KR20060127309A - Apparatus and method for transmitting/receiving of symbol in a mobile communication system - Google Patents

Abstract

An apparatus and a method for transceiving symbols in a mobile communication system are provided to properly arrange the time order of OFDM symbols transmitted within a transmission section in the mobile communication system, thereby effectively utilizing time diversity and improving the performance of turbo decoding. A method for transceiving symbols in a mobile communication system comprises the following steps of: receiving and encoding broadcasting and multicast packets(901); determining which part of an encoded symbol will be transmitted and modulating a determined part through a predetermined modulation type(903,904); collecting the modulated symbols in order and generating OFDM(Orthogonal Frequency Division Multiplexing) symbols(905); determining a transmission order of the generated OFDM symbols to obtain the maximum time diversity within a slot; and transmitting the OFDM symbols according to the determined transmission order(906).

Description

Apparatus and method for transmitting and receiving symbols in a mobile communication system {APPARATUS AND METHOD FOR TRANSMITTING / RECEIVING OF SYMBOL IN A MOBILE COMMUNICATION SYSTEM}

1 illustrates a process of transmitting a signal when a broadcast service is transmitted in a forward direction in a general mobile communication system;

2 is a diagram illustrating a process of transmitting a signal when transmitting an encoded packet according to an embodiment of the present invention;

3 is a diagram illustrating a process of transmitting a signal when transmitting an encoded packet according to another embodiment of the present invention;

4 is a diagram illustrating a process of transmitting a signal when transmitting an encoded packet according to another embodiment of the present invention;

5 is a structural diagram of a base station transmitter according to an embodiment of the present invention;

6 is a structural diagram of a mobile terminal receiver according to an embodiment of the present invention;

7 is a structural diagram of a base station transmitter according to another embodiment of the present invention;

8 is a structural diagram of a mobile terminal receiver according to another embodiment of the present invention.

9 is a control flowchart of symbol transmission in a base station according to an embodiment of the present invention;

10 is a control flowchart when receiving a symbol in a terminal according to an embodiment of the present invention.

The present invention relates to an apparatus and method for transmitting a modulation symbol in a mobile communication system, and more particularly, to an apparatus and method for transmitting modulation symbols in a mobile communication system supporting broadcast and multicast. will be.

In general, a mobile communication system may be classified into a form supporting only a voice service and a form supporting only a data service. A typical example of such a system is a code division multiple access (CDMA) mobile communication system. Currently, in CDMA, a system supporting only voice service is a system conforming to the standard of IS-95. However, as the communication technology is developed with the demand of the user, the mobile communication system is developing in the form of supporting voice service and high speed data service at the same time. For example, CDMA 2000 is a mobile communication system proposed to simultaneously support voice service and high speed data service. As an example of the mobile communication system, a forward link of a high rate packet data communication system (HRPD) uses a TDMA scheme as a multiple access technique and a TDM / CDM scheme as a multiplexing scheme.

A CDMA mobile communication system such as cdma2000 or HRPD (High Rate Packet Data) system supports only unicast service, not broadcast or multicast service, in which a plurality of mobile terminals receive the same voice or data information. . However, as the communication technology develops along with the user's demand, the mobile communication system is also developing in the form of supporting a broadcast service in which a plurality of mobile terminals receive the same voice or data information. Such a switchover is made by creating a new broadcasting service system or changing an existing mobile communication system to be suitable for broadcasting service.

1 illustrates a process in which a signal is transmitted when a broadcast service is transmitted in a forward direction in an HRPD mobile communication system according to the prior art.

