KR100305761B1 - Code Splitting Multiple Channel Terminals and Their Operation - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CDMA terminal, which codes communication signals and uses a multi-channel scheme, and more particularly, to digitally multiplexing each channel data, and then to minimizing the PAR due to the simplification of circuits and the average rate, A digital mux for multiplexing an input CDMA signal and outputting the signal in one channel; A CDMA modem for separating signals output from and input to the digital mux into I and Q phase signals; First and second digital band limiting filters for removing noise signals from I and Q phase signals output from a CDMA modem; First and second D / A converters for converting digital signals input from the plurality of digital band limiting filters into analog signals; First and second analog band limiting filters connected to the plurality of D / A converters to remove noise signals; A time-division multiplexing of N user channel DATAs by means of first and second modulators connected to a plurality of analog band limiting filters and modulating at a first intermediate frequency, one CDMA modem, two digital filters, and D / A converter and analog filter are used, and the average output of HPA is N * Po for the same BER, and the maximum output is N * Po, which requires only 1 / N of peak power compared to the prior art. In addition, the power consumption is small, and the number of parts is dramatically reduced.

Description

Code Division Multiple Access Multi-channel Terminal and Its Operation Method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Code Division Multiple Access (CDMA) terminal, which codes a communication signal and uses multiple channels, and in particular, after digital multiplexing each channel data, the circuit is simplified and averaged. By minimizing the peak to average ratio (PAR), the high power amplifier (HPA) output for radio frequency (RF) is greatly reduced in comparison to the number of channels, and the number of components is greatly reduced. It is about being able to lower the price of.

In general, a terminal occupies one channel to communicate, but a terminal capable of occupying two channels communicates with a personal computer (PC) at the same time for voice communication or data communication, or two Allow users to call and communicate with different state subscribers.

In addition, a single terminal can be used simultaneously by a plurality of users, such as four or eight, in this case, a circuit that can occupy as many channels as necessary in the terminal should be configured.

In other words, a terminal having a structure capable of accommodating a plurality of channels in one terminal is called a multi-channel terminal, and processes a voice or data signal for each channel, and processes them in a high frequency step.

As described above, a CDMA multi-channel terminal capable of simultaneously driving two or more channels with a single terminal uses a single CDMA modem for each channel, and combines the CDMA signals to combine the multiple CDMA signals. By transmitting in the code (Mult-Code) method, the circuit configuration is very complicated, and when the number of channels is N, the maximum value (PAR) by the average rate becomes a large value close to N.

Therefore, the high frequency high power amplifier (RF HPA) of the terminal requires a much larger output amplifier than the single channel method.

Hereinafter, a single code multi-channel terminal transmitter according to the related art will be described with reference to the accompanying drawings.

1 is a functional block diagram of a multi-channel terminal transmitter according to the prior art.

Referring to FIG. 1, the transmitter of the conventional multi-channel terminal receives a signal of 1 bit code that is modulated by PCM (Pulse Code Modulation) from each channel, and receives a phase of I and Q. A plurality of CDMA modems 10 which are converted into signals and outputted;

A digital band limiting filter 20 for receiving the I and Q phase signal outputs of the plurality of CDMA modems 10, respectively, and preventing the frequency signals of the assigned specific bands from passing through;

A plurality of digital / analog (D / A) converters 30 connected to the plurality of digital band limiting filters 20 to convert an applied digital signal into an analog signal;

An analog band limiting filter 40 connected to the plurality of D / A converters 30 to prevent passage of frequency signals of a specific band band, and

A first combiner 50 for receiving and combining all the I phase signals of the analog band limiting filter 40;

A second combiner 55 for receiving and combining all Q phase signals of the analog band limiting filter 40;

A first modulator 60 and a second modulator 65 connected to the first and second drawers 50 and 55, respectively, and modulating the intermediate frequency by mixing with Cos ω _c t and Sin ω _c t frequencies;

An adder 70 which receives the output signals of the first modulator 60 and the second modulator 65, adds them, and then outputs them;

A third modulator 67 which receives the signal of the adder 70 and combines with the frequency of the local oscillator 80 to up-convert to a high frequency;

An analog band pass filter 45 for passing only a frequency signal of a specific band assigned thereto,

A high output amplifier (RF HPA) 90 for amplifying and outputting a high frequency signal input from the band pass filter 45 to a high output;

The duplexer 100 transmits a signal input from the RF HPA 90 to an aerial antenna and receives a signal input as the aerial antenna through another path.

