CN100359956C - Method for Realizing Synchronization and Ranging in Wireless Communication System and Implementation Device - Google Patents

Abstract

The present invention relates to a method for realizing synchronization and distance measurement in a wireless communication system, and an implementation device thereof. The method belongs to the wireless communication field. For enhancing the synchronous precision and the operation stability of the system, the present invention uses the technical scheme that a base station sends a synchronous message frame with a base station time stamp and an up channel allocation message at a nominal interval in the down direction; a terminal receives the up channel allocation message and then sends a distance measurement request message frame; the base station receives the distance measurement request message frame, and compares the arrival moment of the received distance measurement request message frame with a recorded moment to obtain the time offset adjustment value of the terminal and require the terminal to adjust own time scale counter; the terminal adjusts own time scale counter earlier one time delay than the base station. The present invention is mainly suitable for occasions of distance measurement, timing and precise synchronization between sending end base stations in the wireless communication system.

Description

Method for Realizing Synchronization and Ranging in Wireless Communication System and Implementation Device

technical field

The invention belongs to the field of wireless communication, and in particular relates to a method for realizing an air synchronization and ranging mechanism of a point-to-multipoint wireless communication system and an implementing device thereof.

Background technique

Chinese patent application, application number 01137971.5 disclosed on April 24, 2002 a method for transmitting a synchronization signal during a synchronization time slot in time-division multiplexed mobile wireless communication, using a method of determining the delay from maximum power to minimum power, Chinese patent Application, application number 00805498.3 disclosed a method for effective synchronization in a communication system on April 24, 2002, using a method of repeating sequences with the same period length for synchronization, Chinese Patent No. 96193602.9 International Publication WO97/32446 British 1997.9 .4, discloses an apparatus and method for reducing excessive time delay in a wireless communication system, and adopts a transitional base station method. The above-mentioned applications or patents have the disadvantages that the synchronization precision is not accurate enough or the structure is complicated.

Contents of the invention

In a point-to-multipoint wireless communication system, when frequency-division duplex (FDD) and time-division multiple access (TDMA) are used, a major technical challenge is to compensate for large delays, sometimes It is several orders of magnitude larger than the uplink sending burst time. In order to compensate for the large time delay, the terminals must be able to transmit timing accurately so that they can reach the base station at the beginning of the specified mini-slot. Thus, each terminal requires the following two pieces of information:

a. The global clock reference sent by the base station to all terminals;

b. The timing offset calculated by the base station for each terminal during ranging.

In order to accomplish the above tasks and overcome the deficiencies in the prior art, the present invention provides a method for realizing timing synchronization between a base station and a terminal of a point-to-multipoint wireless communication system and determining a timing offset and an implementation device thereof, so as to improve the system synchronization accuracy and operational stability.

Technical scheme of the present invention is:

A method for realizing synchronization and ranging in a wireless communication system, comprising the following steps:

The base station sends synchronization message frames with base station time stamps at nominal intervals in the downlink direction;

When the base station sends the synchronous message frame with the base station time stamp at the nominal interval in the downlink direction, when the sublayer is from the convergence sublayer to the physical sublayer, the counting state of the time stamp counter of the base station at that time is filled into the synchronous message frame timestamp field;

After receiving the synchronization message frame, the terminal replaces the value in the time stamp counter of the terminal with the value in the timestamp field in the synchronization message frame;

The base station sends an uplink channel assignment message, in which the ranging request of the terminal is required to arrive at the base station at the expected time t of the base station that is greater than twice the time delay, and the base station records this time;

The terminal receives the uplink channel allocation message, and sends a ranging request message frame at time t of the terminal;

The base station receives the ranging request message frame, compares the arrival time of the received ranging request message frame with the recorded time, and obtains the time offset adjustment value of the terminal, which is twice the delay, and the base station sends a ranging response The message is sent to the terminal, requiring the terminal to adjust its own time scale counter, that is, to subtract twice the time delay.

The stated nominal interval is 10 milliseconds.

The terminal constantly determines whether it receives the synchronization message frame within the nominal interval to determine whether it maintains synchronization with the base station at the MAC layer, otherwise it must re-establish synchronization.

