KR20010059733A - Transmission method for multiple chip rate in mobile communications system - Google Patents

Abstract

PURPOSE: A transmission method of a mobile communication system for a multiple chip rate is provided so that channel interferences can be reduced by using one transmission device in a wide band code division multiple access(WCDMA) system supporting a multiple chip rate signal. CONSTITUTION: The first chip rate signal and the second chip rate signal are inputted in a mobile communication system. The first chip rate signal is spread by using an orthogonal variable spread code, and the second chip rate signal is spread by using a qusi-orthogonal multiple chip rate code of the orthogonal variable spread code. The first chip rate signal and the second chip rate signal are scrambled by employing an identical complex scrambling code. Thereafter, the first chip rate signal and the second chip rate signal are modulated to identical carriers, and the modulated signals are transmitted. When the first chip rate has a smaller value than the second chip rate, a complex scrambling code of the first chip rate is used as a complex scrambling code of the second rate. That is, the identical scrambling code is utilized for the different chip rate signals. In addition, the qusi-orthogonal multiple chip rate code is employed as a channel code. Accordingly, channel interferences of the multiple chip rate can be reduced through one transmission device.

Description

Transmission method for multiple chip rate in mobile communication system

TECHNICAL FIELD The present invention relates to mobile communications, and in particular, to a method of transmitting a mobile communications system for multiple chip rates adapted to be suitable for transmitting signals of multiple chip rates in a wideband code division multiple access (WCDMA) mobile communications system.

1 is a block diagram illustrating an apparatus for transmitting a single chip rate signal in a conventional wideband code division multiple access (W-CDMA) mobile communication system.

Referring to FIG. 1, a channel code is applied to a serial / parallel converter 100 that receives data or control information and outputs an I signal and a Q signal, and an I signal and a Q signal output from the serial / parallel converter 100. A first mixer 101 and a second mixer 102 multiplying and spreading a data symbol to a chip, and an imaginary converter 103 for imaginary Q signal output from the mixer 102; And a combiner 104 for outputting a complex signal by combining the I signal output from the first mixer 101 and the Q signal output from the imaginary converter 103 and the complex signal output from the combiner 104. A third mixer (105) for multiplying the complex scrambling code by scrambling, a real / imaginary separator (106) for dividing the complex signal output from the third mixer (105) into a real part signal and an imaginary part signal, and the real number Real and imaginary part signals in the imaginary / imaginary separator 106 The first pulse shaping filter 107 and the second pulse shaping filter 108 and the first pulse shaping filter 107 to form a chip waveform so as to transmit the separated signals to the specific frequency band, respectively, and output from the first pulse shaping filter 107 Signal To a signal output from the fourth mixer 109 multiplying the carrier wave and the second pulse shaping filter 108 The fifth mixer 110 multiplies the carrier wave.

The operation of the conventional mobile communication system configured as described above is as follows.

First, data and control information of a specific user are separated into an I signal and a Q signal and then spread by a channelization code (C _ch ). Subsequently, the spread I and Q signals are combined to form a complex signal, and then scrambled by a complex-valued scrambling code (C _scramb ).

In this case, an orthogonal variable spreading factor (OVSF) code is used as the channel code, and the channel code serves to distinguish each user's channel. There are a plurality of such channel codes depending on the spread factor. For example, if the j th channel code having a spread ratio SF is sf, C _{ch, sf, j} (j = 0, 1, 2, 3, sf-1), the channel code uses a matrix as Can be generated.

C _{ch, 1,0} = 1

Meanwhile, the channel code may be generated using a code tree as shown in FIG. 2 in addition to Equation 1 shown above.

The channel code is assigned to a new channel by selecting the code of the spreading rate (SF) required by the channel among the codes except for the following three kinds of codes in the code tree. The following types of codes are excluded. First, it excludes the code already in use by existing channels. Second, the code tree excludes the code belonging to the code tree starting from the code used by the existing channel and extending to the right. Third, the channel codes already used by the existing channel and the code placed on the line connecting C _{ch, 1,0} corresponding to the root of the code tree are excluded.

On the other hand, the complex scrambling code is a pseudo random (Random) code that serves to distinguish the transmission device.

The complex signal scrambled by the third mixer 105 is separated into a real part signal and an imaginary part signal, respectively, passes through each pulse shaping filter 107, 108, and then modulated to a carrier frequency omega and transmitted.

At this time, the rate of the channel code and the complex scrambling code shown in FIG. 1 is 3.84 Mcps, and each of the pulse shaping filters 107 and 108 forms a chip waveform so that a chip rate signal of 3.84 Mcps can be transmitted in a frequency band of 5 MHz. It plays a role.

