with both a low frequency transceiver for data communication with the low frequency base station 11 and a high frequency transceiver for data communication with the high frequency base station 12.

To establish a normal communication link with the high frequency base station 12, the UE13 first needs to acquire downlink synchronization of the high frequency system through a downlink synchronization channel, and then accesses the high frequency system through a random access process.

Fig. 2 shows a synchronous radio frame in a frame structure used by a high frequency base station to transmit a synchronization signal in an embodiment of the present invention. It is understood that the frame structure shown in fig. 2 is a general frame structure of a high frequency communication system.

The frame length of the synchronous radio frame shown in fig. 2 is 10 milliseconds (ms), which is compatible with the frame structure of the existing LTE system. One radio frame is composed of 10 radio subframes with a frame length of 1 ms. In the embodiment of the present invention, two types of radio subframes are defined: general subframes and special subframes. The general sub-frame is mainly used for normal data transmission, and the special sub-frame is used for transmitting high-frequency synchronization signals.

In the embodiment of the present invention, the frame structure used by the high frequency base station 12 may include two types: the radio frame and the general radio frame are synchronized. The synchronous radio frame comprises at least one special subframe and a plurality of general subframes, and the general radio frame comprises 10 general subframes. Moreover, the frame length of a synchronous radio frame is 10ms, and the frame length of a general radio frame is also 10 ms.

In the embodiment of the present invention, the period of the synchronous radio frame used by the high frequency base station 12 may be the length of M radio frames, where M is a positive integer. That is, the high frequency base station 12 uses a frame structure that is spaced by M-1 normal radio frames after one synchronous radio frame, and then uses the next synchronous radio frame, as shown in FIG. 3. In the frame structure used by the high frequency base station 12, each M consecutive radio frames include a synchronous radio frame and M-1 general radio frames.

It is understood that if M is 1, it indicates that each radio frame in the frame structure used by the high frequency base station 12 is a synchronous radio frame.

It is understood that the frame length of one general subframe is 1ms, and the frame length of one special subframe is also 1 ms. One synchronization radio frame includes at least one special subframe, and as shown in fig. 2, one synchronization radio frame includes two

special subframes

201 and 202.

Wherein, a general subframe is divided into 8 slots with a length of 0.125ms, and each slot is composed of Ns Orthogonal Frequency Division Multiplexing (OFDM) symbols. The size of Ns depends on the frequency point adopted by the high-frequency communication system, and specifically, when the frequency point is 72GHz, Ns is 80; when the frequency point is 28GHz, Ns is 40; when the frequency point is 14GHz, Ns is 20.

Alternatively, one general subframe may be divided into a plurality of slots of equal length, wherein each slot may have a length of 0.1ms to 0.2 ms. For example, one general subframe may include 10 slots having a length of 0.1 ms.

The special subframe may include a Downlink synchronization and Beam-training Period (DLBP). In addition, the special subframe may further include a Reserved Data Period (RDP) and a Guard Period (Guard Period, GP) for uplink and downlink switching. It can be understood that the special subframe in the embodiment of the present invention is used for downlink synchronization and beam training.

It should be noted that, in the embodiment of the present invention, DLBP may also be referred to as a downlink synchronization interval or a beam training interval, and a name of the interval is not limited herein.

The embodiments of the present invention do not limit the sequence or the position of the DLBP and the RDP included in the special subframe, as shown in fig. 4 to 7. Fig. 4 shows the case where DLBP starts at the first OFDM symbol and uplink RDP ends at the last (assumed to be Nm-th) OFDM symbol. Fig. 5 shows the case where the uplink RDP starts at the first OFDM symbol and the DLBP ends at the last (assumed to be Nm-th) OFDM symbol. Fig. 6 shows the case where the downlink RDP starts from the first OFDM symbol, ends at the k1-1(k1>1) th OFDM symbol, the DLBP starts at the k1 th OFDM symbol, and the uplink RDP ends at the last (assumed to be the Nm) OFDM symbol. Fig. 7 shows the case where the uplink RDP starts from the first OFDM symbol and the DLBP ends at the k2 th (k2< Nm) OFDM symbol, and the downlink RDP starts from k2+1 OFDM symbols and ends at the last (assumed to be Nm) OFDM symbol.

In the embodiment of the present invention, the DLBP may include Nu subintervals, as shown in fig. 8, where Nu subintervals are: DLBP₀，DLBP₁，…，DLBP_Nu-2，DLBP_Nu-1. Each subinterval may consist of Nd time slices (Slice). FIG. 8 shows the first subinterval DLBP₀The device comprises Nd time slices which are respectively as follows: s₀，S₁，…，S_Nd-1. The values of Nu and Nd correspond to the number of wide beams transmitted by the high-frequency base station 12 and the number of wide beams received by the user equipment 13, respectively, and the values thereof depend on the frequency points adopted by the high-frequency communication system.For example, when the frequency bin is 72GHz, Nd is 16 or 12, and Nu is 12. When the frequency point is 28GHz, Nd is 12 and Nu is 8. When the frequency point is 14GHz, Nd is 8 and Nu is 6.

It can be understood that in the embodiment of the present invention, Ns, Nd, and Nu are all positive integers greater than 1, and the values of Ns, Nd, and Nu are all related to frequency points used by high frequency base stations in the system.

Wherein, the value of Nu is not only related to the frequency point, but also related to the performance of the UE itself. For example, when the frequency point is 28GHz, Nu of one UE is 8, and Nu of another UE is 12.

In addition, each sub-interval may further include Nd Switching Guard intervals (SGPs) respectively located after Nd time slices.

In the embodiment of the present invention, the length of one time slice may be Nr OFDM symbols, where Nr is a positive integer.

For example, Nr may be 1.

For example, Nr may be 2. That is, each time slice includes two OFDM symbols in length. A first OFDM symbol of the two OFDM symbols is used to transmit a Primary Synchronization Signal (PSS), and a second OFDM symbol of the two OFDM symbols is used to transmit a Secondary Synchronization Signal (SSS). As shown in fig. 9, time slice S₀Two OFDM symbols are included for transmitting SSS and PSS, respectively.

For example, Nr may be greater than 2. That is, each time slice includes at least two OFDM symbols in length. Wherein a first OFDM symbol of the at least two OFDM symbols is used for transmitting PSS and a second OFDM symbol of the at least two OFDM symbols is used for transmitting SSS. That is, at least one OFDM symbol among Nr OFDM symbols is used for transmitting the PSS; at least one OFDM symbol of the Nr OFDM symbols is used for transmitting the SSS.

In the frequency domain, the PSS and SSS are transmitted over the middle W mhz of the system bandwidth, typically W500. Similar to the LTE system, a specific sequence of the PSS is transmitted in a specific cell of a given high frequency base station to indicate a cell ID of the UE13 in one high frequency base station, and assuming that one high frequency base station controls 6 high frequency cells at most, the value of the high frequency cell ID is 0 to 5.

In particular, the second OFDM symbol may transmit a specific sequence of SSS. Wherein the specific sequence includes an Identity (ID) of a time slice in which the specific sequence is located and an ID of a subinterval in which the specific sequence is located.

Alternatively, the specific sequence may include at least one of: the ID of the high-frequency base station, the ID of the time slice where the specific sequence is located and the ID of the subinterval where the specific sequence is located. Alternatively, the specific sequence may include at least one of: an ID of the high-frequency base station, an ID of a transmission beam used for a time slice in which the specific sequence is present, and an ID of a subinterval in which the specific sequence is present. The invention is not limited in this regard.

For example, a specific sequence of the SSS may be transmitted on a specific time slice in a specific DLBP subinterval of the high frequency base station, so as to indicate to the UE13 the ID of the high frequency base station where the SSS is located, the subinterval ID (taking a value of 0 to Nu-1) of the specific DLBP, and the transmission beam ID or time slice ID (taking a value of 0 to Nd-1) of the high frequency base station used on the specific time slice.

Specifically, the UE13 first performs incoherent detection on the PSS, obtains symbol synchronization, and obtains a high-frequency cell ID. Assuming that the channel coherence duration is much longer than one OFDM symbol period, coherent detection is performed on the SSS by using the correlation between the PSS and the SSS, and a subinterval ID of the high-frequency base station ID and the DLBP and a base station transmission beam ID (time slice ID) are obtained. In a special subframe, the subinterval ID of the DLBP and the base station sending beam ID (time slice ID) are in one-to-one correspondence with the OFDM symbol position in the special subframe where the SSS is located, so that the OFDM symbol position in the special subframe where the SSS is located can be obtained by obtaining the information, and radio frame synchronization can be obtained. As shown in FIG. 10, suppose UE13 successfully detects DLBP₁PSS signal transmitted between subintervals, DLBP by PSS signal pair₁And carrying out coherent detection on the SSS signals transmitted by the subintervals. If the ID number of the DLBP subinterval is 1 and the ID (time slice ID) of the beam sent by the base station is 1, the starting position and the root of the special subframe can be obtained by pushing a DLBP period plus a time slice period from the position of the SSS symbolAccording to the position of the special subframe in the wireless frame, the position of the starting point of the wireless frame can be directly deduced, and the synchronization of the wireless frame is successfully acquired. For the case of two or more special subframes in one radio frame, it is necessary to distinguish the special subframes by indicating the sequence of high frequency base station IDs.

