WO2000010335A2

WO2000010335A2 - Device and method for multiplexing physical channel in cdma communication system

Info

Publication number: WO2000010335A2
Application number: PCT/KR1999/000455
Authority: WO
Inventors: Hoon Chang; Hyun-Seok Lee
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 1998-08-17
Filing date: 1999-08-17
Publication date: 2000-02-24
Also published as: AU5307499A; BR9906733A; EP1058980A2; US6741618B1; KR100454930B1; CA2305874A1; AU732114B2; CN1286843A; CA2305874C; CN1192526C; KR20000014425A; WO2000010335A3

Abstract

Multiplexing device and method in a mobile communication system. Multiplexing is implemented in two stages to allow a logical channel to be shared, the type of a multiplex unit is defined, and the defined multiplex unit type is determined depending on the type of a physical channel, so that the same kind of physical channels employ the same type of multiplex units.

Description

DEVICE AND METHOD FOR MULTIPLEXING PHYSICAL CHANNEL IN

CDMA COMMUNICATION SYSTEM

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device and method for communicating

a message in a CDMA (Code Division Multiple Access) communication

system, and more particularly, to device and method for multiplexing a message

on a physical channel.

2. Description of the Related Art

CDMA mobile communication systems have developed from the IS-95

standard focusing only on a voice service to the next generation CDMA

(hereinafter referred to as CDMA 2000) which provides a high-speed data

transmission capability for establishing various services including high quality

voice, moving pictures, and internet browsing. An IS-95 CDMA

communication system operates at a maximum data transmission rate of 9.6kbps

or 14.4kbps since it is directed to provide a voice service whereas the CDMA

2000 operates at a much higher maximum data transmission rate of 2Mbps.

Therefore, the CDMA 2000 can transmit data 256 times faster than the IS-95

standard. Furthermore, the two standards may be further differentiated whereby a

base station assigns a physical channel to a terminal for a short time when

necessary in a CDMA communication system based on the CDMA 2000

standard. To similarly assign a physical channel for a short time for a

communication system based on the IS-95 standard, a complex modification

needs to be made to an existing IS-95 multiplex option, in which a multiplex

configuration depends on the number of connected physical channels. Sixteen

( 16) bits are required to implement the IS-95 multiplexing option. However,

it should be noted that it is difficult to apply the multiplex option to a message

as short as 5ms in duration used for rapid assignment of a physical channel.

In view of the above, it is apparent that to implement the IS-95

multiplexing option, a complex table is required to emulate both support of

multiple transmission rates and concurrently connect a plurality of physical

channels to provide various services as is done in a communication system based

on the CDMA 2000 standard. Consequently, there exists a need for a new

multiplex configuration that is superior to the inflexible and complex structures

of the existing IS-95 multiplex option.

SUMMARY OF THE INVENTION An object of the present invention is to provide a device and method for

constructing a multiplex configuration, in which physical channels are rapidly

connected to increase the use efficiency of radio resources in a mobile

communication system.

Another object of the present invention is to provide a multiplexing device

and method which reflect characteristics of various physical channels.

To achieve the above objects, a multiplexing device and method is

provided in a mobile communication system, in which logical channel frames are

separated from a received physical channel frame, multiplex units are separated

from a logical channel frame, and each multiplex unit is sent to its destination.

More precisely, a logical channel multiplexing is performed by receiving a

physical channel frame and separating a logical channel frame from the received

physical channel frame by analyzing the physical channel frame. Then, a

service multiplexing is performed by separating multiplex units from each logical

channel frame whose type is defined depending on the type of physical channel

containing the logical channel frame and transmitting information of each

extracted multiplex unit to a destination.

