WO2019128379A1 - Time division duplex communication system and method combining spread spectrum and narrow-band mimo - Google Patents
Time division duplex communication system and method combining spread spectrum and narrow-band mimo Download PDFInfo
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- WO2019128379A1 WO2019128379A1 PCT/CN2018/109676 CN2018109676W WO2019128379A1 WO 2019128379 A1 WO2019128379 A1 WO 2019128379A1 CN 2018109676 W CN2018109676 W CN 2018109676W WO 2019128379 A1 WO2019128379 A1 WO 2019128379A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7073—Synchronisation aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Definitions
- the present invention relates to the field of wireless communications, and relates to a time division duplex wireless communication method, and in particular to a time division duplex communication system and method combining spread spectrum and narrowband MIMO.
- Time Division Duplex is a communication method of a mobile communication system.
- the transmission and reception of information between a base station and a user equipment is in the form of a burst sequence on the same channel.
- the uplink communication of TDD is that the terminal sends a signal to the base station, and the downlink communication is that the base station sends a signal to the terminal.
- narrowband communication For the Internet of Things, one feature is that the data packet is small, but the power consumption is low, so narrowband communication is a better choice, but one drawback of narrowband communication is frequency selective fading. Therefore, the key is to overcome narrowband communication.
- Frequency selective fading there are two commonly used methods, 1) spread spectrum communication, spread narrowband signals into wider frequency bands, use frequency diversity to overcome frequency selective fading; 2) multi-antenna communication, receive with multiple antennas Narrowband signals use antenna diversity to overcome frequency selective fading.
- the shortcoming of using spread spectrum communication alone is that the spectrum utilization efficiency is low and the communication capacity is low.
- multi-antenna technology is that multi-antenna communication is not feasible in the downlink. In the downlink process, the terminal can only be equipped with one antenna and cannot receive multi-antenna signals. Therefore, there are still many problems in narrow-band communication for the Internet of Things. .
- An important feature of IoT communication is that the uplink communication capacity is greater than the downlink communication capacity, the uplink communication is used for the terminal to report data to the base station and the network, and the data amount is large; and the downlink communication is generally only used for the base station and the network to send the response and control information to the terminal. The amount of data is small.
- the invention combines spread spectrum and narrow-band MIMO (Multiple-Input Multiple-Output) communication technology, and uses spread spectrum communication technology for downlink, so that the terminal can overcome frequency selectivity under single antenna reception.
- MIMO Multiple-Input Multiple-Output
- the base station receives signals with multiple antennas, overcomes frequency selective fading, and supports multiple terminals simultaneously transmitting narrowband signals to the base station, where the narrowband signals refer to signals that have not been spread. Increase the upstream capacity. Furthermore, the present invention also provides a TDD relay supporting the above techniques.
- the technical solution adopted by the present invention is:
- a time division duplex communication system combining spread spectrum and narrowband MIMO characterized in that it comprises:
- the base station is provided with a plurality of antennas.
- the base station uses a spread spectrum communication technology to transmit signals by a single antenna.
- the base station uses a narrowband MIMO technology to receive signals by multiple antennas.
- the terminal has a plurality of terminals.
- the base station receives signals through a single antenna of a spread spectrum communication technology.
- each terminal transmits a narrowband signal to the base station through a single antenna, where the narrowband signal refers to a signal that has not been spread.
- Multiple terminals and base stations transmit signals using narrowband MIMO technology.
- the base station sets a maximum retransmission interval of the narrowband slot synchronization information. During the interval, the base station sends the narrowband slot synchronization information to the terminal at least once, and the terminal determines the narrowband after receiving the narrowband slot synchronization information sent by the base station. Selecting a narrowband subslot to transmit an uplink signal, the number of narrowband subslots in the slot, and the start time and end time of each narrowband subslot;
- the method for the terminal to select a narrowband subslot is:
- the terminal selects a narrowband subslot according to the received base station signal power, and when the received signal power is high, selects a narrowband subslot with a larger sequence number.
- the base station sends the narrowband slot synchronization information to the terminal at least once by using one or more of the following methods:
- the narrowband slot synchronization frame, the downlink response frame, and the downlink data frame that transmit the narrowband slot synchronization information are spread using the maximum spreading multiple.
- the downlink response frame simultaneously responds to multiple terminals, that is, the response data of the multiple terminals is combined in one downlink response frame, and the spreading ratio of the downlink response frame sent by the base station is set to be required by the terminal with the worst signal quality. Spreading multiples.
- the manner in which the terminal searches the working channel of the base station is: the terminal-to-base station listening time is greater than the maximum retransmission interval of the narrow-band time slot synchronization information, and if the narrow-band time slot synchronization information is received, the working channel is found; otherwise, the next possible handover is possible.
- the base station working channel continues to listen; if multiple working channels are found, the working channel with the strongest signal power of the receiving base station is selected.
- a TDD relay is further included, the TDD relay includes an antenna A for transmitting and receiving communication with the base station, an antenna B for transmitting and receiving communication with the terminal, an uplink amplifier and a downlink amplifier, and the antenna A and the antenna B pass the switch
- the A and switch B switches are connected to the uplink amplifier or the downlink amplifier, and the uplink signal and the downlink signal are relay-amplified by the uplink amplifier and the downlink amplifier; the TDD relay normally works in the downlink state, and receives the narrowband slot synchronization frame from the base station.
- the downlink response frame and the downlink data frame carrying the narrowband slot synchronization information determining the number of narrowband subslots, and the start time and end time of each narrowband subslot, and switching to the uplink state in the narrowband slot time .
- each narrowband subslot multiple terminals transmit data packets to the base station, and each data packet is modulated by a narrowband single carrier modulation mode; the format of the terminal transmitting data in the narrowband subslot is pilot
- the signal is added to the line synchronization sequence and the encoded data sequence, wherein the pilot signal is a single frequency signal, and the uplink synchronization sequence is a sequence with good autocorrelation properties.
- a time division duplex communication method combining spread spectrum and narrowband MIMO is characterized in that: in downlink, the base station uses a spread spectrum communication technology to transmit signals to the terminal, and the base station and the terminal both use a single antenna to transmit and receive; when uplinking, the base station uses narrowband MIMO technology Receiving signals from the terminal, multiple terminals form multiple antennas at the transmitting end, and the base station receives multiple antennas.
- the base station sets a maximum retransmission interval of the narrowband slot synchronization information. During the interval, the base station sends the narrowband slot synchronization information to the terminal at least once, and the terminal determines the narrowband after receiving the narrowband slot synchronization information sent by the base station. The number of narrowband subslots in the slot, and the start time and end time of each narrowband subslot, select a narrowband subslot to transmit the uplink signal.
- the invention combines the spread spectrum and narrowband MIMO communication technology, and uses the spread spectrum communication technology for downlink, so that the terminal can overcome the frequency selective fading in the case of single antenna reception; the narrowband MIMO communication technology is used for uplink, and the base station uses multiple The antenna receives the signal and overcomes the frequency selective fading while supporting multiple terminals to simultaneously transmit signals to the base station, thereby improving the uplink capacity.
- the invention not only retains the advantages of low power consumption and long transmission distance of the narrowband communication applied on the Internet of Things, but also overcomes the shortcomings of the frequency selective fading, and further improves the practicability of the Internet of Things technology.
- FIG. 1 is a schematic diagram of three narrowband slot synchronization information transmission methods and narrowband time slots according to the present invention.
- FIG. 2 is a schematic diagram of a TDD relay.
- Figure 3 shows the format of the terminal transmitting data in a narrowband sub-timeslot.
