KR100372927B1 - Wideband code division multiple access base station modem - Google Patents

Abstract

The present invention relates to a wideband code division type base station modem which can simplify the structure by efficiently implementing the use of memory. The delay memory included in the pre-code finder is used to detect timing and extract phase information from the demodulator. In addition, the demodulator and the modulator can variably share the interleaver / deinterleaver memory and the input / output data memory. Therefore, the base station modem can be efficiently configured through the functional separation structure and the memory sharing structure of the broadband code division type modem.

Description

Wideband code division multiple access base station modem

The present invention relates to a wideband code division type base station modem, and more particularly, to a demodulator and a modulator of a base station modem capable of simplifying a structure by efficiently implementing a memory use.

Base station modems must be structured to support a large number of users within a limited physical standard (e.g. one chip). It is one of the biggest problems in terms of aspect. Conventionally, a plurality of existing modules have been integrated to service a larger number of users on one modem chip while lowering the semiconductor process. However, in IMT-2000, due to the difference in services, transmission speeds, and control methods of various quality, the existing 2G There is a limit to the method taken in the same way as (PCS or cellular).

Existing 3GPP WCDMA base station modems (or modules) incorporate all transmitter and receiver functions on a single chip and strive to accommodate as many parallel transmit and receive channel blocks as possible to secure as many channels. However, due to the complexity of the 3GPP WCDMA base station modems, no clear effective method has yet been found.

The present invention has been made in an effort to provide a base station modem of a wideband code division method that can efficiently use components included in a base station modem to increase the efficiency of the overall operating method.

1 is a block diagram illustrating an example of a code division type base station modem.

2 is a block diagram of a base station modem of a wideband code division method according to an embodiment of the present invention.

3 illustrates a configuration related to the phase compensation of FIG. 2.

FIG. 4 is a table comparing the number of modems required for configuring one sector of 128 channels (users), and FIG. 5 shows the memory size required for configuring one sector of 128 users.

In order to achieve the above object, the base station modem of the wideband code division method according to the present invention,

10. A base station modem of a wideband code division method comprising a precode searcher for receiving a spreadband signal to detect timing from a precode signal, and a demodulator for receiving a spreadband signal to compensate for a phase and then decoding the spreadband signal. The searcher includes a delay memory for receiving and storing a spread spectrum signal in a predetermined unit, and the signal delayed by the delay memory is used to detect the timing and is input to the demodulator, and the demodulator receives the spread spectrum signal. A first despreader for despreading; A channel estimator extracting phase information from the signal despread by the first despreader; A second despreader which receives a spread band signal delayed by the delay memory and despreads the spread band signal; And a phase compensator for recovering symbol data by compensating the phase of the signal based on the phase information obtained by the channel estimation and the output signal of the second despreader.

In order to achieve the above object, a demodulator in a base station modem of a wideband code division method according to the present invention,

A demodulator for receiving a spread band signal to compensate for a phase and then decoding the received signal, wherein the demodulator receives a despread spread signal, despreads it, and then compensates the phase of the signal to restore symbol data. Signal compensation unit; A multiplexer which multiplexes signals output from the plurality of signal compensators; A deinterleaver memory for deinterleaving the signal output from the multiplexer; And a decoder which decodes (decodes) the deinterleaved signal.

In order to achieve the above object, a modulator in a base station modem of a wideband code division method according to the present invention,

An encoder for encoding data; An interleaving memory for interleaving the encoded data; A demultiplexer for demultiplexing output data of the interleaving memory; A plurality of diffusion units provided to receive the demultiplexed signal and generate a spread spectrum signal; And an adder configured to add and output the spread signals output from the plurality of spreaders.

In order to achieve the above object, the base station modem of the wideband code division method according to the present invention,

A precode searcher for storing the received spread spectrum signal in a delay memory and detecting a timing based on the stored data; A plurality of phase compensators provided corresponding to a plurality of channels for compensating a phase based on a signal despreading the received spread spectrum signal and a signal despread by the delay memory, and the plurality of phases A demodulator including a multiplexer for multiplexing the signals output from the compensators, a deinterleaver memory for deinterleaving the signals output from the multiplexer, and a decoder for decoding the deinterleaved signal; An encoding unit for encoding data, an interleaving memory for interleaving the encoded data, a plurality of diffusion units provided corresponding to a plurality of channels for demultiplexing and inputting and spreading the output data of the interleaving memory; And a modulator including an adder configured to sum and output the spread signals output from the plurality of spreaders.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is a block diagram illustrating an example of a base station modem of a wideband code division method. The 3GPP WCDMA base station modem, which is an IMT-2000 standard, basically includes a demodulator block including a searcher, a demodulator, and a channel decoder, a channel encoder and a spreader that transmit data. consists of a modulator block containing a spreader. The searcher may be divided into a preamble searcher and a message searcher. The preamble searcher performs a timing search using a bursted presignal signal (for example, a 4096 chip) and performs various search. Used to retrieve timings for common channels that users use together. Since the fast retrieval time is required in the structure of the combined signal of the transposed preamble, the preamble retrieval unit is a matched filter method.