For a description of the transmission beam, reference may be made to the following specific embodiments.

In the embodiment of the present invention, the high frequency base station 12 may transmit the synchronization signal by using the synchronization radio frame as described above. Specifically, on one special subframe (e.g., subframe #1 in fig. 2), the high frequency base station 12 may transmit the synchronization signal using different transmission beams over Nd time slices in each subinterval of the DLBP. In other words, the high frequency base station 12 can transmit Nd synchronization signals through Nd first-order transmission beams at each subinterval. It can also be understood that, on DLBP of one special subframe, the high-frequency base station 12 transmits Nd synchronization signals through Nd first-order transmission beams with a transmission period Nu.

For example, the first order may be #0 to # Nd-1. For example, in time slice S₀Transmitting a synchronization signal via a transmission beam #0 in a time slice S₁The synchronization signal is transmitted via the transmission beam #1, …, in time slice S_Nd-1The synchronization signal is transmitted through the transmission beam # Nd-1. Wherein the SGP is used for switching between different transmission beams. Referring to fig. 8, it can be understood that the ID of the slot may also be the ID of the transmission beam.

With reference to fig. 8, it can be understood that, on DLBP, transmission beams are determined with Nu as a period, where the transmission beams used periodically are Nd transmission beams in the first order.

In the embodiment of the present invention, one special subframe may be regarded as several reserved OFDM symbols. Then, the process of the high frequency base station 12 transmitting the synchronization signal can be understood as follows: the high frequency base station 12 sequentially switches the transmission beam transmission synchronization signal in a fixed transmission beam switching period (Nu periods) and a fixed transmission beam logical order (#0, #1, # …, # Nd-1) over a plurality of reserved consecutive transmission symbols (special subframes).

Note that the logical order (i.e., the first order) of the transmission beams herein is not limited to #0 to # Nd-1. For example, #1, #2, # …, # Nd-1, # 0; or # Nd-1, # Nd-2, …, #1, #0, etc.

In this way, the UE13 can complete synchronization with the high frequency base station 12 and establish a normal communication link after receiving the synchronization signal transmitted by the high frequency base station 12.

Specifically, the UE may receive the synchronization signal through one fixed reception beam within one sub-interval. In different subintervals, the UE13 switches different receive beams to receive the synchronization signals. That is, the UE correspondingly receives beams on Nu subintervals through Nu reception beams, respectively. As shown in fig. 11. UE receives subinterval DLBP through receiving beam #0₀The synchronization signal on, receiving the subinterval DLBP through the receiving beam #1₁The synchronization signal on, …, receives the subinterval DLBP via the receive beam # Nu-1_Nu-1A synchronization signal.

For the high-low frequency hybrid networking system as shown in fig. 1, the UE13 may quickly obtain downlink synchronization of the high-frequency system through low frequency assistance. Fig. 12 shows a radio frame with sequence # k of low frequency base station 11 and a synchronous radio frame with sequence # k of high frequency base station 12. Where 0 to 9 represent the sequence numbers of the subframes.

It should be noted that although one synchronous radio frame with sequence number # k of the high frequency base station 12 shown in fig. 12 includes two special subframes, respectively subframe with

sequence number

1 and 6. However, the number of the special subframes included in one synchronization radio frame is not limited in the present invention, for example, one synchronization radio frame may include only one special subframe, or one synchronization radio frame may include more special subframes (3, 4, etc.).

It should be noted that although the special subframe shown in fig. 12 includes DLBP, GP and RDP, the structure of the special subframe in the present invention is not limited thereto, and reference may be made to the foregoing description related to fig. 2 to 7.

Assuming that the high frequency and the low frequency can be strictly synchronized, the UE13 can obtain the frame synchronization of the high frequency base station 12 through the low frequency base station 11, that is, the UE13 can determine the starting time of the subframe 0 of the high frequency base station 12, and then the UE13 can perform the high frequency downlink synchronization signal detection by starting with the starting time of the special subframe (e.g., the subframe with the sequence number of 1) in the high frequency base station 12.

Specifically, the length of the synchronization detection window is the length of the DLBP defined in the special subframe, and in one synchronization detection window, UE13 can traverse all combinations of the transmission beams of high frequency base station 12 and the reception beams of UE 13. Thus, the UE13 can obtain downlink synchronization of the high frequency system through one synchronization detection window, and obtain the ID numbers of the transmission beam of the corresponding high frequency base station 12 and the reception beam of the UE13, the cell ID number, the subinterval ID number included in the DLBP, and the like.

However, for the system of the high and low frequency hybrid networking shown in fig. 1, it is difficult to achieve strict synchronization of the high and low frequency signals received by the UE 13. For example, if the low frequency base station 11 is not co-located with the high frequency base station 12, the low frequency base station 11 and the high frequency base station 12 cannot guarantee that a strict time synchronization can be obtained. For another example, the distance from the UE13 to the low frequency base station 11 is different from the distance from the high frequency base station 12, and signals respectively transmitted from the low frequency base station 11 and the high frequency base station 12 experience different propagation paths, which causes a difference in signal transmission delay. It can be seen that the low frequency signal of the low frequency base station 11 and the high frequency signal of the high frequency base station 12 received by the UE13 are difficult to be strictly synchronized, and there is generally a high and low frequency delay between the two, and the high and low frequency delay varies with the position of the UE 13.

As shown in fig. 1, the UE13 is closer to the high frequency base station 12 and farther from the low frequency base station 11. Then, the high frequency signal received by the UE13 arrives first and the low frequency signal arrives later in the signal sent by the low frequency base station 11 and the high frequency base station 12 at the same time, and as shown in fig. 13, there is a high and low frequency delay between the low frequency signal and the high frequency signal. The description of the low frequency radio frame and the high frequency synchronization radio frame is the same as the corresponding content in fig. 12, and is not repeated here.

At this time, the UE13 may determine the start position of the high frequency base station synchronization detection window according to the low frequency signal transmitted by the low frequency base station. Wherein the time length of the synchronization detection window is equal to the time length of the DLBP. Further, the UE13 receives the synchronization signal using Nu different reception beams from the start position of the synchronization detection window. Where each receive beam receives Nd synchronization signals. That is, the Nu different reception beams respectively receive Nu sets of synchronization signals, where each set of synchronization signals includes Nd synchronization signals.

It is understood that the UE13 also receives the low frequency signal transmitted by the low frequency base station before high frequency synchronization is performed.

It should be noted that in fig. 13 and subsequent embodiments of the present invention, the start position of the synchronization detection window is located in the special subframe. The invention is not limited in this regard. For example, in other cases, the start position of the synchronization detection window may be located in the general subframe.

The UE13 can detect a high frequency synchronization signal on the synchronization detection window of the special sub-frames (sub-frames with sequence numbers 1 and 6) if it uses a low frequency signal as a synchronization reference point. Due to the existence of the high and low frequency delays, the synchronization detection window (the synchronization detection window in fig. 13) where the UE13 actually performs the synchronization detection is offset from the synchronization detection window (the synchronization detection window in fig. 12, corresponding to DLBP) where the synchronization detection should be performed, which will make the UE13 unable to traverse all combinations of the transmission beams of the high frequency base station 12 and the reception beams of the UE13 in the synchronization detection window. Thereby, a problem of missing detection of the combination of the transmission beam of the high frequency base station 12 and the reception beam of the UE13 occurs. Since the synchronization signals transmitted by the special subframes are periodic, the combination of the transmission beam of the high-frequency base station 12 and the reception beam of the UE13 can never be detected (i.e. the lack of detection problem exists in any special subframe), which may result in the synchronization failure of some users.

Due to the randomness of the high and low frequency delays, the synchronization start time point of the UE13 cannot be guaranteed to be aligned with the start time point of the synchronization symbol (DLBP), which will result in that the sampling point of a certain synchronization symbol cannot be completely received, and the synchronization signal on the symbol cannot be correctly detected. As shown in fig. 14, the synchronization start time point of the UE13 if it falls on S₀In the detection dead zone, the time isSheet S₀None of the synchronization signals transmitted through the transmission beam #0 of the high-frequency base station 12 can be correctly detected.

