KR20060091687A - Method for transmitting broadcast data in a mobile communication system and apparatus thereof - Google Patents

Abstract

The present invention relates to a broadcast data transmission method and apparatus in a mobile communication system. The present invention provides an apparatus and method for providing a broadcast service packet to be more stable and increase the reception efficiency.

The method according to an embodiment of the present invention is a broadcast data transmission method in a mobile communication system that transmits traffic in an interlace structure in units of a predetermined number of slots, wherein at least one slot for transmitting broadcast data in one interlace period is pre-arranged. And determining the broadcast traffic in packet units and continuously transmitting the divided packets by a predetermined number of retransmissions.

Broadcast, multicast, OFDM, CDM

Description

Method and apparatus for transmitting broadcast data in mobile communication system {METHOD {FOR TRANSMITTING BROADCAST DATA IN A MOBILE COMMUNICATION SYSTEM AND APPARATUS THEREOF}

1 is a diagram illustrating an example of transmitting a unicast packet in a 4-slot interlace structure in an HRPD system;

FIG. 2 illustrates an example of transmitting a packet for a broadcast service and a multicast service in a 4-slot interlace structure in an HRPD system; FIG.

3A and 3B are flowcharts illustrating transmission control of a broadcast service packet or a multicast service packet at a base station of an HRPD system having a 4-slot interlace structure.

4 is a diagram illustrating a message for classifying traffic by interlace-multiplex pair for broadcast and multicast service in HRPD system;

5 is a timing diagram illustrating a method of transmitting a broadcast service and / or a multicast packet according to the first embodiment of the present invention.

6 is a diagram illustrating a structure of a signal message for supporting a broadcast service according to a first embodiment of the present invention.

7 is a timing diagram illustrating an example of a method for transmitting a combination of OFDM and CDM according to a second embodiment of the present invention.

8 is a diagram illustrating a block configuration of a transmitter in case of transmitting a combination of OFDM and CDM according to a second embodiment of the present invention.

9 is a control flowchart for transmitting broadcast service traffic according to the second embodiment of the present invention.

FIG. 10A is a diagram for explaining an out of sync boundary according to a third embodiment of the present invention; FIG.

10B illustrates a cellular system in which cells are degraded in a specific cell due to local characteristics or other reasons.

11 is a timing diagram when a packet is transmitted in consideration of cell characteristics according to a third embodiment of the present invention.

12 illustrates a structure of a signal message according to a third embodiment of the present invention.

FIG. 13 is a diagram showing an example of a method for continuously transmitting a combination of OFDM and CDM according to a fourth embodiment of the present invention. FIG.

14 is a diagram illustrating a message structure for channel division in a signaling message to enable continuous transmission using both OFDM and CDM in accordance with a fourth embodiment of the present invention.

FIG. 15 is a diagram illustrating a phenomenon in which the number of cells performing retransmission is reduced in a situation where retransmission occurs according to the fifth embodiment of the present invention.

16 illustrates an example of a configuration of an OFDM symbol that can be transmitted during a data part of an HRPD 1/2 slot according to the fifth embodiment of the present invention.

17 is a diagram illustrating a case in which a transmission format is changed and retransmitted according to the fifth embodiment of the present invention.

18 illustrates a structure of a signal message according to a fifth embodiment of the present invention.

The present invention relates to a method and apparatus for transmitting broadcast data in a mobile communication system, and more particularly, to a method and apparatus for improving cell-specific performance by using OFDM or CDM in order to efficiently provide a multicast service in HRPD.

In general, a mobile communication system is a system developed for providing voice communication to users without wire limitations. Such mobile communication systems have reached a stage capable of providing not only voice services but also data services due to the rapid development of technology. The data service provided by the mobile communication system has basically evolved from a short message service to a mailing service and various multimedia services. These services are provided by a specific user alone. That is, the above services are transmitted to only one terminal by using a predetermined channel allocated only to a specific user from the base station of the mobile communication system. As such, the form in which the service is provided only to a specific terminal in the base station is called a unicast type service. On the other hand, many discussions have been made about multicast type services, not unicast type services, which are provided to only one terminal in a mobile communication system. Such multicast type services include various types of services such as broadcast services, push-to-talk (PTT) services, and messenger services.

Meanwhile, mobile communication systems have evolved into various forms to support the above services. For example, CDM 2000's North American 3GPP2 standard conference introduced 1x EV-DO system that provides only high-speed packet data and 1x EV-DV system that can simultaneously support voice service and high-speed packet data service. Among the above systems, the system currently being commercialized is a 1x EV-DO system, which is a high rate packet data (HRPD) system.

To date, a high rate packet data (HRPD) system uses a code division multiplexing ("CDM") method for broadcasting and multicast, or an orthogonal frequency division multiplexing (hereinafter, "OFDM"). Has been proposed. As such, the broadcast service and the multicast service using CDM or OFDM, which have been proposed in the HRPD system, use a multi-slot transmission method. Next, the multi-slot transmission method will be described in more detail. In the far slot transmission method, a packet is generally divided into multiple slots. In this case, the transmitter may transmit or retransmit the same packet every fourth slot using a four-slot interlace structure. However, following this transmission structure may increase the transmission delay, and in some cases, scheduling restrictions may occur.

In addition, the HRPD system uses only one modulation method of CDM or OFDM. That is, the OFDM scheme cannot be used when the CDM scheme is used, and the CDM scheme cannot be used when the OFDM scheme is used. However, the modulation schemes of the CDM scheme and the OFDM scheme have different advantages and disadvantages, and in general, their performance may vary depending on the channel environment.

Hereinafter, a method of transmitting a packet for broadcast and multicast service according to a 4-slot interlace structure in an HRPD system using a CDM or OFDM modulation scheme will be described with reference to the accompanying drawings.

1 is a diagram illustrating an example of transmitting a unicast packet in a 4-slot interlace structure in an HRPD system.