Hereinafter, the operation of the multi-channel terminal transmitter according to the related art having the above configuration will be described in detail with reference to the accompanying drawings.

The CDMA multi-channel terminal inputs a digital signal applied through each channel to the corresponding CDMA modem 10, respectively.

The plurality of CDMA modems 10 separate and output the input digital signals into "I" and "Q" phase signals, and apply them to the corresponding digital band limit filter 20, respectively.

Each digital band limiting filter 20 removes unwanted waves, that is, unnecessary frequency signals and noise signals, from the applied signal.

The D / A converter 30, which is connected to the digital band limiting filter 20 and converts an input digital signal into an analog signal, outputs an analog output signal to the analog band limiting filter 40, thereby outputting an analog signal. Eliminate unwanted and noise signals.

Among the signals output from the plurality of analog band limiting filters 40, all I phase signals are combined in the first combiner 50 and output to the first modulator 60, and the first modulator 60 is applied. The I phase signal is mixed with the frequency of Cos ω _c t, modulated to an intermediate frequency, and then output to the adder 70.

Meanwhile, all of the Q phase signals output from the plurality of analog band limiting filters 40 are inputted from the second combiner 55 to be combined and output to the second modulator 65.

The second modulator 65 mixes the input Q phase signal with the frequency of Sin ω _c t and modulates it into an intermediate frequency signal and outputs it to the adder 70.

The adder 70 adds a signal input from the first modulator 60 and the second modulator 65, and outputs the added signal to the third modulator 67, and the third modulator 67 The local oscillation frequency applied from the local oscillator 80 and the analog signal output from the adder 70 are mixed and up-modulated to a high frequency RF.

The up-modulated signal is output to the analog band pass filter 45, passes through only the corresponding CDMA frequency necessary for transmission, and is applied to the high frequency high output amplifier 90.

The high frequency high output amplifier 90 amplifies the output signal of the analog band pass filter 45 to a sufficient level of output and then applies it to the duplexer 100, and the duplexer 100 is an aerial antenna ANT. Output to

Therefore, the high frequency CDMA signal sufficiently amplified by the high frequency high output amplifier 90 is transmitted wirelessly.

As described above, the conventional multi-channel terminal uses one CDMA modem for each channel, converts it into an analog signal, combines the signals, and transmits the signals in a multi-code system. It is complicated, and the maximum value PAR due to the average rate according to the increase in the number of channels increases together, so there is a problem that the output of the RF HPA 90 needs to be larger than that of a single code method.

By solving the above problems of the prior art and using one CDMA modem in a multi-channel CDMA terminal, the circuit configuration is simplified, and the maximum value (PAR) value by the average rate does not have to be as large as the number of channels. Another object is to provide a terminal whose maximum power may be small.

The present invention has been made to achieve the above object, in the CDMA multi-channel terminal; A digital mux for multiplexing CDMA signals inputted from a plurality of channels and outputting the signals through one channel; A CDMA modem for separating the signals output from and input to the digital mux into I and Q phase signals; First and second digital band limiting filters for respectively inputting I and Q phase signals output from the CDMA modem and canceling unwanted and distorted noise signals; First and second D / A converters respectively connected to the plurality of digital band limiting filters to convert digital signals into analog signals; First and second analog band limit filters respectively coupled to the plurality of D / A converters to cancel analog clutter and distortion noise signals; A code division multiple access terminal comprising a first modulator and a second modulator connected to the plurality of analog band limiting filters and modulating at a first intermediate frequency.

In addition, the present invention provides a CDMA multi-channel terminal, comprising: a digital mux step of multiplexing signals input from a plurality of channels; A phase shifting step of converting the signal multiplexed by the digital mux step into I and Q phase signals; A digital noise limiting step of removing unwanted waves and noise from the signal output by the phase shifting step; A D / A conversion step of converting a digital signal into an analog signal; An operation method of a code division multiple access terminal comprising an analog noise band limiting step of removing unwanted waves and noise from an analog signal converted by the D / A conversion step is provided.