The information broadcast or multicast in FIG. 1 is output from the turbo encoder 110. When N bits are input to the turbo encoder 110, the turbo encoder 110 outputs N systematic bits, 2N P0 and P0 ′ coded symbols, and 2N P1 and P1. 'Coded symbols are output. That is, when the coding rate is 1/5, the turbo encoder 110 of the mobile terminal outputs coded symbols corresponding to five times the number of bits of the coded packet. For example, when the number of bits of an encoded packet is 100, the turbo encoder 110 outputs 500 encoded symbols. Among the 500 coded symbols, 200 coded symbols corresponding to 100 cystematic bits and P0 and P0 'among parity bits are transmitted, and 200 coded symbols corresponding to P1 and P1' are transmitted.

Among the encoded symbols output from the turbo encoder 110, the systematic bits are input to the interleaver 120 for the systematic bits, and the P0 and P0 ′ encoded symbols are input to the interleaver 130 for the P0 and P0 ′ encoded symbols. P1 and P1 'coded symbols are input to the interleaver 140 for P1 and P1' coded symbols.

Coded symbols inputted to the systematic bit interleaver 120, the P0 and P0 'coded symbol interleaver 130, and the P1 and P1' coded symbol interleaver 140 are listed in the form of signal 150, and then Is modulated and transmitted. Some of the coded symbols included in the signal 150 are transmitted in the first slot (slot = 1.6667ms) in the first transmission slot, and some parts after the transmission in the first transmission are second and third transmissions. Is sent to. In FIG. 1, the signal 160 and the signal 170 represent encoded symbols transmitted in the first transmission and the second transmission, respectively.

In FIG. 1, the encoded symbols transmitted for each slot are transmitted in four OFDM symbols in order.

FIG. 1 illustrates a case in which a packet to be broadcast or multicast is 2048 bits, one OFDM symbol includes 320 subcarriers, and 240 subcarriers are used for data transmission. In addition, FIG. 1 assumes 16 quadrature amplitude modulation (16QAM) as a modulation scheme. In this case, as shown in FIG. 1, it can be seen that most of the systematic bits are transmitted in the first OFDM symbol and the second OFDM symbol.

As shown in FIG. 1, when most of the systematic bits are concentrated and transmitted in the first OFDM symbol and the second OFDM symbol, the time diversity that the systematic bits can obtain is not the time diversity that can be obtained in 1.6667 ms. The problem is that only time diversity can be obtained at 0.8333 ms, which is half of 1.6667 ms. In general, the importance of the system bits among the system bits, P0 and P0 ', P1 and P1' in the Turbo code is relatively high. That is, since the reception performance of the systematic bits among the systematic bits, P0 and P0 ', P1 and P1' has a relatively more influence on the performance of the turbo decoding.

Although the importance of the systematic bits is relatively high as described above, the transmission of the scheme as shown in FIG. 1 limits the time diversity that the systematic bits can obtain to 50% of the transmission interval. Compared to obtaining time diversity corresponding to 100% of the transmission interval, performance of turbo decoding is relatively reduced.

Accordingly, an object of the present invention is to provide an apparatus and method for symbol transmission / reception in a mobile communication system that effectively utilizes time diversity by appropriately arranging the time order of OFDM symbols transmitted within one transmission interval in a mobile communication system. .

Another object of the present invention is to provide an apparatus and method for symbol transmission / reception in a mobile communication system that effectively utilizes time diversity by appropriately arranging the temporal order of modulation symbols transmitted within one transmission interval in a mobile communication system. .

Another object of the present invention is to provide an apparatus and method for transmitting and receiving symbols in a mobile communication system for improving performance of turbo decoding in a mobile communication system.

In the method for transmitting a symbol in a mobile communication system according to an embodiment of the present invention, in the symbol transmission method in a mobile communication system supporting broadcast and multicast, receiving and encoding the broadcast and multicast packets, and encoding symbols Determining which part is to be transmitted, modulating the determined part by a predetermined modulation scheme, generating an OFDM symbol by collecting the modulated symbols in order, and maximum time diversity in one slot. And determining the transmission order of the generated OFDM symbols so as to obtain them, and transmitting the OFDM symbols in the determined transmission order.