As described above, channel signals spread by the channel code and scrambled by the complex scrambling code do not cause inter-signal interference by maintaining orthogonality with each other.

However, since the transmission apparatus of the conventional wideband code division multiple access (W-CDMA) mobile communication system is designed considering only a single chip rate, that is, signal transmission of 3.84Mcps, 7.68Mcps, which is two and four times 3.84Mcps. And failing to transmit a signal having a chip rate of 15.36 Mcps.

In order to solve this problem, a transmission apparatus of a conventional wideband code division multiple access (W-CDMA) mobile communication system can be extended as shown in FIG. 3 to support multi-chip rate signal transmission.

That is, in FIG. 3, one transmitting device transmits signals having two chip rates. If the first chip rate is 3.84 Mcps, the second chip rate is 7.68 Mcps, and if the first chip rate is 7.68 Mcps, the second chip is used. The rate is 15.36 Mcps. In other words, the second chip rate is twice the first chip rate. At this time, the signal of each chip rate is multiplied by the channel code and the complex scrambling code of the chip rate as described above, and then transmitted after passing through the pulse shaping filter of the chip rate. In this case, the orthogonal variable spreading rate (OVSF) code is allocated to the channel code in the same manner as described in FIG. 2, and in particular, the channel code is independently assigned to each chip rate.

Therefore, when a transmission device supporting a single chip rate is extended to support multiple chip rates, inter-signal interference does not occur due to orthogonality of channel codes between signals of the same chip rate, but signals of different chip rates. Since the scrambling codes used are different from each other, there is a problem in that interference between signals is increased due to failure to maintain orthogonality of channel codes.

Accordingly, an object of the present invention is to provide an efficient transmission method of a mobile communication system that supports multiple chip rate signal transmission, which is conceived in view of the above-mentioned problems of the prior art.

According to an aspect of the present invention for achieving the above object, a method of transmitting a mobile communication system for a multiple chip rate is a method for transmitting a signal of the first chip rate and a signal of the second chip rate in a mobile communication system. A first step of receiving a signal of the first chip rate and a signal of the second chip rate, and the input signal of the first chip rate is spread using an orthogonal variable spreading rate (OVSF) code, the input A second chip rate signal is spread using a pseudo orthogonal multiple chip rate (QOMCR) code that is part of the orthogonal variable spreading rate (OVSF) code, A third step of scrambling a signal of two chip rates using the same complex scrambling code, and wherein the signal of the scrambled first chip rate and the signal of a second chip rate are the same It comprises a fourth step of transmitting the modulation to the transmitting.

Preferably, in the third step, the complex scrambling code of the first chip rate is used as the complex scrambling code of the second chip rate when the first chip rate has a value less than the second chip rate.

1 is a block diagram showing an apparatus for transmitting a single chip rate signal in a conventional wideband code division multiple access (W-CDMA) mobile communication system.

2 illustrates a code tree for generating a conventional channel code.

3 is a block diagram illustrating an apparatus for transmitting a multi-chip rate signal in a conventional wideband code division multiple access (W-CDMA) mobile communication system.

4 is a block diagram illustrating an apparatus for transmitting multiple chip rate signals in a wideband code division multiple access (W-CDMA) mobile communication system according to the present invention;

5 shows a code tree for generating a pseudo orthogonal multiple chip rate (QOMCR) code in accordance with the present invention.

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

400,401: Serial / Parallel Converter 402,403,404,405,410,411,420,421: Mixer

406,407: imaginary converter 408,409,418,419: combiner

412,413: Real / imaginary separator 414,415,416,417: Pulse shaping filter

Hereinafter, a configuration and an operation according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

The present invention proposes a transmission method of a mobile communication system for a multi-chip rate to efficiently transmit by reducing interference between signals having different chip rates.

Particularly, in the present invention, a signal of a second chip rate, which is twice the first chip rate and the first chip rate, is transmitted through one transmission device, and the carrier frequencies of the first chip rate and the second chip rate are the same. The present invention proposes a transmission apparatus and method for a mobile communication system. Here, the first chip rate and the second chip rate may be 3.84 Mcps, 7.68 Mcps, and 15.36 Mcps.

In addition, the present invention scrambles a signal of several chip rates using a complex scrambling code of a signal having the lowest chip rate, and also has a high chip of a quasi-orthogonal multiple chip rate code (QOMCR code). It is used as a channel code of rate to reduce the interference between signals of different chip rates.

4 is a block diagram illustrating a multiple chip rate transmission apparatus of a mobile communication system according to the present invention.