As shown in FIG. 1, a general unicast service is transmitted from a base station to a terminal. Therefore, when the base station shown in the upper part of FIG. 1 transmits the first packet (1st TX) to be transmitted to the terminal through a physical space, the terminal receives and decodes and demodulates the result and at least the third slot. The response signal (ACK / NAK) is transmitted to the base station. FIG. 1 illustrates a case where a NAK is transmitted as a response signal because a result of receiving and decoding a first packet (1st TX) transmitted by a base station is bad. Then, the base station receives the response signal transmitted by the terminal and determines whether to retransmit the transmitted packet or the next packet in the fifth slot, which is the second transmission point. Assuming that the base station transmits the first packet as the first slot, the reason for determining whether to transmit the next packet or perform retransmission in the fifth slot is illustrated in the four-slot interlace structure. Because. That is, the base station transmits the packet in the form of "i + 4n" when transmitting the packet to the terminal. Where "i" is greater than or equal to 1 and less than or equal to 4, and "n" is a natural number. That is, a form of transmitting a packet in such a structure is called a 4-slot interlace structure.

In addition, when transmitting a packet, the base station transmits some or all of the coded symbols generated by using one packet. Therefore, when retransmission is required, that is, when the NAK response signal is received from the terminal, the base station may transmit the remaining symbols when transmitting a part of the coded symbols, or may retransmit the previously transmitted symbols. This retransmission is to increase the reception performance of the terminal. The retransmission is determined according to the response signal (ACK / NAK) transmitted by the terminal. In addition, in the mobile communication system, the number of retransmissions that can be performed after the initial transmission time of each packet is generally limited.

FIG. 2 is a diagram illustrating an example of transmitting a packet for a broadcast service and a multicast service in a 4-slot interlace structure in an HRPD system.

2 has a 4-slot interlace structure as in FIG. 1. Therefore, the first interlace section T0-T1, the second interlace section T1-T2, and the third interlace section T2-T3 of FIG. 2 will be described. In FIG. 2, an arrow indicating an assigned slot for delivering a broadcast service and a multicast service (arrow descending from the top of each slot) and an arrow for entering a packet of a broadcast service or a multicast service into each slot (downward) Arrow coming up from) is shown separately. In addition, the slots of FIG. 2 illustrate a case in which a broadcast service or a multicast service is performed instead of two services simultaneously.

Next, a case in which a broadcast service or a multicast service is performed will be described with reference to FIG. 2 under the above assumption. In FIG. 2, it is assumed that a broadcast service or a multicast service is transmitted when four different packets are transmitted, and one packet is divided and transmitted three times. The first packet (Packet # 1) 201 of the broadcast service or multicast service is transmitted in the first slot of the first interlace interval and the first slot of the second interlace interval and the first slot of the third interlace interval. . In addition, the second packet 202 of the broadcast service or the multicast service is transmitted in the second slot of the first interlace interval, the second slot of the second interlace interval, and the second slot of the third interlace interval. As described above, in the 4-slot interlace structure, the same service packet is transmitted by dividing the transmission interval in units of 4 slots. Thereafter, the third packet (Packet # 3) 203 and the fourth packet (Packet # 4) 204 are also transmitted in the same manner.

3A and 3B are flowcharts illustrating transmission control of a broadcast service packet or a multicast service packet at a base station of an HRPD system having a 4-slot interlace structure.

As described above with reference to FIG. 2, the base station transmits different packets according to the interlace number, that is, the slot order in the packet transmission mode. Therefore, the base station determines the interlace number of the current slot in step 300. That is, it is determined whether the current slot is the first slot, the second slot, the third slot, or the fourth slot in the four-slot interlace structure. The reason for determining the slot, that is, distinguishing the interlace number is that the packets transmitted corresponding to the interlace numbers are different. As described above, the base station performs one of routines A to D after determining each interlace number in the four-slot interlace structure in step 300. One of the A to D routines will then be described with reference to FIG. 3B.

After determining the interlace number, the base station proceeds to step 310 and checks whether the current slot is a transmission time of a broadcast service (BCMCS) flow i. That is, it is checked whether the current slot is reserved to transmit a specific broadcast service flow. If the current time point is not the time point reserved for the broadcast service, the base station proceeds to step 320 to perform unicast transmission or transmit a control channel packet for a specific terminal. On the other hand, if it is determined in step 310 that the current time point is a slot reserved for a broadcast service, the process proceeds to step 312 to check whether retransmission of packets is being performed for the broadcast service flow. That is, when the specific packet is divided into three transmissions as described above in FIG. 2, the second and third transmissions, which are the time points after the first transmission, are retransmitted. In this way, if the packet is being retransmitted, the base station proceeds to step 314, and if not, proceeds to step 318 to transmit a new packet for broadcast service flow i.

In step 312 to step 314, the base station determines whether the number of transmissions of the retransmitted packet is smaller than the maximum number of transmissions. 2, the retransmission of the packet of the broadcast service is limited to three times including the initial transmission. Therefore, step 314 is to check whether the number of transmissions is less than three. If the current number of transmissions is less than the maximum number of transmissions, the process proceeds to step 318 and retransmits the packet for the broadcast service. Otherwise, the process proceeds to step 316 to transmit a new packet of the broadcast service. In this way, when the routine of A to D is finished, the base station proceeds to step 300 again.

FIG. 4 is a diagram illustrating a message for classifying traffic by interlace-multiplex pair for broadcast and multicast service in HRPD system.

As shown in FIG. 4, the message for classifying traffic for each interlace-multiplex pair includes information on each interlace. In FIG. 4, reference numerals 410, 420, 430, and 440 denote information on a first interlace slot, information on a second interlace slot, and information on a third interlace slot 2, respectively. And information about a fourth interlace 3 slot.

3A and 3B and FIG. 4, when supporting broadcast and multicast services in an HRPD system, channels may be distinguished for each interlace. When the channels are divided in this way, the transmission channel unit is determined by an interlace-multiplex pair type that separates the channels into multiplexes having variable burst sizes in the same interlace.

In addition, the HRPD service system transmits packet transmission information for receiving a packet as an overhead signal message for broadcast service and multicast service. For example, the BroadcastOverhead message corresponds to this. The overhead signal message includes a broadcast service or multicast service (hereinafter referred to as "BCMC flow") information transmitted from a cell, a frequency allocation (FA) for transmitting a packet for each BCMC flow, location information of a transmission slot, a transmission rate, Transmission slot number information, RS coding (Reed-Solomon coding) information, and the like. After the terminal receives the overhead message for the broadcast and multicast service, the user is to receive the packet in the slot by using the transmission information of the packet for the BCMC flow that the user wants to receive.

