WO2006098550A1

WO2006098550A1 - Method for transmitting and receiving packet in mobile communication system

Info

Publication number: WO2006098550A1
Application number: PCT/KR2006/000402
Authority: WO
Inventors: Chan Ho Kyung; Ki Jun Kim; Jong Hoe An; Young Jun Kim
Original assignee: Lg Electronics Inc.
Priority date: 2005-02-04
Filing date: 2006-02-03
Publication date: 2006-09-21
Also published as: CA2595227A1; CA2595227C

Abstract

The present invention relates to a packet reception method. In a packet reception method applied to a mobile communication system, in which data transmission is performed by repeating at least two interlaces by a predetermined cycle, the present invention includes the steps of receiving a broadcast/multicast packet from a base station, receiving a broadcast overhead message including information of a reference multiplex burst length and information about multiplexes, each having a burst length different from the reference multiplex burst length, and decoding the received broadcast/multicast packet using the information included in the broadcast overhead message. Accordingly, the present invention can efficiently transmit the broadcast overhead message required for the packet data decoding.

Description

Method for Transmitting and Receiving Packet in Mobile

Communication System

[Technical Field]

The present invention relates to a packet

transmitting/receiving method applied to mobile

communications, and more particularly, to a method of

transmitting/receiving a packet to perform packet

transmission more efficiently by transmitting a broadcast

overhead message necessary for packet decoding more

efficiently.

[Background Art]

Generally, in a mobile communication system, a

broadcast overhead message includes information enabling a

mobile station to stably receive and decode packet data

channel or broadcast channel transmitted from a base

station in case of performing a broadcast/multicast

(hereinafter abbreviated ^λBCMC ) service in the mobile

communication system.

In a mobile communication system supporting BCMC, a

high data rate is required since multimedia data including

audio and video needs to be transmitted. To perform the

broadcast/multicast service, a packet data channel of a

physical layer needs to support a high data rate. To stably transmit multimedia data via the

packet data channel in a radio environment having fading,

Hybrid Automatic Repeat Request (hereinafter ^ΛHARQ' ) system

is applied. In HARQ_r technical features of Forward Error

Correction (hereinafter abbreviated ^λFEC) function and

Automatic Repeat Request (hereinafter abbreviated ^ΛARQ/ )

are combined together.

The HARQ system is explained in detail as follows.

First of all, encoding is carried out on data to be

transmitted using a channel coder having an error

correction function, e.g., turbo encoder, and at least one

sub-packet corresponding to one encoded packet is

transmitted.

Once a transmitting side transmits a first sub-packet,

a receiving side decodes the received first sub-packet. If

the decoding is successfully completed, signal notifying a

successful reception (acknowledgement; hereinafter

abbreviated ^ΛACK) is transmitted to the transmitting side.

Meanwhile, if the decoding of the received first sub-packet

fails, signal notifying failure of reception (negative

acknowledgement; hereinafter abbreviated ^ΛNACK' ) is fed

back to the transmitting side.

In case of receiving the ACK signal, the transmitting side transmits a first sub- packet corresponding to a

next packet. Meanwhile, in case of receiving the NACK

signal, the transmitting side transmits a second sub-packet

corresponding to the previously transmitted packet. In this

case, the receiving side stores the first sub-packet in a

buffer to raise a decoding success rate in a manner of

performing decoding by combining the first and second sub-

packets together.

Fig. 1 is an exemplary diagram for a HARQ

implementing method on interlace structure. Referring to

Fig. 1, a channel for packet data transmission can be

implemented with a structure that each interlace is

regularly repeated with each fixed time interval. In an

example shown in Fig. 1, since a packet data channel

includes four interlaces, one packet is transmitted using

one of the four interlaces. Once an interlace to be

transmitted is determined, a corresponding packet is

transmitted via the determined interlace. This is explained

in detail as follows.