1 is a functional block diagram of a multi-channel terminal transmitter according to the prior art;

2 is a functional block diagram of a transmitter of a CDMA multi-channel terminal according to the present invention;

3 is a configuration diagram of two-channel digital mux channel data according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: CDMA Modem 20,20 ': Digital Band Limit Filter

30: D / A converter 40, 40 ', 45: analog filter

50, 55: combiner 60, 65, 67: modulator

70: adder 80: local oscillator

90: RF high power amplifier 110: digital mux

Hereinafter, a transmitter and an operation method of a code division multiple access multi-channel terminal according to the present invention will be described with reference to the accompanying drawings.

2 is a functional block diagram of a transmitter of a CDMA multi-channel terminal according to the present invention, and FIG. 3 is a configuration state of two-channel digital mux channel data according to an embodiment of the present invention. Is also.

In the above drawings, functional blocks that perform the same functions as in the prior art used the same member numbers.

Multi-channel communication signals generated by each user are converted into one channel signal by digital time division multiplex (TDM: Time Division Multiplex) multiplexing. (Code), i.e., a High Speed Bit Stream signal in a single code.

As an example, in the case of the above, in case of two channels of a signal of 32 Kbps per channel and a 1 bit code, when multiplexing by the TDM method, a 64 Kbps 1 bit stream including 34 Kbps of transmission rates of each channel code (Bit Stream) ) Is converted to the baud rate of the code.

As shown in the above example, the signal of the 1-bit stream code that is doubled due to the sum of the transmission rates becomes the 1-bit stream code equal to one channel code, so that the maximum value PAR is 1.

However, since the bit rate of the CDMA input is twice that of the single channel code method, the average power of the RF HPA must be doubled to maintain the Bit Error Rate (BER).

However, with a PAR value of 1, it is not necessary to use a higher output HPA for peak power.

Referring to FIG. 2, the code division multiplexed multi-channel terminal according to the present invention is a CDMA scheme inputted as a signal of 1 bit from each of n channels according to a communication signal to be transmitted by a user. A digital mux 110 that multiplexes a signal in a time division multiple (TDM) manner, multiplies the transmission rate by one channel and outputs it as a 1-bit signal;

CDMA modem 10 for outputting the CDMA signal to be separated into I and Q phase signals by outputting one bit at n times the transmission rate from the digital mux 110, respectively,

First and second digital band limiting filters 20 and 20 'that respectively input digital I and Q phase signals output from the CDMA modem 10 and remove and output unwanted wave and distortion noise signals;

First and second D / A converters 30 and 30 'connected to the plurality of digital band limiting filters 20 and 20', respectively, for converting and outputting an input digital signal into an analog signal; ,

First and second signals connected to the plurality of D / A converters 30 and 30 ', respectively, to remove unwanted wave and distortion noise signals of analog signals output from the respective D / A converters 30 and 30'. 2 analog band limit filters (40, 40 '),

A first intermediate frequency is connected to the plurality of analog band limiting filters 40 and 40 'and by mixing a Cos ωct signal and a Sin ωct signal with a signal output from each of the analog band limiting filters 40 and 40'. First and second modulators 60 and 65 for modulating and outputting at IF (Intermediate Frequency),

An adder 70 which receives signals output from the first and second modulators 60 and 65, respectively, and adds the added signals;

A third modulator 67 which receives an output signal of the adder 70 and combines with a local frequency output from a local oscillator (L0) 80 to up-convert to a high frequency (RF) signal )Wow,

An analog band pass filter 45 which receives a high frequency signal output from the third modulator 67 and passes only a frequency signal of a specific band allocated to a CDMA multi-channel terminal;

A high output amplifier (RF HPA) 90 for amplifying and outputting a high frequency signal input from the analog band pass filter 45 to a high output;

The RF signal received from the RF HPA 90 is transmitted to the aerial antenna ANT for wireless transmission, and the signal received from the aerial antenna is configured as a duplexer 100 for outputting a different path.