The preamble searcher 11 receives a precode signal transmitted from a terminal and detects a round trip delay (RTD) and a multipath timing, and usually uses a matched filter 112 for fast search time. A delay memory 111 for delaying internal data is required for the operation of the matched filter 112. If the preamble length is, for example, a 4096 spreading code chip, a delay memory having a length (4096 x number of samples per spreading code) correspondingly therein. Must have The demodulator 13 includes a channel estimator 133 because the demodulator 13 can recover the correct transmission symbol by compensating for the amplitude and phase of the distorted symbol through the wireless channel. The signal received from the reception filter is despread by the inverse converting unit 131 and then input to the channel estimator 133 and the delay memory II 132. However, the phase compensator 134 stores data symbols to be recovered while the phase estimator 133 detects the distorted phase information in the delay memory II 132 and restores them when the phase detection signal comes out. The phase compensated signal is deinterleaved by the deinterleaver memory 136 and then decoded by the decoder 137 and then stored in the buffer memory 138.

The modulator 15 encodes the data stored in the buffer memory 151 by the encoder 152 and then performs an interleaving process in the interleaver memory 153 and transfers the spread signal from the spreader 155 to the transmission filter. Output As such, the precode finder block 11, the demodulator block 13, and the modulator block 15 are implemented as one chip for each channel. In the mobile communication, a demodulator uses a plurality of finger demodulators for demodulating signals of respective paths for a multipath signal received with a time delay due to reflection or refraction.

Therefore, the finger of the demodulator should have a memory 132 for delaying input data of a predetermined length for a time necessary for channel estimation. The modem shown in FIG. 1 is implemented in a structure in which two memories, that is, delay memory I 111 of the pre-code finder block 11 and delay memory II 132 of the demodulator block 13 are separated. This structure makes it impossible to accumulate a large number of fingers on a chip since the memory must have a certain length of memory for each of the multiple paths served by the fingers. This is more problematic when considering a 3G structure with more than 2G sectors, the number of receive antennas, and the number of multipaths. In addition, since the data input / output memory and the interleaver / deinterleaver memory are inputted to each modulator and demodulator, it is difficult to make a single chip modem with many channels. This is necessary.

2 shows a block diagram of a base station modem of a wideband code division method according to an embodiment of the present invention, a precode finder 21 for receiving a spreadband signal to detect timing from a precode signal, and a spreadband. A demodulator 23 for receiving a signal, compensating for phase, and decoding the signal, and a modulator 25 for encoding, spreading, and outputting the data to a transmission filter.

The overall configuration of a code division base station modem according to an embodiment of the present invention is as follows. The pre code searcher 21 stores the spread band signal received from the reception filter in the delay memory 211, and detects a timing based on the stored data by the matching filter 212. The demodulator 23 compensates for the phase based on a signal despreading the spread band signal received from the reception filter and a signal despread by the delay memory 211. Phase compensators 231, a multiplexer 235 for multiplexing signals output from the plurality of phase compensators, a deinterleaver memory 236 for deinterleaving a signal output from the multiplexer, and a deinterleaved signal. And a decoder 237 to decode the. The modulator 25 includes a coder 252 for encoding data, an interleaving memory 253 for interleaving the encoded data, and output data of the interleaving memory, which are demultiplexed and inputted to a plurality of channels for despreading. A plurality of diffusion units 255 corresponding to each other and an adder unit 256 for adding the diffusion signals output from the plurality of diffusion units and outputting the combined diffusion signals are transmitted to the transmission filter. The modulator and demodulator in FIG. 2 is an example of a configuration for processing three channels.

In this case, the function of dividing into the pre-code searcher 21, the demodulator 23 and the modulator 25 for each function can be integrated into a single chip. In particular, an integrated structure of memory used for each function is proposed as a method to more effectively solve the function integration problem. The present invention implements a functionally separate structure of a modulator, a demodulator, and a preamble finder, and uses a single delay memory, which is used independently of the fingers of the precode finder and the demodulator, to be used as a single preamble as a single memory. A time delay for the matched filter of the searcher and a data time delay for channel estimation of the finger of the demodulator are simultaneously performed. In addition, the multi-channel (user) structure of the demodulator and the modulator implements a structure in which the multi-channel (user) can share the memory for the interleaver / deinterleaver and the buffer memory for data input and output.