Referring to Fig. 1, it is assumed that packet #0 is

transmitted using interlace #0. A transmitting side

transmits a first sub-packet corresponding to packet #0 to

a receiving side via interlace #0. The receiving side receives the first sub- packet and then performs

decoding on the received first sub-packet. As a result of

decoding the received first packet, if the decoding fails,

the receiving side feeds back a NACK signal to the

transmitting side. The transmitting side having received

the NACK signal transmits a second sub-packet corresponding

to the packet #0 to the receiving side using the interlace

#0. Having received the second sub-packet, the receiving

side performs decoding by combining the second sub-packet

and the first sub-packet stored in a buffer together. If

the decoding fails again, the receiving side feeds back a

NACK signal to the transmitting side.

Having received the NACK signal, the transmitting

side transmits a third sub-packet corresponding to the

packet #0 to the receiving side using the interlace #0

again. Such a process is repeatedly performed until an ACK

signal is received or a critical count is reached. Thus,

each sub-packet corresponding one packet is transmitted

using the same interlace.

Broadcast/multicast data is transmitted via a packet

data channel having the above explained interlace structure

and one interlace includes at least one or more multiplexes.

Preferably, one interlace includes four, eight or sixteen multiplexes- So, an interlace-multiplex pair is

used to indicate that a packet is transmitted through which

multiplex within which interlace.

For each interlace-multiplex pair, a burst length is

determined. The burst length is determined by multiplying a

number of sub-packets per packet, which is determined by a

data rate, by a number of packets per buts to be

transmitted. The interlace-multiplex pair consecutively

occupies a specific interval of the same interlace as the

burst length.

So, a packet data channel carrying

broadcast/multicast data includes sub-channels defined by

interlace-multiplex pair. In a base station, one logical

channel including at least one broadcast/multicast service

(hereinafter abbreviated ^ΛBCMCS' ) flow is mapped to at

least one interlace-multiplex pair.

To transmit information associated with interlace-

multiplex pair to a mobile subscriber station, an overhead

message is transmitted from a base station. The overhead

message includes information indicating that BCMC service

flows are transmitted through which interlace from a

specific base station and information about multiplex burst

length. In the related art, all information about burst β length of each multiplex configuring one interlace is

transmitted to increase a size of the overhead message.

[Disclosure of Invention]

The object of the present invention is to raise

packet transmission efficiency in a mobile communication

system by transmitting a broadcast overhead message for

packet transmission decoding more efficiently.

To achieve these and other advantages and in

accordance with the purpose of the present invention, in a

packet reception method applied to a mobile communication

system, in which data transmission is performed by

repeating at least two interlaces by a predetermined cycle,

the packet reception method according to the present

invention includes the steps of receiving a

broadcast/multicast packet from a base station, receiving a

broadcast overhead message including information of a

reference multiplex burst length and information about

multiplexes, each having a burst length different from the

reference multiplex burst length, and decoding the received

broadcast/multicast packet using the information included

in the broadcast overhead message.

In this case, it is preferable that the reference

multiplex burst length corresponds to a burst length of a group having a biggest number of multiplex members

in case that the multiplexes are grouped according to burst

length equality.

And, it is preferable that the broadcast overhead

message further includes information about a value of

totaling the burst length of at least one or more

multiplexes configuring one interlace.

In another aspect of the present invention, in a

packet transmission method applied to a mobile

communication system, in which data transmission is

performed by repeating at least two interlaces by a

predetermined cycle, the packet transmission method

includes the steps of determining a specific burst length

among burst lengths corresponding to at least one or more

multiplexes, respectively as a reference burst length,

transmitting burst length information corresponding to each

of the multiplexes by omitting the burst length information

corresponding to the multiplex having the burst length

equal to the reference burst length, and transmitting a

packet corresponding to the interlace and multiplex.

In this case, it is preferable that the burst length

information is transmitted in a broadcast overhead message

format. And, it is preferable that the reference burst length corresponds to a burst length of a group

having a biggest number of multiplex members in case that

the multiplexes are grouped according to burst length

equality.

In case that packet data is transmitted using an

interlace-multiplex pair structure, the present invention

can transmit the broadcast overhead message necessary for

the packet data decoding more efficiently.