- a time division duplex communication system combining spread spectrum and narrowband MIMO comprising a base station and a terminal, the base station is provided with a plurality of antennas, the terminal has multiple, each terminal is a single antenna, and the communication method between the base station and the terminal For the downlink, the base station transmits the signal to the terminal using the spread spectrum communication technology, and both the base station and the terminal use a single antenna.
- the spread spectrum communication adopts LoRa communication technology
- LoRa is a long distance and low power consumption developed by Semtech.
- the terminal when uplink, the terminal sends a signal to the base station, the terminal uses a single antenna to transmit a narrowband signal, where the narrowband signal refers to a signal that has not been spread, and the base station uses a narrowband MIMO technology to transmit the multi-antenna receiving terminal signal of;
- the downlink uses spread spectrum communication technology, selects the spreading factor according to the communication channel quality of the terminal and the base station, the channel quality is poor, selects a larger spreading factor, the channel quality is better, and a smaller spreading factor is selected.
- the spreading factor is a minimum of 1 and a maximum of 12, corresponding to a spreading factor of 2 to 2 12 times.
- the uplink still uses the option of spreading, so that it is compatible with the new terminal.
- the terminal can select the uplink signal at any time, that is, the uplink time slot can be arbitrarily selected according to needs. .
- the base station For a terminal that uses the MIMO technology to transmit an uplink signal, the base station sets a maximum retransmission interval of the narrowband slot synchronization information. During the interval, the base station sends the narrowband slot synchronization information to the terminal at least once, and the terminal receives the narrowband sent by the base station. After the slot synchronization information, the number of narrowband sub-slots in the narrowband slot is determined, and the start time and end time of each narrowband sub-slot are selected, and a narrow-band sub-slot is selected to transmit an uplink signal, which ensures multiple terminals.
- the signals sent to the base station are aligned in time, so that the multi-user signal receiving capability of the narrowband MIMO can be fully utilized to improve the uplink capacity; an example: as shown in FIG. 1, after the narrowband slot synchronization frame, three are set.
- the narrowband subslots are narrowband subslots 1, 2, and 3, respectively, and the lengths of the three narrowband subslots are 330ms, 150ms, and 100ms, respectively.
- the narrowband time slot is an uplink time slot.
- the uplink time slot and the downlink time slot are not fixed, and are selected as needed.
- the method for selecting a narrowband subslot by the terminal the terminal selects a narrowband subslot according to the received base station signal power, and when the received signal power is high, selects a narrowband subslot with a larger sequence number.
- the narrowband subslot 3 is selected; when the greater than or equal to -120 dBm is less than -90 dBm, the narrowband subslot 2 is selected; when less than -120 dBm, the narrowband subslot 1 is selected. .
- the method for the base station to send the narrowband slot synchronization information to the terminal is one or more of the following three methods:
- the narrowband slot synchronization frame, the downlink response frame, and the downlink data frame that transmit the narrowband slot synchronization information are spread by using a maximum spreading multiple, which can ensure all terminals in the coverage of the base station. Both narrowband slot synchronization information can be received.
- An example: a narrowband slot synchronization frame, a downlink response frame, and a downlink data frame that transmit narrowband slot synchronization information employs a spreading factor of 12.
- the downlink response frame simultaneously responds to multiple terminals, that is, the response data of the multiple terminals is combined in one downlink response frame, and the spreading ratio of the downlink response frame sent by the base station is set to the worst signal.
- the spreading factor required by the quality terminal ensures that multiple terminals can receive the response data. This way can improve the response efficiency.
- the terminal When the terminal does not know the working channel of the base station, the terminal needs to search for the base station, and this process is called network search.
- the manner in which the terminal searches for the working channel of the base station is: the terminal-to-base station listening time is greater than the maximum retransmission interval of the narrow-band time slot synchronization information, and if the narrow-band time slot synchronization information is received, the working channel is found; otherwise, the next possible base station is switched.
- the channel continues to listen; if multiple working channels are found, the working channel with the strongest signal power of the receiving base station is selected.
- the TDD relay in order to extend the coverage distance, includes an antenna A for transmitting and receiving communication with the base station, and is used for An antenna B, an uplink amplifier, and a downlink amplifier that communicate with the terminal, and the antenna A and the antenna B are connected to the uplink amplifier or the downlink amplifier through the switch A and the switch B, and the uplink signal and the downlink signal are performed by the uplink amplifier and the downlink amplifier.
- the TDD relay includes an antenna A for transmitting and receiving communication with the base station, and is used for An antenna B, an uplink amplifier, and a downlink amplifier that communicate with the terminal, and the antenna A and the antenna B are connected to the uplink amplifier or the downlink amplifier through the switch A and the switch B, and the uplink signal and the downlink signal are performed by the uplink amplifier and the downlink amplifier.
- the relay amplifies the signal transmitted by the base station received from the antenna A in the downlink time period, and then forwards the signal to the terminal through the antenna B, and amplifies the signal transmitted by the terminal received from the antenna B in the uplink time period, and then forwards the signal through the antenna A. To the base station.
- the uplink and downlink switching of the TDD relay depends on the switch A and the switch B.
- the switch A and the switch B are both single-pole and double-throw switches. In the downlink state, the switch A and the switch B are connected to the downlink amplifier, and the uplink state, the switch A and the switch B are connected. Go to the upstream amplifier.
- the TDD relay normally works in a downlink state, and determines the number of narrowband sub-timeslots in the narrowband slot by receiving a narrowband slot synchronization frame from the base station or a downlink response frame and a downlink data frame carrying the narrowband slot synchronization information, and The start time and end time of each narrowband subslot, and switch to the uplink state during the narrowband slot time.
- each terminal transmits data packets to the base station, and each data packet is modulated by a narrowband single carrier modulation mode; as shown in FIG. 3, the terminal transmits data in a narrowband subslot.
- a pilot sequence is added to the pilot signal plus a coded data sequence, wherein the pilot signal is a single frequency signal, and the uplink synchronization sequence is a sequence with good autocorrelation properties.
- Both the uplink synchronization sequence and the encoded data sequence are modulated by any one of MSK, GMSK, OQPSK, ⁇ /2-BPSK, QPSK, 16QAM, and 64QAM.
- the terminal randomly selects the center frequency to transmit uplink data, thereby ensuring that the center frequencies of the multiple terminals are staggered as much as possible.
- the base station detects the pilot signal sent by the terminal in the narrowband subslot, and acquires the center frequency of the subchannel according to the pilot signal.
- the specific acquisition method is: the base station performs the J point Fourier on the pilot signal received by all the antennas.
- the transform is denoted as vector S i , S i represents the Fourier transform result of the ith antenna branch, and the Fourier transform result received by each antenna is taken as an absolute value and then squared, and then the results of all antenna branches are phased.
- ABS 2 (S i ) means that all elements in S i are taken as absolute values and then squared; then, according to the threshold value set by the system, the position of the peak in E is judged as n 1 , n 2 ...
- n K , K is the number of detected peaks, each peak corresponds to a terminal transmitting a signal, and then the subchannel center frequency of each terminal is obtained according to the following formula; f s is the system sampling rate, and the subchannel center frequencies of the respective terminals are obtained as f 1 , f 2 ..., f K .
- the method for the base station to perform channel estimation on the terminal is as follows:
- the h k dimension is: M rows, 1 column, and M is the number of base station receiving antennas. It represents n k th element of the vector S i is.
- the base station performs beamforming by using a conjugate, zero-forcing or minimum mean square error method according to the channel response of the terminal, thereby implementing MIMO reception on multiple terminals.
- the base station performs narrowband filtering on the terminal signal received by the beamforming to recover its transmission signal.