In contrast, in the embodiment of the present invention, the transmission beam used by the synchronization signal transmitted by the high-frequency base station 12 may be in the form of: on the first special subframe, the high frequency base station 12 transmits the synchronization signal using the first order of the transmission beams; on the second special subframe, the high frequency base station 12 transmits the synchronization signal using the second order of the transmission beams. Wherein the second order may be generated by cyclic shifting the first order. And the length of the time slice of the cyclic shift is larger than the high-low frequency time delay of the system.

In the embodiment of the present invention, the frame structure used by the high frequency base station 12 to transmit the synchronization signal includes a plurality of synchronization radio frames.

If the number of the special subframes in each synchronous radio frame is 1, one synchronous radio frame comprises one special subframe. Then, the first special subframe may be a special subframe in a first synchronous radio frame, and the second special subframe may be a special subframe in a second synchronous radio frame. And the second synchronous wireless frame is the next synchronous wireless frame adjacent to the first synchronous wireless frame. That is, for two consecutive synchronous radio frames, the transmission beam sequence used by the special subframes is different, specifically, the special subframe in the first synchronous radio frame uses the first sequence transmission beam, and the special subframe in the second synchronous radio frame uses the second sequence transmission beam.

It should be noted that the second synchronous radio frame referred to herein refers to the first synchronous radio frame located after the first synchronous radio frame. For example, the first synchronous radio frame may be the synchronous radio frame 301 in fig. 3, and the second synchronous radio frame may be the synchronous radio frame 302 in fig. 3.

If the number of the special subframes in each synchronous radio frame is even, one synchronous radio frame comprises 2N special subframes. Then, the first special subframe may be the 2 i-th special subframe in a synchronous radio frame, and the second special subframe may be the 2i + 1-th special subframe in a synchronous radio frame.

If the number of the special subframes in each synchronous radio frame is odd, one synchronous radio frame comprises 2N +1 special subframes. Then, the first special subframe may be the 2 i-th special subframe in the first synchronous radio frame or the 2i + 1-th special subframe in the second synchronous radio frame, and the second special subframe may be the 2i + 1-th special subframe in the first synchronous radio frame or the 2 i-th special subframe in the second synchronous radio frame.

Alternatively, all radio frames used by the high frequency base station 12 may be considered as a whole. The special subframes in all radio frames are numbered sequentially and continuously, wherein the sequential numbering may be from 0, or from 1, or from any value, and is not limited herein. Further, odd-numbered special subframes may be defined as the first special subframe, and even-numbered special subframes may be defined as the second special subframe. Alternatively, the even-numbered special subframe may be defined as the first special subframe, and the odd-numbered special subframe may be defined as the second special subframe.

Since one synchronous radio frame includes at least 1 number of special subframes, the number of special subframes for all radio frames (at least two synchronous radio frames) is at least two. And, the number may be sequentially numbered for at least two special subframes. For example, the number of the at least two special subframes may be special subframe #0, special subframe #1, special subframe #2 …, etc. As another example, the number of the at least two special subframes may be special subframe #1, special subframe #2, special subframe #3 …, etc.

The following embodiments of the present invention are described by taking an example in which one synchronous radio frame includes two special subframes. It is assumed that one synchronization radio frame includes two special subframes. For example, assume that 10 subframes of the synchronization radio frame are subframe #0, subframe #1, …, subframe #8, and subframe # 9. Here, subframe #1 and subframe #6 are special subframes. Then the two special subframes may be numbered as special subframe #0 and special subframe #1, or as special subframe #1 and special subframe # 2.

Alternatively, as an embodiment, subframe #1 may be defined as a first special subframe, and subframe #6 may be defined as a second special subframe. Thus, beams may be transmitted using a first order on a first special subframe; on a second special subframe, beams are transmitted using a second order.

Alternatively, in odd-numbered special subframes of the two special subframes, the Nd synchronization signals are transmitted by the high frequency base station 12 using Nd first-order transmission beams. In the even-numbered special sub-frame of the two special sub-frames, the Nd synchronization signals are transmitted by the high frequency base station 12 using Nd second-order transmission beams. Here, the second order may be generated by the first order being cyclically shifted. In other words, the high frequency base station 12 sequentially switches the transmission beam transmission synchronization signals in a first specific order in the subinterval of the DLBP of the first special subframe, and the high frequency base station 12 sequentially switches the transmission beam transmission synchronization signals in a second specific order in the subinterval of the DLBP of the second special subframe. The second particular order is a cyclic shift of the first particular order.

For example, subframe #1 is special subframe #0, and subframe #6 is special subframe # 1. That is, subframe #1 is a special subframe with an even number, and subframe #6 is a special subframe with an odd number. Subframe #6 may then use a first order of transmit beams and subframe #1 may use a second order of transmit beams, as shown in fig. 15, for time slice S_iIndicating that the used transmit beam # i transmits a synchronization signal. Wherein the first order is #0 to # Nd-1, and the second order is # K to # Nd-1, #0 to # K-1. That is, the second order is generated after the first order is subjected to the K-bit cyclic shift.

For example, subframe #1 is special subframe #1, and subframe #6 is special subframe # 2. That is, subframe #1 is a special subframe with odd number, and subframe #6 is a special subframe with even number. Subframe #1 may then use a first order of transmit beams and subframe #6 may use a second order of transmit beams, as shown in fig. 16, for time slice S_iTo representThe used transmission beam # i transmits a synchronization signal. Wherein the first order is #0 to # Nd-1, and the second order is # K to # Nd-1, #0 to # K-1. That is, the second order is generated after the first order is subjected to the K-bit cyclic shift.

Specifically, in this embodiment, the high frequency base station 12 switches the transmission beams in the first special subframe (subframe #6 in fig. 15 or subframe #1 in fig. 16) in the normal transmission beam logical order, that is, switches the transmission beam transmission synchronization signals in the logical sequence numbers #0 to # Nd-1 of the transmission beams in the subintervals #0 to # Nu-1 of the DLBPs in order. In the second special subframe (subframe #1 in fig. 15 or subframe #6 in fig. 16), the high frequency base station 12 switches the transmission beam in the cyclic shifted transmission beam logical order in each of the DLBP subintervals, that is, switches the transmission beam transmission synchronization signal in the logical sequence numbers # K to # Nd-1 to #0 to # K-1 of the transmission beams in each of the DLBP subintervals #0 to # Nu-1 in order.

As another understanding, in the DLBP of the odd-numbered special subframe of the two special subframes, the Nd synchronization signals are transmitted by the high frequency base station 12 using Nd first-order transmission beams. In the DLBP of the special subframe with the even number of the two special subframes, the Nd synchronization signals are transmitted by the high frequency base station 12 using Nd second-order transmission beams. In other words, in the DLBP of the first special subframe, the high frequency base station 12 sequentially switches the transmission beam transmission synchronization signals in a first specific order, and in the DLBP of the second special subframe, the high frequency base station 12 sequentially switches the transmission beam transmission synchronization signals in a second specific order. The second particular order is a cyclic shift of the first particular order.

In this interpretation, the DLBP as a whole is cyclically shifted. Another explanation for the case shown in fig. 16 is that subframe #1 may use a first order of transmission beams and subframe #6 may use a second order of transmission beams as shown in fig. 17. Wherein the first order is #0 to # Nd-1, …, #0 to # Nd-1, and the second order is # K to # Nd-1, #0 to # Nd-1, …, #0 to # Nd-1, #0 to # K-1. That is, the second order is generated after the first order is subjected to the K-bit cyclic shift. Here, the first order is Nu #0 to # Nd-1, i.e., the first order includes Nu × Nd transmission beams.

That is, in the first special subframe (subframe #1 shown in fig. 17), the high frequency base station 12 switches the transmission beams of the base stations in the logical order of the normal transmission beams, that is, switches the transmission beam transmission synchronization signals in the logical sequence numbers #0 to # Nd-1 of the transmission beams in the subintervals #0 to # Nu-1 of the DLBP. In the second special subframe (subframe #6 shown in fig. 17), the high frequency base station 12 switches the transmission beam of the base station, that is, DLBP, in the logical order of the transmission beams after cyclic shift within DLBP₀First K transmission beams (#0 to # K-1), shift to DLBP_Nu-1And then sending. The high frequency base station 12 switches DLBP in turn firstly in the second special subframe₀The transmission beams with logical sequence numbers # K to # Nd-1 in the subintervals transmit synchronization signals, and then the synchronization signals are transmitted in DLBP₁～DLBP_Nu-1Sequentially switching the transmission beams to transmit synchronous signals according to the logic sequence numbers #0 to # Nd-1 of the transmission beams in the subintervals, and finally sequentially switching DLBP₀The transmission beams having logical numbers #0 to # K-1 in the subintervals transmit synchronization signals.