First, a structure in which a delay memory for a finger of a precoder searcher and a demodulator can be used in common will be described. The pre code searcher 21 includes a delay memory 211 for receiving and storing a spread band signal from a reception filter in a predetermined unit, and a signal delayed by the delay memory 211 detects a timing in the matching filter 212. It is used and input to the demodulator 23. The demodulator 23 includes a first despreader 231 for despreading the spread band signal received from the reception filter, a channel estimator 233 for extracting phase information from the signal despread by the first despreader, The delay information obtained by the delayed memory 211 receives the delayed spread band signal and despreads it to the phase information obtained by the second despreader 232 and the channel estimator 233 and the output signal of the second despreader 232. And a phase compensator 234 for compensating the phase of the signal to restore symbol data.

In the structure of the prefix code searcher 21, the data delay memory 211 for the matched filter 212 serves as the data delay memory of the finger 231 of the demodulator 23. Since the pre-code finder 21 is a user shared channel and there is no handover, it can be configured as a specific sector or antenna-oriented structure, and because a single chip can process one sector, a pre-code finder for each sector is provided. In the demodulator stage, no delay memory is required.

Therefore, the demodulation device receives the information directly transmitted from the reception filter and the information delayed by the delay memory of the precoding searcher. Since the data delay memory, which is required for each multipath of the demodulator, can be eliminated, the complexity of the demodulator structure is greatly reduced, thereby increasing the chip density. That is, a plurality of channels may be integrated in the demodulator by separating the function of the precode finder and the demodulator. 3 shows a configuration related to phase compensation. The first despreader 231 receives the spread spectrum signal from the reception filter to despread, and the channel estimator 233 receives the despread signal from the despreader 231 and transmits the despread signal to the control channel. The signal magnitude and phase information is extracted by using a pilot symbol. This information is multiplied by the value of the delayed data (ie, the signal from which the output of the delay memory 211 is despread by the second despreader 232) to compensate for the magnitude and phase of the signal to restore the correct transmission symbol value. do.

Next, the interleaver / deinterleaver memory and data input / output memory in the structure of the demodulator or modulator are shared and used in multiple channel (user) units in a multiplexed channel structure to meet various data service requirements. A structure capable of varying the number of serviceable channels is possible to achieve efficient integration of each chip of the demodulator or modulator.

The configuration of the demodulator 23 for receiving the spread-band signal in the code division base station modem by compensating for the phase and encoding the same will now be described. That is, the demodulator 23 receives a spread spectrum signal and extracts phase information from the signal despread by the first despreader 231 and the first despreader 231. 233, a second despreader 232 for receiving a signal from which the spread-band signal is delayed by a predetermined unit from the delay memory 211 of the pre-code finder 21, and obtained by the channel estimator 233. A plurality of signal compensations provided for the plurality of channels, including a phase compensator 234 for compensating the phase of the signal based on the phase information and the output signal of the second despreader 231 to restore symbol data. The part 231 is provided.

The multiplexer 235 multiplexes the signals for each channel output from the plurality of signal compensators, the deinterleaver memory 236 for deinterleaving the signals output from the multiplexer 235, and the deinterleaved signals. The decoder 237 is decoded and the decoded data is stored in the data buffer memory 238. Accordingly, the deinterleaver memory and the data output buffer memory according to FIG. 1 can be shared and used by several channels (users) according to FIG. 2.

Next, referring to the configuration of the modulator 25 in a code division base station modem, a buffer memory 251 for temporarily storing data, an encoder 252 for encoding data, and an interleaving memory for interleaving encoded data 253, a demultiplexer 254 for demultiplexing the output data of the interleaving memory 253, a plurality of diffusers provided corresponding to a plurality of channels for receiving a demultiplexed signal and generating a spread spectrum signal ( And a summation unit 256 for adding the spreading signals output from the plurality of spreading units 255 and outputting them to the transmission filter. Therefore, the interleaver memory and the data input buffer memory according to FIG. 1 can be shared and used by several channels (users) according to FIG. 2.