Abstract
Disclosed are a time division duplex communication system and method combining spread spectrum and narrow-band MIMO. The system comprises a base station and terminals, wherein the base station is provided with multiple antennae, there are multiple terminals, and each terminal is a single antenna. The communication method between the base station and the terminals involves: in a downlink, a base station using spread spectrum communication technology to transmit a signal to a terminal; in an uplink, the base station using narrow-band MIMO technology to receive the signal transmitted by the terminal via multiple antennae; and the base station setting a maximum retransmission interval of narrow-band time slot synchronization information, and within the interval time, the base station transmitting the narrow-band time slot synchronization information to the terminal at least once, and after receiving the narrow-band time slot synchronization information transmitted by the base station, the terminal determining the number of narrow-band sub time slots in a narrow-band time slot as well as a start time and an end time, and selecting a narrow-band sub time slot to transmit an uplink signal. By means of the present invention, the advantages of low power consumption and long transmission distance of narrow-band communication applied to the Internet of Things can be retained, and the shortcoming of frequency selective fading thereof can also be overcome.
Description
本发明属于无线通信领域，涉及一种时分双工无线通信方法，具体涉及一种结合扩频和窄带MIMO的时分双工通信系统及方法。The present invention relates to the field of wireless communications, and relates to a time division duplex wireless communication method, and in particular to a time division duplex communication system and method combining spread spectrum and narrowband MIMO.
时分双工(Time Division Duplex，简称“TDD”)是一种移动通信系统的通信方式，这种方式在基站和用户设备之间的收发信息，是以突发脉冲序列的形式，在同一个信道上交替传送，即收发双方轮流发和收，或称“乒乓方式”。这样就可以在一个信道上实现一个双工信道，从而提高频谱利用率。TDD的上行通信是终端向基站发送信号，下行通信是基站向终端发送信号。Time Division Duplex ("TDD") is a communication method of a mobile communication system. The transmission and reception of information between a base station and a user equipment is in the form of a burst sequence on the same channel. Alternate transmission, that is, the sending and receiving sides take turns to send and receive, or "ping-pong mode." This allows a duplex channel to be implemented on one channel, thereby increasing spectrum utilization. The uplink communication of TDD is that the terminal sends a signal to the base station, and the downlink communication is that the base station sends a signal to the terminal.
对于物联网来说，一个特点就是数据包较小，但是要求功耗低，因此窄带通信是比较好的选择，但是窄带通信有一个缺陷就是频率选择性衰落，因此采用窄带通信，关键是如何克服频率选择性衰落，目前常用的方法有两种，1)扩频通信，将窄带信号扩展为较宽频带的信号，利用频率分集克服频率选择性衰落；2)多天线通信，用多个天线接收窄带信号，利用天线分集克服频率选择性衰落。单纯使用扩频通信，其缺点是频谱利用效率低，通信容量低。单纯使用多天线技术，其缺点是多天线通信在下行不可行，下行过程中，终端通常只能装备一个天线，不能进行多天线信号接收，因此窄带通信用于物联网中还有很多问题需要解决。For the Internet of Things, one feature is that the data packet is small, but the power consumption is low, so narrowband communication is a better choice, but one drawback of narrowband communication is frequency selective fading. Therefore, the key is to overcome narrowband communication. Frequency selective fading, there are two commonly used methods, 1) spread spectrum communication, spread narrowband signals into wider frequency bands, use frequency diversity to overcome frequency selective fading; 2) multi-antenna communication, receive with multiple antennas Narrowband signals use antenna diversity to overcome frequency selective fading. The shortcoming of using spread spectrum communication alone is that the spectrum utilization efficiency is low and the communication capacity is low. The shortcoming of using multi-antenna technology is that multi-antenna communication is not feasible in the downlink. In the downlink process, the terminal can only be equipped with one antenna and cannot receive multi-antenna signals. Therefore, there are still many problems in narrow-band communication for the Internet of Things. .
发明内容Summary of the invention
本发明的目的在于提供一种能够在上下行通信中有效克服频率选择衰落的窄带无线通信系统及方法。物联网通信的一个重要特征是上行通信容量大于下行通信容量，上行通信用于终端向基站和网络报告数据，数据量较大；而下行通信通常仅用于基站和网络向终端发送应答和控制信息，数据量较小。发明结合了扩频和窄带MIMO(Multiple-Input Multiple-Output，即为多入多出技术)通信技术，将扩频通信技术用于下行，使终端在单天线接收情况下，能够克服频率选择性衰落；将窄带MIMO通信技术用于上行，基站用多个天线接收信号，克服频率选择性衰落的同时，支持多个终端同时向基站发送窄带信号，这里窄带信号指没有经过扩频的信号，从而提升上行容量。此外，本发明还给出支持上述技术的TDD中继。It is an object of the present invention to provide a narrowband wireless communication system and method that is capable of effectively overcoming frequency selective fading in uplink and downlink communications. An important feature of IoT communication is that the uplink communication capacity is greater than the downlink communication capacity, the uplink communication is used for the terminal to report data to the base station and the network, and the data amount is large; and the downlink communication is generally only used for the base station and the network to send the response and control information to the terminal. The amount of data is small. The invention combines spread spectrum and narrow-band MIMO (Multiple-Input Multiple-Output) communication technology, and uses spread spectrum communication technology for downlink, so that the terminal can overcome frequency selectivity under single antenna reception. Fading; using narrowband MIMO communication technology for uplink, the base station receives signals with multiple antennas, overcomes frequency selective fading, and supports multiple terminals simultaneously transmitting narrowband signals to the base station, where the narrowband signals refer to signals that have not been spread. Increase the upstream capacity. Furthermore, the present invention also provides a TDD relay supporting the above techniques.
为了达到上述目的，解决上述技术问题，本发明采用的技术方案是：In order to achieve the above object and solve the above technical problems, the technical solution adopted by the present invention is:
一种结合扩频和窄带MIMO的时分双工通信系统，其特征在于，包括：A time division duplex communication system combining spread spectrum and narrowband MIMO, characterized in that it comprises:
基站，所述基站设有多个天线，下行时，基站采用扩频通信技术单天线发送信号，上行时，基站采用窄带MIMO技术多天线接收信号。The base station is provided with a plurality of antennas. When downlinking, the base station uses a spread spectrum communication technology to transmit signals by a single antenna. When uplinking, the base station uses a narrowband MIMO technology to receive signals by multiple antennas.
终端，所述终端有多个，下行时，与基站对应通过扩频通信技术单天线接收信号，上行时，每个终端通过单天线向基站发送窄带信号，这里窄带信号指没有经过扩频的信号，多个终端与基站采用窄带MIMO技术传输信号。The terminal has a plurality of terminals. When downlinking, the base station receives signals through a single antenna of a spread spectrum communication technology. When uplinking, each terminal transmits a narrowband signal to the base station through a single antenna, where the narrowband signal refers to a signal that has not been spread. Multiple terminals and base stations transmit signals using narrowband MIMO technology.
作为改进，基站设置一个窄带时隙同步信息最大重发间隔，在该间隔时间内，基站向终端至少发送一次窄带时隙同步信息，终端在收到基站发出的窄带时隙同步信息后，确定窄带时隙内窄带子时隙的个数，以及每个窄带子时隙的开始时间和结束时间，选择一个窄带子时隙发送上行信号；As an improvement, the base station sets a maximum retransmission interval of the narrowband slot synchronization information. During the interval, the base station sends the narrowband slot synchronization information to the terminal at least once, and the terminal determines the narrowband after receiving the narrowband slot synchronization information sent by the base station. Selecting a narrowband subslot to transmit an uplink signal, the number of narrowband subslots in the slot, and the start time and end time of each narrowband subslot;
作为改进，终端选择窄带子时隙的方法为：As an improvement, the method for the terminal to select a narrowband subslot is:
终端根据接收到的基站信号功率选择窄带子时隙，接收信号功率较高时，选择序号较大的窄带子时隙。The terminal selects a narrowband subslot according to the received base station signal power, and when the received signal power is high, selects a narrowband subslot with a larger sequence number.