It should be understood that, in the embodiment of the present invention, although the transmission beam used by the high frequency base station 12 to transmit the synchronization signal is explained in the above two different explanations, the actual transmission beam in fig. 16 and fig. 17 is the same.

Note that the length (S) of the time slice of the cyclic shift in fig. 15 to 17₀To S_KThe length of the corresponding time slice) should be greater than the high and low frequency delays of the system (i.e., the length of the high and low frequency delays shown in fig. 13).

Specifically, the high frequency base station 12 may determine the K value before transmitting the synchronization signal. For example, one or more values of K may be preset in the high frequency base station 12, and before the high frequency base station 12 transmits the synchronization signal, the high frequency base station may determine the value of K according to an index such as a coverage area, and then determine the first order and the second order using the determined value of K, and transmit the synchronization signal.

It should be noted that in the embodiment shown in fig. 15 to 17, S_iIndicating that the synchronization signal is transmitted using the transmission beam # i.

As another understanding, if it is assumed that the transmission beams #0, #1, …, # Nd used by the high frequency base station 12 have IDs of 0,1, …, Nd, respectively. Then, the above manner of transmitting the transmission beam used for transmitting the synchronization signal can be understood as:

on the time slice Si of the DLBP of the first special subframe, the ID of the used transmission beam is: b_i＝imodN_d i＝0,1,2...,N_d×N_u-1。

On the time slice Si of the DLBP of the second special subframe, the ID of the used transmission beam is: b_i＝(i+K)modN_di＝0,1,2...,N_d×N_u-1。

Wherein the number of time slices included in a special subframe is N_d×N_u。

Assuming that the low-frequency synchronization signal received by UE13 lags behind the high-frequency synchronization signal, taking Nd as 12 and Nu as 12 as examples, fig. 18 and 19 show the reception of the synchronization signal by UE13 in the first and second special subframes, respectively.

In the first special subframe, as shown in fig. 18, the UE13 starts the detection of the synchronization signal with the receive beam #0 from the second time slice (the first S1 in fig. 18) due to the introduction of the high and low frequency delay Δ t. Since the starting time at which the UE13 starts the synchronization signal detection is located in the middle of the time slice S1, the synchronization signal transmitted through the high frequency base station 12 transmission beam #1 on the time slice S1 cannot be completely received by the UE 13. Since the switching period of the reception beam of the UE13 is equal to the period in which the high frequency base station 12 completes the transmission of the synchronization signal on 12 time slices, the UE13 cannot correctly receive the synchronization signal transmitted by the high frequency base station 12 through the transmission beam #1 on all the reception beams. In addition, since the high and low frequency delays Δ t are greater than the length of one time slice, the UE13 may miss receiving the synchronization signal transmitted in one time slice by the last receiving beam. As shown in fig. 18, UE13 cannot receive the synchronization signal transmitted by high-frequency base station 12 through transmission beam #0 in the reception cycle of reception beam # 11.

In the second special subframe, as shown in fig. 19, the transmission beams in the first special subframe are sequentially cyclically shifted, and the total length of the time slice occupied by the K beams to be cyclically shifted is greater than the high-low frequency delay Δ t, as shown in fig. 19, where K is 2, and the synchronization signal is transmitted from the transmission beam # 2. Similar to the first special subframe, the UE13 starts the detection of the synchronization signal with the reception beam #0 from the second time slice (the first S3 in fig. 19) due to the introduction of the high and low frequency delay Δ t. Since the starting time at which the UE13 starts the synchronization signal detection is located in the middle of the time slice S3, the synchronization signal transmitted through the high frequency base station 12 transmission beam #3 on the time slice S3 cannot be completely received by the UE 13. Since the switching period of the reception beam of the UE13 is equal to the period in which the high frequency base station 12 completes the transmission of the synchronization signal on 12 time slices, the UE13 cannot correctly receive the synchronization signal transmitted by the high frequency base station 12 through the transmission beam #3 on all the reception beams. In addition, since the high and low frequency delays Δ t are greater than the length of one time slice, the UE13 may miss receiving the synchronization signal transmitted in one time slice by the last receiving beam. As shown in fig. 19, UE13 cannot receive the synchronization signal transmitted by high-frequency base station 12 through transmission beam #2 in the reception cycle of reception beam # 11. In the second special subframe, the UE13 can receive the synchronization signal that cannot be successfully received in the first special subframe. As shown in fig. 19, the synchronization signal transmitted by high frequency base station 12 at time slice S1 through transmission beam #1, and the synchronization signal transmitted by high frequency base station 12 through transmission beam #0 and received by UE13 through beam # 11.

The UE13 can traverse all combinations of the high frequency base station 12 transmission beams and the UE13 reception beams by searching the synchronization signals of the first special subframe and the second special subframe, so as to obtain synchronization of the high frequency system.

Alternatively, in the embodiment of the present invention, the form of the transmission beam used for the synchronization signal transmitted by the high-frequency base station 12 may be as follows:

each special subframe in the synchronous radio frame further includes a Cyclic Suffix (CS) located after the DLBP, the CS being used to transmit K synchronization signals, where K is a positive integer less than Nd. That is, CS includes K time slices.

At this time, the high frequency base station 12 transmits Nd synchronization signals using Nd first-order transmission beams for each subinterval of the DLBP. On CS, K synchronization signals are transmitted using the first K of the Nd first-order transmission beams.

For example, a synchronization radio frame includes two special subframes, as shown in fig. 20, where subframe #1 and subframe #6 are special subframes. Taking subframe #1 as an example, DLBP and CS located after DLBP are included. Each subinterval of the DLBP transmits Nd synchronization signals transmitted by the high-frequency base station 12 using Nd first-order transmission beams, #0, #1, # …, # Nd-1 as shown in fig. 20. CS transmits K synchronization signals transmitted by high frequency base station 12 using the first K of Nd first-order transmission beams, the transmission beams used by CS in fig. 20 being: #0, #1, …, # K-1.

As another understanding, this embodiment can also be interpreted as: the special subframe further includes a Cyclic Prefix (CP) located before the DLBP, and the CP transmits K synchronization signals. That is, the CP includes K time slices. At this time, the high frequency base station 12 transmits Nd synchronization signals using Nd first-order transmission beams for each subinterval of the DLBP. On the CP, K synchronization signals are transmitted using the last K of the Nd first-order transmission beams.

As shown in fig. 21, where the CP precedes the DLBP. Each subinterval of the DLBP transmits Nd synchronization signals transmitted by the high-frequency base station 12 using Nd first-order transmission beams, #0, #1, # …, # Nd-1, as shown in fig. 21. The CP uses transmission K synchronization signals transmitted by the high frequency base station 12 using the last K transmission beams of the Nd first-order transmission beams, and the transmission beams used by the CP in fig. 21 are: # Nd-K, # Nd-K +1, # …, # Nd-1.

It is understood that if the first order is # Nd-K, # Nd-K +1, …, # Nd-1, #0, #1, …, # Nd-K-1, then FIG. 21 can also be understood as the CS is located after the DLBP. Therefore, the transmission beams used in fig. 20 and 21 are identical.

It should be noted that the length of the time slice (the length of K time slices) of CS in fig. 20 and CP in fig. 21 should be greater than the high and low frequency delay of the system (i.e., the length of the high and low frequency delay shown in fig. 13).

Specifically, the high frequency base station 12 may determine the K value before transmitting the synchronization signal. For example, one or more values of K may be preset in the high frequency base station 12, and before the high frequency base station 12 transmits the synchronization signal, the high frequency base station may determine the value of K according to an index such as a coverage area, and then determine the CS or CP using the determined value of K, and transmit the synchronization signal.

It should be noted that in the embodiment shown in fig. 20 to 21, S_iIndicating that the synchronization signal is transmitted using the transmission beam # i.

on the time slice Si (including DLBP and CS or CP) of the special subframe, the ID of the used transmission beam is: b_i＝imodN_d i＝0,1,2...,N_d×N_u+K-1。

Wherein the number of time slices included in a special subframe is N_d×N_u+K。

At this time, the UE13 may determine the first start position of the first synchronization detection window according to the low frequency signal transmitted by the low frequency base station. Subsequently, the UE13 receives the synchronization signals using Nu different reception beams starting from the first start position of the first synchronization detection window. Where each receive beam receives Nd synchronization signals. That is, the Nu different reception beams respectively receive Nu sets of synchronization signals, where each set of synchronization signals includes Nd synchronization signals. The UE13 may further determine a second starting position of the second synchronization detection window according to the low frequency signal transmitted by the low frequency base station and the additional receiving delay. Subsequently, the UE13 receives the synchronization signals using Nu different reception beams starting from the second start position of the second synchronization detection window. Where each receive beam receives Nd synchronization signals. That is, the Nu different reception beams respectively receive Nu sets of synchronization signals, where each set of synchronization signals includes Nd synchronization signals.