In the method for transmitting a symbol in a mobile communication system according to an embodiment of the present invention, in the symbol transmission method in a mobile communication system supporting broadcast and multicast, receiving and encoding the broadcast and multicast packets, and encoding symbols Deciding which part is to be transmitted, modulating the determined part by a predetermined modulation method, determining a transmission order of modulation symbols to obtain maximum time diversity in one slot, and performing the modulation And collecting OFDM symbols in order to generate an OFDM symbol, and transmitting the OFDM symbols in the determined transmission order.

In the mobile communication system according to an embodiment of the present invention, a symbol transmitting apparatus is a symbol transmitting apparatus in a mobile communication system supporting broadcast and multicast, comprising: an encoder for receiving and encoding the broadcast and multicast packets, and an encoded symbol A modulator that determines which part is to be transmitted, modulates the determined part by a predetermined modulation scheme, an OFDM symbol generator that collects the modulated symbols in order, and generates an OFDM symbol, and a maximum time diver in one slot OFDM symbol order controller for determining the transmission order of the generated OFDM symbol to obtain a city, and OFDM symbol order controller for controlling the OFDM symbol order controller to determine the transmission order of the OFDM symbol. .

In the mobile communication system according to an embodiment of the present invention, a symbol transmitting apparatus is a symbol transmitting apparatus in a mobile communication system supporting broadcast and multicast, comprising: an encoder for receiving and encoding the broadcast and multicast packets, and an encoded symbol A modulator that determines which part is to be transmitted, modulates the determined part by a predetermined modulation scheme, and a modulation symbol order adjuster which determines a transmission order of modulation symbols to obtain maximum time diversity in one slot. And an OFDM symbol generator for collecting the modulated symbols in order to generate an OFDM symbol, and a modulation symbol order controller for controlling the modulation symbol order controller to determine a transmission order of the modulation symbols.

In the following description of the present invention, detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Terms to be described later are terms defined in consideration of functions in the present invention, and may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the contents throughout the specification.

According to an embodiment of the present invention, a process of transmitting a signal when transmitting a 2048-bit broadcast or multicast encoded packet will be described with reference to FIG. 2.

2, 3, and 4 of the turbo encoder 210, the interleaver 220 for the systematic bits, the interleaver 230 for the P0 and P0 'coded symbols, and the interleaver 240 for the P1 and P1' coded symbols. The function is performed by the turbo encoder 110, the interleaver 120 for the systematic bits, the interleaver 130 for the P0 and P0 'coded symbols, and the interleaver 140 for the P1 and P1' coded symbols in FIG. Is the same as Signals 260 and 270 of FIGS. 2, 3, and 4, respectively, which represent the encoded symbols transmitted in the first transmission and the second transmission, are the same as the signal 160 and the signal 170 of FIG. 1. In addition, the coded symbols input to the systematic bit interleaver 220, the P0 and P0 'coded symbol interleaver 230, and the P1 and P1' coded symbol interleaver 240 are listed in the same form as the signal 250. 1 is also modulated and transmitted by the modulator.

However, the difference between FIG. 2 representing the present invention and FIG. 1 representing the prior art is the position of an OFDM symbol carried after the encoded symbols are modulated. In FIG. 1, coded symbols are loaded from the first OFDM symbol after being modulated. On the other hand, in FIG. 2, after the coded symbols are modulated, they are loaded in the order of the first, third, second, and fourth OFDM symbols.

When transmitting in the same manner as in FIG. 2, since the systematic bits are mainly loaded in the first and third transmitted OFDM symbols, an improved time diversity effect can be obtained when compared with FIG. When the time diversity effect is improved as shown in FIG. 2, the reception performance for the systematic bits is relatively improved, and as a result, the turbo decoding performance is improved.

According to another embodiment of the present invention, a process of transmitting a signal when transmitting a 2048-bit broadcast or multicast packet will be described with reference to FIG. 3.