Referring to FIG. 4, a transmission apparatus according to the present invention includes a first transmission branch for transmitting a signal of a first chip rate and a second transmission branch for transmitting a signal of a second chip rate.

In this case, the first transmission branch includes a first serial / parallel converter 400 that receives data or control information having a first chip rate and outputs the I signal and the Q signal, and the first serial / parallel converter 400. A first mixer 402 and a second mixer 403 for multiplying the output I signal and the Q signal by a first channel code of a first chip rate to spread a data symbol onto a chip; The first imaginary converter 406 for imaginary Q signal output from the mixer 403, the I signal output from the first mixer 402 and the Q signal output from the first imaginary converter 406 The first combiner 408 for combining and outputting a complex signal, the third mixer 410 for multiplying the complex signal output from the first combiner 408, and scrambled by the complex scrambling code, and the complex scrambling code are multiplied. The complex signal is divided into a real part signal and an imaginary part signal for output. A first pulse forming a chip waveform so that the first real / imaginary separator 412 and the first real / imaginary separator 412 can transmit signals separated into a real part signal and an imaginary part signal in a specific frequency band It consists of a shaping filter 414 and a second pulse shaping filter 415.

The second transmission branch is a second serial / parallel converter 401 that receives data or control information having a second chip rate and outputs the I signal and the Q signal, and outputs the second serial / parallel converter 401. A fourth mixer 404 and a fifth mixer 405 for multiplying the received I signal and the Q signal by a second channel code of a second chip rate and spreading a data symbol to a chip; A second imaginary converter 407 for imaginary Q signal output from the mixer 405 and an imaginary Q output from the second imaginary converter 407 and the I signal output from the fourth mixer 404. A second combiner 409 for combining the signals and outputting a complex signal, a sixth mixer 411 for multiplicating the complex signal output from the second combiner 409 by a complex scrambling code, and the complex scrambling code Divide the multiplied complex signal into a real part signal and an imaginary part signal A second waveform that forms a chip waveform so that the second real / imaginary separator 413 and the second real / imaginary separator 413 output the signals separated by the real part signal and the imaginary part signal in a specific frequency band. The real-time partial signal output from the third pulse shaping filter 416 and the fourth pulse shaping filter 417, the first pulse shaping function 414 of the first transmission branch, and the third pulse shaping filter 416. The third combiner 418 which combines the real part signal, the imaginary part signal output from the second pulse shaping function 415 of the first transmission branch and the imaginary part signal output from the fourth pulse shaping filter 417. A fourth coupler 419 for coupling and a real part signal output from the third coupler 418 To the imaginary part signal output from the seventh mixer 420 multiplying the carrier wave and the fourth combiner 419 The eighth mixer 421 multiplies the carrier wave.

Operation of the transmission device according to the present invention configured as described above is as follows.

First, the transmission device according to the present invention is characterized in that it uses the same scrambling code for signals of different chip rates and uses a pseudo orthogonal multiple chip rate (QOMCR) code as the channel code.

That is, assuming that the first chip rate is less than the second chip rate, an orthogonal variable spreading rate (OVSF) code is assigned to the signal of the first chip rate in the same manner as before, and similar to the signal of the second chip rate. Spread by assigning orthogonal multiple chip rate (QOMCR) codes. Then, the complex scrambling code of the first chip rate is used for both the first chip rate and the second chip rate to scramble.

The pseudo orthogonal multiple chip rate (QOMCR) code is generated as part of an orthogonal variable spreading rate (OVSF) code. Therefore, it can be generated using the code tree used in generating the orthogonal variable spreading rate (OVSF) code.

That is, as shown in FIG. 5, the code tree corresponding to the lower portion is divided into half based on the horizontal in the code tree of the orthogonal variable spreading rate (OVSF) code, and thus the code tree of the pseudo orthogonal multiple chip rate (QOMCR) code. .

A method of assigning a pseudo orthogonal multiple chip rate (QOMCR) code using such a code tree is the same as the above-described orthogonal variable spreading rate (OVSF) code.

That is, as shown in FIG. 5, the code tree of the pseudo-orthogonal multiple chip rate (QOMRC) code corresponds to the code tree extending to the right starting from the code currently used by another channel and the code currently being used by another channel. Select a pseudo-orthogonal multiple chip rate (QOMCR) code from all other codes except the code, the code currently used by other channels, and the code C _{ch, 1,0} corresponding to the root of the tree. do. At this time, the channel code allocated to the channel of the second chip rate may be overlapped with the channel of the first chip rate, and likewise, the channel code allocated to the channel of the first chip rate may be overlapped with the channel of the second chip rate. have.