Even when transmitting a packet for the BCMC flow, it maintains a four-slot interlace type of transmission like unicast packet transmission. However, in the case of broadcast and multicast services, since there may be more than one receiving terminal, in general, retransmission is performed a predetermined number of times without transmitting a response from the terminal.

In addition, the HRPD service system improves the reception performance of the terminal by synchronizing soft combing or transmitting the same packet in a predetermined number of cells for broadcasting and multicast services. In this case, the performance can be greatly increased than the packet reception using the signal received in one cell.

In a mobile communication system operating as described above, when a packet is divided into multiple slots using a 4-slot interlacing scheme, packets are transmitted at intervals of four slots, and thus a delay until all packets are received. Will occur. As described above, the processing power consumed by the UE increases as the time for storing the broadcast packet in the buffer increases due to the delay caused by the retransmission. In addition, when simultaneously providing a broadcast service and / or a multicast service with a unicast service, unicast performance may be degraded due to scheduling limitations caused by the broadcast service and / or multicast packet transmission, and scheduling complexity may also be reduced. There is a problem that increases.

In addition, if only OFDM or high order modulation is used, the system can increase the transmission rate. However, if the neighboring cell interference is large, the performance decreases. In addition, when the broadcast service and / or multicast service packet is transmitted using the OFDM scheme, performance in the middle region that is synchronized is good, but performance in the boundary cell is greatly degraded. On the other hand, if only CDM or low order modulation is used, the performance degradation at the boundary cell may be relatively small compared to OFDM. However, since the transmission rate in the system is lower than OFDM, the number of retransmissions may be reduced or high quality may be required. There is a problem in that a broadcast service cannot be provided.

Accordingly, an object of the present invention is to provide a method and apparatus that can reduce the scheduling complexity when simultaneously providing a broadcast service and a unicast service.

Another object of the present invention is to provide a method and apparatus for increasing throughput of a channel when simultaneously providing a broadcast service and a unicast service.

Another object of the present invention is to provide a method and apparatus for improving the performance of neighboring cells when transmitting broadcast data using only the OFDM scheme.

Another object of the present invention is to provide a method and apparatus for increasing the reception efficiency of a broadcast service.

In order to achieve the above object, an apparatus according to an embodiment of the present invention is a broadcast data transmission apparatus in a mobile communication system that transmits traffic in an interlace structure of a predetermined number of slots, and broadcast data in one interlace period. A scheduler for predetermining at least two slots to transmit the information, an information signal generator for dividing and outputting the broadcast traffic in packet units, a channel encoder for encoding and outputting the output of the information signal generator, and an output from the channel encoder. A buffer for storing an encoded signal, an OFDM modulator for modulating the encoded signal in an OFDM scheme, a CDM modulator for modulating the encoded signal in a CDM scheme, and a signal read from the buffer to one of the modulators; Switches and stores and outputs to the buffer And a control unit for controlling switching of the switch and controlling driving of the respective modulators.

A method according to an embodiment of the present invention for achieving the above object is a broadcast data transmission method in a mobile communication system for transmitting traffic in an interlace structure of a predetermined number of slots, the broadcast data in the one interlace period Pre-determining at least one slot to transmit the data; and dividing the broadcast traffic in packet units, and continuously transmitting the divided packets by a predetermined number of retransmissions.

A method according to another embodiment of the present invention for achieving the above object is a broadcast data transmission method in a mobile communication system for transmitting traffic in an interlace structure of a predetermined number of slots, the broadcast data in one interlace period Pre-determining at least two or more slots to be transmitted, dividing the broadcast traffic into packet units, alternately transmitting at least two or more packets among the divided packets by a predetermined number of transmissions, and transmitting the packet by CDM modulation. And modulating by the OFDM modulation scheme and transmitting at least one time.

A method according to another embodiment of the present invention for achieving the above object is a broadcast data transmission method in a mobile communication system that provides a broadcast service, the broadcast service is transmitted in synchronization with each higher node of the network, Transmitting broadcast traffic in an OFDM scheme through predetermined broadcast traffic transmission slots in a center cell of a network upper node, and broadcasting the same broadcast data through the same slots as the center cell in an edge cell of the network upper node in an OFDM scheme Transmitting at least one of a slot for transmitting a unicast packet in the center cell in a boundary cell of the upper node of the network, and modulating and transmitting broadcast traffic transmitted at a previous time point by using a CDM method Process.

In the method, the OFDM traffic broadcast traffic in the center cell of the network upper node alternately transmits different broadcast packets, and modulates the CDM method in the boundary cell of the network upper node by the CDM method. It can be configured to transmit within the transmission period of the broadcast packet alternately transmitted by the OFDM scheme in the center cell.

Alternatively, the broadcast packet modulated by the CDM scheme in a boundary cell of the upper node of the network may be transmitted in a slot immediately after the broadcast scheme in the OFDM scheme is transmitted.

Hereinafter, with reference to the accompanying drawings will be described in detail the operating principle of the preferred embodiment of the present invention. Like reference numerals are used to designate like elements even though they are shown in different drawings, and detailed descriptions of related well-known functions or configurations are not required to describe the present invention. If it is determined that it can be blurred, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

Hereinafter, various embodiments that can solve the above-described problems will be described. The embodiments described below will be described with four embodiments, each of which can solve at least one of the problems described above. In addition, the embodiments described below may be operated independently, but it is more preferable to use two or more embodiments together.

 <First Embodiment: Method of Continuous Transmission of Packets>

In the first embodiment of the present invention, a method for continuously transmitting a packet for a broadcast service and / or a multicast service in a slot allocated for a broadcast service and / or a multicast service will be described.

5 is a timing diagram illustrating a method of transmitting a broadcast service and / or a multicast packet according to the first embodiment of the present invention.

FIG. 5 illustrates a system in which packet data is transmitted according to a 4-slot interlace structure as described in the prior art. Therefore, four slots exist in one interlace period. That is, the section of T0-T1 becomes the first 4-slot interlacing section, and the section of T1-T2 becomes the second 4-slot interlacing section. Thereafter, the third and fourth four-slot interlace sections become T2-T3 sections and T3-T4 sections.

In each of the above sections, as in the prior art, it is assumed that the first slot and the second slot are slots allocated for broadcast service and / or multicast service. In the following description, all broadcast services and multicast services are referred to as " broadcasting services " In addition, it is assumed that the broadcast service packet is transmitted up to three times including the initial transmission.

