KR970002957B1 - Data transmission apparatus in dual-mode wideband spread spectrum cellular system - Google Patents

Abstract

A data transmission apparatus of a spread spectrum system is disclosed. The data transmission apparatus of the spread spectrum system comprises: a spreader for spreading first and second messages by a Walsh code; a first message converter for generating I-ARM and Q-ARM signals of the first message; a second message converter for generating the I-ARM and Q-ARM signals of the second message; a digital combiner for digital combining the I-ARM and Q-ARM signals received from the first and second message converters; and a phase shift keying modulator for modulating the digital combined I-ARM and Q-ARM signals by a phase shift keying modulation. Thereby, the data transmission apparatus of the spread spectrum system may minimize a transmission error.

Description

Data transmission device of spread spectrum communication system

1 is a block diagram of a base station transmission apparatus of a conventional dual mode wideband spread spectrum cellular system.

2 is a block diagram of a base station transmission apparatus of a dual mode wideband spread spectrum cellular system according to the present invention.

* Explanation of symbols for main parts of the drawings

52, 58: digital-to-analog converter 54, 60: filter

56, 62, 70: mixer 64: local oscillator

66: ideal phase 68: the adder

72 carrier oscillator 74 phase keying modulator

76: low power amplifier 78: antenna

101 to 119: multiplier 121 to 131: adder

The present invention relates to a data transmission apparatus of a spread spectrum communication system, and more particularly, to a base station transmission apparatus of a dual mode wideband spread spetrum cellular system.

Spread spectrum system is a communication method that is designed by a designer or user to protect information from interference or detection of communication. The spread spectrum system is a communication system in which the frequency bandwidth of a transmission signal is much wider than that of a message signal. The bandwidth of the signal used in the band-assurance system should be at least 10 to 100 times the information rate (information rate).

1 is a block diagram of a base station transmission apparatus of a conventional dual mode wideband spread spectrum cellular system.

The circuit configured as shown in FIG. 1 includes spreading call processing-related messages and voice data by Walsh codes, respectively, and an I-PN (Pseudo Nmoise) code of an I-channel preset for each of the spread signals. Multiply the Q-PN code of the Q-shape to convert the signals of I-ARM and Q-ARM, and digitally combine the converted I-ARM signals and Q-ARM signals for each channel to an analog signal. After converting the signal for each channel modulated PSK (Phase shift keyig) modulated and transmitted.

The operation of the conventional circuit shown in FIG. 1 will be described below.

Now, when the pilot signal PT, the sync signal, the paging signal Pshinhz PG, and the forward traffic signal FT are input to one side of the multipliers 12 to 18, Each of the multipliers 12 to 18 spreads the signals input by a Walsh code W1 to W4 input to another input terminal. Here, the pilot signal PT is a code synchronization message for hardware synchronization between a receiver and a transmitter when a message is transmitted, and the synchronization signal Sync is for software synchronization of a transmitter and a receiver. As a parameter transmission message, this is a message used for channel movement between a transmitter and a receiver, and the paging signal PG is a telephone related call processing message. These messages are signals supplied from a central processing unit (not shown) which is the main subject of the system. The forward traffic signal FT is a coded voice message, which is coded voice data from a voice codec (not shown).

Each of the multipliers 12 to 18 is a pilot signal PT, a synchronization signal, a paging signal PG, and a forward traffic signal FT spread by a Walsh code W1 to W4. ) Are output to the respective paths P1 and P2. The paths P1 and P2 are paths for generating signals of the I-channel and the Q-channel, and the I-PN codes I-PN of the preset I-channel are respectively input to the paths P1. Multipliers 20 to 26 are connected. The paths P2 are connected to multipliers 28 to 34 that respectively input Q-PN codes Q-PN of a preset Q-channel.

The I-PN code (I-PN) and the Q-PN code (Q-PN) are spread as described above to convert the data input to the path P1 or the path P2 into data of different logic. It is set as data for.

