JPH0865780A - Time division multiple access frame synchronizing device - Google Patents

Abstract

PURPOSE: To exclude reception waves provided with propagation delay larger than the detection accuracy of a phase comparison means for detecting a time division multiple access frame phase difference from the input of a mutual synchronization means. CONSTITUTION: Time division multiple access frame phase difference signals for the past (k) times are stored in a history storage means 102-i. When the time division multiple access frame phase difference signal is received, a delay wave detection means 101-i stores it in a register Reg i(0) inside the history storage means 102-i and a delay wave judgement means 103-i checks values held in the registers Reg i(0) to Reg i(-k) of (k+1) stages inside the history storage means 102-i. When all the values of the registers inside the history storage means 102-i are the same value different from '0', the delay wave judgement means 103-i outputs a base station identification number (i).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which a plurality of base stations are connected to a plurality of mobile stations in a time division multiplex access.
The present invention relates to a time division multiple access frame synchronizer that synchronizes the phases of TDMA frames transmitted from all base stations and mobile stations that can communicate with each other in a wireless communication system that performs bidirectional communication using the cess (TDMA) method.

[0002]

2. Description of the Related Art The TDMA method is a method of performing communication between predetermined stations for each frame in units of a fixed length frame, and it is necessary to prevent TDMA signals from overlapping in time within the frame. There is. Figure 4 shows TDM
It is a figure which shows an example which compared the asynchronous state (refer FIG. 4 (1)) of A frame, and the synchronous state (refer FIG. 4 (2)).
In FIG. 4 (1), four stations A to D can communicate with each other, but there are many times when there is no TDMA signal on the time axis, and the frequency utilization rate deteriorates. On the other hand, in FIG. 4B, 6 stations A to F can communicate. As described above, when the TDMA frame is in the synchronous state, the frequency utilization rate is improved as compared with the asynchronous state.

FIG. 5 is a schematic diagram showing a state in which a mobile station moves across a plurality of zones. First, a state in which a mobile station is performing wireless TDMA communication in zone 1 while maintaining TDMA frame synchronization with base station 1 (step T1).
Then, if the mobile station moves to zone 2 and communicates with the base station 2 (step T2), if the TDMA frame of the base station 1 and the TDMA frame of the base station 2 are not synchronized, the mobile station moves. The station has to regain TDMA frame synchronization with the base station 2 (step T3). Therefore, the base station 1
By synchronizing the TDMA frame of the base station 2 with the TDMA frame of the base station 2,
The MA frame synchronization is reestablished instantly, and quick zone switching is possible. Therefore, also in this case, it is necessary to synchronize the TDMA frames of the base stations with each other.

FIG. 6 is a block diagram showing a conventional configuration example of a mutual synchronizing means for synchronizing TDMA frames between base stations. In addition, it is assumed that there are n inputs of the reception time of the reception signal from the base station in each neighboring zone.
In FIG. 6, the oscillation frequency of the frequency variable oscillation means 503 is changed by the output signal Y of the weighted average means 502. The output of the frequency variable oscillating means 503 becomes the signal transmission time of its own station as it is, and the phase comparing means 501-1 to 50-1
It is fed back to 1-n.

Phase comparing means 501-1 to 501-n
Calculates the time difference between the reception time of the reception signal from another base station and the signal transmission time of the own station, and uses this as the TDMA frame phase difference between the transmission signal of the own station and the reception signal. FIG.
An example of the TDMA frame phase difference between the transmission signal of the own station (zone 1) and the reception signals from the base stations of the neighboring zones 2 to 4 is shown. Each phase comparison means 501-1 to 501-n
TDMA frame phase difference signals φ _{1 to} φ output from
_n is input to the weighted average means 502.

FIG. 8 is a block diagram showing an example of the configuration of the weighted averaging means 502. The TDMA frame phase difference signal with respect to the reception time of the reception signal from the i-th other base station is φ _i . Each weight coefficient register 505-1 to 505-
n stores the weight for each TDMA frame phase difference signal, and when the TDMA frame phase difference signals are equally averaged, each weight coefficient register 505-1 to 505.
Set the weighting factor for -n to (1 / n). Each TDMA frame phase difference signal φi is supplied to each multiplier 504-1 to 504.
After being multiplied by the weighting coefficient at −n, the signal is input to the adder 506 as the signal X _i . The output signal Y of the adder 506 is input to the frequency variable oscillation means 503 shown in FIG.