In addition, the operating method of the CDMA multi-channel terminal according to the present invention, in the CDMA multi-channel terminal, the digital mux step for multiplexing the digital communication signals input from the N multiple channels,

A digital phase conversion step of converting the digital signal multiplexed by the digital mux step into I and Q phase signals;

A digital noise limiting step of removing unwanted waves and noise from the digital signal output by the phase shifting step;

A D / A conversion step of converting the digital signal output by the digital noise limiting step into an analog signal;

It consists of an analog noise band limiting step of removing the unwanted wave and noise from the analog signal converted by the D / A conversion step.

Hereinafter, a CDMA multi-channel terminal and an operation method thereof according to the present invention having the above configuration will be described in detail with reference to the accompanying drawings.

The digital mux step of multiplexing a communication signal of each 1 bit code applied by a plurality of or n user channels in a time division (TDM) manner, outputs a signal output from each channel to one channel. do.

As an example, referring to the accompanying FIG. 3, a 1-bit bit code communication data signal having a 34 Kbps transmission rate from two user channels is input to the TDMA digital multiplexor 110. In this case, the output of the digital mux 110 is multiplexed at the same rate as each transmission rate input for each channel and outputs the multiplex.

That is, in the case of multiplexing a 32 Kbps 1 bit code signal of channel 1 and a 32 Kbps 1 bit code signal of channel 2, the digital mux 110 multiplexes at a 64 Kbps transmission rate, thereby converting one bit (1 Bit) code signal. Output

Accordingly, the digital mux 110 converts a plurality of channels of codes into one channel code signal.

In addition, the 1-bit code digital output signal of each user channel has a transmission rate of 32 Kbps, as well as various transmission rates such as 8/16 Kbps and 64/80/144 Kbps can be used.

As described above, the 1-bit code signal input from each user channel is input to the digital mux 110 in multiples of n, and the transmission speed input by each channel is multiplexed by the digital mux 110, thereby increasing the number of times. It is output as a 1-bit code signal with a transmission rate of.

In the digital phase shifting step, the output signal of the digital multiplexer 110, in the case of two channels, is fastened at a transmission rate of 64 Kbps in one example, but because it is a signal of one bit code, one CDMA modem ( 10) and divides and outputs the 1 bit code signal having the 64 Kbps transmission rate into the 1 bit code signal of the I phase signal and the Q phase signal.

In the digital noise band limiting step, the first and second digital band limiting filters 20, 20 'are divided into 1-bit code signals which are divided or separated into an I phase signal and a Q phase signal from the digital phase shifting step. ) To eliminate digital unwanted and noise signals.

In the D / A conversion step, the I and Q phase signals of the 1-bit code output from the first and second digital band limiting filters 20 and 20 'are respectively converted into first and second digital / analog (D) signals. / A) By inputting to the converters 30 and 30 ', a digital signal of one bit code is converted into an analog signal of one bit code and output.

The analog I and Q phase output signals of the 1-bit code output from the first and second D / A converters 30 and 30 'by the analog noise band limiting step are respectively the first and second analog band limiting filters ( 40, 40 '), and removes an unwanted wave and a noise signal from the input analog signal and outputs it.

After the noise signal is removed by the first and second analog band limiting filters 40 and 40 ', the analog I phase signal and the Q phase signal of the 1-bit code output are Cos ω, which is a first intermediate frequency. _{By being} mixed with the _c t and Sin ω _c t signals, they are input to the first and second modulators 60, 65 to be modulated into intermediate frequency signals.

By inputting to the first and second modulators 60 and 65, an I phase signal and a Q phase signal of a 1-bit code that are modulated at an intermediate frequency and output are added to the adder 70, thereby adding to each other. .

After being added by the adder 70, the output 1-bit code channel signal is input to the third modulator 67 and mixed with the local oscillation frequency of the local oscillator (L0) 80, thereby providing a CDMA multichannel terminal. It is up-converted to a high frequency (RF) signal of a 1-bit code channel assigned to the Rx.