According to the above assumption, the first packet (Packet # 1) 501 of the broadcast service is transmitted in the first slot and the second slot of the first section, and the transmission is performed in the first slot of the second section. In addition, the second packet (Packet # 2) 502 is transmitted in the first and second slots of the third interval from the second slot of the second interval. In this way, a method of continuously transmitting one packet is selected.

As compared with the prior art, it can be seen that the present invention in which one packet is continuously transmitted shortens the time for storing one packet in a buffer for demodulation and decoding. Therefore, since the terminal saves one packet time, power consumption can be reduced. In addition, the base station has an advantage in that scheduling is easier as compared with the conventional technology in which two different packets must be continuously transmitted in one 4-slot interlace period as described above.

Meanwhile, FIG. 5 illustrates an example of allocating the first and second slots as slots for a broadcast service in one 4-slot interlace period. However, when a slot other than the first slot and the second slot, or all or more slots are allocated to the broadcast service, the packet may be continuously transmitted in the above-described manner. That is, the second slot and the third slot may be sequentially transmitted, or may be configured to transmit consecutively in the third and fourth slots. Therefore, in the method according to the first embodiment of the present invention, the number and location of slots allocated for broadcast service may be applied in any form.

However, more preferably, the case where packets are transmitted continuously is preferable to the case where two slots are transmitted consecutively when the processing delay time and soft combining of the transmitted data are performed. can do. When transmitting as shown in FIG. 5, each packet data can transmit a broadcast service packet through the method of FIG. 3B described above in the prior art. The only difference is that the next packet is transmitted after the maximum number of retransmissions of one broadcast service packet is transmitted.

6 is a diagram illustrating a structure of a signal message for supporting a broadcast service according to a first embodiment of the present invention.

As described in FIG. 5, when one packet for a broadcast service is continuously transmitted, a form of a signal message transmitted as shown in FIG. 6 is shortened. That is, in contrast to the message of Salping Figure 4 in the prior art, it can be seen that the message of the present invention is shortened. That is, unlike the conventional signal message to distinguish the channel for packet transmission of the broadcast service in an interlace-multiplex pair, in the present invention, only the interlace used for packet transmission of the broadcast service is designated. Multiplexes are constructed without distinguishing interlaces, and each multiplex is informed of the burst length. The meanings of the fields shown in FIG. 6 are as follows.

MultiplexCount: This is the number of multiplexes for traffic transmission for broadcast and multicast services, and has the same meaning as used in the related art. An example of the number of multiplexes indicated by the above 2-bit value is as follows.

'00': 4 '01': 8

'10': 16 '11': reserved

InterlaceMap: represents an interlace used for traffic transmission for broadcast and multicast services. Composed of 4 bits, each bit represents interlaces 0, 1, 2, 3, and 4, respectively. For example, the meaning of each bit is as follows.

'0': not used for broadcast and multicast services

'1': used for broadcast and multicast services

SameBurstLengths indicates whether bursts of the same length are used in each multiplex. Illustrating what the 1 bit means as follows.

'0': use burst lengths of different lengths

'1': use the same burst length in all multiplexes

TotalBurstLength: Total burst length, with each new length starting from multiplex zero again.

BurstLength: Burst length used in each multiplex. If SameBurstLengths described above is set to '1', it is included only once, otherwise it is included as "Multiplex-1".

 Second Embodiment Method of Concurrently Using OFDM / CDM

In a second embodiment according to the present invention, a method of transmitting by applying another modulation method during initial transmission and retransmission is disclosed. When transmitting over multiple slots to transmit one packet, some slots transmit all or part of the encoded symbols of one packet using OFDM and a predetermined modulation order, and the other slots use OFDM for CDM. The transmission method is used with the same or different order of modulation used during transmission. In general, the modulation order is lower when using the CDM method than when using the OFDM method.

7 is a timing diagram illustrating an example of a method for transmitting a combination of OFDM and CDM according to a second embodiment of the present invention.

It is assumed that FIG. 7 also has a 4-slot interlace structure. In addition, although the transmission method may use continuous transmission, which is a method according to the first embodiment of the present invention, it is assumed that the transmission method is performed in the same manner as the prior art for the convenience of contrast between the prior art and the second embodiment of the present invention. Based on the above assumption, the second embodiment of the present invention has a first 4-slot interlace section T0-T1 to a fourth 4-slot interlace section T3-T4, and each of the four slot interlace sections is There are four packet transmission slots. In addition, a slot allocated for transmission of a broadcast service in one section is assumed to be the first and third slots while transmitting the first two packets, and the first and second slots after transmitting two packets thereafter. Assumed. As a final assumption, the maximum number of transmissions is assumed to be two.

First, the intervals in which the first two packets are transmitted will be described. The first packet (Packet # 1) 701 and the second packet (Packet # 2) 702 of the broadcast service are transmitted twice, including the initial transmission and retransmission, so that the first 4-slot interlace interval and the second It is transmitted once each in 4-slot interlace interval. Therefore, the first packet 701 is transmitted in the first slot of the first interval and the first slot of the second interval. The second packet 702 is transmitted in the third slot of the first section and the third slot of the second section. At this time, in the first section of the first packet 701 and the second packet 702, the packet is transmitted by the OFDM scheme, and in the second section by the CDM scheme. In this case, 16QAM and 8-PSK, which are modulation orders described at the bottom of FIG. 7, are shown as an example. That is, it is not limited to the said modulation order.

Thereafter, the third packet (Packet # 3) 703 and the fourth packet (Packet # 4) 704 of the broadcast service are transmitted in the third four-slot interlace section and the fourth four-slot interlace section. In the third section and the fourth section, since the first slot and the second slot are reserved slots for broadcast service, the third packet 703 and the fourth packet 704 are transmitted in the corresponding slot. In this case, packets transmitted in the third section are modulated using the OFDM scheme, and are modulated using the CDM scheme in the fourth transmission section.

In the second embodiment described with reference to FIG. 7, it is assumed that the number of transmissions is 2 times to explain that the OFDM scheme and the CDM scheme cross each other. However, when the number of transmissions is three times, if the OFDM scheme and the CDM scheme are included at least once, the gain described in FIG. 7 can be enjoyed. That is, it is possible to enjoy all the advantages of the OFDM scheme and the CDM scheme.