The time length of the first synchronous detection window is equal to the time length of DLBP, and the time length of the second synchronous detection window is equal to the time length of DLBP.

Wherein the second special subframe may be a first special subframe located after the first special subframe. For example, for the synchronization radio frame shown in fig. 2, the first special subframe may be subframe #1, and the second special subframe may be subframe # 6.

The length of the additional receiving time delay is greater than the high-low frequency time delay of the system, and the length of the time slice occupied by the CS and the CP is greater than or equal to the sum of the high-low frequency time delay and the additional receiving time delay.

The additional receiving delay may be preset in the UE13, or the additional receiving delay may be obtained by the UE13 from the low frequency base station 11, for example, the additional receiving delay may be obtained by receiving low frequency signaling sent by the low frequency base station 11.

Wherein the additional receiving delay can be pre-configured in the UE13 according to the high and low frequency delays of the system. Alternatively, the low frequency base station 11 determines an additional receiving delay according to the high and low frequency delays of the system, and transmits the additional receiving delay to the UE 13.

For example, before UE13 accesses the high frequency system, low frequency base station 11 may notify UE13 of the additional receiving delay (e.g., Δ t) by sending low frequency signaling (e.g., the low frequency signaling may be Radio Resource Control (RRC) signaling)_a)。

Assuming that the low frequency synchronization signal received by the UE13 lags behind the high frequency synchronization signal, as shown in fig. 22, the UE13 starts the first high frequency synchronization signal detection by using the start time of the special subframe obtained by the low frequency synchronization as the start point of the first synchronization detection window, and the length of the first synchronization detection window is the length of the DLBP. The UE13 starts the second high frequency synchronization signal detection with an additional receiving delay after the start time of the next adjacent special subframe obtained by the low frequency synchronization as the start point of the second synchronization detection window.

Specifically, the length of the cyclic prefix or cyclic postfix interval, that is, the length of the total time slice occupied by the K beams, needs to be greater than the sum of the high-frequency delay and the low-frequency delay and the additional receiving delay.

Assuming that the low frequency synchronization signal received by UE13 lags behind the high frequency synchronization signal, taking Nd as 12 and Nu as 12 as examples, fig. 23 and fig. 24 show the reception of the synchronization signal by UE13 in the first special subframe and the second special subframe, respectively. Wherein K is 4. Fig. 23 corresponds to a first synchronization detection window, and fig. 24 corresponds to a second synchronization detection window.

In the first special subframe, as shown in fig. 23, the UE13 starts the detection of the synchronization signal with the receive beam #0 from the second time slice (the first S1 in fig. 23) due to the introduction of the high and low frequency delay Δ t. Since the starting time at which the UE13 starts the synchronization signal detection is located in the middle of the time slice S1, the synchronization signal transmitted through the high frequency base station 12 transmission beam #1 on the time slice S1 cannot be completely received by the UE 13. Since the switching period of the reception beam of the UE13 is equal to the period in which the high frequency base station 12 completes the transmission of the synchronization signal on 12 time slices, the UE13 cannot correctly receive the synchronization signal transmitted by the high frequency base station 12 through the transmission beam #1 on all the reception beams. However, due to the presence of the CP, the length of the time slice occupied by the CP is greater than the high and low frequency delays. As shown in fig. 23, UE13 can receive the synchronization signal transmitted by high-frequency base station 12 through transmission beam #0 in the reception cycle of reception beam # 11.

In the second special sub-frame, as shown in fig. 24, the second sync detection window additionally introduces an additional receive delay Δ t_aThe additional receiving delay Deltat_aThe time delay delta t of high and low frequencies is required to be more than or equal to, namely delta t_a>At. Similar to the first synchronous detection window, due to the high and low frequency delays Δ t and the additional receive delay Δ t_aBy introduction, the starting time of the UE13 to start the second synchronization signal detection is located in the middle of the time slice S3, so the synchronization signal transmitted through the transmission beam #3 of the high frequency base station 12 on the time slice S3 cannot be completely received by the UE 13. Because the switching period of the UE13 receiving beam is equal to that of the high frequency base station 12 which completes the synchronous signal transmission on Nd-12 time slicesThis causes the UE13 not to correctly receive the synchronization signal transmitted by the high frequency base station 12 through the transmission beam #3 on all the reception beams. In the second synchronization detection window, the UE13 can receive the synchronization signal that cannot be successfully received in the first special subframe. As shown in fig. 24, the synchronization signal transmitted by the base station at time slice S1 through transmission beam #1 can be successfully detected in the second synchronization detection window.

The UE13 can traverse all combinations of the high frequency base station 12 transmission beams and the UE13 reception beams through the synchronization signal search of the first synchronization detection window and the second synchronization detection window to obtain synchronization of the high frequency system.

It should be noted that, in the embodiment of the present invention, before the UE13 accesses the high frequency system, the method may further include: the low frequency base station 11 sends low frequency signaling (e.g., RRC signaling) to the UE 13. The low frequency signaling may include at least one of: the reception delay, the frequency bin of the high-frequency system, and the number of subintervals included in the DLBP (i.e., the value of Nd) are added.

Specifically, to successfully acquire frame synchronization, the UE 14 needs to know the length of the DLBP subinterval in advance, that is, the number of time slices in the DLBP subinterval in the high-frequency system, that is, the number Nd of transmission beams of the high-frequency base station 12. The number of time slices in the DLBP subinterval, i.e., the number Nd of transmission beams of the high-frequency base station 12, may be preset by a standard as a fixed value related to frequency points, for example, for 72GHz, 28GHz, and 14GHz systems, Nd may be typically set to 16, 12, and 8, respectively. The UE13 may obtain the frequency point of the high frequency system to be accessed through the low frequency signaling, that is, the Nd value can be obtained. Alternatively, UE13 may obtain the Nd value directly through low frequency signaling, that is, before accessing the high frequency system, low frequency base station 11 notifies UE13 of the frequency point of the high frequency system to be accessed and/or the number of time slices in the DLBP subinterval in the high frequency system, that is, the number Nd value of the transmission beams of high frequency base station 12, through its low frequency signaling (e.g., RRC signaling).

Fig. 25 is a flowchart of a method of downlink synchronization according to an embodiment of the present invention. The method shown in fig. 25 is executed by a user equipment and is applied to a high-low frequency hybrid networking system. The method comprises the following steps:

s110, the user equipment receives synchronization information sent by a high-frequency base station, the synchronization information is carried by a synchronization radio frame, the synchronization radio frame comprises at least one special subframe, the special subframe is used for transmitting synchronization signals, the special subframe comprises DLBP, the DLBP comprises Nu subintervals, and each subinterval transmits Nd synchronization signals, wherein Nu and Nd are positive integers larger than 1.

And S120, the user equipment carries out synchronization according to the synchronization information.

In the embodiment of the invention, the high-frequency base station sends the synchronization information in the special subframe, and the UE completes the synchronization with the high-frequency base station by receiving the synchronization signal in the special subframe, so that the UE can be conveniently and quickly accessed into a high-frequency system, and the power consumption during the access can be saved.

Wherein, the values of Nu and Nd are related to the frequency points used by the system. For example, when the frequency point used by the high-frequency base station is 72GHz, Nd is 16, Nu is 12; when the frequency point adopted by the high-frequency base station is 28GHz, Nd is 12, and Nu is 8; and when the frequency point adopted by the high-frequency base station is 14GHz, Nd is 8, and Nu is 6.

Optionally, as an embodiment, before S110, the UE may further receive low frequency signaling sent by a low frequency base station in the system, where the low frequency signaling includes a frequency point used by the high frequency base station and/or a value of Nd. Wherein the low frequency signaling may be RRC signaling.

Wherein each subinterval of the DLBP may include Nd time slices, and each time slice includes at least two OFDM symbols in length. A first OFDM symbol of the at least two OFDM symbols is used for transmitting a primary synchronization signal, and a second OFDM symbol of the at least two OFDM symbols is used for transmitting a secondary synchronization signal.

Specifically, the second OFDM symbol is used for transmitting a specific sequence of the secondary synchronization signal. The specific sequence comprises an identification ID of the high-frequency base station, an ID of a time slice where the specific sequence is located, and an ID of a subinterval where the specific sequence is located.

It should be noted that, for the primary synchronization signal and the secondary synchronization signal, the foregoing detailed description of fig. 9 and fig. 10 can be referred to, and in order to avoid repetition, the description is omitted here.

The special subframe may further include RDP and uplink and downlink switching guard interval GP, as shown in fig. 4 to fig. 7. Each subinterval may also include Nd switching guard intervals SGP, respectively located after the Nd time slices, as illustrated in fig. 8, previously described.