[Brief Description of the Drawings]

Fig. 1 is an exemplary diagram for a HARQ

implementing method on an interlace structure.

[Best Mode for Carrying Out the Invention]

The aforesaid objectives, features and advantages of

the invention will be set forth in the description which

follows, and in part will be apparent from the description.

Reference will now be made in detail to one pre-ferred

embodiment of the present invention, examples of which are

illustrated in the accompanying drawing.

The present invention is applicable to such a

technology as cdma2000 Ix EVDO, cdma2000 Ix EVDV, GPRS,

HSDPA and the like. In the description of the present

invention, the cdma2000 Ix EVDO system is adopted for

example. BCMC service and interlace structure of the

present invention are described in detail in 3GPP2 standard,

which can be referred to by the detailed description of the

present invention.

Table 1 shows an example of a broadcast overhead

message.

[Table 1]

Each field of the broadcast overhead message is

explained in detail as follows.

In Table 1, InterlaceOIncluded, Interlacellncluded,

Interlace2lnclude and Interlace3Included are fields to

indicate what kind of interlace is used in transmitting

BCMC service flows from a base station. 1-bit length is

allocated to each of the fields. If the field is set to ^Λl' ,

it means that a logical channel is transmitted via a

corresponding interlace. If the field is set to ^Λ0' , it

means that a logical channel is not transmitted via a

corresponding interlace.

The SameBurstLengthO field is an indicator indicating whether burst lengths of all multiplexes configuring

interlace #0 are identical to each other. Namely, if the

SameBurstLengthO is ^yl^r , it means that burst lengths of all

multiplexes are identical. If the SameBurstLengthO is ^Λ0' ,

it means that burst lengths of all multiplexes are

different from each other.

TotalBurstLengthO is not transmitted if

SameBurstLengthO is ^yl^r . Yet, if SameBurstLengthO is ^Λ0'

since lengths of multiplex bursts are different from each

other, TotalBurstLengthO plays a role in indicating a total

length of all multiplexes. And. 10 bits are allocated to

TotalBurstLengthO field.

In Table 1, the BurstLengthO field is omitted if the

InterlaceOIncluded is ^Λ0' . Meanwhile, if InterlaceOIncluded

is ^λl' and if SameBurstLengthO is ^Λl' , it means that

lengths of all multiplex bursts configuring Interlace #0

are equal to each other. So, 4-bits are allocated to

BurstLengthO to indicate a length common to all multiplexes.

If a value of SameBurstLengthO is ^Λ0' , it means that

lengths of multiplexes are different from each other. So,

BurstLengthO are needed as many as the number of

(MultiplexesPerlnterlace-l) . The MultiplexesPerlnterlace is

a parameter indicating how many multiplexes configure on interlace . And, the MultiplexesPerlnterlace can

have a value of 4, 8 or 16. BurstLengthO has a 4-bit length,

and a mapping .table is needed to designate a multiplex

burst length using 4-bit information. Table 2 shows an

example of a mapping table,

[Table 2\

For Interlace #1, Interlace #2 and Interlace #3,

fields having the same structure of the above-explained

Interlace #0 are configured, respectively.

In transmitting a broadcast overhead message in a

manner according to Table 1, there occurs no problem if

burst lengths of all multiplexes configuring a specific

interlace are equal to each other. Yet, if burst lengths of

all multiplexes configuring a specific interlace are

different from each other, a broadcast overhead message

needs to include a BurstLength value amounting to the

number of (MultiplexesPerlnterlace-l) .

A multiplex burst length from 1^st multiplex to

(MultiplexesPerlnterlace-l) ^th multiplex is determined by a

BurstLengthO field value amounting to

(MultiplexesPerlnterlace-l) and Table 2. Meanwhile, a

length of a last ( (MultiplexesPerlnterlace-l) ^th) multiplex

burst is determined by Formula 1. For instance, if

MultiplexesPerlnterlace is 16, i.e., 'if one interlace is

configured with sixteen multiplexes (0^th to 15^th) , a length

of the 15^th multiplex burst can be calculated by Formula 1. [ Formula 1]

MultiplmsPerlrterlacβ-l

Burst _ Length(MultiplexesPerInterhce)=Total _ Burst _ Length - ^T Burst _ LengthQ)

M

In Formula 1, Burst_Length (i) means a multiplex burst

length of i^th multiplex and Total_Burst_JLength means a

multiplex burst length of all multiplexes.

