KR20010019479A - Multi-rate channels combining communication system using a accumulator - Google Patents

Abstract

PURPOSE: A communication system for combining information having various transmission speeds with one accumulator is provided to combine symbol data of channels having the various transmission speeds in the accumulator, so as to be appropriate for an IMT(International Mobile Telecommunications)-2000 without highly increasing a hardware size. CONSTITUTION: Each of demodulators(10-40) has five channel demodulators(11-15). The five channel demodulators(11-15) demodulate symbol data of five channels(#1-#5) corresponding to 9.6Kbps, 76.8Kbps, and 153.6Kbps, respectively. Multiplexers(18-48) respond to selection signals(S) to selectively output one of the demodulated symbol data. A combiner(50) comprises as follows. A symbol accumulator(52) receives the demodulated symbol data from the multiplexers(18-48), and adds the symbol data. A round-off controller(54) supplies a round-off constant to the symbol accumulator(52). The round-off constant has different values according to symbol transmission speeds. A multiplexer selection signal generator(56) generates the selection signals(S), and supplies the selection signals(S) to the multiplexers(18-48).

Description

MULTI-RATE CHANNELS COMBINING COMMUNICATION SYSTEM USING A ACCUMULATOR}

The present invention relates to a communication terminal, and more particularly, to an apparatus for combining information having various transmission rates received by a modem of a communication terminal into one accumulator.

In a call mode of an IS-95 system that supports a general Code Division Multiple Access (CDMA) cellular method, information data (voice data or video data) is transmitted and received at a predetermined transmission rate (64 Kbps). In the current mobile station (subscriber terminal) structure, four demodulators are used to demodulate each of the same symbol data coming in with temporal differences so as to be suitable for a fading environment by various paths.

However, in the IMT2000, the next-generation standard method of the CDMA method, not only voice data but also various control information and video data can be transmitted and received at different transmission speeds in a call mode.

Accordingly, the mobile station demodulates symbol data of channels having different transmission rates in different demodulators and then combines them. Therefore, accumulators as many as the number of each channel are needed independently, which leads to an increase in hardware size.

Accordingly, an object of the present invention is to provide an apparatus for combining symbol data of channels having various transmission rates using one accumulator.

1 is a block diagram showing a modem of a CDMA mobile station according to a preferred embodiment of the present invention;

2A is a timing diagram showing symbol data output from channel demodulators when the frequency of the symbol clock of the channel demodulators shown in FIG. 1 is 1.2288 MHz; And

FIG. 2B is a timing diagram illustrating a multiplexer selection signal output from the multiplexer selection signal generator shown in FIG. 1 and a clock signal of an accumulator.

* Description of the symbols for the main parts of the drawings *

10, 20, 30, 40: demodulator 11, 12, 13, 4, 15: channel demodulator

18, 28, 38, 48: multiplexer 50: combiner

52: symbol accumulator 54: rounding controller

56: Multiplexer Select Signal Generator

According to a feature of the present invention for achieving the object of the present invention as described above, a communication system for combining information having various transmission rates into one accumulator includes: a plurality of demodulators for demodulating symbol data input from the outside; The demodulator comprises a plurality of channel demodulators each corresponding to a plurality of channels having different transmission rates; A plurality of multiplexers respectively corresponding to the demodulators and selectively outputting one of the symbol data demodulated by the channel demodulators in response to a selection signal; And a combiner that receives and combines symbol data from the multiplexers. The combiner includes: a symbol accumulator that accepts and adds demodulated symbol data from the multiplexers; A rounding controller for providing a rounding constant with the symbol accumulator; And a selection signal generator for generating the selection signal.

By such an apparatus, a communication system suitable for IMT2000 can be implemented without greatly increasing the hardware size.

(Example)

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a modem of a CDMA mobile station according to a preferred embodiment of the present invention.

Referring to FIG. 1, the modem of the CDMA mobile station includes four demodulators 10 to 40, multiplexers 18 to 48 and a combiner 50 corresponding to the demodulators 10 to 40, respectively. Equipped.

Each of the demodulators 10 to 40 includes five channel demodulators for demodulating symbol data of five channels corresponding to 9.6 Kbps, 19.2 Kbps, 76.8 Kbps, and 153.6 Kbps, respectively. 11 to 15 are provided.