In addition, in this embodiment of the present invention, the synchronous radio frame further includes a general subframe, where the general subframe includes 8 slots with a length of 0.125ms, and the slot includes Ns OFDM symbols, where Ns is a positive integer. As an example, it can be as shown in fig. 2.

Wherein the value of Ns is related to the frequency used by the system. For example, when the frequency point adopted by the high-frequency base station is 72GHz, Ns is 80; when the frequency point adopted by the high-frequency base station is 28GHz, Ns is 40; when the frequency point adopted by the high-frequency base station is 14GHz, Ns is 20.

In the embodiment of the present invention, the period of the synchronous radio frame used by the high frequency base station may be the length of M radio frames, where M is a positive integer. That is, each M radio frames includes one synchronization radio frame and M-1 general radio frames. Here, M may be equal to 1.

Alternatively, as an embodiment, Nd synchronization signals transmitted by each subinterval of the DLBP may be sequentially transmitted by the high-frequency base station using Nd different transmission beams. That is, the high frequency base station transmits the synchronization signal with Nu as a period and Nd different transmission beams in each period.

Accordingly, in S110, the UE may receive the synchronization signals on Nu subintervals using Nu different reception beams, respectively. That is, the UE uses Nu different reception beams, each of which receives the transmission beams of Nd high frequency base stations.

In order to solve the problem caused by the high and low frequency delays, as an example, in an embodiment of the present invention, on a first special subframe in the synchronization information, the high frequency base station transmits the synchronization signal using a first sequence of transmission beams. On a second special subframe in the synchronization information, the high frequency base station transmits the synchronization signal using a second sequence of transmit beams. The second sequence is generated by the first sequence through cyclic shift, and the length of the time slice of the cyclic shift is larger than the high-low frequency time delay of the system.

In particular, this understanding may be: transmitting the synchronization signal using a first sequence of transmission beams on a DLBP of a first special subframe; transmitting the synchronization signal using a second sequential transmission beam on the DLBP of the second special subframe. Alternatively, the understanding may also be: transmitting the synchronization signal using a first order of transmission beams on each subinterval of the DLBP of the first special subframe; transmitting the synchronization signal using a second sequential transmission beam on each subinterval of the DLBP of the second special subframe.

Wherein, if each synchronous radio frame comprises a special subframe. Then, the first special subframe is a special subframe in a first synchronous radio frame, and the second special subframe is a special subframe in a second synchronous radio frame. Wherein the second synchronization radio frame is a next synchronization radio frame adjacent to the first synchronization radio frame.

Wherein, if each synchronous radio frame comprises 2N special subframes. Then, the first special subframe is a 2 i-th special subframe of the 2N special subframes, and the second special subframe is a 2i + 1-th special subframe of the 2N special subframes. Wherein N is a positive integer, and i is a positive integer less than or equal to N.

Wherein, if each synchronous radio frame comprises 2N +1 special subframes. Then, the first special subframe is the 2 i-th special subframe in the 2N +1 special subframes in the first synchronous radio frame or the 2i + 1-th special subframe in the 2N +1 special subframes in the second synchronous radio frame; the second special subframe is a 2i +1 th special subframe in 2N +1 special subframes in the first synchronous radio frame or a 2 i-th special subframe in 2N +1 special subframes in the second synchronous radio frame. The second synchronous wireless frame is the next synchronous wireless frame adjacent to the first synchronous wireless frame, N is a positive integer, and i is a positive integer smaller than or equal to N.

For example, the first synchronous radio frame may be the synchronous radio frame 301 in fig. 3, and the second synchronous radio frame may be the synchronous radio frame 302 in fig. 3.

Accordingly, for this embodiment, S110 may include: the user equipment determines the initial position of a synchronous detection window according to a low-frequency signal sent by a low-frequency base station in the system; the user equipment receives Nu groups of synchronization signals respectively from the starting position by using Nu different receiving beams, wherein each group of synchronization signals comprises Nd synchronization signals.

Specifically, for this embodiment, reference may be made to the corresponding descriptions in fig. 13 to fig. 19, and details are not repeated here to avoid repetition.

In the embodiment of the invention, the UE rapidly obtains the downlink synchronization of the high-frequency system through low-frequency assistance. In a radio frame structure used by the high-frequency base station, different sequences (cyclic shift) of transmitting beams are used on two adjacent special subframes, so that all combinations of receiving beams traversing UE and transmitting beams of the high-frequency base station can be ensured, and the efficiency and quality of synchronization are ensured.

In order to solve the problem caused by high and low frequency delays, as another example, in an embodiment of the present invention, the special subframe may further include a CS located after the DLBP, and the CS transmits K synchronization signals, where K is a positive integer smaller than Nd. The Nd synchronization signals of each subinterval are sequentially transmitted by the high-frequency base station by using Nd transmission beams. The K synchronization signals of the CS are sequentially transmitted by the high frequency base station using the first K transmission beams among the Nd transmission beams. That is, the CS sequentially switches the transmission beams in the order of the first K transmission beams of the first subinterval of the DLBP to transmit the synchronization signal.

Alternatively, it is also understood that the special subframe may further include a CP located before the DLBP, and the CP transmits K synchronization signals, where K is a positive integer smaller than Nd. The Nd synchronization signals of each subinterval are sequentially transmitted by the high-frequency base station by using Nd transmission beams. The K synchronization signals of the CP are sequentially transmitted by the high frequency base station using the last K transmission beams among the Nd transmission beams. That is, the CP sequentially switches the transmission beams in the order of the last K transmission beams of the last subinterval of the DLBP to transmit the synchronization signal.

Accordingly, for this embodiment, S110 may include: the user equipment determines a first initial position of a first synchronous detection window according to a low-frequency signal sent by a low-frequency base station in the system; the user equipment respectively receives Nu groups of synchronization signals from the first starting position by using Nu different receiving beams, wherein each group of synchronization signals comprises Nd synchronization signals; the user equipment determines a second initial position of a second synchronous detection window according to a low-frequency signal sent by a low-frequency base station in the system and the additional receiving time delay; and the user equipment respectively receives Nu groups of synchronous signals from the second starting position by using Nu different receiving beams, wherein each group of synchronous signals comprises Nd synchronous signals.

Wherein the second special subframe is a first special subframe located after the first special subframe.

Wherein the additional receive delay is preset in the user equipment; or, the additional receiving delay is obtained by the user equipment from the low frequency base station. For example, the additional receiving delay is obtained by the ue through RRC signaling sent by the low frequency base station.

The length of the additional receiving time delay is greater than the high-low frequency time delay of the system, and the length of the time slice occupied by the CS or the CP is greater than or equal to the sum of the high-low frequency time delay and the additional receiving time delay.

In the embodiment of the invention, the UE rapidly obtains the downlink synchronization of the high-frequency system through low-frequency assistance. In a radio frame structure used by the high frequency base station, a cyclic suffix (or cyclic prefix) is additionally added on a special subframe so as to additionally use K transmission beams to transmit a synchronization signal. And the UE can ensure all combinations of the reception beams traversing the UE and the transmission beams of the high-frequency base station by utilizing the additional reception time delay, thereby ensuring the efficiency and the quality of synchronization.

Fig. 26 is a method of downlink synchronization according to another embodiment of the present invention. The method shown in fig. 26 is executed by a high-frequency base station and is applied to a high-frequency and low-frequency hybrid networking system. The method comprises the following steps:

s210, the high-frequency base station generates synchronous information, the synchronous information is borne by a synchronous radio frame, the synchronous radio frame comprises at least one special subframe, the special subframe is used for transmitting synchronous signals, the special subframe comprises DLBP, the DLBP comprises Nu subintervals, and Nd synchronous signals are transmitted in each subinterval, wherein Nu and Nd are positive integers.

S220, the high-frequency base station sends the synchronization information to user equipment.

Wherein each subinterval of the DLBP comprises Nd time slices, and the length of each time slice comprises at least two OFDM symbols. A first OFDM symbol of the at least two OFDM symbols is used for transmitting a primary synchronization signal, and a second OFDM symbol of the at least two OFDM symbols is used for transmitting a secondary synchronization signal.

Specifically, the second OFDM symbol may be used for transmitting a specific sequence of the secondary synchronization signal. Wherein the specific sequence comprises an ID of the high-frequency base station, an ID of a time slice in which the specific sequence is positioned, and an ID of a subinterval in which the specific sequence is positioned.

Optionally, as an embodiment, S220 may include: the high frequency base station transmits the Nd synchronization signals using Nd different transmission beams.

To solve the problem caused by high and low frequency delays, as an example, in the embodiment of the present invention, S220 may include: on a first special subframe in the synchronization information, the high frequency base station transmits the synchronization signal using a first sequence of transmit beams; on a second special subframe in the synchronization information, the high frequency base station transmits the synchronization signal using a second sequence of transmit beams. The second sequence is generated by the first sequence through cyclic shift, and the length of the time slice of the cyclic shift is larger than the high-low frequency time delay of the system.