Therefore, each of the multipliers 20 to 26 multiplies the information inputted to the respective paths P1 after spreading the band as described above and converts the information into an I-ARM signal by multiplying the I-PN code (I-PN). It is provided to one side of the adders 42, 40, 380, 36 connected to the path P1. Each of the multipliers 28 to 34 multiplies the Q-PN code Q-PN by multiplying each piece of information input through the respective paths P2 after spreading from the multipliers 12 to 18. The signal is converted into an ARM signal and provided to one side of the adders 50, 48, 46, 44 connected to the path P2. Here, the adders 36 to 50 are digital adders for adding a digital signal.

Accordingly, the I-ARM signals of each message generated as described above are digitally added by the adders 36 to 42 and digitally combined, and digitally coupled by the Q-ARM signals adders 44 to 50.

The digitally coupled I-ARM signal and Q-ARM signal are outputted to the phase shift keyig (PSK) modulator 74 connected to the output terminal of the adder 42 and the adder 50 by the above operation. At this time, the digital-analog converter (hereinafter, referred to as "DAC") 52 and 58 in the PSK modulator 74 are output from the adder 42 and the adder 50, respectively. The ARM and Q-ARM signals are converted into analog signals and output. The I-ARM signal and the Q-ARM signal converted into analog signals by the DACs 52 and 58, respectively, are supplied to the respective filters 54 and 60, and each of the filters 54 and 60 is input. The signal is filtered and input to the mixer 56 and the mixer 62, respectively.

At this time, the mixer 56 mixes and outputs the signal output from the local oscillator 64 and the signal output from the filter 54, and the mixer 62 shifts the output of the local oscillator 64 by 90 °. The output of the phase shifter 66 and the signal output from the filter 60 are mixed and output.

Therefore, the phases of the I-ARM signal and the Q-ARM signal output from the mixer 56 and the mixer 62 are output with a phase difference of 90 °, and the adder 68 is mixed with the above-described I-ARM signal. And the Q-ARM signal are added to output the PSK modulated signal S (t) to the mixer 70.

The mixer 70 up-converts the carrier signal output from the carrier oscillator 72 and the PSK modulation signal S (t) output from the adder 68 to a downlink frequency. The signal is converted and output to the power amplifier 76.

Therefore, in the conventional spread spectrum system configured as shown in FIG. 1, an error occurs in transmitting a message by combining the following signals when digitally combining the I-ARM signal and the Q-ARM signal of each path P1 and P2. Will cause problems.

That is, I-ARM signals are generated by multiplying all the messages carried in the path P1 of each message channel by the I-PN code (I-PN) of the same I-channel, and carried in the path P2 of the message channel. Q-ARM signal is generated by multiplying the Q-PN code (Q-PN) of the same Q-channel by all the messages so that the digital combining signal of I, Q-channel crosses at zero point. The case occurs. Therefore, in the conventional system configured as shown in FIG. 1, when the power amplifier 76 amplifies the modulated signal S (t), which is multiplied by the carrier signal generated from the carrier oscillator 72, the linearity is reduced. This leads to the problem of having to design a good power amplifier 76.

Accordingly, an object of the present invention is to provide a spread spectrum communication system that minimizes transmission errors by suppressing the level of zero point crossing during digital combining by spreading messages of I-channel and Q-channel.

Another object of the present invention is to minimize the occurrence of the zero point crossing when the digital coupling of the I-channel and the Q-channel to prevent the unbalance of the I-channel and the Q-channel (Unbalancd), and the burden on the linearity This is to provide a spread spectrum system that can use less power amplifier.