Meanwhile, in case that Interlace #0 includes sixteen

multiplexes of 0^th to 15^th for example, TotalBurstLengthO is

not transmitted for 15^th multiplex burst length information

transmission but 15^th MurstLengthO can be directly

transmitted.

Table 3 shows an example of a broadcast overhead

message .

[Table 3]

Referring to Table 3, an overhead message without

TotalBurstLength field indicating a total burst length can

be transmitted. In this case, a field indicating a last

burst length is appended to transmit multiplex length

information.

For instance, in case that Interlace #0 is configured

with sixteen multiplexes (0 to 15 ) , a case that 15 :th

BurstLengthO field is directly configured is compared to a

case that BurstLengthO field for burst length information

transmission of 15 multiplex is not separately configured in message length as follows.

In case that BurstLengthO field for burst length

information transmission of 15^th multiplex is not

separately configured, TotalBurstLengthO field having a 10-

bit length and BurstLengthO field having a

(4X (MultiplexesPerlnterlace-l) ) -bit length should be

transmitted. Meanwhile, in case that BurstLengthO field is

directly configured, a (4XMultiplexesPerInterlace) -bit

BurstLengthO field is just transmitted without configuring

TotalBurstLengthO field.

Hence, an overhead message length in case of

configuring BurstLength field separately is smaller than

that in case of not configuring BurstLengthO field

separately by 6-bits per interlace. Considering four

interlaces, the overhead message length is reduced by 24-

bits. Namely, in aspect of a transmitting side, an overhead

message reduced by 24-bits can be transmitted.

In aspect of a receiving side, in case of not

configuring BurstLengthO field separately for 15^th

multiplex, calculation according to Formula 2 is required

for obtaining a length of 15^th multiplex burst. Yet, in

case of configuring BurstLengthO field directly, such a

calculation process is not necessary. Table shows an example of a broadcast

overhead message.

[Table 4]

Zero, one, MultiplexesPerlnterlace-l or Total Number of

SameLengthWithMajority set to ¹O' occurrence of the

following field:

BurstLength3

Each field of the broadcast overhead message is

explained in detail as follows.

Similar to the case of Table 1, the

InterlaceOlncluded, Interlacellncluded, Interlace2lnclude

and Interlace3Included are fields to indicate what kind of

interlace is used in transmitting BCMC service flows from a

base station. 1-bit length is allocated to each of the

fields. If the field is set to ^Λl^r , it means that a logical

channel is transmitted via a corresponding interlace. If

the field is set to ^Λ0' , it means that a logical channel is

not transmitted via a corresponding interlace.

The SameBurstLengthO field is an indicator indicating

whether burst lengths of all multiplexes configuring

interlace #0 are identical to each other. Namely, if the

SameBurstLengthO is ^Λl' , it means that burst lengths of all

multiplexes are identical. If the SameBurstLengthO is ^λ0' ,

it means that burst lengths of all multiplexes are different from each other.

TotalBurstLengthO is not transmitted if

SameBurstLengthO is ^Λl' . Yet, if SameBurstLengthO is ^Λ0'

since lengths of multiplex bursts are different from each

other, TotalBurstLengthO plays a role in indicating a total

length of all multiplexes. And. 10 bits are allocated to

TotalBurstLengthO field.

UseProposedMethod field is a field indicating whether

a reference length shall be used or not. Namely, although

burst lengths of multiplexes configuring a specific

interlace are not equal to each other, if most of the

multiplexes are equal to each other in burst length

( 'reference length' ) and if the rest of the multiplexes

differ from each other in burst length, the

UseProposedMethod field has a value of ^Λl' .