In accordance with the present invention, multiplexing is implemented in two stages to allow a logical channel to be shared and the type of multiplex unit

is defined and the defined multiplex unit type is determined depending on the

physical channel type, so that the same kind of physical channels employ the

same type of multiplex units.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and advantages of the present invention will become

more apparent by describing in detail a preferred embodiment thereof with

reference to the attached drawings in which:

FIG. 1 illustrates a layer which performs a two-stage multiplexing in a

CDMA communication system according to an embodiment of the present

invention;

FIG. 2 is a flowchart depicting a logical channel multiplexing in the two-

stage multiplexing method in the CDMA communication system according to the

embodiment of the present invention;

FIG. 3 is a flowchart depicting service multiplexing according to an

embodiment of the present invention;

FIG. 4 illustrates multiplex unit types for service multiplexing according

to an embodiment of the present invention;

FIG. 5 illustrates an example of a type 5 multiplex unit according to an

embodiment of the present invention; FIG. 6 illustrates a multiplex configuration in the CDMA communication

system according to an embodiment of the present invention; and

FIG. 7 illustrates channel assignment and data exchanges between a base

station and a terminal in the CDMA communication system according to an

embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENT

A mobile communication system (CDMA communication system

hereinbelow) according to an embodiment of the present invention includes a 2-

stage multiplexing to support characteristics of various physical channels. The

2-stage physical channel multiplexing comprises a first stage defined as logical

channel multiplexing followed by a second stage defined as service multiplexing,

performed as follows: (1) logical channel frames are separated from a received

physical channel frame. This stage is termed logical channel multiplexing in

the present invention.; and (2) multiplex units are then separated from each

logical channel frame and each multiplex unit is transmitted to a destination.

This stage is referred to as service multiplexing in the present invention.

In accordance with the present invention, prior to performing physical

channel multiplexing in accordance with the present invention, a multiplex

configuration specifying procedure must be performed. At the configuration stage, a multiplex unit type is determined for each physical channel.

FIG. 1 illustrates an embodiment of the 2-stage physical channel

multiplexing method in the CDMA communication system according to the

present invention.

Referring to FIG. 1 , upon receipt of a physical channel frame as indicated

by reference numeral 115, a multiplex layer 113 multiplexes the physical channel

frame into logical channels as indicated by 115. After logical channel frames

are separated from the physical channel frame by the logical channel multiplexing

(i.e., Stage 1), the multiplex layer 113 implements service multiplexing (i.e.,

Stage 2). To perform service multiplexing, each of the logical channel frames

is divided into multiplex units and each multiplex unit is sent to a destination, to

thereby provide proper services.

FIG. 2 is a flowchart depicting logical channel multiplexing according to

an embodiment of the present invention.

Referring to FIG. 2, in step 212, a determination is made as to whether a

physical channel frame has been received. If so, a message processor (not

shown) determines the structure of the received physical channel frame in step 214. The structure of the physical channel frame is preset by mutual agreement

between a transmitting side and a receiving side. In the IS-95 standard, the

number of logical channel frames contained within the physical channel frame

and their location can be determined by checking format bits at the left end of the

physical channel frame. For compatibility, the presently described embodiment

of the present invention follows the IS-95 standard. However, other

embodiments which do not conform or are compatible with the IS-95 standard

are within the scope of the present invention. The structure of a physical

channel frame based on the IS-95 standard is exemplarily specified as follows.

Table 1

It is noted from (table 1) that one physical channel frame can support a

maximum of three logical channel frames in accordance with the IS-95

multiplexing option. A receiving side can determine what logical channel

frames a physical channel frame contains and where they are located by analyzing

format bits. In one embodiment of the present invention, a modification is made

to the physical channel structure based on the IS-95 standard in such a way that

the structure of a physical channel without format bits is preset between a

transmitting side and a receiving side. As a result, the format bits are saved and

as a result, additional data bits can be further transmitted and received.

After the receiving side detects the number, locations, and sizes of the

logical channel frames in the above procedure, it sets a variable N which equates

to the number of the logical channel frames detected and sets a variable i to an

initial value 1 in step 216 and then performs a service multiplexing procedure.