The mutual synchronization means shown in FIG. 6 requests the reception time of the reception signal from another base station as an input, but these reception signals do not necessarily have to be signals dedicated to TDMA frame synchronization. FIG. 9 is a schematic diagram showing an example in which a large number of inputs are input from the neighboring zones 2 to 10 to the own station (zone 1). In FIG. 9, a signal transmitted from a base station in zone 2 to a mobile station in zone 2 can be received by the base station in zone 1 as an input of the mutual synchronization means if the base station in zone 1 can receive the signal. It is available. Similarly,
If the signals from zones 3 to 10 can be received by the base stations in zone 1 in addition to zone 2, the number of inputs of the mutual synchronization means of the base stations in zone 1 will be nine.

By the way, a reference time is set for each frame period of the TDMA frame, and, for example, the reference time and A
The time difference from the signal transmitted by the station will be called the absolute phase of station A. Hereinafter, the same applies to the absolute phases of other stations. FIG. 10 is a diagram for explaining the absolute phase.
Further, FIG. 11 is a diagram showing an example of a process in which the mutual synchronization means performs phase synchronization. In FIG. 11, the vertical axis represents the absolute phase and the horizontal axis represents the elapsed time. Also, FIG. 10 and FIG.
In the above, in order to simplify the explanation, the weighted average is a uniform average, and the number of stations is three stations A to C. Since the mutual synchronization means does not have a TDMA frame phase which is a time reference common to all base stations, the absolute phase of each station cannot be observed and only the relative phase difference between the stations can be detected.

In FIG. 11, at time 0, the three stations A to C are in an asynchronous state, and there is a phase difference between the stations. At the beginning, when the station A reaches the phase correction time, the mutual synchronization means of the station A evenly averages the frame phase differences between the transmission signal of the station B and the transmission signal of the station C to perform its own phase correction. The TDMA frame phase of the station is modified to be intermediate between the TDMA frame phase of the B station and the TDMA frame phase of the C station. Next, when the station B reaches the phase correction time, the TDMA frame phase of the station B is corrected to an intermediate point between the TDMA frame phase of the station A and the TDMA frame phase of the station C, as in the case described above. Below, the phases are corrected in order,
After a sufficient time has elapsed, the TDMA frame phase of each station is synchronized and transmission / reception is performed with the same TDMA frame phase.

[0010]

By the way, in the above description of the operation of the conventional TDMA frame synchronizer,
Time from when one base station transmits a TDMA frame until when another base station receives it, that is, TDMA between base stations
It is assumed that the propagation delay time of the frame is 0. However, actually, it takes a finite time to propagate the TDMA frame between the base stations. Therefore, if the phase comparison unit 501 has detection accuracy capable of detecting a time interval as close as possible to 0, the detected TDMA frame phase difference includes the propagation delay time between the base stations of the TDMA frame. It will be.

Generally, in wireless TDMA communication, TD
Since the time required for a radio signal such as an MA frame to propagate between base stations is shorter than the TDMA frame phase difference detected by the phase comparison means 501 in each base station, T
It is not necessary to consider the propagation delay time within the DMA frame phase difference. However, when the propagation delay time is long due to the large distance between the base stations or when the detection accuracy of the phase comparison unit 501 is high, the propagation delay time of the TDMA frame becomes larger than the detection accuracy of the phase comparison unit 501. As a result, the TDMA frame phase difference detected by the phase comparison means 501 is equal to the actual TDMA frame phase difference by TDMA.
It becomes the value which added the frame propagation delay time.

As an example, consider wireless TDMA communication in an environment as shown in FIG. The base stations are arranged in a grid, and the distance between adjacent base stations is L.
(M). Also, the shaded area in FIG. 12 is a building made of a material that does not allow radio signals to pass therethrough, and therefore radio signals can be propagated only along roads. Each base station has the mutual synchronization means shown in FIG. 6, and detects the TDMA frame phase difference and the base station identification number that transmitted the TDMA frame.

At this time, δ (s): detection accuracy of the phase comparison means 501, v (m / s): propagation velocity of a radio signal, L (m) / v (m / s) <δ (s) ... In the case of (Equation 1), the propagation delay time of the radio signal is the phase comparison means 5
Since it is smaller than the detection accuracy of 01, the propagation delay time of the radio signal is not included in the TDMA frame phase difference and is not detected. However, in the case of L (m) / v (m / s)> δ (s) …………………… (Equation 2), the phase comparison means 501 causes the propagation delay time of the radio signal. Is detected as a part of the TDMA frame phase difference.