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

2 is a block diagram of an apparatus for transmitting a base station of a dual-mode wideband spread spectrum cellular system according to the present invention, a band spreader for spreading and outputting inputs of a first message and a second message to an input of a Walsh code; I-ARM of the first message by computing the code first message spread from the spreader with the I-PN code (I-PN) of the pre-set I-channel and the Q-PN code (Q-PN) of the Q-channel, respectively. A first message converter for generating a signal and a Q-ARM signal, and a Q-PN code (/ Q-PN) inverted in phase by inverting the phase of the Q-PN code (Q-PN) of the Q-channel (where A Q-PN code converter for outputting " / " bar, and the spread second message is the phase-inverted Q-PN code (/ Q-PN) and the I-PN code (I-PN). A second message converter for generating the I-ARM signal and the Q-ARM signal of the second message, respectively, and the I-ARM signal and the Q-ARM signal output from the first and second message converters, respectively. And digitally add the respective digital combiner to output the digitally coupled I-ARM signal and the Q-ARM signal, and input the I-ARM signal and the Q-ARM signal output from the digital combiner to output the phase shift keying modulation. And a phase shift keying modulation transmitter.

In the configuration of FIG. 2, the multipliers 101 to 105 correspond to the band spreader, the multipliers 107 and 109 correspond to the first message converter, and the multiplier 110 corresponds to the Q-PN code converter. . The multipliers 113-119 correspond to the second message conversion section, the adders 121-131 correspond to the digital coupling section, and the PSK modulator 74 and the power amplifier 76 provide a phase shift keying modulation transmitter. Corresponds. The first message is the pilot signal PT described with reference to FIG. 1, and the second message is a mark signal Mark which is a call processing related message and a forward traffic signal FT which is a coded voice message. it means. Here, the mark signal Mark is a synchronization signal Sync, which is a parameter transmission message for synchronizing software between the transmitter and the receiver as described in FIG. 1, and a paging signal PG, which is a call-related call processing message. It should be recognized that it is a message that includes a.

Hereinafter, an operation example of FIG. 2 according to the present invention will be described in detail.

Now, when the pilot signal PT, the mark signal Mark, and the forward traffic signal FT generated in each channel are input to a circuit constructed as shown in FIG. 2, the signals of the respective channels are Walsh codes W1 to W3. Is spread by the operations of the multipliers 101 to 103 for inputting. The signals spread as described above are branched into the paths P1 and P2 of each channel.

The multiplier 107 connected to the path P1 receives the pilot signal PT, which is the first message, in response to the input of the I-PN code I-PN of the I-channel and the I-PN code I-PN. The multiplier 109 connected to the path P2 multiplies the Q-PN code (Q-PN) and the pilot signal (PT) of the Q-channel to produce a Q-ARM signal. Convert and output That is, the pilot signal PT for facilitating the code synchronization of the receiver is multiplied by the I-PN code I-PN in the multiplier 117 to be output as an I-ARM signal, and the Q- in the multiplier 109. It is multiplied by the PN code (Q-PN) to output as a Q-ARM signal.

On the other hand, the multiplier 110 for inputting the Q-PN code (Q-PN) of the Q-channel multiplies the Q-PN code (Q-PN) by "-1" Q-PN code (/ The Q-PN is input to the multipliers 113 and 115 connected to the second spread spectrum message, that is, to the input path P1 of the spread spectrum mark signal Mark and the forward traffic signal FT. In this case, the multipliers 113 and 115 multiply the Q-PN code (/ Q-PN) whose phase is inverted as described above by the mark signal Mark inputted to the path P1 and the forward traffic signal FT. The I-ARM signal for the signal is output to the adders 123 and 121, respectively.

The multiplier 117 and the multiplier 119 connected to the path P2 for inputting the spread mark signal Mark and the forward traffic signal FT are connected to the I-PN code I-PN of the I-channel. The signals input to the path P2 are multiplied to generate a Q-ARM signal of a Q-channel.

Therefore, the I-ARM signal for the mark signal Mark and the forward traffic signal FT is " -1 " in the multiplier 110 using the Q-PN code Q-PN used in the pilot signal PT. It can be seen that it is multiplied by the value of and multiplied by the phase inverted signal. In addition, it can be seen that the Q-ARM signal of the mark signal Mark and the forward traffic signal FT is multiplied by the I-PN code I-PN used in the pilot signal PT.