FIG. 8 is a diagram illustrating a block configuration of a transmitter when transmitting in combination with OFDM and CDM according to a second embodiment of the present invention.

Referring to FIG. 8, the signal generated by the information signal generator 801 is encoded by the channel encoder 803 and buffered in the buffer 805. Here, the signal generated by the information signal generator 801 may be a packet or data divided for transmitting specific broadcast traffic. Then, the controller 811 controls the switch 807 according to a control method to be described later to output the data stored in the buffer 805 to the OFDM modulator 809 or the CDM modulator 813. That is, a switching control signal for generating data stored in the buffer 805 to the OFDM modulator 809 or the CDM modulator 813 through the switch 807 is generated and output to the switch 807. At this time, the controller 811 outputs an address in which a packet to be transmitted currently is stored among the data stored in the buffer 805 and a buffer read control signal for outputting the same to the buffer 805. That is, the signal transmitted from the controller 811 to the buffer 430 is a signal for selectively transmitting a portion of the encoded signal. In addition, the controller 811 outputs a driving control signal for driving the corresponding modulator to the OFDM modulator 809 or the CDM modulator 813 according to the selection of the modulation scheme. In this case, the driving control signal input to each of the modulators 809 and 813 includes modulation order information required for packet transmission. Then, the corresponding modulator modulates the input coded signal based on the driving control signal and outputs the modulated coded signal to the FR module 815. The RF module 455 receives an OFDM or CDM signal, generates a radio wave signal, and transmits the signal through an antenna.

9 is a control flowchart when transmitting broadcast service traffic according to the second embodiment of the present invention.

The controller 811 waits for a scheduling result from the scheduler (not shown in the drawing of the present invention) in operation 900. Herein, the scheduling result means service termination, a terminal to be serviced, a size of a packet to be transmitted, and related information thereof. Accordingly, when the controller 811 receives the scheduling result in step 900, the controller 811 proceeds to step 902, and otherwise maintains step 900. In step 902, the controller 811 determines an encoding portion to be transmitted and transmits an encoding portion selection related signal to a buffer. The controller 811 then proceeds to step 904 to determine a modulation method. After the modulation method is determined as described above, the controller 811 proceeds to step 906 and determines whether the determined modulation method is the OFDM method or the CDM method. In case of the OFDM result, the control unit 811 proceeds to step 910. Otherwise, in case of the CDM method, the control unit 811 proceeds to step 920. When OFDM is selected first, the controller 811 transmits a switching control signal to the switch 807 so that data stored in the buffer 805 is input to the OFDM modulator 809. After that, the controller 811 determines the modulation order in step 912, and transmits modulation order information to the OFDM modulator 809 in step 914.

On the other hand, if the CDM is selected, the controller 811 proceeds to step 920 and transmits a switching control signal to the switch 807 so that data stored in the buffer 805 is input to the CDM modulator 813. After that, the controller 811 determines the modulation order in step 922, and then proceeds to step 924 to transmit the modulation order information to the CDM modulator 813. When this process is completed, the controller 811 goes back to step 900 and waits for the next signal from the scheduler.

 <Third Embodiment: OFDM / CDM Concurrent Transmission in Cells in a Harsh Environment>

The third embodiment is a method of restrictively applying a continuous transmission method only to a specific cell or sector. Next, a third embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 10A is a diagram for explaining a boundary in synchronization according to a third embodiment of the present invention. FIG.

In FIG. 10A, the two different regions shown in the upper portion are at least one base station controller (ANC) or one packet control function unit (PCF) unit or more in the case of an HRPD system. Therefore, the above areas include a plurality of base stations (ANTSs). The reference numerals 1000 and 1010 are separated from the different elements in the upper network. When configured in this way, the inner region can be viewed as a synchronized region because it has one upper network, and the outer region is an unsynchronized region because it receives an unsynchronized signal from another adjacent region. A hatched portion in the upper view of FIG. 10A is an out-of-sync region outside.

The lower part of FIG. 10 illustrates this in more detail. That is, cells 1000a and 1010a shown as boundary cells are areas for receiving an unsynchronized signal from an adjacent area. Intermediate cells, which are cells of a synchronized region, first use methods for improving performance when providing broadcast and multicast services in a mobile communication network. First, in the case of the CDM scheme, the UE may enable soft combining by transmitting the same information from the slots synchronized in each cell. In addition, in the OFDM scheme, a macro diversity performance gain can be obtained. However, due to the characteristics of the mobile communication network, the number of cells that can be synchronized with transmission is possible only from a specific upper end of the network as described above. That is, the number of cells that can synchronize transmission is limited. This results in inconsistent boundaries. In the case of a terminal that receives broadcast service traffic, the cells located in the border region have a poor performance of receiving broadcast service traffic.

Next, as shown in FIG. 10B, a cell in an intermediate region having poor performance may exist according to cell characteristics. FIG. 10B is a diagram illustrating a cellular system in which cells deteriorate in a specific cell due to local characteristics or other reasons. The reason for the occurrence of the phenomenon as shown in FIG. 10B may occur in various cases, such as a local characteristic or a case where a device generating a strong interference signal exists in an adjacent region. That is, the phenomenon as shown in FIG. 10B may occur regardless of FIG. 10A described above. As described above, if a phenomenon such as FIG. 10A or FIG. 10B occurs, a solution for solving the problem is the third embodiment of the present invention.

11 is a timing diagram when a packet is transmitted in consideration of cell characteristics according to the third embodiment of the present invention.

In FIG. 11, for convenience of description, an example in which a packet is transmitted is divided into 4 slot units similar to a 4-slot interlace structure. That is, it is divided into a first section up to T0-T1, a second section up to T1-T2, a third section up to T2-T3, and a fourth section up to T3-T4. Among the above sections, intermediate cells or cells having good reception performance as shown in FIG. 10B as shown in FIG. 10A perform transmission as shown in the upper portion of the timing diagram. That is, the traffic of the broadcast service is transmitted by the OFDM scheme in the first section and the broadcast service traffic is transmitted again in the third section. That is, do not perform retransmission or take a short number of retransmissions.