In FIG. 3, the coded symbols are loaded on the first, third, fourth, and second OFDM symbols after they are modulated. When transmitting in the same manner as in FIG. 3, since the systematic bits are mainly loaded in the first and fourth transmitted OFDM symbols, the time diversity effect can be improved as compared with FIG. When the time diversity effect is improved as shown in FIG. 3, the reception performance for the systematic bits is relatively improved, and as a result, the turbo decoding performance is improved.

2 and 3, an improved time diversity can be obtained by appropriately adjusting the order of OFDM symbols carrying encoded symbols.

2 and 3 illustrate a case in which a broadcast or multicast packet is 2048 bits, one OFDM symbol includes 320 subcarriers, and 240 subcarriers are used for data transmission. In addition, 16 Quadrature Amplitude Modulation (16QAM) is assumed as a modulation scheme. The present invention can be equally applied even when the number of subcarriers of an OFDM symbol transmitted per one slot is not 320. In addition, the same may be applied when the size of the broadcast or multicast packet to be transmitted is not 2048 bits.

Meanwhile, when time diversity is obtained using cyclic shift according to another embodiment of the present invention, a process of transmitting a signal when transmitting a 2048-bit broadcast or multicast packet is illustrated in FIG. 4. A description is as follows.

In FIG. 4, the coded symbols are loaded on four OFDM symbols constituting one slot in order after they are modulated. The four OFDM symbols are cyclically shifted by three OFDM symbols and transmitted in the order as shown in FIG. 4. Therefore, after the coded symbols are modulated, they are loaded in the order of the second, third, fourth, and first OFDM symbols.

When transmitted in the same manner as in FIG. 4, the systematic bits are divided into the first OFDM symbol (second OFDM symbol) and the last OFDM symbol (first OFDM symbol) transmitted among the transmission signals for one slot. As transmitted, it is possible to obtain a relatively improved time diversity effect compared to continuously transmitting OFDM symbols.

4 illustrates a method of improving time diversity of the systematic bits transmitted in the first slot when transmitting broadcast and multicast information. As described above, the same method may be applied to the second and third slots transmitted along the first slot. In this case, the degree of cyclic shift applied is whether the transmitted symbol is a systematic bit, P0 or P0 ', P1 or P1' and before applying the cyclic shift, the systematic bits, P0 and P0 ', P1. And the position of P1 '. For example, FIG. 4 illustrates cyclic shifts corresponding to three OFDM symbols when the first transmission is performed on 2048 bits. On the other hand, when performing the third transmission on the same 2048 bit, cyclic shift corresponding to one OFDM symbol increases time diversity for the systematic bit.

Table 1 below shows a transmission order of four OFDM symbols transmitted per slot when 2048 bits are transmitted in an OFDM symbol having 320 tones according to an embodiment of the present invention. The OFDM symbol transmission order 1 has been described with reference to FIG. 2, the OFDM symbol transmission order 2 is shown in FIG. 3, and the OFDM symbol transmission order 3 is described with reference to FIG. 4.

OFDM symbol transmission sequence 1 1, 3, 2, 4 OFDM symbol transmission sequence 2 1, 3, 4, 2 OFDM symbol transmission sequence 3 2, 3, 4, 1

5 is a diagram illustrating a structure of a base station transmitter for transmitting broadcast and multicast packets according to an embodiment of the present invention.

In FIG. 5, the turbo encoder 510 receives broadcast and multicast packets as inputs and encodes them. The encoded result is input to an interleaver 520 and interleaved for each of the systematic bits, P0 and P0 ', P1 and P1'. The encoded symbols interleaved in the interleaver 520 are input to a symbol selector 530. The symbol selector 530 determines which part of the input coded symbol is to be transmitted and outputs the coded symbol to be transmitted to the modulator 540. The modulator 540 modulates the signal input from the symbol selector 530 in a modulation scheme such as 16QAM, and then outputs the modulated signal to the OFDM symbol generator 550. The OFDM symbol generator 550 collects the modulation symbols input from the modulator 540 in order to generate four OFDM symbols for each slot. The OFDM symbol output from the OFDM symbol generator 550 is changed by an OFDM symbol permutator 560. The OFDM symbol order controller 560 is controlled by an OFDM symbol position controller 570. That is, the OFDM symbol order controller 570 determines the transmission order of OFDM symbols as shown in FIGS. 2, 3, and 4 so as to obtain maximum time diversity in one slot.