In case that the UseProposedMethod field has a value

of ^Λl', a base station includes 1-bit

SameBurstLengthWithMajority information corresponding to

the number of MultiplexesPerlnterlace. Namely, if a burst

length of a corresponding multiplex coincides with the

burst length ( ^λ reference length' ) of each of multiplexes

with majority, a value of the SameBurstLengthWithMajority

field is ^Λl' . Yet, if a burst length of a corresponding multiplex is different from the reference length, the

SameBurstLengthWithMajority field has a value of ^Λ0' .

In determining the reference length, multiplexes are

classified into several groups with reference to the

equality of burst length and a burst length corresponding

to the group having the biggest number of multiplex members

can be determined as the reference length. Meanwhile, if

there exist at least two groups having the biggest number

of multiplex members, one of the at least two groups is

selected to determine the corresponding burst length as the

reference length.

If UseProposedMethod has a value of ^λl' , BurstLengthO

field can be included as many as the number of

SameBurstLengthWithMajority fields having values of ^λ0' and

can have a 4-bit length. A first BurstLengthO field has

information about a reference length. Meanwhile, other

BurstLengthO field (s) includes burst length information of

multiplexes each of which has a burst length different from

the reference length.

In this case, even if a multiplex having a burst

length different from the reference length, burst length

information for a last multiplex can be omitted. This is

because a burst length for a last multiplex can be calculated from the TotalBurstLength,

MultiplexesPerlnterlace and BurstLength.

Table 5 shows an example of a burst length

corresponding to each multiplex. In Table 5, (a, b)

indicates an interlace (a) -multiplex (b) pair.

[Table 5]

Table 5 shows an example of a case that Interlace #0

includes sixteen multiplexes. In the example of Table 4,

thirteen multiplexes except 2^nd, 4^th and 15^th multiplexes has

the same burst length. In this case, fifteen BurstLengthO

fields are needed using the overhead message shown in Table

1. Namely, the respective BurstLengthO fields should be

configured using 60-bits like ^Λ0001 0001 1111 0001 0011

0001 0001 0001 0001 0001 0001 0001 0001 0001 0001' .

Yet, in case of using the overhead message shown in

Table 4, sixteen SameBurstLengthWithMajority fields are

configured to indicate multiplexes differing from the

reference length. Namely, by such a setting as

^λ1101011111111110' , information about a multiplex having a

burst length different from the reference length can be

included.

Meanwhile, it is unnecessary to configure sixteen

BurstLengthO fields to include entire burst length

information about fifteen multiplexes. Namely, 1^st

BurstLengthO field includes information about a reference

length, and 2^nd and 3^rd BurstLengthO fields include information about burst lengths of 2 nd a _ „nd j _Λ th

multiplexes. Meanwhile, although 15th multiplex has a burst

length different from the reference length, it is able to

calculate the burst length from TotalBurstLength,

MultiplexesPerlnterlace and another BurstLength fields. So,

BurstLengthO field for burst length information

transmission of the 15^th multiplex can be calculated in a

manner of Formula 2 instead of being separately configured.

[Formula 2]

Burst length of 15th mul tiplex = TotalBurstLength -

(No . of SameBurstLengthWithMaj ority having a value of ^λl ' )

* 1i^sε BurstLength - BurstLength corresponding to 2 •nd

BurstLength corresponding to 4 th

Table 6 shows an example of comparison between

overhead message sizes according to Table 1 and Table 4.

[Table 6]

Referring to Table β, it can be seen that total 72-

bits are required for the broadcast overhead ^"message

according to Table 1. Meanwhile, in the same situation, it

can be seen that total 41-bits are required for the

broadcast overhead message according to Table 4.

Table 7 shows an example of a broadcast overhead

message .

[Table 7]

Referring to Table 7, an overhead message can be

transmitted without TotalBurstLength field indicating a

total burst length.

In case of Table 4, TotalBurstLength field is

transmitted by omitting the field indicating a last burst

length. In case of Table 7, a field indicating a last burst

length is added to transmit multiplex length information

instead of omitting TotalBurstLength field.

