JPH04371028A - Digital radiotelephone equipment - Google Patents

Abstract

PURPOSE:To satisfactorily switch a base station by detecting the frame difference and the intra-frame phase difference between communicated digital data and digital data from another base station adjacent to a communicating base station and storing them in a memory. CONSTITUTION:A reception processing circuit 2 receives the signal from a prescribed base station by the control of a controller 9. A reproducing circuit 4 detects the base station ID and the frame number. The base station ID is stored in a RAM 8 as data of a base station A. If the signal from adjacent base stations is received in the period of an idle slot, it is stored in the order of base station ID detection. In this case, the difference from the frame number of the base station A is obtained by a frame difference detecting circuit 7 and is store. Intra-frame offset data is detected and stored as the output of an n-notation counter 5. In this constitution, the communication control synchronized with digital data which is sent from another base station and is structured as frames is performed on the telephone equipment side even just after switching, and disturbance due to switching is prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital radio telephone device for wireless communication of digital data.

0002

2. Description of the Related Art A so-called cellular system has been put into practical use in communication systems with mobile bodies, such as car telephone systems. In this cellular system, the communication area is divided into multiple cells, each cell is equipped with a base station (fixed station), and this base station communicates with mobile objects within the cell. . In this case, each mobile unit performs transmission and reception with the base station, and also receives control signals to determine which cell base station it can communicate with. That is, for example, in the case of a mobile phone system using a digital line, the communication data structure when each mobile unit accesses a base station is a frame structure in which frames of a predetermined length are consecutive, as shown in FIG. A transmission slot T from the mobile body, a reception slot R at the mobile body, and an idle slot I are allocated in a time-division manner. In this case, as shown in FIG. 4, the mobile unit is configured by repeating 26 frames from the 0th frame to the 25th frame, and uses the transmission slot T and the reception slot R from the 0th frame to the 24th frame. Communication such as audio data is performed with the base station, and control data from the base station is received in the 25th frame. A communication system in which reception slots and transmission slots are arranged in time division in this way is T
DMA method (Time Division Multi
ple Access).

[0003] In the period of idle slot I,
Measures the electric field strength of the cell currently in use and the adjacent cell. That is, a control signal transmitted from a base station of an adjacent cell is received in idle slot I, and the field strength is determined from the reception level of this field strength determination control signal. In this case, each cell is assigned a frequency (channel) of the control signal for field strength determination, and adjacent cells are set to have different frequencies of the control signal. Based on this determination, if the electric field strength of the currently communicating cell is stronger, communication with the same base station is continued, and if the electric field strength of the adjacent cell is stronger, it is determined that the neighbor cell has approached the base station. Then, a command to switch to communication with a base station of an adjacent cell is transmitted to the base station. When switching to communication with this adjacent cell, after transmitting this command, the communication is switched to communication with the adjacent cell at a predetermined timing based on an instruction from the base station side.

0004

[Problem to be solved by the invention] By the way, when switching to communication with an adjacent cell in this way, the base station of the cell currently communicating and the base station of the adjacent cell may be out of synchronization. In such a case, the timing of the current communication does not match the timing of the communication carried out by the base station on the adjacent cell side. Therefore, when switching, it is necessary for the mobile side to communicate in accordance with the communication timing of the base station of the adjacent cell, and there is a risk that communication may be temporarily disrupted until the communication timing of the base station of the adjacent cell is matched. There is.

SUMMARY OF THE INVENTION An object of the present invention is to enable a cellular digital radio telephone device to perform base station switching effectively.

[0006]

[Means for Solving the Problems] The present invention provides communication between a base station having the best communication condition among a plurality of installed base stations.
When a digital radio telephone device that performs wireless communication of frame-structured digital data is communicating with any base station, the digital data being communicated at this time and the base station being communicated with are Frame differences and intra-frame phase differences with digital data transmitted from other adjacent base stations are detected, and the detected data is stored in memory.

[0007]

[Operation] By doing this, data regarding the communication status of the adjacent station is stored in the memory within the telephone device, and when switching to communication with the adjacent station, the communication status ( By determining the communication timing of frame-structured digital data, communication with adjacent stations can be performed immediately with accurate timing.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

In this example, the present invention is applied to a cellular type digital wireless telephone device that communicates via a digital line, and the reception system is configured as shown in FIG. That is,
In FIG. 1, 1 indicates an antenna that receives data transmitted from a base station, and this antenna 1 is connected to a reception processing circuit 2.
The reception processing circuit 2 performs processing to receive signals in a predetermined frequency band. In this case, the received signal in this example is digital data structured into a frame with a period of 26 frames as shown in FIGS. 3 and 4. The receiving operation of the receiving frequency etc. in the receiving processing circuit 2 is performed under the control of the system controller 9, and the audio signal received and demodulated by the receiving processing circuit 2 is supplied to an audio circuit (not shown). Performs audio output processing.

Further, the signal received by the reception processing circuit 2 is supplied to a frame synchronization signal extraction circuit 3, and the frame synchronization signal extraction circuit 3 extracts a frame synchronization signal included in the received digital data. In this case, the frame synchronization signal includes frame number and base station ID data, and the detected frame synchronization signal is supplied to the frame number and base station ID reproducing circuit 4 to reproduce the frame number and base station ID. . Also,
The frame synchronization signal detected by the frame synchronization signal extraction circuit 3 is supplied to an n-ary counter 5 and a TDMA counter 6. The n-ary counter 5 and the TDMA counter 6 are synchronized, and the n-ary counter 5 is a counter that can output a count with one frame as one cycle, and the TDMA counter 6 can output a count with 26 frames as one cycle. This is the counter obtained. In this case, the TDMA counter 6 is
The count value is reset under the control of the system controller 9 each time the communicating base station changes.