6 is a structural diagram of a mobile terminal receiver for receiving broadcast and multicast packets according to an embodiment of the present invention.

The signal received in FIG. 6 is input to an OFDM symbol depermutator 610, and the order of the OFDM symbols is changed in the order before the transmission apparatus (ie, the base station) is adjusted. The OFDM symbol reordering unit 610 operates under the control of an OFDM symbol position controller 620, and the OFDM symbol ordering controller 620 restores the order according to the OFDM symbol transmission order applied by the transmitter. Control the position change to The OFDM symbols reordered in the OFDM symbol reordering unit 610 are output to an OFDM symbol receiver 630. The OFDM symbol receiver 630 receives OFDM symbols and outputs modulation symbols. The modulation symbols are input to a demodulator 640 and demodulated into encoded symbols. The output coded symbols are input to a deinterleaver 660 through a zero insertion and combiner 650. The coded symbols deinterleaved by the deinterleaver 660 are turbo decoded by a decoder 670.

5 and 6 illustrate a transmission / reception structure that may be applied when the order of signals transmitted as shown in FIGS. 2, 3, and 4 is changed in the OFDM symbol unit. It can also be applied by changing the order in the modulation symbol unit rather than the OFDM symbol unit, in this case, the transceiver structure shown in Figs.

7 is a diagram of a base station transmitter for transmitting broadcast and multicast packets according to another embodiment of the present invention.

In FIG. 7, the turbo encoder 710 receives broadcast and multicast packets as inputs and encodes them. The encoded result is input to the interleaver 720 and interleaved for each of the systematic bits, P0 and P0 ', P1 and P1'. The encoded symbols interleaved in the interleaver 720 are input to a symbol selector 730. The symbol selector 730 determines which part of the input coded symbol is to be transmitted and outputs the coded symbol to be transmitted to the modulator 740. That is, only a portion of the encoding sequence output from the interleaver 720 to be transmitted to the corresponding slot is truncated and output. The modulator 740 modulates the signal input from the symbol selector 730 in a modulation scheme such as 16QAM, and then outputs it to a modulation symbol permutator 760. The modulation symbol output from the modulator 740 is changed by the modulation symbol order controller 760. The modulation symbol order controller 760 is controlled by a modulation symbol controller 750. The modulation symbols output from the modulation symbol order controller 760 are output to the OFDM symbol generator 770. The OFDM symbol generator 770 collects the modulation symbols inputted from the modulation symbol order controller 760 in order to generate four OFDM symbols for each slot.

8 is a structural diagram of a mobile terminal receiving broadcast and multicast packets according to an embodiment of the present invention.

In FIG. 8, the OFDM symbol receiver 810 receives OFDM symbols and outputs OFDM symbols, and the OFDM symbols are input to a modulation symbol depermutator 830 so that the order of the modulation symbols is transmitted to the transmitting apparatus (i.e. , Base station). The modulation symbol order re-regulator 830 operates under the control of a modulation symbol position controller 820, and the modulation symbol order controller 820 adjusts the order according to the modulation symbol transmission order applied by the transmitter. Control location changes to restore. The modulation symbols whose order is reconstructed by the modulation symbol reordering unit 830 are input to the demodulator 840, demodulated into coding symbols, and then output. The output coded symbols are input to the deinterleaver 860 through a zero insertion and combiner 850. The coded symbols deinterleaved by the deinterleaver 860 are turbo decoded by the decoder 870.