On the contrary, in a boundary cell or a cell having poor reception performance at the terminal, this should be compensated. Therefore, in the first interval and the third interval, the transmission is performed in the same manner as a cell having good reception performance in an intermediate cell or a terminal. In this case, packets of the same modulation order are transmitted in the first third period in which packets are transmitted in the same way as the intermediate cell. In the present invention, there is a packet transmitted only in a cell having poor reception performance in a boundary cell or a terminal in a second section and a fourth section. That is, the packets transmitted in the second and fourth intervals become retransmission packets of the packets transmitted in the first and third intervals, respectively. In this case, it is preferable to transmit the packet transmitted in the boundary cell or the cell having poor reception performance in the terminal by the CDM method according to the present invention. This is because, by transmitting the packet data in the CDM scheme, interference of the packet transmitted in the OFDM scheme can be prevented and the problems caused by the OFDM scheme can be more compensated for. In addition, if signals received from different base stations are the same at the same time, it may be used in a flexible combination.

That is, in a boundary cell, a macro diversity effect is obtained by a signal received from another cell and a signal received from its own cell, but a reception performance may be degraded due to a signal received from a boundary cell of another adjacent area. Therefore, the CDM packet received in the second and fourth sections in which the broadcast service packet is not transmitted in the OFDM scheme can be compensated for. In other slots, unicast packets are transmitted. That is, packets that are not broadcast traffic are transmitted.

12 is a diagram showing the structure of a signal message according to a third embodiment of the present invention.

Referring to FIG. 12, it is informed whether a packet is additionally transmitted for each BCMCS flow, and a modulation scheme and a modulation order used at this time. In addition, in order to inform transmission information of the neighboring cells, the same information about whether additional packets are transmitted in the neighboring cell is informed, and the modulation scheme and the modulation order used at this time. Next, each of the fields shown in FIG. 12 will be described.

NeighborCount: This is the number of neighbor cells containing broadcast transmission information included in this message.

NumExtendedSlotIncluded: This indicator indicates whether or not fields including additional transmission slots and additional transmission methods are included. The transmission slot and the transmission method determined in the related art are equally applied to the neighbor cells included in this message, but the information included by the indicator may vary from cell to cell.

BCMCSFlowCount: The number of BCMCS flows included in this message.

BCMCSFlowID: Identifier of BCMCS flow.

NumExtendedSlot: Number of additional slots transmitted per packet. The field is included only when NumExtendedSlotIncluded is '1'.

ModulationIndicator indicates whether OFDM or CDM is used. The field is included only when NumExtendedSlotIncluded is '1' and NumExtendedSlot is not '0'. The meaning of the 1-bit value of the field will be described as follows.

'0': OFDM

'1': CDM

ModulationOrder: Modulation order used for transmission. Fraud fields are only included if NumExtendedSlotIncluded is '1' and NumExtendedSlot is not '0'. In addition, although the field is assumed to be 2 bits, the number of bits must be further increased when the type of modulation order is increased. For example, the following modulation orders may be included.

'00': BPSK

'01': QPSK

'10': 8-PSK

'11': 16-QAM

 <Fourth Embodiment: Method for Concurrent OFDM / CDM Concurrent Transmission in Border Region Cell in a Broadcast Service>

The fourth embodiment according to the present invention combines the method of the third embodiment and the first embodiment described above. In other words, OFDM, CDM, and modulation order may be changed for transmission of one packet, but unlike the third embodiment, one packet is transmitted in a slot allocated for broadcast and multicast transmission as in the first embodiment. It enables continuous transmission rather than 4-slot interlaced transmission. In particular, in the fourth embodiment, as in the third embodiment, transmission is performed for more slots in order to transmit one packet than the transmission of the intermediate cell or sector in the boundary cell or sector or the degraded cell.

13 is a view showing an example of a method for continuously transmitting by using OFDM and CDM in accordance with a fourth embodiment of the present invention.

Referring to FIG. 13, when a packet for one BCMCS flow is transmitted every 4 slots, the boundary cell additionally transmits the same packet for 2 slots. This is indicated by reference numeral 1309 in FIG. 13. In this case, in the slot transmitted from the intermediate cells, the same coded symbol of the same packet is transmitted in the boundary cell using the same modulation method. Through this, in case of a terminal capable of receiving both cells, the received packet can be combined and processed. This is indicated by reference numeral 1305. However, in this case, the reception performance may be deteriorated in the case of a terminal mainly receiving only in the boundary cell. Therefore, the boundary cell performs two slot transmission for one packet, and the second slot repeatedly transmits a coded symbol transmitted from the first slot or another coded symbol of the same packet. This is shown by reference numerals 1307 and 1309. The terminal recovers one packet using the coded symbols received during the two slots. In this case, the second slot transmitting one packet continuously uses slots allocated for broadcast and multicast transmission, not the fourth slot in the first slot. In addition, the unicast packet can be transmitted in both the broadcast of the intermediate cell and the slot in which the multicast packet is not transmitted. As such, the transmission of the unicast packet is indicated by reference numeral 1303.

FIG. 14 is a diagram illustrating a message structure for channel division in a signal message to enable continuous transmission using OFDM and CDM in accordance with a fourth embodiment of the present invention.

Referring to FIG. 14, the use of the field is the same as that of the field used in FIGS. 6 and 12. Then, the fields of the message shown in FIG. 14 will be described again.

NeighborCount: This is the number of neighbor cells containing broadcast transmission information included in this message.

NumExtendedSlotIncluded: This indicator indicates whether or not to include fields indicating additional transmissions in addition to the previously defined transmission slots and transmission methods. The transmission slot and the transmission method determined in the related art are equally applied to the neighbor cells included in this message, but the information included by the indicator may vary from cell to cell.

MultiplexCount: This is the number of multiplexes for traffic transmission for broadcast and multicast services, and has the same meaning as used in the related art. Here is an example:

'00': 4

'01': 8

'10': 16

'11': reserved

InterlaceMap: Represents an interlace used for traffic transmission for broadcast and multicast services. Each bit consists of 4 bits, meaning interlaces 0, 1, 2, 3, and 4, respectively. Here is an example:

'0': not used for broadcast and multicast services

'1': used for broadcast and multicast services

SameBurstLengths: Indicates whether bursts of the same length are used in each multiplex. Here is an example:

'0': use burst lengths of different lengths

'1': use the same burst length in all multiplexes

TotalBurstLength: Total burst length, with each new length starting from multiplex zero again.