The implementation device of the method for realizing synchronization and ranging in a wireless communication system includes a base station and a terminal, and the base station includes a synchronization message sending cycle timer, a synchronization message frame insertion control sending logic, a time stamp counter, multiplexing logic, and an uplink MAC frame Parsing, registers, subtractors, the cycle indicator signal of the synchronization message sending cycle timer, the fixed part of the synchronization message frame domain value, and the count value that the time scale counter counts the nominal frequency are inserted into the control sending logic as the synchronization message frame Input, synchronous message frame insertion control transmission logic according to the input to form a synchronous message frame and send it downlink through multiplexing logic, the upstream MAC frame analysis parses the upstream flow and outputs it to the register, and the value of the time stamp counter Input to the register, the input of the subtractor is the output of the register and the value of the arrival time, and the time offset value of its output is sent by other downlink frame sending timing control logic and multiplexing logic;

The terminal includes downstream analysis, a control unit, an adder and write control logic, the downstream analysis sorts out the synchronization message and the timestamp value therein from the downstream and outputs it to the control unit, and the control unit converts the timestamp value and The delay parameter adjustment value is output to the adder for addition, and the adder outputs the added value to the time stamp counter under the output control of the write control logic, and the write control logic analyzes the control requirements from the control unit and the downstream flow The control requirements are combined and output to the time scale counter through the adder.

The time scale counter is a 32-bit time scale counter.

In order to compensate for the large time delay, the terminal must be able to perform transmission timing accurately.

The ranging mechanism adopted in the present invention can make the terminal earlier than the base station by a time delay, so that the base station does not feel the delay caused by the different distances of each terminal, thereby improving the synchronization accuracy and operation stability of the system.

A good synchronization and ranging mechanism will greatly increase the length of the synchronization header of the uplink burst, greatly reduce the probability of mutual coverage of the uplink bursts of different end stations, and improve the utilization rate of the bandwidth.

By adopting the method and device of the present invention, the system synchronization requirements of the point-to-multipoint wireless communication system are met, and the expected effect is achieved. At the same time, because it does not rely on too many other devices, the structure is simple, the cost can be greatly reduced, and the product quality can be improved. Competitiveness.

Description of drawings

Figure 1 is a block diagram of the hardware implementation of the base station part

Detailed ways

A method for implementing synchronization and ranging in a wireless communication system, implemented by a base station and a terminal, includes the following steps. By sending timing synchronization messages at nominal intervals in the downlink direction, the base station creates a global clock reference. The message includes a timestamp that identifies exactly when the base station sent the message. The endpoint must compare the actual time the message was received with the timestamp and thereby adjust the local clock reference. It is assumed here that the delay introduced by the physical layer is relatively fixed. Any variation in physical layer delay must be accounted for in the guard time in the physical layer overhead.

The nominal interval for sync messages is 10ms. This makes the downlink overhead very small when the terminal quickly obtains the global clock reference.

The terminal constantly judges whether it receives a synchronization message within a specified time interval to determine whether it maintains synchronization with the base station at the MAC layer. Otherwise synchronization must be re-established.

Ranging adjusts the time offset of each terminal so that the terminals are in close proximity from the perspective of the base station. The terminal must set the initial time offset as an internal fixed delay, which is equivalent to making the terminal near the base station.

In actual work, the base station and the terminal perform ranging on the basis of maintaining synchronization, so synchronization and ranging are inseparable in actual implementation.

The implementation device of the air synchronization and ranging mechanism of the point-to-multipoint wireless communication system of the present invention is composed of the following parts:

A. Base station part: the synchronization message transmission period timer is used to control the transmission period of the synchronization message, and its period indication signal is sent to the synchronization message frame insertion control transmission logic. Here, the synchronization message frame refers to the domain value of the synchronization message frame. The invariant part is used as the input of the synchronous message frame insertion control sending logic, and a 32-bit time scale counter counts a nominal frequency, and its count value is used as the input of the synchronous message frame insertion control sending logic, and the synchronous message The frame insertion control transmission logic composes a synchronous message frame according to the input timing and sends it downlink through the multiplexing logic; the upstream MAC frame analysis analyzes the upstream flow, and when a ranging request message arrives, the ranging request arrival time register is analyzed according to the upstream MAC frame The output records the value of the 32-bit time scale counter, the input of the subtractor is the estimated time value and the value of the arrival time of the ranging request, and the output is the time offset value.

