JP4943050B2 - Inter-node synchronization method and node device - Google Patents

Description

  The present invention relates to an inter-node synchronization method and a node device that can realize synchronization between nodes by simple processing regardless of the installation location.

  In general, a wireless communication system includes a terminal, a base station that communicates with the terminal, and a base station controller that controls radio signals of a plurality of base stations. In order to operate highly efficient packet transmission in such a system, it is desirable to synchronize the frame timing between the base station and the base station in addition to between the terminal and the base station. This is because, for example, in a cellular system, when a terminal is at a cell boundary, signals from adjacent base stations are received together, but signals transmitted from adjacent base stations have the same frequency. If the synchronization is not achieved, the signal from the adjacent base station becomes interference, and the quality of the received signal is greatly degraded. If inter-station synchronization is established, transmission scheduling that avoids simultaneous transmission of packets between cells is possible, interference signals from other cells can be suppressed, and throughput can be improved.

As a method of synchronization between stations,
(1) A method in which each base station receives a signal from a GPS (Global Positioning System) satellite, generates a time signal synchronized with UTC (Coordinated Universal Time), and generates a transmission timing;
(2) There is a method in which a base station receives a transmission wave from another base station and corrects a transmission timing difference from the base station (see Patent Document 1 or Non-Patent Document 1). The method (2) will be described with reference to FIG. The base station X receives the transmission wave U2 of the base station Y and knows the transmission timing of the base station Y, and the base station Y receives the transmission wave U of the base station X and knows the transmission timing of the base station X. Therefore, the base station X detects the difference in transmission timing with the base station Y, and the base station Y detects the difference in transmission timing with the base station X. If each station corrects the transmission timing so that the difference between these transmission timings becomes small, the base station X and the base station Y are synchronized.

Japanese translation of PCT publication No. 2003-507957 Y. Akaiwa, H .; Andoh and T.W. Kohama, “Autonomous Decentralized Inter-Base-Station Synchronization for TDMA Microcellular Systems”, Proc. 41st IEEE Vehicular Technology Conf. , May 1991, pp. 257-262

  However, the conventional method using the GPS signal requires a GPS receiver, and the GPS satellite signal is weak, so that it is difficult to implement indoors and outdoors in unfavorable environments such as buildings. In the method of Patent Document 1 or Non-Patent Document 1, the timing of the detected other station is delayed according to the distance between the stations (hereinafter referred to as propagation delay), and thus the propagation delay needs to be corrected. However, there is no description about it.

  The present invention has been made in view of the above, and does not require any special equipment such as a GPS receiver, does not depend on the installation location, operates autonomously, and communicates even when a new node is added. An object of the present invention is to obtain an inter-node synchronization method and a node device that perform simple and stable inter-node synchronization that can synchronize the entire system.

  In order to solve the above-described problems and achieve the object, the present invention provides an inter-node synchronization method in which the first and second nodes are synchronized with each other. A first step of detecting a timing difference between the transmission timing of its own transmission pulse and the reception timing of a pulse from the partner node upon receiving a pulse indicating the transmission timing of the communication node, and a communication line with the detected timing difference as a communication line And a third step of adjusting its own pulse transmission timing so that the timing difference calculated in the first step is equal to the timing difference received from the counterpart node. Features.

  According to this invention, when the first and second nodes receive a pulse indicating the transmission timing of the counterpart node from the counterpart node, the timing difference between the transmission timing of its own transmission pulse and the reception timing of the pulse from the counterpart node And the detected timing difference is transmitted to the partner node via a communication line, and synchronization is performed by adjusting its own pulse transmission timing so that the calculated timing difference is equal to the timing difference received from the partner node. To achieve this, no special equipment such as a GPS receiver is required. Synchronization between stations can be achieved anywhere, indoors or outdoors. There is an effect that synchronization can be performed.