9 is a flowchart illustrating control of symbol reception at a base station according to an embodiment of the present invention. In step 901, the base station encodes broadcast and multicast packets to be transmitted. In step 902, the base station is interleaved for each of the systematic bits, P0 and P0 ', P1 and P1'. In step 903, the base station selects a coded symbol to be transmitted to a corresponding slot among the interleaved coded symbols. In step 904, the base station modulates the selected coded symbols into modulation symbols in a modulation scheme such as 16QAM. In step 905, the base station generates four OFDM symbols among the modulation symbols. In step 906, the base station transmits an OFDM symbol according to the determined transmission order.

10 is a flowchart illustrating control of symbol reception in a terminal according to an exemplary embodiment of the present invention.

In step 1001, the terminal changes the order of the OFDM symbols to the order before the transmission apparatus (ie, the base station) is adjusted. In step 1002, the UE outputs modulation symbols in which the OFDM symbols have been reordered, and in step 1003, the modulation symbols are demodulated into encoded symbols. The terminal deinterleaves the coded symbols demodulated in step 1004, and then turbo-decodes the coded symbols in step 1005.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

According to the present invention, after coding symbols are modulated in a mobile communication system supporting broadcast and multicast functions, time diversity can be effectively utilized by appropriately arranging and transmitting positions of OFDM symbols.

In addition, the present invention can effectively utilize the time diversity by appropriately placing and transmitting the position of the modulation symbol after the encoded symbols are modulated in a mobile communication system supporting the broadcast and multicast functions.

In addition, the present invention has the effect of improving the performance of turbo decoding in a mobile communication system.

Claims (6)

In the symbol transmission method in a mobile communication system supporting broadcast and multicast, Receiving and encoding the broadcast and multicast packets; Determining which part of the coded symbol is to be transmitted, and modulating the determined part by a predetermined modulation scheme; Generating an OFDM symbol by collecting the modulated symbols in order; Determining a transmission order of the generated OFDM symbol to obtain maximum time diversity in one slot; And transmitting the OFDM symbols in the determined transmission order. The method of claim 1, The process of determining the transmission order of the OFDM symbol, The method of claim 1, further comprising the step of determining the transmission order of the OFDM symbol using the cyclic shift. In the symbol transmission method in a mobile communication system supporting broadcast and multicast, Receiving and encoding the broadcast and multicast packets; Determining which part of the coded symbol is to be transmitted, and modulating the determined part by a predetermined modulation scheme; Determining transmission order of modulation symbols to obtain maximum time diversity in one slot; Generating an OFDM symbol by collecting the modulated symbols in order; And transmitting the OFDM symbols in the determined transmission order. The method of claim 3, The process of determining the transmission order of the OFDM symbol, The method of claim 1, further comprising the step of determining the transmission order of the OFDM symbol using the cyclic shift. In the symbol transmission apparatus in a mobile communication system supporting broadcast and multicast, An encoder for receiving and encoding the broadcast and multicast packets; A modulator for determining which part of an encoded symbol is to be transmitted and modulating the determined part in a predetermined modulation scheme; An OFDM symbol generator for collecting the modulated symbols in order to generate an OFDM symbol; An OFDM symbol order controller for determining a transmission order of the generated OFDM symbols to obtain maximum time diversity in one slot; And an OFDM symbol order controller for controlling the OFDM symbol order controller to determine the transmission order of OFDM symbols. In the symbol transmission apparatus in a mobile communication system supporting broadcast and multicast, An encoder for receiving and encoding the broadcast and multicast packets; A modulator for determining which part of an encoded symbol is to be transmitted and modulating the determined part in a predetermined modulation scheme; A modulation symbol order controller for determining transmission order of modulation symbols to obtain maximum time diversity in one slot; An OFDM symbol generator for collecting the modulated symbols in order to generate an OFDM symbol; And a modulation symbol order controller for controlling the modulation symbol order controller to determine a transmission order of modulation symbols.

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