In the service multiplexing procedure, it is determined whether service

multiplexing has been completed for all the logical channel frames (N), in step

218. If service multiplexing is not complete, a current logical channel frame is

service-multiplexed in step 220. Then, the next logical channel frame is

designated (i=i+l) in step 222 and the procedure returns to step 218. Upon

completion of service-multiplexing the last logical channel frame (i.e., i=N) procedure ends.

As shown in FIG. 2, service multiplexing is implemented for the first

through the Nth logical channel frames detected. A detailed description of

service multiplexing will be given hereinbelow with reference to FIGs. 3 and 4.

In FIG. 3, at determination step 311, it is determined what multiplex unit

type is defined for each logical channel. The multiplex unit is a minimum

multiplexed unit which identifies a destination. A single logical channel may

include one or more multiplex units. Multiplex unit types are shown in FIG. 4.

FIG. 4 illustrates five types of multiplex units used in the CDMA

communication system according to the embodiment of an present invention.

In the case of a multiplex unit type 1 as indicated by 412 in FIG. 4, a

logical channel frame is free of an overhead field and occupied with information

data for one service.

Two formats are available for a multiplex unit type 2 as indicated by 414.

A logical channel frame has 0 at the left end in one format as indicated by 414A,

and a logical channel frame has 111 1 at the left end in the other format as indicated by 414B. Logical channel frames of the multiplex unit type 2 are used

to achieve compatibility with the IS-95 standard.

A multiplex unit type 3 also has two formats. In one format as indicated

by 416 A, a logical channel frame has 0 at the left end and in the other format as

indicated by 416B, a logical channel frame has 10111 at the left end. Logical

channel frames of the multiplex unit type 3 are also used to achieve compatibility

with the IS-95 standard.

A logical channel frame of a multiplex unit type 4 as indicated by 418

includes a service identification (SID) of two bits at the left end. The service

type for which the information field of this multiplex unit type will be sent can

be determined from the two-bit SID.

Each of the multiplex unit types 1 to 4 occupies a single logical channel

frame. Therefore, if a logical channel frame has N bits, each multiplex unit type

is also as long as N bits.

A multiplex unit type 5 further includes a field representing length (LEN)

and thus a single logical frame can have a plurality of multiplex units of this type.

The multiplex unit type 5 has a two-bit SID followed by a four-bit LEN at the left end. The field LEN indicates a value expressed in terms of bytes. The

multiplex unit type 5 can support 2¹⁴-1 bytes at maximum.

As described above, each logical channel knows what multiplex unit type

it employs.

Returning to FIG. 3, the receiving side determines if the multiplex unit

type included in the received logical channel frame is type 5. If the multiplex

unit is type 5, indicating a plurality of multiplex units, the procedure goes to step

313. Otherwise, for types 1 -4, an information field is extracted from a multiplex

unit and transmitted to a destination in step 325. That is, since a logical channel

frame of each multiplex unit type is comprised of an overhead field of a few bits

at the left end and a corresponding information field, the information field is

transmitted to the destination defined by the overhead field of the received

multiplex unit.

If it was determined, at step 311, that the multiplex unit type is type 5,

then the receiving side extracts each of the plurality of multiplex units from the

logical channel frame and transmits each extracted multiplex unit to a

corresponding destination in step 313. To do so, the receiving side sets the

length of an information field in the logical channel frame to N and p to 1 to represent the location of a multiplex unit under process. FIG. 5 illustrates a

logical channel frame of the multiplex unit type 5.

In step 315, the receiving side determines whether p £ N. If p > N, the

receiving side reads a pth byte and a (p+l)th byte in the logical channel frame in

step 317. Since the first two bits indicate an SID and the following 14 bits

indicate LEN in the multiplex unit type 5, the values of the SID and LEN are

stored as SID and LEN variables at step 319. Then, the receiving side sends as

many bytes as LEN starting from a (p+2)th byte to a destination designated by

the SID in step 321. Thus, a multiplex unit is completely processed. In step

323, the receiving side increments p by the size of the processed multiplex unit,

that is, LEN+2 so that the location of the next multiplex unit is designated.