  Embodiments of an inter-node synchronization method and a node device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a base station when a base station is adopted as a node apparatus to which the present invention is applied. Base station A and base station B are any two of a number of base stations. Here, an example of a synchronization method between two stations is shown. The base station A receives the signal transmitted from the other station such as the base station B, and calculates the timing difference Tab between the signal reception timing from the base station B and the signal transmission timing of the own station A. Using the difference calculation unit 11 and the calculation result of the timing difference calculation unit 11, the timing correction amount calculation unit 12 that calculates the correction amount of the transmission timing of the own station A, and the transmission signal generation that generates the data to be transmitted by the own station And a signal transmission unit 14 for transmitting the transmission data of the own station and transmitting the timing difference Tab calculated by the timing difference calculation unit 11 to the base station B. The base station B has the same configuration.

  Next, a timing adjustment method for inter-station synchronization will be described with reference to FIG. The base station A transmits a pulse Ua indicating the transmission timing of the own station A, and the base station B2 transmits a pulse Ub indicating the transmission timing of the own station B. Base station A receives pulse Ub, and base station B2 receives pulse Ua. The pulse Ub is received at the base station A with the propagation delay Tpd as shown in FIG. 2, and the pulse Ub is received at the base station B with the propagation delay Tpd as shown in FIG.

  The base station A receives the pulse Ub and calculates a timing difference Tab between its own transmission pulse Ua and the reception pulse Ub. The base station B receives the pulse Ua and calculates the timing difference Tba between its own transmission pulse Ub and the reception pulse Ua.

  The timing differences Tab and Tba calculated in this way are transmitted to the base station B and Tba to the base station A using the communication line set between the base station A and the base station B, respectively. Is done. The communication line may be a wired line or a wireless line.

  The base station A corrects the pulse transmission timing of the base station A so that the timing difference Tab calculated by itself is equal to the timing difference Tba transmitted from the base station B. The base station B corrects the pulse transmission timing of the base station B itself so that the Tba calculated by the base station B is equal to the Tab transmitted from the base station A.

  Specifically, in the base station A, Tab−Tba = M, when M> 0, the pulse transmission timing is delayed by an absolute value of M (| M |), and when M <0, The pulse transmission timing is advanced by | M |. The correction method is not limited to this, and may be a method in which the transmission timing is advanced by a certain amount or delayed by a certain amount and converged to M = 0 by the code of M.

  With the above method, the pulse transmission timings of the base station A and the base station B coincide as shown in FIG. 3, and the synchronization between the base station A and the base station B is established.

  When there are three or more base stations, all the stations have the same configuration as the station A, and each station performs timing correction by the synchronization method for all stations other than its own station, The base stations of the entire communication system can be synchronized.

  FIG. 4 shows an operation procedure executed by the base station A. The transmission signal generator 13 of the base station A transmits a pulse Ua indicating the transmission timing of the local station A via the signal transmitter 14 (step S100). The signal receiving unit 10 of the base station A receives the pulse Ub from the base station B (step S110). The base station A receives the pulse Ub, and calculates the timing difference Tab between its own transmission pulse Ua and the reception pulse Ub (step S120). The timing difference Tab calculated in this way is transmitted to the base station B using the communication line established between the base station A and the base station B via the signal transmitter 14 (step S130). ). The signal receiving unit 10 of the base station A receives the timing difference information Tba from the base station B calculated by the base station B with the base station A (step S140). In the base station A, the timing correction amount calculation unit 12 calculates the timing correction amount of the transmission pulse so that the difference M between the timing difference Tab calculated by itself and the timing difference Tba transmitted from the base station B becomes zero. (Step S150), the transmission signal generation unit 13 corrects the timing of the transmission pulse based on the calculated correction amount (Step S160). If the transmission / reception operation is not terminated (step S170), such an operation is repeated.