作为改进，在窄带时隙同步信息最大重发间隔内，基站采用下列方法中一种或多种向终端至少发送一次窄带时隙同步信息：As an improvement, in the maximum retransmission interval of the narrowband slot synchronization information, the base station sends the narrowband slot synchronization information to the terminal at least once by using one or more of the following methods:
(1)在窄带时隙同步帧中发送窄带时隙同步信息；(1) transmitting narrowband slot synchronization information in a narrowband slot synchronization frame;
(2)在下行应答帧中携带窄带时隙同步信息，即在下行应答帧中，发送应答信息之外，还顺带发送窄带时隙同步信息；(2) carrying the narrowband slot synchronization information in the downlink response frame, that is, transmitting the narrowband slot synchronization information in addition to the response information in the downlink response frame;
(3)在下行数据帧中携带窄带时隙同步信息，即在下行数据帧中，发送下行数据之外，还顺带发送窄带时隙同步信息。(3) Carrying narrowband slot synchronization information in the downlink data frame, that is, transmitting downlink data in the downlink data frame, and transmitting the narrowband slot synchronization information in the same direction.
作为改进，发送窄带时隙同步信息的窄带时隙同步帧、下行应答帧和下行数据帧采用最大扩频倍数进行扩频。As an improvement, the narrowband slot synchronization frame, the downlink response frame, and the downlink data frame that transmit the narrowband slot synchronization information are spread using the maximum spreading multiple.
作为改进，下行应答帧同时对多个终端进行应答，即合并对多个终端的应答数据于一个下行应答帧内，基站发送的下行应答帧的扩频倍数设为最差信号质量的终端所需要的扩频倍数。As an improvement, the downlink response frame simultaneously responds to multiple terminals, that is, the response data of the multiple terminals is combined in one downlink response frame, and the spreading ratio of the downlink response frame sent by the base station is set to be required by the terminal with the worst signal quality. Spreading multiples.
作为改进，终端搜索基站工作信道采用的方式为：终端对基站监听时间大于窄带时隙同步信息最大重发间隔，如果收到了窄带时隙同步信息，则找到了工作信道；否则，切换下一个可能的基站工作信道继续监听；如果找到多个工作信道，则选择接收基站信号功率最强的工作信道。As an improvement, the manner in which the terminal searches the working channel of the base station is: the terminal-to-base station listening time is greater than the maximum retransmission interval of the narrow-band time slot synchronization information, and if the narrow-band time slot synchronization information is received, the working channel is found; otherwise, the next possible handover is possible. The base station working channel continues to listen; if multiple working channels are found, the working channel with the strongest signal power of the receiving base station is selected.
作为改进，还包括TDD中继，所述TDD中继包括用于与基站收发通讯的天线A、用于与终端收发通讯的天线B、上行放大器和下行放大器，所述天线A和天线B通过开关A和开关B切换与上行放大器或下行放大器相连，通过上行放大器和下行放大器对上行信号和下行信号进行中继放大；TDD中继平时工作在下行状态，通过接收来自基站的窄带时隙同步帧， 或者携带窄带时隙同步信息的下行应答帧和下行数据帧，确定窄带子时隙的个数，以及每个窄带子时隙的开始时间和结束时间，并在窄带时隙时间内切换到上行状态。As an improvement, a TDD relay is further included, the TDD relay includes an antenna A for transmitting and receiving communication with the base station, an antenna B for transmitting and receiving communication with the terminal, an uplink amplifier and a downlink amplifier, and the antenna A and the antenna B pass the switch The A and switch B switches are connected to the uplink amplifier or the downlink amplifier, and the uplink signal and the downlink signal are relay-amplified by the uplink amplifier and the downlink amplifier; the TDD relay normally works in the downlink state, and receives the narrowband slot synchronization frame from the base station. Or the downlink response frame and the downlink data frame carrying the narrowband slot synchronization information, determining the number of narrowband subslots, and the start time and end time of each narrowband subslot, and switching to the uplink state in the narrowband slot time .
作为改进，每个窄带子时隙中，多个终端向基站传输数据包，每个数据包均采用窄带单载波调制方式进行调制；所述终端在窄带子时隙中传输数据的格式为导频信号加上行同步序列再加编码数据序列，其中导频信号为单频率信号，上行同步序列是一个具有良好自相关特性的序列。As an improvement, in each narrowband subslot, multiple terminals transmit data packets to the base station, and each data packet is modulated by a narrowband single carrier modulation mode; the format of the terminal transmitting data in the narrowband subslot is pilot The signal is added to the line synchronization sequence and the encoded data sequence, wherein the pilot signal is a single frequency signal, and the uplink synchronization sequence is a sequence with good autocorrelation properties.
一种结合扩频和窄带MIMO的时分双工通信方法，其特征在于：下行时，基站采用扩频通信技术向终端发送信号，基站和终端均采用单天线收发；上行时，基站采用窄带MIMO技术接收终端发出的信号，多个终端组成发射端的多天线，基站采用多天线接收。A time division duplex communication method combining spread spectrum and narrowband MIMO is characterized in that: in downlink, the base station uses a spread spectrum communication technology to transmit signals to the terminal, and the base station and the terminal both use a single antenna to transmit and receive; when uplinking, the base station uses narrowband MIMO technology Receiving signals from the terminal, multiple terminals form multiple antennas at the transmitting end, and the base station receives multiple antennas.
作为改进，基站设置一个窄带时隙同步信息最大重发间隔，在该间隔时间内，基站向终端至少发送一次窄带时隙同步信息，终端在收到基站发出的窄带时隙同步信息后，确定窄带时隙内窄带子时隙的个数，以及每个窄带子时隙的开始时间和结束时间，选择一个窄带子时隙发送上行信号。As an improvement, the base station sets a maximum retransmission interval of the narrowband slot synchronization information. During the interval, the base station sends the narrowband slot synchronization information to the terminal at least once, and the terminal determines the narrowband after receiving the narrowband slot synchronization information sent by the base station. The number of narrowband subslots in the slot, and the start time and end time of each narrowband subslot, select a narrowband subslot to transmit the uplink signal.
本发明的有益效果是：The beneficial effects of the invention are:
本发明结合了扩频和窄带MIMO通信技术，将扩频通信技术用于下行，使终端在单天线接收情况下，能够克服频率选择性衰落；将窄带MIMO通信技术用于上行，基站用多个天线接收信号，克服频率选择性衰落的同时，支持多个终端同时向基站发送信号，从而提升上行容量。本发明既保留了窄带通信在物联网上应用的低功耗，传输距离长的优势，又克服了其频率选择性衰落的缺点，使得物联网技术的实用性更进一步发展。The invention combines the spread spectrum and narrowband MIMO communication technology, and uses the spread spectrum communication technology for downlink, so that the terminal can overcome the frequency selective fading in the case of single antenna reception; the narrowband MIMO communication technology is used for uplink, and the base station uses multiple The antenna receives the signal and overcomes the frequency selective fading while supporting multiple terminals to simultaneously transmit signals to the base station, thereby improving the uplink capacity. The invention not only retains the advantages of low power consumption and long transmission distance of the narrowband communication applied on the Internet of Things, but also overcomes the shortcomings of the frequency selective fading, and further improves the practicability of the Internet of Things technology.
图1为本发明三种窄带时隙同步信息发送方法及窄带时隙示意图。FIG. 1 is a schematic diagram of three narrowband slot synchronization information transmission methods and narrowband time slots according to the present invention.
图2为TDD中继示意图。2 is a schematic diagram of a TDD relay.