Thus, in FIG. 4, the first mixer 402 and the second mixer 403 spread the signal of the first chip rate using an orthogonal variable spreading rate (OVSF) code, and the fourth mixer 404 and the fifth mixer. 405 spreads the signal of the second chip rate using a pseudo orthogonal multiple chip rate (QOMCR) code.

The third mixer 410 and the sixth mixer 411 scramble the signals of the first chip rate and the second chip rate using a complex scrambling code of the first chip rate.

Thereafter, the third combiner 418 and the fourth combiner 419 combine the real part signal and the imaginary part signal of each chip rate, modulate the carrier frequency, and omega.

In the case of assigning channel codes in this way, it has already been proposed that there is no interference due to orthogonality between channels having the same chip rate and channels having different chip rates.

In the patent of P99-31733, the chip pulse waveform generated by the pulse shaping function is a time-limited chip pulse waveform having a meaningful value in a chip interval that is an inverse of the chip rate and a zero value in the remaining intervals. However, in a wideband code division multiple access (WCDMA) communication system, a root-raised cosine filter in which the chip pulse waveform is not limited within the chip interval, but the time of the chip pulse shaping function is limited in time by several orders of magnitude. Use

In consideration of the chip pulse waveform, interference between channel codes of the first chip rate and the second chip rate is shown in Table 1 below.

Table 1 shows an example of interference energy that the channel codes C _{ch, sf2, n2} of the second chip rate have on the channel codes C _{ch, sf1, n1} of the first chip rate.

Table 1 shows energy values normalized to 1 when a desired signal energy is 1.

Referring to Table 1 _, the channel codes of C _{ch, 4,2} and C _{ch, 4,3} of the second chip rate (i.e., codes belonging to the QOMRC code) are equal to C _{ch, 4,0} of the second chip rate. It can be seen that there is less interference on the channel code of the first chip rate compared to the C _{ch, 4,1} channel code (that is, the code not belonging to the QOMRC code).

The same holds true for other diffusion rates. That is, C _{ch, sf, sf / 2} , C _{ch, sf, sf / 2 + 1} , ..., C _{ch, sf and sf-1} of the _sf channel codes having the second chip rate diffusion rate sf. There is little interference that the channel code has on the channel code of the first chip rate. Here _, the channel codes of C _{ch, sf, sf / 2} , C _{ch, sf, sf / 2 + 1} , ..., C _{ch, sf, sf-1} are pseudo orthogonal multiple chip rate (QOMCR) codes.

Table 2 below shows an example of the interference energy of the channel codes C _{ch, sf1, n1} of the first chip rate to the channel codes C _{ch, sf2, n2} of the second chip rate.

Referring to Table 2, the interference energy received from a channel code belonging to a pseudo-orthogonal multiple chip rate (QOMCR) code among channel codes of a second chip rate from a channel code of any first chip rate is similar to orthogonality of a second chip rate. It can be seen that it is less than the rest of the channel codes that do not belong to the multiple chip rate (QOMCR) code.

As described above, in the present invention, in consideration of the pulse shaping filter of a wideband code division multiple access (WCDMA) communication system, an orthogonal variable spreading rate (OVSF) code is used as a channel code of a first chip rate to reduce interference between channels of different chip rates. And spread the signal using a pseudo orthogonal multiple chip rate (QOMCR) code as the channel code of the second chip rate. The complex scrambling code of the first chip rate and the complex scrambling code of the second chip rate are used as the same, and in particular, the complex scrambling code of the first chip rate is used as the complex scrambling code of the second chip rate.

As described above, according to the transmission method of a mobile communication system for a multi-chip rate according to the present invention, a multi-chip using a single transmission device in a wideband code division multiple access (WCDMA) system supporting a multi-chip rate signal There is an effect that can be transmitted by reducing the interference between the channels of the rate.

Claims (2)

A method of transmitting a signal of a first chip rate and a signal of a second chip rate in a mobile communication system, A first step of receiving a signal of the first chip rate and a signal of the second chip rate, The input first chip rate signal is spread using an orthogonal variable spreading rate (OVSF) code, and the input second chip rate signal is a pseudo orthogonal multiple chip that is part of the orthogonal variable spreading rate (OVSF) code. A second step of spreading using a rate code; Scrambling the spread first and second chip rate signals using the same complex scrambling code; And a fourth step of modulating and transmitting the scrambled signal of the first chip rate and the signal of the second chip rate to the same carrier wave. The method of claim 1, wherein in the third step, When the first chip rate has a smaller value than the second chip rate, the complex scrambling code of the first chip rate is used as the complex scrambling code of the second chip rate. Transmission method of the system.