  Thus, according to Embodiment 1, when base stations A and B receive a pulse indicating the transmission timing of the counterpart node from the counterpart node, the transmission timing of the transmission pulse of itself and the reception timing of the pulse from the counterpart node And the detected timing difference is transmitted to the partner node via a communication line, and the pulse transmission timing is adjusted so that the calculated timing difference is equal to the timing difference received from the partner node. In order to achieve synchronization, there is no need for special equipment such as a GPS receiver. Synchronization between stations can be achieved anywhere, indoors or outdoors, and the entire communication system can be synchronized even if new stations are added. It is possible to perform inter-node synchronization.

  Although the wireless communication system is shown in the first embodiment, synchronization can be established in the same manner in the case of a wired communication system. Further, as a node device, a mobile station, a base station, and a base station controller are conceivable, and the present invention can be applied to synchronization in the case of a mobile station and a fixed station, and a mobile station and a mobile station.

Embodiment 2. FIG.
FIG. 5 is a block diagram showing the internal configuration of the base station according to the second embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Here, only operations different from those of the first embodiment will be described.

  The inter-station distance calculation unit 15 added to the configuration of the first embodiment includes the timing difference Tab between the own station and the base station B calculated by the timing difference calculation unit 11 and the base station B transmitted from the base station B. The distance between the base station A and the base station B is calculated based on the calculated timing difference Tba between the base station B and the base station A.

A method for calculating the distance between the base station A and the base station B will be described below. The pulse Ua and the pulse Ub are respectively received by the base station B and the base station A with a delay of the propagation delay Tpd. At this time, the distance L between the bases can be obtained as follows using c as the speed of light.
L = TPD × c
TPD = (Tab + Tba) / 2

  The second embodiment can calculate the distance between the mobile terminal and the base station by implementing the same mode in communication between the mobile terminal and the base station, and can be applied to a ranging system.

  As described above, the inter-node synchronization method and node device according to the present invention are useful for communication systems that require a plurality of base stations, and are particularly suitable for mobile terminal communication systems such as mobile phones.

It is a block diagram which shows the structure of Embodiment 1 of this invention. It is a figure showing the transmission-and-reception timing of the transmission pulse before implementation of a synchronous process. It is a figure showing the transmission / reception timing of the transmission pulse after synchronous processing implementation. It is a flowchart which shows the operation | movement procedure of Embodiment 1 of this invention. It is a block diagram which shows the structure of Embodiment 2 of this invention. It is a figure explaining a prior art.

Explanation of symbols

A base station B base station 10 signal reception unit 11 timing difference calculation unit 12 timing correction amount calculation unit 13 transmission signal generation unit 14 signal transmission unit 15 inter-station distance calculation unit

Claims (4)

In the inter- node synchronization method for synchronizing two or more nodes ,
All the nodes are
A first step of transmitting a pulse indicating its transmission timing;
For all of the nodes other than its own, for each of the nodes, first detects the reception timing of the pulses indicating the transmission timing from the node, to detect the timing difference between the reception timing and transmission timing of its own transmission pulse 2 And the steps
A third step of transmitting via a communication line to the node corresponding pre Kita timing difference,
For each of the nodes, a fourth step of adjusting the transmission timing of the second own pulse as calculated timing difference and timing difference received from the node are equal in step,
Node synchronization method characterized by comprising a. The timing difference calculated by itself in the second step, according to claim 1, further comprising a fifth step of calculating the inter-node distance with a timing difference received from the node Synchronization method between nodes. In a node device having a function of synchronizing two or more nodes ,
Transmission means for transmitting a pulse indicating its own transmission timing;
Each said node receives a pulse that indicates the transmission timing of the node from the node, and the timing difference detector for detecting the timing difference between the reception timing of the pulses from the nodes and the transmission timing of its own transmission pulse,
Receiving means for receiving the timing difference detected by the node via a communication line;
A transmission timing adjusting means for timing difference received from the node and timing difference detected by said timing difference detection unit to adjust its pulse transmission timing to be equal,
With
The node device transmits the timing difference detected by the timing difference detector to the corresponding node via a communication line . Node device according to claim 3, further comprising a timing difference detected by said timing difference detection section, the inter-node distance calculation means for calculating the inter-node distance using the timing difference received from the node.

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