Then, the procedure returns to step 315.

By repeating steps 317 to 323, a logical channel frame of the multiplex

unit type 5 is sent to one or more destinations. During the procedure, a number

of information bytes (i.e., LEN bytes) are sent to a destination represented by an

SID. Referring again to step 315, if the value of p is larger than the size of the

logical channel frame, the receiving side determines that all the multiplex units

have been completely processed, in step 315, and service multiplexing is then

terminated. As compared to the IS-95 standard where only logical channel

multiplexing is implemented, the 2-stage physical channel frame multiplexing

method of the present invention is a more flexible solution to achieve a support

level commensurate with the CDMA 2000 system which supports various

services while simultaneously ensuring compatibility with the existing IS-95

system.

To employ the 2-stage physical channel frame multiplexing scheme of

the present invention, a specification of positioning logical channel frames in a

physical channel frame and further positioning multiplex units in the logical

channel frames should be preset between a transmitting side and a receiving side

at a configuration stage. The multiplexing specification is referred to herein as

a multiplex configuration.

The multiplex configuration includes two aspects: physical channel

frame configuration and multiplex unit configuration. The present invention

preferably follows the physical channel frame configuration defined by the

CDMA 2000 standard. To specify a different multiplex configuration for each

physical channel type, Table 2 lists physical channels and associated transmission

rates which the CDMA 2000 should support. Table 2

The physical channels listed in Table 2 can have logical channels as

shown in Table 3 in the IS-95 standard.

Table 3

As shown in Table 3, the fundamental channel is comprised of four

logical channels, the supplemental channel is comprised of a plurality of logical

channels, and the dedicated control channel is comprised of three logical

channels. To support the 2-stage multiplexing scheme, multiplex unit types for

the logical channels of the physical channels should be predetermined by mutual

agreement between a transmitting side and a receiving side. The present invention describes a multiplex configuration in which a

multiple unit type is specified for each logical channel according to the type of

physical channel. Assuming that a terminal has a fundamental channel, a

dedicated control channel, and three supplemental channels where each

supplemental channel includes eight logical channels, the terminal and a base

station should determine a multiple unit type for each of 31 logical channels in

total, that is, 4 logical channels for the fundamental channel, 3 logical channels

for the dedicated control channel, and 24 logical channels for the three

supplemental channels. In an embodiment of the present invention, multiplex

unit types are determined for as many logical channels of the fundamental

channel indicated by 612 in FIG. 6 and the dedicated control channel indicated

by 616, and one multiplex unit type is determined for the supplemental channel

regardless of the number of supplemental channels and their logical channels, to

thereby efficiently implement a multiplex configuration.

The present invention determines a multiplex unit type according to the

type of physical channels, whereas the IS-95 standard determines multiplex units

type for physical channels in current use. The CDMA 2000 is too complicated

to employ as an extension of the IS-95 standard. Therefore, the multiplex

configuration according to the embodiment of the present invention is free of complexity of the IS-95 multiplex option and obviates the need for renewing a

multiplex configuration when the number of physical channels is changed.

FIG. 7 illustrates an example of the multiplex configuration as one

embodiment of the present invention.

Referring to FIG. 7, upon request for a call set-up by a terminal in step

71 1 , the terminal and a base station perform a call set-up procedure and determine

the multiplex configuration together in step 713. They specify a multiplex unit

type for each physical channel type as shown in FIG. 6. Thus, there is no need

for constructing a new multiplex configuration regardless of the generation or

release of a physical channel.