The multiplexers 18 to 48 selectively output one of the symbol data demodulated by the demodulators 10 to 40 in response to the selection signal S.

The combiner 50 includes a symbol accumulator 52, a rounding controller 54, and a multiplexer select signal generator 56. The symbol accumulator 52 accepts and adds demodulated symbol data from the multiplexers 18 to 48. The rounding controller 54 provides a rounding constant to the symbol accumulator 52. The rounding constant has a different value depending on the symbol transmission rate. The multiplexer select signal generator 56 generates a select signal S and provides the select signal S to the multiplexers 18 to 48.

FIG. 2A is a timing diagram illustrating symbol data output from channel demodulators when the frequency of the symbol clock of the channel demodulators illustrated in FIG. 1 is 1.2288 MHz.

As shown in Fig. 2A, when the frequency of the symbol clock is 1.2288 MHz, the demodulator 11 of the first channel having a transmission rate of 9.6 Kbps demodulates one symbol data every 64 clocks. Similarly, the demodulator 12 of the second channel having a transmission rate of 19.2 Kbps is used for every 32 clocks, and the demodulator 13 of the third channel having a transmission rate of 38.4 Kbps is used for the fourth channel having a transmission rate of 76.8 Kbps every 16 clocks. The demodulator 14 demodulates symbol data every four clocks, and the demodulator 15 of the fifth channel having a transmission rate of 153.6 Kbps every four clocks.

FIG. 2B is a timing diagram illustrating a multiplexer selection signal output from the multiplexer selection signal generator shown in FIG. 1 and a clock signal of an accumulator.

Referring to Fig. 2B, in general, the frequency of the main clock signal in the modem in the mobile station is 9.8304 MHz, and in this embodiment the symbol accumulator 52 operates at 9.8304 MHz. In addition, the accumulator 52 performs an accumulating operation for five channels during six clock cycles.

During the first clock cycle, the accumulator 52 is reset. During the second to fifth clock cycles, the accumulator 52 accepts and adds demodulated symbol data in the demodulators 10 to 40 through multiplexers 18 to 48. During the last sixth clock cycle, the accumulator 52 adds the rounding constant provided from the rounding controller 54 to the added result. According to this method, it takes 6 clock cycles because it takes 1 clock to transfer the operation result to the next stage. In order to improve the processing speed, the rounding constant is loaded from the rounding controller 54 during the reset of the symbol adder 52 in the first clock cycle, and the operation result is provided to the next stage in the last six cycles.

As shown in FIG. 2A, while one symbol data is demodulated in the first channel demodulator 11, the second channel demodulator 12 is two, the third channel demodulator 13 is four, Eight of the fourth channel demodulators 14 and the fifth channel demodulator 15 demodulate 16 symbol data.

Therefore, the order of reading the demodulated symbol data from the channel demodulators 11 to 15 is channel "1, 2, 3, 4, 5, 2, 3, 4, 5, 3, 4, 5, 3, 4". , 5, 4, 5, ..., 4, 5 ", the multiplexer select signal generator 56 generates the select signal in the same manner as the above procedure.

As described above, symbol data for up to five channels can be combined for 32 clock cycles with a 9.8304 MHz main clock signal, and six clock cycles are sufficient to combine one symbol data.

While the invention has been described using exemplary preferred embodiments, it will be understood that the scope of the invention is not limited to the disclosed embodiments. Rather, the scope of the present invention is intended to include all of the various modifications and similar configurations. Accordingly, the claims should be construed as broadly as possible to encompass all such modifications and similar constructions.

According to the present invention as described above, a modem of a mobile station capable of combining symbol data of channels having various transmission rates in one accumulator is implemented. Therefore, a communication system suitable for IMT2000 can be implemented without greatly increasing the hardware size.

Claims (1)

In a communication system: A plurality of demodulators for demodulating symbol data input from the outside; The demodulator comprises a plurality of channel demodulators each corresponding to a plurality of channels having different transmission rates; A plurality of multiplexers respectively corresponding to the demodulators and selectively outputting one of the symbol data demodulated by the channel demodulators in response to a selection signal; A combiner that accepts and combines symbol data from the multiplexers; The combiner, A symbol accumulator that accepts and adds demodulated symbol data from the multiplexers; A rounding controller for providing a rounding constant with the symbol accumulator; And And a selection signal generator for generating said selection signal.