Variable channel device for wideband CDMA system

Details Variable channel device for wideband CDMA system Variable channel device for wideband CDMA system

1999-10-20

2003-04-15

Chin, Wellington (Department: 2738)

Multiplex communications

Channel assignment techniques

Combining or distributing information via code word channels...

C375S146000

Reexamination Certificate

active

06549542

ABSTRACT:

CLAIM OF PRIORITY
This application claims priority to an application entitled “Variable Channel Device for Wideband CDMA System” filed in the Korean Industrial Property Office on Oct. 20, 1998 and assigned Ser. No. 98-43931, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a CDMA (Code Division Multiple Access) system, and in particular, to a variable channel device for a wideband CDMA system which can be used both in a base station and a radio terminal of a wideband CDMA WLL (Wireless Local Loop) system.
2. Description of the Related Art
A CDMA system multiplies user signals with unique codes to spread the user signals and then transmits the spread user signals on a single carrier frequency. At the receiving end, the received signals are despread and then demultiplied using the same code to retrieve the user signals. The CDMA system uses this spread band scheme to increase the frequency utilization efficiency, and further provides message encryption using codes to enhance the authentication process and to protect sensitive subscriber information.
In a CDMA system, a channel for transmitting a signal from a base station to a radio terminal is called a forward link, and a channel for transmitting a signal from the radio terminal to the base station is called a reverse link.
A wideband CDMA (hereinafter, referred to as “W-CDMA”) system has a channel spacing of 5 MHz or 10 MHz. A convolutional encoder is typically used for reducing errors in the transmission bits. Orthogonal codes are uniquely assigned to respective channels for identifying the forward link channels. The W-CDMA system employs a direct sequence spreading technique and supports a chip rate of 4.096 Mcps (chips per second). Each channel is transmitted by Binary Phase Shift Keying (BPSK) waveform, and thereafter is transmitted by Quadrature Phase Shift Keying (QPSK). Thus, the channel spacing can be spread at much higher spreading rates.
The W-CDMA channel structure is disclosed in RHEE, “CDMA Cellular Mobile Communications and Network Security”, Chapter 9 and 10: Prentice Hall PTR, 1997. According to that reference, a channel for a W-CDMA system is classified into a power control and signaling (PCS) channel and a traffic channel. The PCS channel includes the reverse and forward pilot channels, and the signaling channels. The traffic channel includes an access channel, a sync channel, a paging channel, and a traffic channel for transmitting the actual data.
A brief description will be made hereinbelow with regard to a channel structure specified in “Radio Access Standard V2.0 for WLL” as proposed by Korea Electronics Telecommunications Research Institute (ETRI).
The reverse modulation channel of a radio terminal includes an access channel and a reverse traffic channel. The access channel is comprised of an access pilot channel and an access information channel. As shown in
FIG. 1A
, the input bits of the access pilot channel, which are all 0's, are spread with a reverse link sequence R
c
(
101
) and Hadamard codes H
0
and H
1
(
102
), and then converted to a final pilot signal through a baseband filter
103
and a carrier multiplier
104
. As shown in
FIG. 1B
, information bits of the access channel (ACH) are spread after passing a convolutional encoder
107
, a block interleaver
108
, and a symbol repeater
109
.
The reverse traffic channel is comprised of a pilot, a PCS channel, and a traffic channel. As shown in
FIG. 2A
, information bits of the PPCS channel are multiplexed by a multiplexer
201
before spreading. As shown in
FIG. 2B
, information bits of the reverse traffic channel (R-TCH) are spread after passing a convolutional encoder
213
, a symbol puncturer
214
, symbol repeaters
215
and
217
, and a serial-to-parallel (S/P) converter
216
.
The reverse traffic channel operating in a multi-signal mode is comprised of a pilot channel, a PCS channel, a reserve channel, and a plurality of reverse traffic channels. As shown in
FIG. 3A
, information bits of the pilot channel, the PCS channel, the reverse channel, and the signaling channel, which constitute the reverse traffic channel operating in the multi-signal mode, are multiplexed by a multiplexer
301
before spreading. As shown in
FIGS. 3B and 3C
, information bits of an n
th
(or m
th
) reverse traffic channel (R-TCH) are spread after passing a convolutional encoder
313
(or
323
), a symbol puncturer
314
(or
324
), symbol repeaters
315
and
317
(or
325
and
327
) and an S/P converter
316
(or
326
).
The access channel operating in a packet mode is comprised of an access pilot channel and a packet access channel. As shown in
FIG. 4A
, information bits of the access pilot channel are all 0's. As shown in
FIG. 4B
, information bits of the packet access channel (PACH) are spread after passing a convolutional encoder
407
, a block interleaver
408
and a symbol repeater
409
.
The reverse traffic channel operating in the packet mode is composed of a pilot channel, a packet signaling channel, and a reverse packet traffic channel. As shown in FIG.
5
A, information bits of the pilot channel and the packet signaling channel (PSCH) are multiplexed by a multiplexer
501
before spreading. As shown in
FIG. 5B
, information bits of the reverse packet traffic channel (R-PTCH) are spread after passing a convolutional encoder
512
, a block interleaver
513
, symbol repeaters
514
and
516
, and an S/P converter
515
.
A forward modulation channel of the base station is comprised of a pilot channel, a sync channel, a paging channel, a traffic channel, and a power control and signaling (PCS) channel. As shown in
FIG. 6A
, information bits of the pilot channel, which are all 0's, are spread with a Hadamard code H
0
(
601
) and a forward link I/Q-arm sequences R
c
(
602
), and then converted to a final transmission signal s(t) while passing through a baseband filter
603
and a carrier multiplier
604
. Furthermore, information bits of the sync channel are spread after passing a convolutional encoder
607
, a block interleaver
608
, an S/P converter
609
, and a symbol repeater
610
.
As shown in
FIG. 6B
, information bits of the paging channel are spread after passing a convolutional encoder
617
, a block interleaver
618
, an S/P converter
619
, and a symbol repeater
620
. As shown in
FIG. 6C
, information bits of the traffic channel are spread after passing a convolutional encoder
626
, a symbol puncturer
627
, a scramble code spreader
629
, an S/P converter
630
, and a symbol repeater
631
. As shown in
FIG. 6D
, information bits of the signaling channel are spread after passing a convolutional encoder
638
, a block interleaver
639
and a symbol repeater
640
. Furthermore, information bits of the power control and reserve channel are spread after passing symbol repeaters
646
and
647
. The signal on the signaling channel can be exchanged with the signal on the power control and reserve channel.
As shown in
FIG. 6E
, information bits of the forward packet traffic channel operating in the packet mode are spread after passing a convolutional encoder
646
, a block interleaver
647
, a scramble code spreader
649
, an S/P converter
650
, and a symbol repeater
651
.
Constructing a channel device for a CDMA system having various channels as illustrated in
FIGS. 1 through 6
is undesirable, especially if the channel devices are implemented in a single chip, such as an ASIC (Application Specific Integrated Circuit). The ASIC will experience decreased reliability and increased power consumption.
SUMMARY OF THE INVENTION
It is, therefore, one of the objects of the present invention to provide a variable channel device for a W-CDMA system, in which various channels share similar function blocks, and these shared function blocks are controlled by an external register.
In accordance with one aspect of the present invention, a PCS/PPCS variable channel device for a W-CDMA system comprises a frame quality indi

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