Upon completion of constructing the multiplex configuration, the

terminal makes a request for a new physical channel in step 715 and the base

station responds by assigning the physical channel in step 717. Then, the

terminal sends data on the physical channel in accordance with the 2-stage

multiplexing method of the present invention using the predetermined multiplex

configuration in step 719. The terminal returns the physical channel to the base

station in step 721. Note, however, that the multiplex configuration is not

changed. Therefore, when the base station assigns a new physical channel to

the terminal and sends data on the new physical channel to the terminal, the pre- established multiplex configuration in the 2-stage multiplexing method remains

valid (steps 721 to 727).

In accordance with an embodiment of the present invention as described

above, the 2-stage multiplexing method overcomes the disadvantages of the IS-95

standard by enabling a physical channel to be rapidly assigned, resulting in

efficient use of radio resources by pre-constructing a simplified multiplex

configuration specifying procedure.

While the present invention has been described in detail with reference

to the specific embodiment, it is a mere exemplary application. Thus, it is to be

clearly understood that many variations can be made by anyone skilled in the art

within the scope and spirit of the present invention.

Claims

CLAIMS:

1. A physical channel frame multiplexing method in a CDMA

communication system, comprising the steps of:

performing a logical channel multiplexing by receiving a physical

channel frame including one or more logical channel frames and separating

said logical channel frames from the received physical channel frame, each of

said logical channel frames having at least one multiplex unit; and

performing a service multiplexing by separating said multiplex units

whose type are defined by the received physical channel type and transmitting

information of each multiplex unit to a destination.

2. The method of claim 1 , wherein the multiplex unit types include

a first multiplex unit type in which one multiplex unit is assigned to one

logical channel frame, and a second multiplex unit type in which a multiplex

unit is comprised of a service identification (SID), a length, and information

fields.

3. The method of claim 2, wherein the service multiplexing step

further comprises the steps of: extracting an information field of the received logical channel frame

and transmitting the information field to a destination, if the logical channel

frame is of the first multiplex unit type; and

determining the SID and length information of the received logical

channel frame, extracting an information field whose length corresponds to

said length information from the logical channel frame, transmitting the

information field to a destination, and repeating the determining, extracting,

and transmitting procedure a number of times equal to the numbers of the

multiplex unit of the logical channel frame, if the logical channel frame is of

the second multiplex unit type.

4. The method of claim 1, wherein the physical channel is defined

as one of a fundamental channel, a supplemental channel, and a dedicated

control channel.

5. The method of claim 4, wherein the fundamental channel is one of a

traffic channel 1 , a traffic channel 2, a MAC channel, and a signaling

channel.

6. The method of claim 4, wherein the supplemental channel is a traffic

channel.

7. The method of claim 4, wherein the dedicated control channel is one

of a traffic channel, MAC channel, and a signaling channel.

8. A multiplex configuration constructing method in a CDMA

communication system, comprising the steps of:

(i) performing a call set-up procedure when an initial call is set-up, and

determining a regulation of positioning multiplex units in a physical frame

performed by a base station and a terminal;

(ii) assigning a physical channel and multiplexing a physical channel

frame received on the assigned channel based on the multiplex configuration; and

(iii) multiplexing a received physical channel frame upon generation of

a new call based on the multiplex configuration.

9. The method of claim 8, wherein the step (iii) comprises the

substeps of:

performing a logical channel multiplexing by receiving a physical

channel frame and separating a logical channel frame from the received physical

channel frame by analyzing the physical channel frame; and

performing a service multiplexing by separating multiplex units from the

logical channel frame whose type are defined depending on the type of the

physical channel from the logical channel frame and transmitting information of each multiplex unit to a destination.

10. A physical channel frame multiplexing device in a CDMA

communication system, comprising:

a logical channel multiplexer for receiving a physical channel frame and

separating a logical channel frame from the received physical channel frame; and

a service multiplexer for separating multiplex units from said logical

channel frame whose type is defined by the physical channel type and

transmitting information of each separated multiplex unit to a destination.