图3为终端在窄带子时隙中传输数据的格式Figure 3 shows the format of the terminal transmitting data in a narrowband sub-timeslot.
下面结合附图对本发明进行举例说明。The invention is illustrated by the following figures in conjunction with the accompanying drawings.
需要指出的是，本专利申请中定义的名词以本发明定义为准，没有定义的名词以行业通用理解为准。It should be noted that the nouns defined in this patent application are subject to the definition of the present invention, and the nouns defined are based on the general understanding of the industry.
一种结合扩频和窄带MIMO的时分双工通信系统，包括基站和终端，基站设有多个天线，所述终端有多个，每个终端均为单天线，基站和终端之间的通信方法为：下行时，基站向终端采用扩频通信技术发送信号，基站和终端都采用单天线；一个例子：扩频通信采用LoRa 通信技术，LoRa是Semtech公司开发的一种长距离、低功耗、扩频的、无线传输的物理层通信技术；上行时，终端向基站发送信号，终端采用单天线发送窄带信号，这里窄带信号指没有经过扩频的信号，基站采用窄带MIMO技术多天线接收终端发送的信号；A time division duplex communication system combining spread spectrum and narrowband MIMO, comprising a base station and a terminal, the base station is provided with a plurality of antennas, the terminal has multiple, each terminal is a single antenna, and the communication method between the base station and the terminal For the downlink, the base station transmits the signal to the terminal using the spread spectrum communication technology, and both the base station and the terminal use a single antenna. One example: the spread spectrum communication adopts LoRa communication technology, and LoRa is a long distance and low power consumption developed by Semtech. Spread spectrum, wireless transmission physical layer communication technology; when uplink, the terminal sends a signal to the base station, the terminal uses a single antenna to transmit a narrowband signal, where the narrowband signal refers to a signal that has not been spread, and the base station uses a narrowband MIMO technology to transmit the multi-antenna receiving terminal signal of;
下行采用扩频通信技术，根据终端与基站的通信信道质量选择扩频因子，信道质量较差，选择较大的扩频因子，信道质量较好，选择较小的扩频因子。一个例子：扩频因子最小为1，最大为12，分别对应扩频倍数2到2
12倍。
The downlink uses spread spectrum communication technology, selects the spreading factor according to the communication channel quality of the terminal and the base station, the channel quality is poor, selects a larger spreading factor, the channel quality is better, and a smaller spreading factor is selected. An example: the spreading factor is a minimum of 1 and a maximum of 12, corresponding to a spreading factor of 2 to 2 12 times.
对于一些老的终端可以保留了上行仍然采用扩频这一选项，从而和新终端兼容，在上行采用扩频通讯技术中，终端可以选择任意时间发送上行信号，即上行时隙可以根据需要任意选择。For some old terminals, the uplink still uses the option of spreading, so that it is compatible with the new terminal. In the uplink using spread spectrum communication technology, the terminal can select the uplink signal at any time, that is, the uplink time slot can be arbitrarily selected according to needs. .
对于采用MIMO技术发送上行信号的终端，基站设置一个窄带时隙同步信息最大重发间隔，在该间隔时间内，基站向终端至少发送一次窄带时隙同步信息，终端在收到基站发出的窄带时隙同步信息后，确定窄带时隙内窄带子时隙的个数，以及每个窄带子时隙的开始时间和结束时间，选择一个窄带子时隙发送上行信号，这种方式保证了多个终端发送到基站的信号在时间上是对齐的，从而可以充分利用窄带MIMO的多用户信号接收能力，提升上行容量；一个例子：如图1所示，在窄带时隙同步帧之后，设置了三个窄带子时隙，分别为窄带子时隙1、2、3，三个窄带子时隙的长度分别是330ms、150ms和100ms。For a terminal that uses the MIMO technology to transmit an uplink signal, the base station sets a maximum retransmission interval of the narrowband slot synchronization information. During the interval, the base station sends the narrowband slot synchronization information to the terminal at least once, and the terminal receives the narrowband sent by the base station. After the slot synchronization information, the number of narrowband sub-slots in the narrowband slot is determined, and the start time and end time of each narrowband sub-slot are selected, and a narrow-band sub-slot is selected to transmit an uplink signal, which ensures multiple terminals. The signals sent to the base station are aligned in time, so that the multi-user signal receiving capability of the narrowband MIMO can be fully utilized to improve the uplink capacity; an example: as shown in FIG. 1, after the narrowband slot synchronization frame, three are set. The narrowband subslots are narrowband subslots 1, 2, and 3, respectively, and the lengths of the three narrowband subslots are 330ms, 150ms, and 100ms, respectively.
窄带时隙即为上行时隙，本技术中上行时隙和下行时隙分配不固定，根据需要选择。The narrowband time slot is an uplink time slot. In the present technology, the uplink time slot and the downlink time slot are not fixed, and are selected as needed.
终端选择窄带子时隙的方法：终端根据接收到的基站信号功率选择窄带子时隙，接收信号功率较高时，选择序号较大的窄带子时隙。一个例子：终端接收到的基站信号功率大于等于-90dBm时，选择窄带子时隙3；大于等于-120dBm小于-90dBm时，选择窄带子时隙2；小于-120dBm时，选择窄带子时隙1。The method for selecting a narrowband subslot by the terminal: the terminal selects a narrowband subslot according to the received base station signal power, and when the received signal power is high, selects a narrowband subslot with a larger sequence number. An example: when the base station signal power received by the terminal is greater than or equal to -90 dBm, the narrowband subslot 3 is selected; when the greater than or equal to -120 dBm is less than -90 dBm, the narrowband subslot 2 is selected; when less than -120 dBm, the narrowband subslot 1 is selected. .
在窄带时隙同步信息最大重发间隔内，基站向终端发送窄带时隙同步信息的方法为下列三种方法中一种或多种：In the maximum retransmission interval of the narrowband slot synchronization information, the method for the base station to send the narrowband slot synchronization information to the terminal is one or more of the following three methods:
(1)在窄带时隙同步帧中发送窄带时隙同步信息；(1) transmitting narrowband slot synchronization information in a narrowband slot synchronization frame;
(2)在下行应答帧中携带窄带时隙同步信息，即在下行应答帧中，发送应答信息之外，还顺带发送窄带时隙同步信息；(2) carrying the narrowband slot synchronization information in the downlink response frame, that is, transmitting the narrowband slot synchronization information in addition to the response information in the downlink response frame;
(3)在下行数据帧中携带窄带时隙同步信息，即在下行数据帧中，发送下行数据之外，还顺带发送窄带时隙同步信息；(3) carrying the narrowband slot synchronization information in the downlink data frame, that is, transmitting the downlink data in the downlink data frame, and transmitting the narrowband slot synchronization information along the way;
作为一种更优的实施例，发送窄带时隙同步信息的窄带时隙同步帧、下行应答帧和下行数据帧采用最大扩频倍数进行扩频，这种方式可以保证基站覆盖范围内的所有终端都能接收 到窄带时隙同步信息。一个例子：发送窄带时隙同步信息的窄带时隙同步帧、下行应答帧和下行数据帧采用扩频因子12。As a more preferred embodiment, the narrowband slot synchronization frame, the downlink response frame, and the downlink data frame that transmit the narrowband slot synchronization information are spread by using a maximum spreading multiple, which can ensure all terminals in the coverage of the base station. Both narrowband slot synchronization information can be received. An example: a narrowband slot synchronization frame, a downlink response frame, and a downlink data frame that transmit narrowband slot synchronization information employs a spreading factor of 12.