BurstLength: Burst length used in each multiplex. If SameBurstLengths is set to '1', it is included only once, otherwise it is included as multiplex 1.

BCMCSFlowCount: The number of BCMCS flows included in this message.

BCMCSFlowID: Identifier of BCMCS flow.

NumExtendedSlot: Number of additional slots sent per packet. Only included if NumExtendedSlotIncluded is '1'.

ModulationIndicator: Indicates whether OFDM or CDM is used. Below is an example. Only included if NumExtendedSlotIncluded is '1' and NumExtendedSlot is not '0'.

'0': OFDM

'1': CDM

-ModulationOrder: Modulation order used when transmitting. The number of bits increases when considering higher modulation orders. Below is an example. Only included if NumExtendedSlotIncluded is '1' and NumExtendedSlot is not '0'.

'00': BPSK

'01': QPSK

'10': 8-PSK

'11': 16-QAM

Fifth Embodiment Retransmission Method Using OFDM Format Different from Initial Transmission

A fifth embodiment according to the present invention relates to a method of using OFDM symbols in a format different from initial transmission in retransmission of a broadcast packet. In general, in a single frequency network OFDM broadcasting system (including a broadcasting system using a communication system), a guard interval of an OFDM symbol is set to be relatively long in order to obtain a gain of a single frequency network. do. The guard interval is a signal attached to the front end of the OFDM symbol and is a signal interval that exists to suppress inter-symbol interference when the receiver receives multi-path signals. OFDM symbols, which are delayed more than this guard interval based on the signal that arrives first at the receiver, cause inter-symbol interference in the receiver to reduce reception performance. Set the protection interval long enough to make the size of the. This also applies to broadcast and multicast services provided by the CDMA2000 HRPD system. In the CDMA2000 HRPD system, cells in a specific area transmit the same broadcast signal. However, since the receiver can combine as many signals as possible to reduce interference and improve reception quality, the guard interval of the OFDM symbol can be set longer as described above. do.

However, as described in the above embodiment, a cell at a boundary point with another broadcast area or cells present in a strong shadowed area (see FIGS. 10A and 10B) receive a unicast slot to compensate for the decrease in reception rate by only a single transmission. The broadcast and multicast packets are retransmitted. Generally, retransmission is limited to a region where reception is poor. As the area of the cell transmitting the same signal is reduced, the delay time of the signals arriving at the receiver is reduced, and thus the guard interval length of the OFDM symbol does not need to be long. In other words, when the retransmission is made, the gain of the single frequency network described above cannot be obtained. If retransmission can occur more than once in a particular cell, the delay time is reduced because the area of retransmission will gradually decrease as the number of retransmissions increases.

FIG. 15 is a diagram illustrating a phenomenon in which the number of cells performing retransmission is reduced when retransmission occurs according to the fifth embodiment of the present invention.

Referring to FIG. 15, a situation in which the number of cells performing retransmissions in a region consisting of a plurality of cells is decreasing according to an initial transmission 1500, a second transmission 1510, and a third transmission 1520 is divided into three steps. Shown. After the initial transmission 1500, there are five weak cells 1503 inside the high performance cells 1501. After the second transmission 1510, two weak cells 1503 exist inside the high performance cell 1501, and after the third transmission 1520, there are no weak cells. .

In view of the fact that the broadcast reception characteristics change during retransmission, it is preferable to change the format of the OFDM signal according to the reception environment and transmit the retransmission. That is, when retransmitting, reducing the length of the guard interval and increasing the weight of the data symbol has the effect of lowering the code rate, thereby improving performance.

16 is a diagram illustrating an example of a configuration of an OFDM symbol that can be transmitted during a data part of an HRPD 1/2 slot according to the fifth embodiment of the present invention.

Referring to FIG. 16, one OFDM symbol 1601 using 400 chips, a MAC 1602 using 64 chips, a pilot 1603 using 96 chips, and 64 chips A MAC 1604 using a chip and one OFDM symbol 1605 using a 400 chip may be transmitted during the data part of the 1/2 slot. The one OFDM symbol 1601 uses 400 chips, and includes a guard interval 1606 and useful data 1607.

Two slots having a configuration as shown in FIG. 16 can be transmitted during slots that can be used for broadcast and multicast. However, OFDM symbols that can be transmitted in the data part can have a plurality of different formats. Table 1 below shows the format of a transmittable OFDM symbol. The format of the symbol can be various formats other than the examples shown in Table 1 below.

Format 0 Format 1 Format 2 Protective section (chip) 80 40 16 Useful data (chip) 320 360 384 Pilot tone count 64 36 16 Number of protection tones 20 0 4

As shown in Table 1, the longer the length of the guard interval, the longer the multipath delay is, the more formats of the single frequency network to gain. On the other hand, in the case of a format with a short protection interval, data transmission volume has a big advantage.

In Table 1, the guard interval indicates the number of chips that can be used for the guard interval of the OFDM symbol in the HRPD 1/2 slot, and useful data are chips that can be used for data transmission except the guard interval. number of chips). The number of pilot tones indicates the number of pilot tones inserted in the data interval, and the number of guard tones indicates the number of guard tones inserted in the data interval.

FIG. 17 is a diagram illustrating a case in which a transmission format is changed and retransmitted according to the fifth embodiment of the present invention. FIG.

It is assumed that FIG. 17 also has a 4-slot interlace structure. In addition, although the transmission method may use continuous transmission, which is a method according to the first embodiment of the present invention, it is assumed that the transmission method is performed in the same manner as the prior art for the convenience of contrast between the prior art and the fifth embodiment of the present invention. According to the above assumption, the fifth embodiment of the present invention has a first 4-slot interlace section T0-T1 to a fourth 4-slot interlace section T3-T4, and each of the four slot interlace sections is 4 respectively. Has slots capable of transmitting packets.

Referring to FIG. 17, according to a fifth embodiment of the present invention, a first packet (Packet # 1) 1701 and a second packet in a first slot and a third slot of a four-slot interlace transmission structure with different OFDM symbol formats (Packet # 2) 1702 is retransmitted.