B. Terminal part: the downstream is used as the input of the downstream analysis, the output of the downstream analysis is used as the input of the synchronization message and the time stamp, the output of the synchronization message and the time stamp is directed to the control unit and the adder, and the delay parameter adjustment value is determined by the control unit Setting, the delay parameter adjustment value is used as the input of the adder, the write control logic determines the output state according to the output of the control unit and downstream analysis, the output of the write control logic is used as the input of the multiplexer, and the multiplexer is used for the 32-bit time scale counter The reset value of = time stamp + delay parameter adjustment value, the counting frequency of the 32-bit time scale counter is the nominal frequency of the same frequency as the base station.

The above devices are implemented in programmable logic circuits.

The implementation method of the air synchronization and ranging mechanism of the point-to-multipoint wireless communication system of the present invention is as follows:

Step 1: The end station periodically sends a synchronization message with the base station time stamp. Since this message needs hardware processing, when it is from the convergence sublayer to the physical sublayer, the counting status of the 32-bit time stamp counter at that time is filled in the time stamp field of the synchronization message frame.

Step 2: After the terminal receives the synchronization message frame, it is processed by hardware, and the 32-bit time stamp counter of the terminal is replaced by the value in the time stamp field in the synchronization message frame. At this moment, the value of the terminal time stamp counter has been delayed by a propagation delay and processing time compared with the base station clock counter.

Step 3: The base station sends an uplink channel allocation message, in which the ranging request of the terminal is required to arrive at the base station at time t of the base station, and the base station records the time. At the same time, note that the sending interval allocated to the ranging request is greater than twice the maximum air transmission delay and processing time. This is because the value of the time stamp counter of the terminal is one delay later than that of the base station at this time, the terminal transmits at its time t (time t of the base station + time delay), and arrives at the base station after a time delay. In this way, the actual arrival time at the base station is two delays later than the time t of the base station. Therefore, the sending interval allocated to the ranging request is greater than twice the delay.

Step 4: The terminal receives the uplink channel assignment message, and sends a ranging request message at time t of the terminal.

Step 5: The base station receives the ranging request. The ranging request frame itself does not have a time stamp field, and requires hardware processing. The time when the frame is received is compared with the original arrival time t of the terminal, and the time offset adjustment value of the terminal is obtained, which is twice the delay. The base station sends a measurement The response message is sent to the terminal, requiring the terminal to adjust its own time stamp counter, that is, to subtract twice the time delay.

Step 7: After the time scale counter value of the terminal is adjusted, its clock is actually one time delay earlier than the base station. In this way, if the base station requires the data sent by the terminal to arrive at the base station at time t2 in the uplink channel allocation frame, the terminal sends it at its own time t2 according to the instruction of the uplink channel allocation frame, and these data arrive at the base station at time t2.

In this way, the base station can not feel the delay caused by the different distances of each terminal.

The implementation of the technical solution will be further described in detail below in conjunction with the accompanying drawings and specific embodiments:

Fig. 1 is the functional block diagram of the hardware realization of the base station part. In the base station part, the synchronization message frame insertion control transmission logic is the core part, the synchronization message frame transmission period timer notifies the synchronization message frame insertion control transmission logic when the transmission time arrives, and the synchronization message frame insertion control transmission logic will synchronize the fixed part of the synchronization message frame and The value of the 32-bit time scale counter forms a downlink synchronization message frame and sends it to the multiplexing logic, and then the multiplexing logic sends it out.

The downstream analysis of the terminal sorts out the synchronization message and its timestamp value from the downstream. The synchronization message is used by the control unit to detect whether it maintains the synchronization of the MAC sublayer with the base station. The control unit analyzes the downstream to obtain the ranging from the base station. Respond to the message, and get the delay parameter adjustment value from it, the adder will add the time stamp value and the delay parameter adjustment value, and use the obtained value to complete the count value of the 32-bit time stamp counter under the control of the write control logic Amendment, write control logic to combine the control request from the control unit and the control request from the downstream analysis to complete the adjustment of the count value of the 32-bit time stamp counter, the control request from the control unit is used for initial synchronization control parameters Adjustment, the control requirements from the downstream analysis are used to adjust the control parameters in the normal operation state. In this way, under the premise of fixed message processing and propagation delay, the 32-bit time scale counter of the terminal and the 32-bit time scale counter of the base station have a relatively stable synchronization relationship.