作为一种更优的实施例，下行应答帧同时对多个终端进行应答，即合并对多个终端的应答数据于一个下行应答帧内，基站发送下行应答帧的扩频倍数设为最差信号质量的终端所需要的扩频倍数，从而保证多个终端都可以收到应答数据。这种方式可以提高应答效率。一个例子：同时对三个终端应答，这三个终端分别需要的扩频因子为7、8和10，那么合并的应答帧采用扩频因子10。As a preferred embodiment, the downlink response frame simultaneously responds to multiple terminals, that is, the response data of the multiple terminals is combined in one downlink response frame, and the spreading ratio of the downlink response frame sent by the base station is set to the worst signal. The spreading factor required by the quality terminal ensures that multiple terminals can receive the response data. This way can improve the response efficiency. An example: responding to three terminals simultaneously, the three terminals need to have spreading factors of 7, 8, and 10 respectively, then the combined response frame uses a spreading factor of 10.
当终端不知道基站的工作信道的情况下，终端需要搜索基站，这个过程称为网络搜索。终端搜索基站工作信道采用的方式为：终端对基站监听时间大于窄带时隙同步信息最大重发间隔，如果收到了窄带时隙同步信息，则找到了工作信道；否则，切换下一个可能的基站工作信道继续监听；如果找到多个工作信道，则选择接收基站信号功率最强的工作信道。When the terminal does not know the working channel of the base station, the terminal needs to search for the base station, and this process is called network search. The manner in which the terminal searches for the working channel of the base station is: the terminal-to-base station listening time is greater than the maximum retransmission interval of the narrow-band time slot synchronization information, and if the narrow-band time slot synchronization information is received, the working channel is found; otherwise, the next possible base station is switched. The channel continues to listen; if multiple working channels are found, the working channel with the strongest signal power of the receiving base station is selected.
作为一种更优的实施例，为了扩展覆盖距离，除基站和终端之外，引入TDD中继，如图2所示，所述TDD中继包括用于与基站收发通讯的天线A、用于与终端收发通讯的天线B、上行放大器和下行放大器，所述天线A和天线B通过开关A和开关B切换与上行放大器或下行放大器相连，通过上行放大器和下行放大器对上行信号和下行信号进行中继放大。该中继在下行时间段，将接收自天线A的基站发送的信号放大后，通过天线B转发给终端，在上行时间段，将接收自天线B的终端发送的信号放大后，通过天线A转发给基站。As a more preferred embodiment, in order to extend the coverage distance, a TDD relay is introduced in addition to the base station and the terminal. As shown in FIG. 2, the TDD relay includes an antenna A for transmitting and receiving communication with the base station, and is used for An antenna B, an uplink amplifier, and a downlink amplifier that communicate with the terminal, and the antenna A and the antenna B are connected to the uplink amplifier or the downlink amplifier through the switch A and the switch B, and the uplink signal and the downlink signal are performed by the uplink amplifier and the downlink amplifier. Following the enlargement. The relay amplifies the signal transmitted by the base station received from the antenna A in the downlink time period, and then forwards the signal to the terminal through the antenna B, and amplifies the signal transmitted by the terminal received from the antenna B in the uplink time period, and then forwards the signal through the antenna A. To the base station.
TDD中继的上下行切换，依靠开关A和开关B，开关A和开关B均为为单刀双掷开关，下行状态，开关A和开关B连接到下行放大器，上行状态，开关A和开关B连接到上行放大器。The uplink and downlink switching of the TDD relay depends on the switch A and the switch B. The switch A and the switch B are both single-pole and double-throw switches. In the downlink state, the switch A and the switch B are connected to the downlink amplifier, and the uplink state, the switch A and the switch B are connected. Go to the upstream amplifier.
TDD中继平时工作在下行状态，通过接收来自基站的窄带时隙同步帧，或者携带窄带时隙同步信息的下行应答帧和下行数据帧，确定窄带时隙内窄带子时隙的个数，以及每个窄带子时隙的开始时间和结束时间，并在窄带时隙时间内切换到上行状态。The TDD relay normally works in a downlink state, and determines the number of narrowband sub-timeslots in the narrowband slot by receiving a narrowband slot synchronization frame from the base station or a downlink response frame and a downlink data frame carrying the narrowband slot synchronization information, and The start time and end time of each narrowband subslot, and switch to the uplink state during the narrowband slot time.
每个窄带子时隙中，多个终端向基站传输数据包，每个数据包均采用窄带单载波调制方式进行调制；如图3所示，所述终端在窄带子时隙中传输数据的格式为导频信号加上行同步序列再加编码数据序列，其中导频信号为单频率信号，上行同步序列是一个具有良好自相关特性的序列。In each narrowband subslot, multiple terminals transmit data packets to the base station, and each data packet is modulated by a narrowband single carrier modulation mode; as shown in FIG. 3, the terminal transmits data in a narrowband subslot. A pilot sequence is added to the pilot signal plus a coded data sequence, wherein the pilot signal is a single frequency signal, and the uplink synchronization sequence is a sequence with good autocorrelation properties.
所述上行同步序列和编码数据序列都采用MSK、GMSK、OQPSK、π/2-BPSK、QPSK、16QAM和64QAM中的任意一种方法调制。Both the uplink synchronization sequence and the encoded data sequence are modulated by any one of MSK, GMSK, OQPSK, π/2-BPSK, QPSK, 16QAM, and 64QAM.
终端随机选择中心频率发射上行数据，从而保证多个终端的中心频率尽可能相互错开。The terminal randomly selects the center frequency to transmit uplink data, thereby ensuring that the center frequencies of the multiple terminals are staggered as much as possible.
基站在窄带子时隙，检测终端发送的导频信号，并根据该导频信号获取终端的子信道中心频率，具体获取方法为：基站对所有天线接收到的导频信号做J点傅里叶变换记为矢量S
i，S
i代表第i个天线支路的傅里叶变换结果，将每个天线接收的傅里叶变换结果取绝对值再进行平方，之后将所有天线支路的结果相加记为
其中，ABS
2(S
i)表示将S
i中的所有元素取绝对值后再平方；然后根据系统设定的门限值，判断出E中的峰值的位置，记为n
1,n
2…,n
K，K为被检测出的峰值个数，每个峰值对应一个发射信号的终端，之后根据下面公式得到各终端的子信道中心频率；
f
s为系统采样率，得到各个终端的子信道中心频率记为f
1,f
2…,f
K。
The base station detects the pilot signal sent by the terminal in the narrowband subslot, and acquires the center frequency of the subchannel according to the pilot signal. The specific acquisition method is: the base station performs the J point Fourier on the pilot signal received by all the antennas. The transform is denoted as vector S i , S i represents the Fourier transform result of the ith antenna branch, and the Fourier transform result received by each antenna is taken as an absolute value and then squared, and then the results of all antenna branches are phased. Add as Wherein, ABS 2 (S i ) means that all elements in S i are taken as absolute values and then squared; then, according to the threshold value set by the system, the position of the peak in E is judged as n 1 , n 2 ... , n K , K is the number of detected peaks, each peak corresponds to a terminal transmitting a signal, and then the subchannel center frequency of each terminal is obtained according to the following formula; f s is the system sampling rate, and the subchannel center frequencies of the respective terminals are obtained as f 1 , f 2 ..., f K .
基站对终端进行信道估计的方法如下：The method for the base station to perform channel estimation on the terminal is as follows:
根据第k个终端对应在E中峰值的位置n
k，k＝1,2,…,K，k为自然数，对所有天线支路的傅里叶变换结果：S
1,S
2,…S
M，取第n
k个元素，并合并为矢量h
k，即为终端k对基站各天线的信道响应，
h
k维度为：M行，1列，M为基站接收天线数，
表示矢量S
i的第n
k个元素。
The k-th terminal corresponding to peaks in the E position n k, k = 1,2, ... , K, k is a natural number, the Fourier transformation result of all antenna branches: S 1, S 2, ... S M Taking the nthth element and combining them into a vector h k , which is the channel response of the terminal k to each antenna of the base station. The h k dimension is: M rows, 1 column, and M is the number of base station receiving antennas. It represents n k th element of the vector S i is.