In other words, the first packet (Packet # 1) 1701 and the second packet (Packet # 1) 1701 and the OFDM symbol format 0 (1710) in the first slot and the third slot of the first four-slot interlace interval (T0-T1) # 2) 1702 is initially transmitted. First packet (Packet # 1) 1703 and second packet (Packet # 2) from the first slot and the third slot of the second four-slot interlace interval (T1-T2) to the next OFDM symbol format 11720. 1704 is sent (retransmitted) a second time. In addition, the first packet (Packet # 1) 1705 and the second packet (Packet # 2) to the OFDM symbol format 2 (1730) in the first slot and the third slot of the third four-slot interlace interval (T2-T3). 1706 is transmitted third (second retransmission).

In this manner, three (or generally n) OFDM symbol formats are alternately transmitted, and then the first slot and three of the fourth four-slot interlace interval (T3-T4) to OFDM symbol format 0 (1710). It is preferable that the fourth packet (Packet # 1) 1707 and the fifth packet (Packet # 2) 1708 are initially transmitted in the first slot.

18 is a diagram showing the structure of a signal message according to a fifth embodiment of the present invention.

Referring to FIG. 18, the signal message indicates whether additional packets are transmitted for each broadcast and multicast flow (BCMCS flow), and indicates an OFDM format used at this time. In addition, the same indicates whether additional packets are transmitted in the neighboring cell in order to indicate transmission information in the neighboring cell, and also indicates the OFDM format used at this time. Each field of the signaling message is used for the following purposes.

NeighborCount: This is the number of neighbor cells containing broadcast transmission information included in the message.

NumExtendedSlotIncluded: An indicator indicating whether there are fields indicating additional transmissions in addition to the existing transmission slot and transmission method. Existing transmission slots and transmission methods are equally applicable to neighboring cells included in this message, but the information included by this indicator may vary from cell to cell.

BCMCSFlowCount: The number of BCMCS flows included in this message.

BCMCSFlowID: Identifier of BCMCS flow.

NumExtendedSlot: Number of additional slots to transmit per packet. Only included if NumExtendedSlotIncluded is '1'.

ModulationIndicator: Indicates whether OFDM or CDM is used. The following is an example and is included only when NumExtendedSlotIncluded is '1' and NumExtendedSlot is not '0'.

'0': OFDM

'1': CDM

ModulationOrder: Modulation order to be used for transmission. Below is an example and the number of bits is increased when considering higher modulation orders. Only included if NumExtendedSlotIncluded is '1', NumExtendedSlot is not '0' and ModulationIndicator is '1'.

'00': BPSK

'01': QPSK

'10': 8-PSK

'11': 16-QAM

TransmissionFormat: Transmission format used for transmission. Below is an example and the number of bits is increased when considering more formats. Only included when NumExtendedSlotIncluded is '1', NumExtendedSlot is not '0' and ModulationIndicator is '0'.

'00': Format 0

'01': Format 1

'10': Format 2

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 defined 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.

The present invention has the effect of providing a method and apparatus that can reduce the complexity of scheduling when providing a broadcast service and a unicast service at the same time. In addition, the present invention has the effect of providing a method and apparatus that can increase the throughput (throughput) of the channel when simultaneously providing a broadcast service and a unicast service. In addition, the present invention has an effect that can provide a method and apparatus that can improve the performance of the neighboring cell when transmitting broadcast data only by the OFDM scheme. In addition, the present invention has an effect that can provide a method and apparatus that can increase the reception efficiency of the broadcast service.

Claims (8)

In the broadcast data transmission method in a mobile communication system for transmitting traffic in an interlace structure of a predetermined number of slots, Determining at least one slot to transmit broadcast data in the one interlace period; And dividing the broadcast traffic into packet units and continuously transmitting the divided packets by a predetermined number of retransmissions. In the broadcast data transmission method in a mobile communication system for transmitting traffic in an interlace structure of a predetermined number of slots, Determining at least two slots to transmit broadcast data in the one interlace period; The broadcast traffic is classified in packet units, at least two or more packets among the divided packets are alternately transmitted by a predetermined number of transmissions, and the transmitted packets are modulated by a CDM modulation scheme and an OFDM modulation scheme at least once. The method comprising the step of transmitting. In the broadcast data transmission apparatus in a mobile communication system for transmitting traffic in an interlace structure of a predetermined number of slots, A scheduler that predetermines at least two or more slots to transmit broadcast data in the one interlace period; An information signal generator for dividing and outputting the broadcast traffic in packet units; A channel encoder for encoding and outputting the output of the information signal generator; A buffer for storing the coded signal output from the channel encoder; An OFDM modulator for modulating the encoded signal by an OFDM scheme; A CDM modulator for modulating the encoded signal by a CDM scheme; A switch for coupling a signal read from the buffer to one of the modulators; And a control unit for controlling storage and output in the buffer, controlling switching of the switch, and controlling driving of the respective modulators. In the broadcast data transmission method in a mobile communication system for providing a broadcast service, the broadcast service is transmitted in synchronization with each higher node of the network, Transmitting broadcast traffic in an OFDM scheme through predetermined broadcast traffic transmission slots in a center cell of the upper node of the network; Transmitting broadcast traffic by OFDM in the same broadcast data through the same slots as the center cell in the boundary cell of the upper node of the network; Selecting at least one of slots for transmitting a unicast packet in the center cell in a boundary cell of the upper node of the network, and modulating and transmitting broadcast traffic transmitted at a previous time point by using a CDM method Said method. The method of claim 4, wherein In the center cell of the network upper node, OFDM broadcast traffic alternately transmits different broadcast packets. The modulation method is characterized in that for transmitting in the transmission period of the broadcast packet transmitted by alternating the OFDM cell in the center cell of the network upper node when the modulation is transmitted by the CDM scheme in the boundary cell of the network upper node. The method of claim 4, wherein And transmitting a broadcast packet modulated and transmitted in a CDM scheme in a boundary cell of the upper node of the network in a slot immediately after the broadcast packet in the OFDM scheme is transmitted. In the broadcast data transmission method in a mobile communication system for transmitting traffic in an interlace structure of a predetermined number of slots, Determining at least one slot to transmit broadcast data in the one interlace period by OFDM; And classifying the broadcast traffic in packet units and transmitting the divided packets in OFDM symbols having different formats by a predetermined number of retransmissions in the predetermined slot. The method of claim 7, wherein The OFDM format may take various formats by having a value in which a guard interval, useful data, a pilot tone number, and a guard tone number are variable.

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