The signal output after being up-modulated by the third modulator 67 into the high frequency signal of the 1-bit code channel is input to the analog band pass filter 45 so that only the high frequency signal of the CDMA band from which the noise signal is removed is passed. The high power amplifier 90 is applied to the high power amplifier 90 to amplify the high frequency signal to the high power.

The high frequency high output amplifier 90 receives and amplifies a channel signal of 1-bit code, so that the average power is doubled to maintain a bit error rate (BER) according to an increase in transmission speed. It is necessary, but since it is a channel of 1-bit code, Peak Power does not need any further increase.

The high frequency signal amplified by the high frequency high output amplifier 90 is applied to the duplexer 100 and transmitted through the aerial antenna.

Conventionally, the number of user channels, that is, the CDMA modem 10 corresponding to n, was required. Accordingly, 2n digital band limiting filters 20, 2n D / A converters 30, and 2n Two analog band limiting filters 40 and couplers 50 and 55 were required.

However, in the present invention, by using the time-division type digital mux 110, the subscriber's communication signal input through n channels is multiplexed and output into a signal of 1 bit code channel, and only one CDMA modem 10 needs to be used. Only the first and second digital band limiters 20,20 ', the first and second D / A converters 30 and 30', and the first and second analog band limit filters 40,40 '. All you need is

In addition, the couplers 50 and 55 are not used.

In addition, as in the above example, a circuit configuration for two user channels requires about 500,000 gates in the related art, but when the present invention is applied, the circuit may be configured as about 10,000 gates.

In addition, in the case of the two channels according to the above example, the output of the high frequency high output amplifier 90 may be one half of the output of the prior art, and as the user channel increases to n, the rate of decrease decreases more. Appears as 1 / n.

Therefore, as the number of channels increases, a high frequency high output amplifier having a low number of gates and a low price can be used, and accordingly, a single multi-channel single code terminal can be realized.

In a multi-channel terminal having N number of user channel codes, the prior art requires N CDMA modems, 2N digital filters, D / A converters, and analog filters, and combines transmission signals and the like and then modulates uplink. (Up-Conversion) and amplified by RF HPA. In this case, if the power required by the single channel code is Po, for example, for the N channel, the mean power is N * Po and the peak power is N ² * Po. According to the present invention, two digital filters, a D / A converter, and an analog filter are required by TDMA muxing a plurality of user channel data and using only one CDMA modem, and the average power of HPA is the same. In the case of BER, N * Po, and the peak power is N * Po, which requires only 1 / N of peak power compared to the prior art, thereby lowering the cost of HPA, reducing power consumption, and dramatically reducing the number of parts. It has the effect of making it compact by reducing it.

Claims (4)

In the CDMA multi-channel terminal, The terminal includes a duplexer, a high frequency high power amplifier, an analog band pass filter, a third modulator, a local oscillator, an adder, A digital mux for multiplexing CDMA signals inputted from multiple channels and outputting the signals through one channel; A CDMA modem for separating the signals output and input from the digital mux into phase signals of I and Q, First and second digital band limiting filters for inputting I and Q phase signals outputted from the CDMA modem, respectively, and removing and outputting unwanted wave and distortion noise signals; First and second D / A converters respectively connected to the plurality of digital band limiting filters and converting input digital signals into analog signals; First and second analog band limiting filters respectively connected to the plurality of D / A converters to remove analog clutter and distortion noise signals; And a first and second converters coupled to the plurality of analog band limiting filters and coupled to a first intermediate frequency. According to claim 1, And a channel input to the digital mux is a multiple of two. According to claim 1, The CDMA modem, the digital band limiting filter, the D / A converter, and the analog band limiting filter operate at the same data rate as the sum of the data rates of the multiple channels multiplexed in the digital mux. Divisional multi-channel terminal. In the CDMA multi-channel terminal, A digital mux step of multiplexing signals input from multiple channels, A digital phase conversion step of converting the signal multiplexed by the digital mux step into I and Q phase signals; A digital noise limiting step of removing unwanted waves and noise from the signal output by the phase shifting step; A D / A change step of converting the digital signal output by the above step into an analog signal, A method of operating a code division multiple access terminal, comprising: an analog noise band limiting step of removing unwanted waves and noise from a signal converted in the D / A change step.