Data communication apparatus and method in multi-carrier...

Details Data communication apparatus and method in multi-carrier... Data communication apparatus and method in multi-carrier...

2000-11-13

2004-12-21

Patel, Ajit (Department: 2664)

Multiplex communications

Communication over free space

Combining or distributing information via code word channels...

C370S335000, C370S341000

Reexamination Certificate

active

06834047

ABSTRACT:

PRIORITY
This application claims priority to an application entitled “Data Communication Apparatus and Method in a Multi-Carrier CDMA Communication System” filed in the Korean Industrial Property Office on Nov. 10, 1999 and assigned Serial No. 99-49801, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a channel communication apparatus and method in a CDMA (Code Division Multiple Access) mobile communication system, and in particular, to a frequency assigning method for voice and data services and a channel transmitting and receiving apparatus and method using the same.
2. Description of the Related Art
The IS-95 CDMA communication system uses a single carrier, whereas the IMT-2000 CDMA communication system can provide multi-carrier service. The latter can provide spreading rates three times, six times, nine times, twelve times or higher than those in the former. A spreading rate based on the IS-95 standards will be referred to as “spreading rate
1
” and a spreading rate three times higher than spreading rate
1
be “spreading rate
3
”, etc.
A conventional spreading rate
1
system uses a frequency band of 1.25 MHz for voice and data services.
FIG. 1
illustrates the 1.25-MHz frequency band and a single carrier in the spreading rate
1
system. The 1.25-MHz frequency band is called a “Frequency Assignment (FA)”.
The spreading rate
1
system transmits voice, data, and control signals associated with the voice and data transmission at the same time using the single FA. This is possible because orthogonal codes provide channelization for transmission of the voice, data; and control signals. As to the orthogonal code channels, voice is transmitted on a fundamental channel (FCH), data on a supplemental channel (SCH), and a control signal on a dedicated control channel (DCCH) or a common control channel (CCCH) depending on use of the control signal. The CCCH was a main control channel and a plurality of control channels may exist in reality. As shown in
FIG. 1
, the spreading rate
1
system orthogonally spreads a plurality of orthogonal code channel signals including the FCH, SCH, DCCH, and CCCH to one FA.
FIGS. 2 and 3
are respective block diagrams of a transmitting device and a receiving device in the spreading rate
1
system. The following description is conducted on the assumption that the channel transmitting and receiving device transmits and receives FCH, SCH, DCCH, and CCCH.
Referring to
FIG. 2
, each of channel transmitters
111
,
113
,
115
, and
117
is comprised of an encoder, a symbol rate matcher, an interleaver, and an orthogonal spreader. Each orthogonal spreader generates an orthogonal code assigned to identify a corresponding channel. Thus, the channel transmitters
111
,
113
,
115
, and
117
encode input signals, spread coded signals with their respective orthogonal codes, and transmit the transmission signals on their corresponding-channels. An adder
119
sums the output signals of the channel transmitters
111
,
113
,
115
, and
117
and a complex spreader.
121
complex-spreads the summed channel signals with a PN code. A low pass filter (LPF)
123
passes the PN-spread signal in the 1.25-MHz frequency band, and a modulator
127
transmits the output signal of the LPF
123
over a carrier signal received from an oscillator
125
(frequency upconversion).
Referring to
FIG. 3
, a demodulator
152
removes a carrier signal from an input signal (frequency downconversion) and an LPF
155
passes a signal in the 1.25-MHz frequency band from the demodulated signal. A complex despreader
157
despreads the output signal of the LPF
155
with a PN code by multiplying them and feeds the despread signal to channel receivers
161
,
163
,
165
, and
167
. Each channel receiver is comprised of an orthogonal despreader, a deinterleaver, and a decoder. Each orthogonal despreader generates an orthogonal code assigned to a corresponding channel. Thus, the channel receivers
161
,
163
,
165
, and
167
despread the complex-despread signals with corresponding orthogonal codes and decode the orthogonally despread signals.
In operation, the channel transmitters
111
,
113
,
115
, and
117
subject FCH, SCH, DCCH, and CCCH signals to encoding, interleaving, and orthogonal spreading. The adder
119
sums the orthogonally spread channel signals and the LPF
123
passes only a 1.25-MHz frequency band signal from the sum signal. The modulator
127
modulates the output signal of the LPF
123
using the carrier signal of the FA received from the oscillator
125
by multiplying the signals. The radio signal is converted to a baseband signal in the demodulator
153
and the LPF
155
in the receiving device. The demodulator
153
utilizes the oscillator
151
for generating the carrier of the corresponding FA like the modulator
127
in the transmitting device shown in FIG.
2
. The baseband signal is orthogonally despread, divided into corresponding channel signals, deinterleaved, and channel-decoded in the channel receivers
161
,
163
,
165
, and
167
.
On the other hand, the spreading rate
3
system uses three FAs for voice and data services. That is, FCH, SCH, DCCH, and CCCH transmitters spread channel signals to three separate 1.25-MHz FAs in a multi-carrier scheme. This three FA structure for the spreading rate
3
system is illustrated in FIG.
4
.
One third of each of the FCH, SCH, DCCH, and CCCH is present in each one FA in FIG.
4
.
FIGS. 5 and 6
are respective block diagrams of a transmitting device and a receiving device in the spreading rate
3
system.
Referring to
FIG. 5
, each of channel encoders
211
,
213
,
215
, and
217
is comprised of an encoder, a symbol rate matcher, and an interleaver, for encoding corresponding input channel signals. Demultiplexers (DEMUXs)
221
,
223
,
225
, and
227
dermultiplex the outputs of their corresponding channel encoders
211
,
213
,
215
, and
217
and distribute the demultiplexed signals to the three FAs. Since the spreading rate
3
system uses three FAs, each of the DEMUXs
221
,
223
,
225
, and
227
demultiplexes its corresponding channel encoder output into three signals. Four orthogonal-spreaders (
231
,
233
,
235
,
237
;
241
,
243
,
245
,
247
,
249
; and
251
,
253
,
255
,
257
,
259
) are provided for each FA to identify four channels transmitted from four channel transmitters within the FA. Therefore, a total of
12
orthogonal spreaders are required for the three FAs. One complex spreader is needed for each FA and thus three complex spreaders
261
,
263
, and
265
are provided for the three FAs. LPFs
271
,
273
, and
275
low-pass filter the output signals of the complex spreaders
261
,
263
, and
265
. Modulators
282
,
294
, and
286
are provided with oscillators
281
,
283
, and
285
for generating carrier frequency signals in the FAs and generate multi-carrier transmit signals.
Referring to
FIG. 6
, the receiving device is so configured that a receiving operation is performed in the reverse order of the transmitting operation in the transmitting device shown in FIG.
5
. Demodulators
312
,
314
, and
317
demodulate the signals of corresponding FAs from an input multi-carrier signal using carrier frequencies related with the corresponding FAs generated from oscillators
311
,
313
, and
315
. LPFs
321
,
323
, and
325
output baseband signals in the corresponding FAs. Complex despreaders
331
,
333
, and
335
and orthogonal despreaders (
341
,
343
,
345
,
347
;
351
,
353
,
355
,
357
; and
361
,
363
,
365
,
367
) subject the baseband signals to complex depreading and orthogonal despreading. MUXs
371
,
373
,
375
, and
377
each selectively receive a portion of the orthogonally despread signals and multiplex them. For example, the MUX
371
receives FCH signals from among the three-FA orthogonal despread signals, multiplexes them, and feeds the multiplexed signal to an FCH decoder
381
.
Referring to
FIGS. 5 and 6
, in operation, FCH, SC

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