For the above reasons, the actual TDMA
When the propagation delay time of the radio signal is added to the frame phase difference and the detected TDMA frame phase difference is larger than the actual value, how does this affect the synchronization of the TDMA frame between the radio stations? Is shown using FIGS. In FIG. 13, the phase synchronization of the TDMA frame between the base stations is performed by the same method as shown in FIG. The difference from FIG. 11 is that the propagation delay time of the radio signal is included in the absolute phase of the received TDMA frame. At the correction time of station A shown in FIG. 13, the average value of the two phase differences is calculated by the TDMA frame phase difference between stations A and B and the TDMA frame phase difference between stations A and C. Then, a value obtained by subtracting the average value from the current TDMA frame absolute phase of station A is set as the corrected TDMA frame absolute phase of station A.

At this time, the TD between station B and station C and station A
Since the MA frame phase difference is larger than the actual value by the propagation delay time, the average value thereof is also larger by the propagation delay time. Since this average value becomes the correction value as it is, the absolute phase of the TDMA frame of the station A is corrected in the direction of becoming excessively small. The same applies to the phase correction of the B station and the C station. As a result, the absolute phase of each station continues to decrease as shown in FIG. 14, and the synchronization of the TDMA frame is not established.

The present invention has been made under such a background, and excludes a received wave including a propagation delay time larger than the detection accuracy of the phase comparison means for detecting the TDMA frame phase difference from the input of the mutual synchronization means. With the aim of doing so, it is an object of the present invention to provide a TDMA frame synchronizer capable of specifying a base station identification number corresponding to the received wave.

[0017]

According to the first aspect of the present invention,
A time division multiple access frame between a time division multiple access frame transmitted by a predetermined wireless station performing wireless communication by the time division multiple access system and a time division multiple access frame transmitted by a wireless station different from the predetermined wireless station. With respect to the phase difference, the presence or absence of a propagation delay time required for signal propagation between the predetermined wireless station and a wireless station different from the predetermined wireless station is determined, and the predetermined wireless station is determined based on the determination result. In a time division multiplex connection frame synchronization device for selecting a phase correction method for a time division multiplex connection frame transmitted by, the phase comparison means for detecting the time division multiple connection frame phase difference, and the time division detected by the phase comparison means. History storage means for storing history of phase difference of multiple connection frame, latest value of time division multiple connection frame phase difference and time division multiple connection frame in the history storage means If the history of the phase difference is the same value that is different from all 0, it is provided with a delay wave determination means for determining that the latest value of the time division multiplex connection frame phase difference includes the propagation delay time. Is characterized by.

According to a second aspect of the present invention, in the time division multiple access frame synchronization device according to the first aspect, the predetermined wireless station and the wireless station different from the predetermined wireless station are respectively uniquely identified. A transmission signal having a number and including the identification number in the transmission signal, and the delay wave determination means determines that the propagation delay time is included in the time division multiple access frame phase difference. It is characterized in that the identification number of the wireless station that has transmitted the division multiple access frame is output.

[0019]

According to the first aspect of the present invention, the history storage means stores the history of the time division multiple access frame phase difference, and the delayed wave determining means stores the latest value of the time division multiple access frame phase difference and the history storage means. From the history of the time division multiple access frame phase difference, it is determined whether or not the latest value of the time division multiple access frame phase difference includes the propagation delay time of the radio signal. It can be determined that the propagation delay time of the signal is included.

According to the second aspect of the present invention, each radio station has a unique identification number, and the transmission signal includes the identification number for transmission, and the delay wave determination means uses the time division multiple access frame position. It outputs the identification number of the wireless station that transmitted the time division multiple access frame that was determined to include the propagation delay time in the phase difference. It is possible to specify the wireless station that has transmitted the time division multiple access frame determined to include time.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. Note that the technical contents of the present invention will be described before entering into specific examples. Consider propagation of a radio signal between two stations. The two stations are separated by a distance d [m], and when the propagation speed of the radio signal is v, the propagation delay time τ when the radio signal propagates between the two stations is d / v (s). When the apparent TDMA frame phase difference detected by the phase comparison means of each station is ΔΦ and the actual TDMA frame phase difference is Δφ, ΔΦ = Δφ + τ ……………………………………………………………… ……… (Equation 3) If the time variation of τ is small and Δφ → 0 at t → ∞, ΔΦ → τ. Thus, the TDMA frame phase difference detected by each base station can be monitored, and a received wave whose value is constantly a constant value different from 0 can be identified as a received wave to which a delayed wave is added. It will be possible.