On the path P1 and the I-ARM signal of the I-channel with respect to the path P1 of each pilot signal PT, mark signal Mark, and forward traffic FT generated by the above process. Digitally coupled by the connected digital adders 121 to 129 and input to the DAC 52 of the PSK modulator 74, Q-ARM signals of the Q-channel are connected to the digital adders 123 to 131 connected on the path P2. Digitally coupled to the DAC 58 of the PSK modulator 74.

In this case, the DACs 52 and 58 in the PSK modulator 74 convert the input I-ARM signal and the Q-ARM signal into analog signals, respectively. Each band limit is performed at 60, and then multiplied by the carrier signal of the carrier generator 72 through the signal synthesis procedure described above to be transmitted through the power amplifier 76 through the power amplified antenna 78.

Here, it should be noted that since the digitally coupled I-ARM signal and the Q-ARM signal as described above cross each other with respect to the I-PN code (I-PN) and the Q-PN code (Q-PN), the zero point. This minimizes the possibility of crossover, which makes the system stable even without the use of highly linear power amplifiers, and has the advantage that the signals of the I- and Q-channels are not unbalanced.

As described above, the present invention minimizes the digitally coupled I-ARM signal and the Q-ARM signal by intersecting each other with respect to the I-PN code (I-PN) and the Q-PN code (Q-PN). -The signal quality of the channel and Q-channel is not unbalanced, which can improve the call quality.

Claims (5)

A base station transmission apparatus of a spread spectrum system, comprising: a spreader for spreading an input of a first message and a second message to an input of a Walsh code, and a preset code I message spread from the spreader; A first message converting unit configured to generate an I-ARM signal and a Q-ARM signal of a first message by calculating the I-PN code of the channel and the Q-PN code of the Q-channel, respectively, and the spread second message A second operation of generating an I-ARM signal of a second message by operating with the Q-PN code of the Q-channel and a second operation of generating a Q-ARM signal of a second message by operating with an I-PN code of the I-channel. A digital combiner for digitally adding an I-ARM signal and a Q-ARM signal respectively output from the first and second message converters to output a digitally coupled I-ARM signal and a Q-ARM signal; Phase by inputting the I-ARM signal and Q-ARM signal output from the digital coupling unit And a phase shift keying modulation transmitter for outputting the shift keying modulation. 2. The method of claim 1, wherein the first message is a code synchronization message for synchronizing hardware between a receiver and a transmitter when a message is transmitted, and the second message is a channel movement and call-related call processing between a transmitter and a receiver. A base station transmission apparatus of a spread spectrum system, characterized in that the message and the coded voice message. A base station transmission apparatus of a spread spectrum system, comprising: a spreader for spreading an input of a first message and a second message to an input of a Walsh code, and a preset code I message spread from the spreader; A first message converter which generates an I-ARM signal and a Q-ARM signal of the first message by calculating the I-PN code of the channel and the Q-PN code of the Q-channel, respectively, and the Q- of the Q-channel. A Q-PN code converter for inverting the phase of the PN code to output a phase-inverted Q-PN code, and calculating the Q-PN code of the spread second message and the I-PN code, respectively, to calculate the I-PN code of the second message. A second message converter for generating an ARM signal and a Q-ARM signal, and a digitally coupled I-ARM by digitally adding the I-ARM and Q-ARM signals respectively output from the first and second message converters. A digital coupling unit for outputting a signal and a Q-ARM signal, and I output from the digital coupling unit And a phase shift keying modulation transmitter for inputting an ARM signal and a Q-ARM signal to perform phase shift keying modulation. 4. The method of claim 3, wherein the first message is a code synchronization message for synchronizing hardware between the receiving side and the transmitting side when the message is transmitted, and the second message is a channel movement and telephone-related call processing between the transmitting apparatus and the receiving apparatus. A base station transmission apparatus of a spread spectrum system, characterized in that the message and the coded voice message. The base station of a spread spectrum system according to claim 3 or 4, wherein the Q-PN code converter is a multiplier that inverts the phase of an input value by multiplying an input digital code by a value of "-1". Transmission device.