基站对终端进行波束成形接收过程中，根据此终端的信道响应采用共轭、迫零或者最小均方误差方法进行波束赋形，从而实现对多个终端的MIMO接收。During the beamforming reception process of the terminal, the base station performs beamforming by using a conjugate, zero-forcing or minimum mean square error method according to the channel response of the terminal, thereby implementing MIMO reception on multiple terminals.
基站对波束成形接收的终端信号进行窄带滤波，恢复其发送信号。The base station performs narrowband filtering on the terminal signal received by the beamforming to recover its transmission signal.
以上所述为本发明的最佳实例，并未对本发明作任何形式上的限制，凡是依据本发明的技术实质对以上实例所作的任何简单修改、等同变化与修饰，均落入本发明的保护范围之内。The above is a preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes and modifications made to the above examples in accordance with the technical spirit of the present invention fall within the protection of the present invention. Within the scope.
Claims (17)
- 一种结合扩频和窄带MIMO的时分双工通信系统，其特征在于，包括：A time division duplex communication system combining spread spectrum and narrowband MIMO, characterized in that it comprises:基站，所述基站设有多个天线，下行时，基站采用扩频通信技术单天线发送信号，上行时，基站采用窄带MIMO技术多天线接收信号；a base station, the base station is provided with a plurality of antennas. When downlinking, the base station uses a spread spectrum communication technology to transmit signals by a single antenna, and when uplinking, the base station uses a narrowband MIMO technology to receive signals by multiple antennas;终端，所述终端有多个，下行时，与基站对应通过扩频通信技术单天线接收信号，上行时，每个终端通过单天线向基站发送窄带信号，多个终端与基站采用窄带MIMO技术传输信号。The terminal has a plurality of terminals. When downlinking, the base station receives signals through a single antenna of a spread spectrum communication technology. When uplink, each terminal transmits a narrowband signal to a base station through a single antenna, and multiple terminals and base stations transmit by using narrowband MIMO technology. signal.
- 如权利要求1所述的时分双工通信系统，其特征在于：基站设置一个窄带时隙同步信息最大重发间隔，在该间隔时间内，基站向终端至少发送一次窄带时隙同步信息，终端在收到基站发出的窄带时隙同步信息后，确定窄带时隙内窄带子时隙的个数，以及每个窄带子时隙的开始时间和结束时间，选择一个窄带子时隙发送上行信号。The time division duplex communication system according to claim 1, wherein the base station sets a maximum retransmission interval of the narrowband slot synchronization information, and during the interval, the base station transmits the narrowband slot synchronization information to the terminal at least once, and the terminal is in the After receiving the narrowband slot synchronization information sent by the base station, determining the number of narrowband subslots in the narrowband slot, and the start time and end time of each narrowband subslot, selecting a narrowband subslot to send the uplink signal.
- 如权利要求2所述的时分双工通信系统，其特征在于：终端选择窄带子时隙的方法为：The time division duplex communication system according to claim 2, wherein the method for the terminal to select the narrowband subslot is:终端根据接收到的基站信号功率选择窄带子时隙，接收信号功率高时，选择序号大的窄带子时隙。The terminal selects a narrowband subslot according to the received base station signal power, and when the received signal power is high, selects a narrowband subslot with a large sequence number.
- 如权利要求2所述的时分双工通信系统，其特征在于：在窄带时隙同步信息最大重发间隔内，基站采用下列方法中一种或多种向终端至少发送一次窄带时隙同步信息：The time division duplex communication system according to claim 2, wherein in the maximum retransmission interval of the narrowband slot synchronization information, the base station transmits the narrowband slot synchronization information to the terminal at least once by using one or more of the following methods:(1)在窄带时隙同步帧中发送窄带时隙同步信息；(1) transmitting narrowband slot synchronization information in a narrowband slot synchronization frame;(2)在下行应答帧中携带窄带时隙同步信息，即在下行应答帧中，发送应答信息之外，还顺带发送窄带时隙同步信息；(2) carrying the narrowband slot synchronization information in the downlink response frame, that is, transmitting the narrowband slot synchronization information in addition to the response information in the downlink response frame;(3)在下行数据帧中携带窄带时隙同步信息，即在下行数据帧中，发送下行数据之外，还顺带发送窄带时隙同步信息。(3) Carrying narrowband slot synchronization information in the downlink data frame, that is, transmitting downlink data in the downlink data frame, and transmitting the narrowband slot synchronization information in the same direction.
- 如权利要求4所述的时分双工通信系统，其特征在于：发送窄带时隙同步信息的窄带时隙同步帧、下行应答帧和下行数据帧采用最大扩频倍数进行扩频。The time division duplex communication system according to claim 4, wherein the narrowband slot synchronization frame, the downlink response frame, and the downlink data frame for transmitting the narrowband slot synchronization information are spread using a maximum spreading multiple.
- 如权利要求4所述的时分双工通信系统，其特征在于：下行应答帧同时对多个终端进行应答，即合并对多个终端的应答数据于一个下行应答帧内，基站发送下行应答帧的扩频倍数设为最差信号质量的终端所需要的扩频倍数。The time division duplex communication system according to claim 4, wherein the downlink response frame simultaneously responds to the plurality of terminals, that is, the response data for combining the plurality of terminals is in a downlink response frame, and the base station transmits the downlink response frame. The spreading factor is set to the spreading factor required by the terminal with the worst signal quality.
- 如权利要求2所述的时分双工通信系统，其特征在于：终端搜索基站工作信道采用的方式为：终端对基站监听时间大于窄带时隙同步信息最大重发间隔，如果收到了窄带时隙同步信息，则找到了工作信道；否则，切换下一个可能的基站工作信道继续监听；如果找到多个工作信道，则选择接收基站信号功率最强的工作信道。The time division duplex communication system according to claim 2, wherein the manner in which the terminal searches for the working channel of the base station is: the terminal to base station listening time is greater than the maximum retransmission interval of the narrowband slot synchronization information, if the narrowband slot synchronization is received. Information, the working channel is found; otherwise, the next possible base station working channel is switched to continue to listen; if multiple working channels are found, the working channel with the strongest signal power of the receiving base station is selected.
- 如权利要求2所述的时分双工通信系统，其特征在于：还包括TDD中继，所述TDD中继包括用于与基站收发通讯的天线A、用于与终端收发通讯的天线B、上行放大器和下行放大器，所述天线A和天线B通过开关A和开关B切换与上行放大器或下行放大器相连，通过上行放大器和下行放大器对上行信号和下行信号进行中继放大，TDD中继平时工作在下行状态，通过接收来自基站的窄带时隙同步帧，或者携带窄带时隙同步信息的下行应答帧和下行数据帧，确定窄带子时隙的个数，以及每个窄带子时隙的开始时间和结束时间，并在窄带时隙时间内切换到上行状态。The time division duplex communication system according to claim 2, further comprising a TDD relay, wherein the TDD relay includes an antenna A for transmitting and receiving communication with the base station, an antenna B for transmitting and receiving communication with the terminal, and uplink. The amplifier and the downlink amplifier, the antenna A and the antenna B are connected to the uplink amplifier or the downlink amplifier through the switch A and the switch B, and the uplink signal and the downlink signal are relay-amplified by the uplink amplifier and the downlink amplifier, and the TDD relay works normally in the In the downlink state, by receiving a narrowband slot synchronization frame from the base station, or a downlink response frame and a downlink data frame carrying the narrowband slot synchronization information, determining the number of narrowband subslots and the start time of each narrowband subslot End time and switch to the upstream state during the narrowband slot time.