In the embodiment of the invention, in a radio frame structure used by the high-frequency base station, different sequences (cyclic shift) of transmitting beams are used on two adjacent special subframes, so that when the UE performs downlink synchronization, all combinations of receiving beams traversing the UE and transmitting beams of the high-frequency base station can be ensured, and the synchronization efficiency and quality are ensured.

In order to solve the problem caused by high and low frequency delays, as another example, in an embodiment of the present invention, the special subframe further includes a CS located after the DLBP, and the CS transmits K synchronization signals, where K is a positive integer smaller than Nd. S220 may include: the high-frequency base station sequentially transmits the Nd synchronous signals by using Nd transmitting beams; and the high-frequency base station sequentially transmits the K synchronous signals by using the first K transmitting beams in the Nd transmitting beams.

Alternatively, it may be understood that the high frequency base station transmits the Nd synchronization signals using Nd first-order transmission beams, and transmits the K synchronization signals using the first K transmission beams among the Nd first-order transmission beams.

Alternatively, it is also understood that the special subframe may further include a CP located before the DLBP, and the CP transmits K synchronization signals, where K is a positive integer smaller than Nd. The Nd synchronous signals of each subinterval are transmitted by the high-frequency base station by using Nd first-order transmission beams. The K synchronization signals of the CP are transmitted by the high frequency base station using the last K transmission beams of the Nd first-order transmission beams. That is, the CP sequentially switches the transmission beams in the order of the last K transmission beams of the last subinterval of the DLBP to transmit the synchronization signal.

In the embodiment of the invention, in a radio frame structure used by the high-frequency base station, CS (or CP) is additionally added on a special subframe so as to additionally use K transmission beams to transmit the synchronous signals. Therefore, when the UE carries out downlink synchronization, all combinations of the reception beams traversing the UE and the transmission beams of the high-frequency base station can be ensured by utilizing the additional reception time delay, so that the efficiency and the quality of the synchronization are ensured.

Fig. 27 is a block diagram of a user equipment according to an embodiment of the present invention. The user equipment 300 shown in fig. 27 is in a high-low frequency hybrid networking system, and the user equipment 300 includes a receiving unit 310 and a processing unit 320.

A receiving unit 310, configured to receive synchronization information sent by a high-frequency base station, where the synchronization information is carried by a synchronization radio frame, and the synchronization radio frame includes at least one special subframe, and the special subframe is used to transmit a synchronization signal, where the special subframe includes a DLBP, and the DLBP includes Nu subintervals, and each subinterval transmits Nd synchronization signals, where Nu and Nd are positive integers greater than 1.

A processing unit 320, configured to perform synchronization according to the synchronization information.

Optionally, as an embodiment, the receiving unit 310 is further configured to receive low-frequency signaling sent by a low-frequency base station in the system, where the low-frequency signaling includes a frequency point used by a high-frequency base station and/or a value of Nd. Wherein the low frequency signaling may be RRC signaling.

In addition, in this embodiment of the present invention, the synchronous radio frame may further include a general subframe, where the general subframe includes 8 slots with a length of 0.125ms, and the slot includes Ns OFDM symbols, where Ns is a positive integer. As an example, it can be as shown in fig. 2.

Alternatively, as an embodiment, the Nd synchronization signals may be transmitted by the high frequency base station using Nd different transmission beams.

Optionally, as another embodiment, the receiving unit 310 is specifically configured to: and respectively receiving the synchronization signals on the Nu subintervals by using Nu different receiving beams. That is, the receiving unit 310 receives Nd synchronization signals over one sub-interval using one reception beam.

Optionally, as another embodiment, on a first special subframe in the synchronization information, the high frequency base station transmits the synchronization signal using a first sequence of transmission beams. On a second special subframe in the synchronization information, the high frequency base station transmits the synchronization signal using a second sequence of transmit beams. The second sequence is generated by the first sequence through cyclic shift, and the length of the time slice of the cyclic shift is larger than the high-low frequency time delay of the system.

Accordingly, the receiving unit 310 is specifically configured to: determining the initial position of a synchronous detection window according to a low-frequency signal sent by a low-frequency base station in the system; nu groups of synchronization signals are respectively received from the start position using Nu different reception beams, wherein each group of synchronization signals includes Nd synchronization signals.

Optionally, as another embodiment, the special subframe may further include a cyclic postfix CS located after the DLBP, the CS transmitting K synchronization signals, where K is a positive integer smaller than Nd. The Nd synchronous signals of each subinterval are transmitted by the high-frequency base station by using Nd first-order transmission beams. The K synchronization signals of CS are transmitted by the high frequency base station using the first K transmission beams of the Nd first-order transmission beams. That is, the CS sequentially switches the transmission beams in the order of the first K transmission beams of the first subinterval of the DLBP to transmit the synchronization signal.

Alternatively, it may be understood that the special subframe may further include a CP located before the DLBP, and the CP transmits K synchronization signals, where K is a positive integer smaller than Nd. The Nd synchronous signals of each subinterval are transmitted by the high-frequency base station by using Nd first-order transmission beams. The K synchronization signals of the CP are transmitted by the high frequency base station using the last K transmission beams of the Nd first-order transmission beams. That is, the CP sequentially switches the transmission beams in the order of the last K transmission beams of the last subinterval of the DLBP to transmit the synchronization signal.

Accordingly, the receiving unit 310 is specifically configured to: determining a first initial position of a first synchronous detection window according to a low-frequency signal sent by a low-frequency base station in the system; receiving Nu groups of synchronization signals, respectively, starting from the first start position using Nu different reception beams, wherein each group of synchronization signals comprises Nd synchronization signals; determining a second initial position of a second synchronous detection window according to a low-frequency signal and additional receiving time delay sent by a low-frequency base station in the system; nu groups of synchronization signals are respectively received from the second starting position by using Nu different receiving beams, wherein each group of synchronization signals comprises Nd synchronization signals.

It should be noted that, in the embodiment of the present invention, the receiving unit 310 may be implemented by a transceiver, and the processing unit 320 may be implemented by a processor. As shown in fig. 28, user equipment 400 may include a processor 410, a transceiver 420, and a memory 430. The memory 430 may be used for storing the reception beams, etc., and may also be used for storing codes executed by the processor 410, etc. Wherein the transceiver 420 may be implemented by a receiver.

The various components in user device 400 are coupled together by a bus system 440, wherein bus system 440 includes a power bus, a control bus, and a status signal bus in addition to a data bus.

The user equipment 300 shown in fig. 27 or the user equipment 400 shown in fig. 28 can implement the processes implemented by the user equipment in the foregoing method embodiments, and in order to avoid repetition, details are not described here.

It should be noted that the above-described method embodiments of the present invention may be applied to or implemented by a processor. The processor may be an integrated circuit chip having signal processing capabilities. In implementation, the steps of the above method embodiments may be performed by integrated logic circuits of hardware in a processor or instructions in the form of software. The Processor may be a general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, or discrete hardware components. The various methods, steps and logic blocks disclosed in the embodiments of the present invention may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present invention may be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in a memory, and a processor reads information in the memory and completes the steps of the method in combination with hardware of the processor.

It will be appreciated that the memory in embodiments of the invention may be either volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory. The non-volatile Memory may be a Read-Only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically Erasable PROM (EEPROM), or a flash Memory. Volatile Memory can be Random Access Memory (RAM), which acts as external cache Memory. By way of example, but not limitation, many forms of RAM are available, such as Static random access memory (Static RAM, SRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic random access memory (Synchronous DRAM, SDRAM), Double Data Rate Synchronous Dynamic random access memory (DDR SDRAM), Enhanced Synchronous SDRAM (ESDRAM), Synchronous link SDRAM (SLDRAM), and Direct Rambus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to comprise, without being limited to, these and any other suitable types of memory.

Fig. 29 is a block diagram of a high frequency base station according to an embodiment of the present invention. The high frequency base station 500 shown in fig. 29 is a high frequency base station in a high and low frequency hybrid networking system, and the high frequency base station 500 includes a generating unit 510 and a transmitting unit 520.

A generating unit 510, configured to generate synchronization information, where the synchronization information is carried by a synchronization radio frame, where the synchronization radio frame includes at least one special subframe, and the special subframe is used to transmit a synchronization signal, where the special subframe includes a DLBP, and the DLBP includes Nu subintervals, and each subinterval transmits Nd synchronization signals, where Nu and Nd are positive integers greater than 1.

A sending unit 520, configured to send the synchronization information to the user equipment.

And the user equipment is in the high-low frequency hybrid networking system.