For instance, in case that Interlace #0 includes

sixteen multiplexes of 0^th to 15^th, 15^th BurstLengthO can be

transmitted instead of transmitting TotalBurstLengthO for

15^th multiplex burst length information transmission.

While the present invention has been described and

illustrated herein with reference to the preferred embodiments thereof, it will be apparent to those skilled

in the art that various modifications and variations can be

made therein without departing from the spirit and scope of

the invention. Thus, it is intended that the present

invention covers the modifications and variations of this

invention that come within the scope of the appended claims

and their equivalents.

[Industrial Applicability]

Accordingly, the present invention is applicable to a

mobile communication field and enables packet transmission

to be more efficiently performed.

Claims

[CLAIMS]

[Claim 1]

In a packet reception method applied to a mobile

communication system, in which data transmission is

performed by repeating at least two interlaces by a

predetermined cycle, the packet reception method comprising

the steps of;

receiving a broadcast/multicast packet from a base

station;

receiving a broadcast overhead message including

information of a reference multiplex burst length and

information about multiplexes, each having a burst length

different from the reference multiplex burst length; and

decoding the received broadcast/multicast packet

using the information included in the broadcast overhead

message.

[Claim 2]

The packet reception method of claim 1, wherein the

reference multiplex burst length corresponds to a burst

length of a group having a biggest number of multiplex

members in case that the multiplexes are grouped according

to burst length equality.

[Claim 3] The packet reception method of claim 1, wherein

the broadcast overhead message further includes information

about a value of totaling the burst length of at least one

or more multiplexes configuring one interlace.

[Claim 4]

The packet reception method of claim 3, wherein the

broadcast overhead message further includes an indicator

indicating whether to include the reference multiplex burst

length information and the information about the

multiplexes, each having the burst length different from

the reference multiplex burst length.

[Claim 5]

The packet reception method of claim 4, wherein the

broadcast overhead message further includes information

indicating whether the burst length of each of the

multiplexes is equal to the reference multiplex burst

length.

[Claim 6]

The packet reception method of claim 5, wherein the

broadcast overhead message includes burst length

information corresponding to each of the multiplexes and

wherein the burst length information of the multiplex

having the burst length equal to the reference multiplex burst length is omitted.

[Claim 7]

In a packet transmission method applied to a mobile

communication system, in which data transmission is

performed by repeating at least two interlaces by a

predetermined cycle, the packet transmission method

comprising the steps of;

determining a specific burst length among burst

lengths corresponding to at least one or more multiplexes,

respectively as a reference burst length;

transmitting burst length information corresponding

to each of the multiplexes by omitting the burst length

information corresponding to the multiplex having the burst

length equal to the reference burst length; and

transmitting a packet corresponding to the interlace

and multiplex.

[Claim 8]

The packet transmission method of claim 7, wherein

the burst length information is transmitted in a broadcast

overhead message format.

[Claim 9]

The packet transmission method of claim 8, wherein

the reference burst length corresponds to a burst length of a group having a biggest number of multiplex members

in case that the multiplexes are grouped according to burst

length equality.

[Claim 10]

In a packet reception method applied to a mobile

communication system, in which data transmission is

performed by repeating at least two interlaces by a

predetermined cycle, the packet reception method comprising

the steps of;

receiving a broadcast/multicast packet from a base

station;

receiving a broadcast overhead message including

information about burst length information of each of the

multiplexes wherein information about a total of burst

lengths of the multiplexes is omitted in the broadcast

overhead message; and

decoding the received broadcast/multicast packet

using the information included in the broadcast overhead

message.

[Claim 11]

In a packet reception method applied to a mobile

communication system, in which data transmission is

performed by repeating at least two interlaces by a predetermined cycle, the packet reception method

«. comprising the steps of;

receiving a broadcast/multicast packet from a base

station;

receiving a broadcast overhead message including

information of a reference multiplex burst length and

information about multiplexes, each having a burst length

different from the reference multiplex burst length wherein

information about a total of burst lengths of the

multiplexes is omitted in the broadcast overhead message;

and

decoding the received broadcast/multicast packet

using the information included in the broadcast overhead

message .