Even when a large number of stations exist and are communicating with each other, the TDMA frame phase difference can be monitored individually by including the identification number unique to each station in the transmission signal. It is possible to specify the wireless station that is transmitting the received wave to which the delayed wave is added.

FIG. 1 shows a TDMA according to an embodiment of the present invention.
It is a block diagram showing the structure of a frame synchronization device. In this figure, parts corresponding to the parts in FIG. 6 are assigned the same reference numerals and explanations thereof are omitted. In the TDMA frame synchronizer shown in this figure, the delayed wave detecting means 101-1
-10-n are newly provided. The structure of the delayed wave detecting means 101-i is shown in FIG. In this figure, 10
2-i is a history storage means, which stores the outputs of the phase comparison means 501-i up to the present and past k times by using shift registers Reg i (0) to Regi (-k) of k + 1 stages.

103-i is a delay wave determination means, which is a CP
U (Central Processing Unit), ROM (Read Only Memory) for incorporating control programs, RAM for work
(Random access memory).
Based on the contents of the history storage means 102-i, it is determined whether or not there is a propagation delay time within the TDMA frame phase difference detected by the phase comparison means 501-i.

Details of the operation of the delayed wave determining means 103-i will be described with reference to FIG. The history storage means 102 stores the TDMA frame phase difference signal output from the phase comparison means 501-i.
Store in register Reg i (0) in -i. When the values stored in the registers Reg i (0) to Reg i (-k) are all the same value and the values are not 0, the TDMA frame phase difference output by the phase comparison unit 501-i. Is determined to include the propagation delay time, and the base station identification number i is output. After judgment, Reg i (0)
Move the contents of Reg i (-1) to ... Reg i (-
Move the contents of k-2) to Reg i (-K-1), Re
The contents of g i (−k−1) are moved to Reg i (−K), and the contents of the history storage unit 102-i are shifted one step at a time.

Next, the operation of the TDMA frame synchronizer having the above configuration will be described. As an example, consider wireless TDMA communication in the environment shown in FIG. 12 described above.
That is, the base stations are arranged in a grid pattern, and the distances between adjacent base stations are all L (m). Further, it is assumed that the radio signal can be propagated only along the road. When a start switch (not shown) is input, history storage means 102-1 to 102-1 to 101-n in the delayed wave detection means 101-1 to 101-n are input.
102-n is cleared and the registers of the k + 1th stage are all initialized to 0. The variable frequency transmission means 503 outputs a clock signal synchronized with the transmission signal of its own station and feeds it back to the phase comparison means 501-1 to 501-n.

When there is a received signal from the i-th base station, the clock signal synchronized with the received signal is input to the phase comparison means 501-i. Phase comparison means 501-i
Since the transmission clock signal of its own station is feedback-input to, the difference between the two inputs is output as a TDMA frame phase difference signal. This TDMA phase difference signal is input to the weighted averaging means 502 and the delayed wave detecting means 501-i. The operations of the weighted averaging means 502 and the frequency transmitting means 503 after the input of the TDMA phase difference signal are the same as those of the conventional example shown in FIG. The delay wave detecting means 101-i is TDM
When the A phase difference signal is received, it is stored in the register Reg i (0) in the history storage means 102-i.

Next, the delay wave judging means 103-i is held in the registers Reg i (0) to Reg i (-k) of the k + 1th stage in the history storing means 102-i as shown in FIG. Examine the value and check if it is the same value different from 0. If the registers Reg i (0)-
When the values of Reg i (−k) are all the same values different from 0, the delayed wave determination unit 103-i outputs the base station identification number i.

The delayed wave determination means 103-i mixes the propagation delay time with the TDMA frame phase difference between the TDMA frame received from the base station whose base station identification number is i and the TDMA frame transmitted by the local station. This is notified to a TDMA frame phase synchronization correction means (not shown), and appropriate processing is requested so that there is no TDMA frame phase synchronization failure due to the mixture of propagation delay times as shown in FIG. Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the scope of the invention. Also included in the present invention.