Optionally, as an embodiment, the sending unit 520 is specifically configured to: the Nd synchronization signals are transmitted using Nd different transmit beams.

Optionally, as another embodiment, the sending unit 520 is specifically configured to: transmitting the synchronization signal using a first order of transmit beams on a first special subframe in the synchronization information; transmitting the synchronization signal using a second order of transmit beams on a second special subframe in the synchronization information. The second sequence is generated by the first sequence through cyclic shift, and the length of the time slice of the cyclic shift is larger than the high-low frequency time delay of the system.

Optionally, as another embodiment, the special subframe further includes a CS located after the DLBP, where the CS transmits K synchronization signals, where K is a positive integer smaller than Nd. The sending unit 520 is specifically configured to: transmitting the Nd synchronization signals using Nd first-order transmission beams; transmitting the K synchronization signals using the first K of the Nd first-order transmit beams.

It should be noted that, in the embodiment of the present invention, the sending unit 520 may be implemented by a transceiver, and the generating unit 510 may be implemented by a processor. As shown in fig. 30, the high frequency base station 600 may include a processor 610, a transceiver 620, and a memory 630. The memory 630 may be used for storing the transmission beams, etc., and may also be used for storing codes executed by the processor 610, etc. The transceiver 620 may be implemented by a transmitter, among others.

The various components in high frequency base station 600 are coupled together by a bus system 640, wherein bus system 640 includes a power bus, a control bus, and a status signal bus in addition to a data bus.

The high frequency base station 500 shown in fig. 29 or the high frequency base station 600 shown in fig. 30 can implement each process implemented by the high frequency base station in the foregoing method embodiment, and for avoiding repetition, details are not described here again.

It should be noted that the above-described method embodiments of the present invention may be applied to or implemented by a processor. The processor may be an integrated circuit chip having signal processing capabilities. In implementation, the steps of the above method embodiments may be performed by integrated logic circuits of hardware in a processor or instructions in the form of software. The processor described above may be a general purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware components. The various methods, steps and logic blocks disclosed in the embodiments of the present invention may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present invention may be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in a memory, and a processor reads information in the memory and completes the steps of the method in combination with hardware of the processor.

It will be appreciated that the memory in embodiments of the invention may be either volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory. The non-volatile memory may be a ROM, PROM, EPROM, EEPROM, or flash memory, among others. Volatile memory can be RAM, which acts as external cache memory. By way of example and not limitation, many forms of RAM are available, such as SRAM, DRAM, SDRAM, DDR SDRAM, ESDRAM, SLDRAM, and DR RAM. It should be noted that the memory of the systems and methods described herein is intended to comprise, without being limited to, these and any other suitable types of memory.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a U disk, a removable hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A downlink synchronization method is applied to a high-frequency and low-frequency hybrid networking system, and comprises the following steps:

the method comprises the steps that user equipment receives synchronous information sent by a high-frequency base station, the synchronous information is carried by a synchronous radio frame, the synchronous radio frame comprises at least one special subframe, the special subframe is used for transmitting synchronous signals, the special subframe comprises a downlink synchronization interval and a beam training interval DLBP, the DLBP comprises Nu subintervals, Nd synchronous signals are transmitted in each subinterval, and Nu and Nd are positive integers larger than 1;

the user equipment carries out synchronization according to the synchronization information;

on a second special subframe in the synchronization information, the high frequency base station transmitting the synchronization signal using a second sequence of transmit beams,

the second sequence is generated by the first sequence through cyclic shift, and the length of the time slice of the cyclic shift is larger than the high-low frequency time delay of the system.

2. The method of claim 1, wherein each subinterval comprises Nd time slices, and wherein each time slice comprises at least two Orthogonal Frequency Division Multiplexing (OFDM) symbols, and wherein a first OFDM symbol of the at least two OFDM symbols is used for transmitting a primary synchronization signal, and wherein a second OFDM symbol of the at least two OFDM symbols is used for transmitting a secondary synchronization signal.

3. The method of claim 2, wherein the second OFDM symbol is used for transmitting a specific sequence of the secondary synchronization signal,

wherein the specific sequence comprises an identification ID of a time slice in which the specific sequence is positioned and an ID of a subinterval in which the specific sequence is positioned.

4. The method according to any of claims 1 to 3, wherein each synchronous radio frame comprises one special subframe;

5. The method according to any of claims 1 to 3, wherein each synchronous radio frame comprises 2N special subframes;

6. The method according to any one of claims 1 to 3, wherein the receiving, by the UE, the synchronization information transmitted by the high frequency base station comprises:

the user equipment determines the initial position of a synchronous detection window according to a low-frequency signal sent by a low-frequency base station in the system;

the user equipment receives Nu groups of synchronization signals respectively from the starting position by using Nu different receiving beams, wherein each group of synchronization signals comprises Nd synchronization signals.

7. The method according to any one of claims 1 to 3, wherein before the user equipment receives the synchronization information transmitted by the high frequency base station, the method further comprises:

8. The method according to any of claims 1 to 3, wherein the special subframe further comprises a reserved data interval (RDP) and an uplink and downlink switching guard interval (GP).

9. The method according to any of claims 1 to 3, wherein the periodicity of the synchronous radio frames used by the high frequency base station is the length of M radio frames, where M is a positive integer.

10. A downlink synchronization method is applied to a high-frequency and low-frequency hybrid networking system, and comprises the following steps:

the method comprises the steps that a high-frequency base station generates synchronous information, the synchronous information is carried by a synchronous radio frame, the synchronous radio frame comprises at least one special subframe, the special subframe is used for transmitting synchronous signals, the special subframe comprises a downlink synchronization interval and a beam training interval DLBP, the DLBP comprises Nu subintervals, and Nd synchronous signals are transmitted in each subinterval, wherein Nu and Nd are positive integers larger than 1;

the high-frequency base station sends the synchronization information to user equipment;

11. The method of claim 10, wherein each subinterval comprises Nd time slices, wherein each time slice comprises at least two Orthogonal Frequency Division Multiplexing (OFDM) symbols, and wherein a first OFDM symbol of the at least two OFDM symbols is used for transmitting a primary synchronization signal, and wherein a second OFDM symbol of the at least two OFDM symbols is used for transmitting a secondary synchronization signal.

12. The method according to claim 10 or 11, wherein each synchronization radio frame comprises a special subframe;

13. The method according to claim 10 or 11, wherein each synchronous radio frame comprises 2N special subframes;

14. A user equipment in a hybrid high and low frequency networking system, comprising:

a receiving unit, configured to receive synchronization information sent by a high-frequency base station, where the synchronization information is carried by a synchronization radio frame, where the synchronization radio frame includes at least one special subframe, and the special subframe is used to transmit a synchronization signal, where the special subframe includes a downlink synchronization and beam training interval DLBP, and the DLBP includes Nu subintervals, and each of the Nu subintervals transmits Nd synchronization signals, where Nu and Nd are positive integers greater than 1;

the processing unit is used for carrying out synchronization according to the synchronization information;

15. The UE of claim 14, wherein each of the subintervals comprises Nd time slices, and wherein each time slice has a length comprising at least two OFDM symbols, and wherein a first OFDM symbol of the at least two OFDM symbols is used for transmitting a primary synchronization signal and a second OFDM symbol of the at least two OFDM symbols is used for transmitting a secondary synchronization signal.

16. The UE of claim 14 or 15, wherein each synchronization radio frame comprises a special subframe;

17. The UE of claim 14 or 15, wherein each synchronization radio frame comprises 2N special subframes;

18. The ue of claim 14 or 15, wherein the receiving unit is specifically configured to:

19. A high frequency base station, comprising:

a generating unit, configured to generate synchronization information, where the synchronization information is carried by a synchronization radio frame, where the synchronization radio frame includes at least one special subframe, and the special subframe is used to transmit a synchronization signal, where the special subframe includes a downlink synchronization and beam training interval DLBP, and the DLBP includes Nu subintervals, and each subinterval transmits Nd synchronization signals, where Nu and Nd are positive integers greater than 1;

a sending unit, configured to send the synchronization information to a user equipment;

the sending unit is specifically configured to:

transmitting the synchronization signal using a second sequence of transmit beams on a second special subframe in the synchronization information,

20. The high frequency base station of claim 19, wherein each subinterval comprises Nd time slices, wherein each time slice comprises at least two orthogonal frequency division multiplexing, OFDM, symbols, and wherein a first OFDM symbol of the at least two OFDM symbols is used for transmitting a primary synchronization signal and a second OFDM symbol of the at least two OFDM symbols is used for transmitting a secondary synchronization signal.

21. The high-frequency base station according to claim 19 or 20, wherein each synchronization radio frame comprises a special subframe;

22. The high-frequency base station according to claim 19 or 20, wherein each synchronization radio frame comprises 2N special subframes;