[0011] Then, the data of the frame number detected by the frame number and base station ID reproducing circuit 4 and the count output of the TDMA counter 6 are supplied to the frame difference detection circuit 7, and the frame difference detection circuit 7 receives the data. The difference between the frame number of the signal and the frame number counted by the TDMA counter 6 is detected, and this detected value is transferred to the R for data storage at a predetermined time under the control of the system controller 9.
Store it in AM8.

Further, the count output of the n-ary counter 5 when the difference between the received frame number and the counted frame number is stored is stored in the data storage RAM 8 under the control of the system controller 9 as offset data within the frame. be memorized as

The data storage RAM 8 stores data regarding the communication status of a base station in communication and a base station adjacent to this base station, and has storage areas set as shown in FIG. In other words, the base station currently in communication (base station A
Base stations of cells in each direction (base station B,
C, D, E, F) frame difference data and intra-frame offset data can be stored. Further, the frame number and the base station ID detected by the base station ID reproducing circuit 4 are also supplied to the data storage RAM 8, and this base station ID is stored. Note that since the value of the reception state from base station A serves as a reference value, the frame difference data and offset data of base station A are not stored in the RAM 8. In addition, the data of the neighboring stations of 5 stations (base stations B, C, D, E,
F), but there are only 5 adjacent stations.
If the number of adjacent stations is less than that, only the data for the number of existing adjacent stations is stored.

When switching the base station with which this telephone device communicates, the system controller 9 reads out the data stored in the data storage RAM 8.
Determine the timing of communication with the base station to newly communicate with,
Communication control is performed by determining the time when a transmission slot, a reception slot, etc. exist based on this determined communication timing.

Next, the operation of communication using the digital radio telephone device of this example will be explained. First, under the control of the controller 9, the reception processing circuit 2 receives a signal from a predetermined base station. When a call is made with the received station, the frame number and base station ID reproducing circuit 4 detects the base station ID transmitted from the base station in communication, and stores the detected base station ID as data. The base station A data is stored in the RAM 8 for use as base station A data. Then, during the period of idle slot I,
When a signal from an adjacent base station is received, if the base station ID is detected from the received signal by the frame number and base station ID reproducing circuit 4, base stations B and C are selected in the order in which the base station ID is detected.
, D, E, and F data. and,
When storing the base station ID in each base station B, C, D, E, F, the frame difference detection circuit 7 detects the difference between the frame number detected at the same time and the frame number of base station A.
The value of the detected frame difference is sent to each base station B.
, C, D, E, and F as frame difference data. Further, at this time, offset data within the frame is detected as the count output of the n-ary counter 5, and the detected offset data is stored as offset data of each base station B, C, D, E, F.

[0016] Note that it is only necessary to store the frame difference data and offset data only once, at the time when each data can be detected after a call is made using base station A. The stored data may be updated every time frame difference data and offset data are detected during a call.

In this way, each adjacent base station B, C, D,
When the frame difference data and offset data of E and F are stored in the data storage RAM 8, the communication condition from the base station currently in use deteriorates and communication is switched to one of the adjacent base stations. When switching timing is instructed from the base station side, frame difference data and offset data regarding the base station with which new communication is to be performed (this base station is identified by the base station ID) are transferred from the data storage RAM 8 to the controller 9. is read out, and the communication timing is shifted by the timing indicated by the frame difference data and offset data to switch the communication.

By switching the base station for communication in this way, even immediately after switching, the wireless telephone device can perform communication control in synchronization with frame-structured digital data transmitted from the base station for new communication. This is done locally, so there is no disruption to communications due to base station switching. Therefore, even if the base station is switched during a call using the digital radio telephone device of this example, there will be no problem with the call.

In the above-mentioned embodiment, frame difference data and offset data based on the communication timing of the base station in communication are stored in the data storage RAM 8, but the time difference with the absolute time The data may be stored. Furthermore, the configurations of communication data shown in FIGS. 3 and 4 are merely examples, and can be applied to wireless telephone devices that communicate using data having other frame structures.

[0020]

According to the present invention, when communication is made with any base station and a call is made, data regarding the communication status of the adjacent station is stored in the memory within the telephone device.
When switching to communication with an adjacent station, communication with the adjacent station can be performed immediately at accurate timing based on the data stored in this memory, and communication is not disrupted at the time of switching.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a data storage area of a memory according to one embodiment.

FIG. 3 is a configuration diagram showing a slot configuration during communication according to an embodiment.

FIG. 4 is a configuration diagram showing a frame structure of communication data according to one embodiment.

[Explanation of symbols]

1 Antenna 2 Reception processing circuit 3 Frame synchronization signal extraction circuit 4 Frame number and base station ID reproduction circuit 5 N-ary counter 6 TDMA counter 7 Frame difference detection circuit 8 Data storage RAM 9 Controller

Claims (1)

[Claims] Claim 1. A digital wireless telephone device that performs wireless communication of frame-structured digital data with a base station with the best communication condition among a plurality of installed base stations, wherein any one of the base stations When communication is being conducted between the base station and the base station being communicated with, the frame difference and phase difference within the frame between the digital data being communicated at this time and the digital data transmitted from another base station adjacent to the base station in communication. A digital wireless telephone device that detects and stores detected data in memory.