The control unit of the terminal uses the uplink MAC frame transmission control logic to compare the count value of the time stamp counter of the terminal with the count value of the time stamp counter of the base station within the time period indicated by the specified time stamp counter value. One-way delay, because the synchronization message is downloaded to the terminal, and when its timestamp value is used as the initial value of the terminal's 32-bit time scale counter, a one-way delay has been introduced) The ranging request message is sent to the base station, and the base station records When the ranging request message is received, the base station subtracts the arrival time of the ranging request from the designated end station from the actual arrival time to obtain the time offset value of the terminal and transmits the ranging response message sent to the terminal downlink to the terminal. The terminal uses this time offset value as its delay parameter adjustment value, and adds the time stamp value of the synchronization message and the delay parameter adjustment value to adjust the 32-bit time scale counter, so that all terminals and base stations maintain spatially the same distance.

The terminal waits for the available UCD (uplink channel description message). After receiving the UCD, it will hand over the software to process, initialize the uplink channel parameters of the terminal, and wait for the synchronization message at the same time. Slot clock), after that, the terminal waits for the uplink channel assignment message sent by the base station, and the terminal starts initial ranging according to the instruction of the uplink channel assignment message, and enters terminal initialization if the ranging is successful, otherwise returns to the state of waiting for available UCD.

In addition, when the signal is lost or the initialization process is performed, the terminal needs to search the downlink channel and establish synchronization with the base station. The terminal should save its operating parameters and first restore the synchronization with the downlink channel from the stored operating parameters. If not, the terminal will continue to search all downlink channels until it obtains a valid downlink signal.

Claims (6)

1. realize in the wireless communication system synchronously and the method for range finding, it is characterized in that, comprise the following steps:

The base station sends the synchronization message frame that has the base station timestamp at down direction with nominal spacing;

After terminal is received the synchronization message frame, the numerical value in the usefulness synchronization message frame in the markers counter of the numerical value replacement terminal in timestamp territory;

The base station sends the up channel assignment messages, wherein requires the expectation t of base station of distance measurement request propagation delay in greater than the maximum empty of twice of terminal to arrive the base station constantly, writes down this moment;

Terminal is received described up channel assignment messages, sends the distance measurement request message frame constantly at the t of terminal;

The base station receives the distance measurement request message frame, the due in of the distance measurement request message frame received and the moment of described record are made comparisons, the time migration adjusted value that draws terminal is the twice time delay, the base station is sent out ranging response message and is given terminal, requires the markers counter of terminal adjustment oneself promptly to deduct the time delay of twice.

2. realize method synchronous and range finding in the wireless communication system according to claim 1, it is characterized in that, send when having the synchronization message frame of base station timestamp with nominal spacing at down direction in described base station, during to physical sublayer, base station markers counter count status is at that time being inserted the timestamp territory of synchronization message frame by convergence sub-layer.

3. realize method synchronous and range finding in the wireless communication system according to claim 1, it is characterized in that described nominal spacing is 10 milliseconds.

4. realize method synchronous and range finding in the wireless communication system according to claim 1, it is characterized in that, described terminal constantly judge whether in described nominal spacing, to receive described synchronization message frame whether judge with described base station remain on the MAC layer synchronously, otherwise must rebulid synchronously.

5. realize the device of the described method of claim 1, this device comprises base station and terminal, it is characterized in that:

Described base station comprises that synchronization message sends cycle timer, the synchronization message frame inserts control and sends logic, the markers counter, the multiple connection logic, up mac frame is resolved, register, subtracter, described synchronization message sends the cycle index signal of cycle timer, synchronization message frame thresholding standing part, the markers counter inserts the input that control sends logic to the count value that nominal frequency is counted as the synchronization message frame, the synchronization message frame inserts control and sends logical foundation input composition synchronization message frame by the descending transmission of multiple connection logic, described up mac frame is resolved described register is resolved and outputed to upstream, the value of described markers counter is input to register, the input of described subtracter is the output of described register and the value of due in, and output is time offset value;

Described terminal comprises downstream parsing, control unit, adder, markers counter and write control logic, downstream is resolved and is sorted out synchronization message and timestamp value wherein and output to control unit from downstream, control unit outputs to the adder addition with timestamp value and delay parameter adjusted value, the value that adder draws addition under the output control of write control logic outputs to the markers counter, and write control logic will require from the control of control unit and require to make up and output to the markers counter by adder from the control that downstream is resolved.

6. the device of the described method of realization claim 1 according to claim 5 is characterized in that, described markers counter is 32 markers counters.

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