FIG. 4 is a table showing the number of modems required to configure one sector of 128 channels (users), and FIG. 5 shows the memory size required to configure one sector of 128 users. In the drawing, R: chip time / resolution time = 4, S: bits / sample = 5, A: antenna number / sector = 2, M: multipath number / user = 6, U: user number / sector = 128, T: TTI = 8 (80 ms), C: increasing bit number factor after coding = 3 (1/3 code rate), S2: bits / despreaded symbol = 6. Figures 4 and 5 show the preamble finder and finger (demodulator) It can be seen that the total number of chips and memory capacity can be reduced due to the shared memory function and the shared channel memory structure of the modulator and demodulator.

As described above, the present invention makes it possible to efficiently configure the base station configuration through the functional separation structure of the base station modem of the wideband code division method, and the shared memory structure of the precode finder and the demodulator and the channel sharing of the modulator and the demodulator. Through the memory structure, it is possible to implement a structure that reduces the number of used memories as a whole by improving the integration degree of each chip.

According to an embodiment of the present invention, it is possible to implement a function separation structure and a function shared memory structure for the integration and control of a code division base station modem, and to cope with the base station configuration through an efficient function separation and through an efficient memory configuration. A structure that can increase the integration of each functional chip can be implemented. In particular, it integrates the delay memory of the precode finder and the demodulator and shares the data for input / output memory and the inter / deinterleaver memory in the modulator and the demodulator for several channels.

The present invention can construct an efficient base station with a small number of modems in terms of base station architecture design that can handle the required overall service capacity, and for this purpose, the function of the modem is divided into a plurality of chips and individual functions are integrated as much as possible on the chip. The way it is. In this case, a much smaller number of modem chips are required to handle the channel capacity of the base station compared to the conventional method, which is advantageous in terms of cost and simplified in terms of control.

Claims (8)

A baseband modem of a wideband code division method comprising a precode searcher for receiving a spreadband signal to detect timing from a precode signal, and a demodulator for receiving a spreadband signal to compensate for a phase and then decoding the signal. The precode finder includes a delay memory for receiving and storing a spread spectrum signal in a predetermined unit, and the signal delayed by the delay memory is used to detect the timing and is input to the demodulator. The demodulator A first despreader for despreading the received spread spectrum signal; A channel estimator extracting phase information from the signal despread by the first despreader; A second despreader which receives a spread band signal delayed by the delay memory and despreads the spread band signal; And And a phase compensator for recovering symbol data by compensating the phase of the signal based on the phase information obtained by the channel estimation and the output signal of the second despreader. In a base station modem of a wideband code division method, a demodulator for receiving a spread spectrum signal to compensate for a phase and then decoding the same, A plurality of signal compensators provided corresponding to a plurality of channels for receiving spread spectrum signals, despreading them, and then compensating the phases of the signals to restore symbol data; A multiplexer which multiplexes signals output from the plurality of signal compensators; A deinterleaver memory for deinterleaving the signal output from the multiplexer; And And a decoding unit for decoding the deinterleaved signal. The signal compensator of claim 2, wherein each signal compensator A first despreader which receives a spread band signal and despreads it; A channel estimator extracting phase information from the signal despread by the first despreader; A second despreader configured to receive a signal delayed by the spread band signal by a predetermined unit and despread it; And a phase compensator for recovering symbol data by compensating the phase of the signal based on the phase information obtained by the channel estimation and the output signal of the second despreader. Demodulator. The demodulator of the BS modem of claim 2, further comprising a buffer memory for storing data output from the decoder. An encoder for encoding data; An interleaving memory for interleaving the encoded data; A demultiplexer for demultiplexing output data of the interleaving memory; A plurality of diffusion units provided to receive the demultiplexed signal and generate a spread spectrum signal; And And a summation unit for summating and outputting the spreading signals output from the plurality of spreading units. 6. The modulator of a base station modem of a wideband code division method according to claim 5, further comprising a buffer memory for storing data input to the encoder. A precode searcher for storing the received spread spectrum signal in a delay memory and detecting a timing based on the stored data; A plurality of phase compensators provided corresponding to a plurality of channels for compensating a phase based on a signal despreading the received spread spectrum signal and a signal despread by the delay memory, and the plurality of phases A demodulator including a multiplexer for multiplexing the signals output from the compensators, a deinterleaver memory for deinterleaving the signals output from the multiplexer, and a decoder for decoding the deinterleaved signal; And An encoding unit for encoding data, an interleaving memory for interleaving the encoded data, a plurality of diffusion units provided corresponding to a plurality of channels for demultiplexing and inputting and spreading the output data of the interleaving memory; And a modulator including an adder configured to sum up and output spread signals output from the plurality of spreaders. 8. The wideband code division base station modem according to claim 7, wherein the precode finder, the demodulator, and the modulator are each implemented as a single chip.