[0030]

As described above, according to the invention described in claim 1, the history storage means stores the history of the time division multiplex connection frame phase difference, and the delay wave determining means the time division multiplex connection frame phase difference. From the latest value of and the history of the time division multiple access frame phase difference in the history storage means, it is determined whether or not the latest value of the time division multiple access frame phase difference includes the propagation delay time of the radio signal. It can be determined that the phase difference of the division multiple access frame includes the propagation delay time of the radio signal.

According to the second aspect of the present invention, each radio station has a unique identification number, the transmission signal includes the identification number for transmission, and the delay wave determination means uses the time division multiple access frame position. It outputs the identification number of the wireless station that transmitted the time division multiple access frame that was determined to include the propagation delay time in the phase difference. It is possible to specify the wireless station that has transmitted the time division multiple access frame determined to include time.

Therefore, the method of removing the influence of the propagation delay time by removing the received wave from the radio station from the input of the mutual synchronizing means, performing the inverse phase addition and equalizing, etc. It is possible to utilize the output of the means.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a time division multiple access frame synchronizer according to an embodiment of the present invention.

FIG. 2 is a block diagram of a delay wave detecting means constituting a time division multiple access frame synchronizer according to an embodiment of the present invention.

FIG. 3 is a flow chart for explaining the operation of the delayed wave detecting means according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram comparing a state in which a time division multiple access frame is asynchronous and a state in which a time division multiple access frame is synchronized.

FIG. 5 is an explanatory diagram showing a state in which a mobile station moves across a plurality of zones.

FIG. 6 is a block diagram showing a configuration example of a conventional time division multiple access frame synchronizer.

FIG. 7 is an explanatory diagram of a time division multiple access frame phase difference.

FIG. 8 is a block diagram of a weighted averaging means that constitutes a conventional time division multiple access frame synchronizer.

FIG. 9 is an explanatory diagram showing that there are many inputs from neighboring zones.

FIG. 10 is an explanatory diagram of an absolute phase of a time division multiple access frame.

FIG. 11 is an explanatory diagram showing a phase synchronization process in the mutual synchronization means.

FIG. 12 is an explanatory diagram showing the arrangement of base stations.

FIG. 13 is an explanatory diagram of a problem of mutual synchronization means which constitutes a conventional time division multiple access frame synchronization device.

FIG. 14 is an explanatory diagram showing a time change of an absolute phase when a propagation delay time is added in a conventional time division multiple access frame synchronizer.

[Explanation of symbols]

101 ... Delayed wave detection means, 102 ... History storage means, 103 ... Delayed wave determination means, 501 ... Phase comparison means, 502 ... Weighted averaging means, 503 ... Frequency variable oscillation means, 504 ... Multiplier , 505 ... Weighting coefficient register, 506 ... Adder

Claims (2)

[Claims] 1. Between a time division multiple access frame transmitted by a predetermined wireless station performing wireless communication by the time division multiple access system and a time division multiple access frame transmitted by a wireless station different from the predetermined wireless station. With respect to the time division multiplex connection frame phase difference, it is determined whether or not there is a propagation delay time required for signal propagation between the predetermined wireless station and a wireless station different from the predetermined wireless station, and based on the determination result. In a time division multiple access frame synchronization device that selects a phase correction method for a time division multiple access frame transmitted by the predetermined wireless station, a phase comparison unit that detects the time division multiple access frame phase difference, and the phase comparison unit is History storage means for storing a history of the detected time division multiplex connection frame phase difference; and a latest value of the time division multiplex connection frame phase difference and the time division multiplex in the history storage means. If the history of the multiple connection frame phase difference is the same value that is different from all 0, the delay wave determining means for determining that the latest value of the time division multiple connection frame phase difference includes the propagation delay time. A time division multiple access frame synchronization device comprising: 2. The time division multiple access frame synchronizer according to claim 1, wherein each of the predetermined wireless station and a wireless station different from the predetermined wireless station has a unique identification number and a transmission signal thereof. The transmission including the identification number therein, the delay wave determination means, the radio that transmitted the time division multiple access frame determined to include the propagation delay time in the time division multiple access frame phase difference A time division multiple access frame synchronizer characterized by outputting an identification number of a station.