- 如权利要求2所述的时分双工通信系统，其特征在于：每个窄带子时隙中，多个终端向基站传输数据包，每个数据包均采用窄带单载波调制方式进行调制；所述终端在窄带子时隙中传输数据的格式为导频信号加上行同步序列再加编码数据序列，其中导频信号为单频率信号，上行同步序列是一个具有良好自相关特性的序列。The time division duplex communication system according to claim 2, wherein each of the narrowband subslots transmits a data packet to the base station, and each data packet is modulated by a narrowband single carrier modulation mode; The format of the data transmitted by the terminal in the narrowband sub-timeslot is a pilot signal plus a line synchronization sequence plus an encoded data sequence, wherein the pilot signal is a single frequency signal, and the uplink synchronization sequence is a sequence with good autocorrelation properties.
- 一种结合扩频和窄带MIMO的时分双工通信方法，其特征在于：下行时，基站采用扩频通信技术向终端发送信号，基站和终端均采用单天线收发；上行时，基站采用窄带MIMO技术接收终端发出的信号，多个终端组成发射端的多天线，基站采用多天线接收。A time division duplex communication method combining spread spectrum and narrowband MIMO is characterized in that: in downlink, the base station uses a spread spectrum communication technology to transmit signals to the terminal, and the base station and the terminal both use a single antenna to transmit and receive; when uplinking, the base station uses narrowband MIMO technology Receiving signals from the terminal, multiple terminals form multiple antennas at the transmitting end, and the base station receives multiple antennas.
- 如权利要求10所述的时分双工通信方法，其特征在于：基站设置一个窄带时隙同步信息最大重发间隔，在该间隔时间内，基站向终端至少发送一次窄带时隙同步信息，终端在收到基站发出的窄带时隙同步信息后，确定窄带时隙内窄带子时隙的个数，以及每个窄带子时隙的开始时间和结束时间，选择一个窄带子时隙发送上行信号。The time division duplex communication method according to claim 10, wherein the base station sets a maximum retransmission interval of the narrowband slot synchronization information, in which the base station transmits the narrowband slot synchronization information to the terminal at least once, and the terminal is in the After receiving the narrowband slot synchronization information sent by the base station, determining the number of narrowband subslots in the narrowband slot, and the start time and end time of each narrowband subslot, selecting a narrowband subslot to send the uplink signal.
- 如权利要求11所述的时分双工通信方法，其特征在于：终端选择窄带子时隙的方法为：The time division duplex communication method according to claim 11, wherein the method for selecting a narrowband subslot by the terminal is:终端根据接收到的基站信号功率选择窄带子时隙，接收信号功率高时，选择序号大的窄带子时隙。The terminal selects a narrowband subslot according to the received base station signal power, and when the received signal power is high, selects a narrowband subslot with a large sequence number.
- 如权利要求11所述的时分双工通信方法，其特征在于：在窄带时隙同步信息最大重发间隔内，基站采用下列方法中一种或多种向终端至少发送一次窄带时隙同步信息：The time division duplex communication method according to claim 11, wherein in the maximum retransmission interval of the narrowband slot synchronization information, the base station transmits the narrowband slot synchronization information to the terminal at least once by using one or more of the following methods:(1)在窄带时隙同步帧中发送窄带时隙同步信息；(1) transmitting narrowband slot synchronization information in a narrowband slot synchronization frame;(2)在下行应答帧中携带窄带时隙同步信息，即在下行应答帧中，发送应答信息之外，还顺带发送窄带时隙同步信息；(2) carrying the narrowband slot synchronization information in the downlink response frame, that is, transmitting the narrowband slot synchronization information in addition to the response information in the downlink response frame;(3)在下行数据帧中携带窄带时隙同步信息，即在下行数据帧中，发送下行数据之外，还顺带发送窄带时隙同步信息。(3) Carrying narrowband slot synchronization information in the downlink data frame, that is, transmitting downlink data in the downlink data frame, and transmitting the narrowband slot synchronization information in the same direction.
- 如权利要求13所述的时分双工通信方法，其特征在于：下行应答帧同时对多个终端进行应答，即合并对多个终端的应答数据于一个下行应答帧内，基站发送下行应答帧的扩频倍数设为最差信号质量的终端所需要的扩频倍数。The time division duplex communication method according to claim 13, wherein the downlink response frame simultaneously responds to the plurality of terminals, that is, the response data of the plurality of terminals is combined in one downlink response frame, and the base station transmits the downlink response frame. The spreading factor is set to the spreading factor required by the terminal with the worst signal quality.
- 如权利要求11所述的时分双工通信方法，其特征在于：终端搜索基站工作信道采用的方式为：终端对基站监听时间大于窄带时隙同步信息最大重发间隔，如果收到了窄带时隙同步信息，则找到了工作信道；否则，切换下一个可能的基站工作信道继续监听；如果找到多个工作信道，则选择接收基站信号功率最强的工作信道。The time division duplex communication method according to claim 11, wherein the method for the terminal to search for the working channel of the base station is: the terminal to base station listening time is greater than the maximum retransmission interval of the narrowband time slot synchronization information, if the narrowband time slot synchronization is received. Information, the working channel is found; otherwise, the next possible base station working channel is switched to continue to listen; if multiple working channels are found, the working channel with the strongest signal power of the receiving base station is selected.
- 如权利要求11所述的时分双工通信方法，其特征在于：基站和终端之间通讯还通过TDD中继，所述TDD中继包括用于与基站收发通讯的天线A、用于与终端收发通讯的天线B、上行放大器和下行放大器，所述天线A和天线B通过开关A和开关B切换与上行放大器或下行放大器相连，通过上行放大器和下行放大器对上行信号和下行信号进行中继放大，TDD中继平时工作在下行状态，通过接收来自基站的窄带时隙同步帧，或者携带窄带时隙同步信息的下行应答帧和下行数据帧，确定窄带子时隙的个数，以及每个窄带子时隙的开始时间和结束时间，并在窄带时隙时间内切换到上行状态。The time division duplex communication method according to claim 11, wherein the communication between the base station and the terminal is further performed by TDD relay, and the TDD relay includes an antenna A for transmitting and receiving communication with the base station, and is used for transmitting and receiving with the terminal. The antenna B, the uplink amplifier and the downlink amplifier of the communication, the antenna A and the antenna B are connected to the uplink amplifier or the downlink amplifier through the switch A and the switch B, and the uplink signal and the downlink signal are relay-amplified by the uplink amplifier and the downlink amplifier. The TDD relay normally works in a downlink state, and determines the number of narrowband sub-timeslots and each narrowband by receiving a narrowband slot synchronization frame from the base station or a downlink response frame and a downlink data frame carrying narrowband slot synchronization information. The start time and end time of the time slot, and switch to the uplink state during the narrowband time slot.
- 如权利要求11所述的时分双工通信方法，其特征在于：每个窄带子时隙中，多个终端向基站传输数据包，每个数据包均采用窄带单载波调制方式进行调制；所述终端在窄带子时隙中传输数据的格式为导频信号加上行同步序列再加编码数据序列，其中导频信号为单频率信号，上行同步序列是一个具有良好自相关特性的序列。The time division duplex communication method according to claim 11, wherein each of the narrowband subslots transmits a data packet to the base station, and each data packet is modulated by a narrowband single carrier modulation mode; The format of the data transmitted by the terminal in the narrowband sub-timeslot is a pilot signal plus a line synchronization sequence plus an encoded data sequence, wherein the pilot signal is a single frequency signal, and the uplink synchronization sequence is a sequence with good autocorrelation properties.
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