JPH08167866A - Signal processor of spread spectrum communication system - Google Patents

Abstract

PURPOSE: To increase the system capacity and/or to improve the signal quality by configuring a signal with a plurality of segments having significance of different levels and providing high immunity to an error to the more significant portions of signal. CONSTITUTION: A UEP(unequal error protection)-DS-CDMA(direct sequence code division multiple access) transmitter 108 uses an input voice data interface 1000 to separate a signal into a 1st data stream including the more significant portions and a 2nd data stream including the less significant portions. Then 1st and 2nd channel coders 1002, 1004 coded 1st and 2nd data streams. Then the amplitude of the signal is adjusted so that power used to transmit the more significant signal portions is higher than the power to transmit the less significant signal portions by a variable power modulator 1014.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to spread spectrum (S
The present invention relates to communication of signals using the S) method, and more particularly to a technique for improving capacity and / or transmission quality of a spread spectrum system.

[0002]

2. Description of the Prior Art Spread spectrum multiple access (SSM
A) technology is of widespread interest in the field of personal communications, such as digital cellular radio. SS
In MA systems, the time and frequency domains can be assigned to multiple users at the same time. This simultaneous time and frequency domain allocation is a time division multiple access (TDMA) system and frequency division multiple access (FDM) that provides a unique time slot or frequency band for each user.
A) It should be distinguished from the system.

Direct spreading / code division multiple access (DS-CD
In SSMA systems, such as (MA) cellular systems, a base station can simultaneously transmit different information signals to individual users using a single frequency band. The individual information signals transmitted simultaneously in one frequency band can be identified and separated by each receiving user. This is because the base station uses a unique spreading sequence in transmitting each information signal. Prior to transmission, each information signal is multiplied by the spreading sequence signal assigned to the user who intends to receive the signal. This product is a "spreader" that spreads the spectrum of the information signal over a wide frequency band assigned to all users.
It is performed by

In order to recover the correct signal from the signals transmitted simultaneously in this wide frequency band, the receiving mobile user combines the received signal (including all of the transmitted signal) and its own unique spreading sequence signal. Multiply and integrate the result. This procedure is performed by a "despreader". By doing so, the user despreads the received signal. The signal destined for that user is identified because it is different from the other signals destined for another user.

Recently, The Telecommunications Institute
of America (TIA) has adopted the SSMA standard by the DS-CDMA system. This is the TIA, "Mobile Station-Base Station Compa" announced as IS-95.
tibility Standard for Dual-Mode Wideband Spread-Sp
ectrum Cellular System, 1993 ".

[0006]

However, the spread spectrum system as described in the IS-95 standard has the following problems.
There is a drawback that certain signals cannot be processed efficiently. This inefficient processing will reduce system capacity and / or signal quality. It is an object of the present invention to provide spread spectrum communication technology that makes it possible to increase system capacity and / or improve signal quality.

[0007]

To achieve the above objectives, the present invention employs unequal error protection (UEP) in a spread spectrum system. In one embodiment of the invention, the signal to be communicated by the spread spectrum multiple access system consists of at least two parts with different levels of significance. For example, this different level of significance reflects a different level of sensitivity to signal error. The first part represents information that is relatively insensitive to signal errors that occur during transmission, and the second part represents information that is relatively insensitive to such signal errors. Because of this difference in relative error sensitivity,
These parts are handled with different error protection processes. This different error protection process gives these parts a large error protection and a small error protection respectively.

One embodiment of the present invention adapts the likelihood of error protection to the signal error sensitivity, unlike conventional spread spectrum systems that use error protection such as the IS-95 standard, thus reducing the available channel bandwidth. The width can be used efficiently. For example, the IS-95 standard employs an error protection process suitable for the most error sensitive parts of the signal. Therefore, the IS-95 standard provides some parts of the signal with a degree of error protection that is greater than that required for that part. This excessive degree of error protection (this is
Called coding ") wastes channel bandwidth.

The present invention, on the other hand, uses the channel bandwidth more efficiently due to the approach adapted to error protection. For a given channel bandwidth, the present invention provides greater system capacity. For a given channel bandwidth and a given number of users, the invention provides an improvement in the quality of the signals communicated. Therefore, embodiments of the present invention can provide both increased system capacity and improved signal quality.

An example of a signal exhibiting at least two parts with relatively different levels of significance is a compressed audio signal. As is known in the audio compression art, a compressed audio signal comprises a sequence of frames. Each frame typically represents 20-30 ms of uncompressed speech. A frame of compressed audio contains a set of bit fields. Each bit field represents the parameters needed to decompress the audio from the compressed frame. For example, these bit fields represent parameters such as linear prediction coefficient, pitch, codebook indication, codebook gain. In the present invention, these bit fields are the descriptive part of the compressed audio signal with different levels of significance.

Another example of a signal containing parts with relatively different levels of significance is a signal representing different types of information, such as audio information and numerical information. In this case, the voice part and the numerical part have different levels of significance. Therefore, the present invention can be applied to signals for improving the capacity and / or quality of SS systems.

Those skilled in the art will appreciate that they are applicable to a variety of SS signals and systems. For example, the invention can be applied to provide the possibility of adapted error protection, in which the signal to be communicated comprises two or more parts with different sensitivity to errors. Here, for example, the signal is the first, which is relatively sensitive to signal errors.
Part, a second part relatively moderately sensitive to signal errors, and a third part relatively insensitive to signal errors.

The illustrated embodiment of the invention is a DS-CDM.
The present invention relates to a frequency hopping (FH) system, a time hopping (TH) system,
It is also applicable to systems using other SS communication technologies, including chirp systems, single user versions of the other multiple access systems described above. Also, the illustrated embodiment is I
Although related to wireless communication channels according to the S-95 standard, the present invention is directed to SSMA with other types of channels such as fiber optic channels, cable transmission channels, infrared wireless channels, optical free space channels.
It can also be applied to systems.

[0014]

EXAMPLES Examples of the present invention will now be described with reference to wireless UEP / DS.
Describe the CDMA phone application environment. Note that only one base station is shown for the sake of simplicity. However, those skilled in the art will appreciate that the present invention can be used with various types
It will be appreciated that it can be used in a system, various types of applications and / or various types of channels.

Embodiments of the present invention are shown for the communication of compressed audio signals. As is well known in the audio compression art, a compressed audio signal consists of a sequence of frames. Here, typically, each frame is
Represents 20-30 ms uncompressed speech. A frame of compressed audio consists of a set of bit fields. Each bit field represents the parameters needed to decompress the audio from the compressed frame. For example, these bit fields represent parameters such as linear prediction coefficient, pitch, codebook indication, codebook gain, and so on.

Applicant's Applicant's US Patent Application SN08
/179831,B.kleijn,"Method and Apparatus for Prototyp
e Waveform Speech Coding ". In this example, these bit fields are the descriptive part of the compressed speech signal and have different levels of significance. The bit field representing the pitch is It is a more significant part than the other bit fields of the frame.Packing and unpacking of bit fields in the coding of speech is a conventional technique. It does not describe field packing and unpacking.

Further, in the embodiment, "processor"
The description will be made assuming that it is composed of individual functional blocks including functional blocks named as follows. The functions represented by these blocks may be provided by shared or dedicated hardware. The hardware includes, but is not limited to, one capable of executing software. Here, "processor" should not be construed as limited to hardware capable of executing software.

This embodiment is based on a digital signal processor (D) such as AT & T DSP16 or DSP32C.
SP), a read-only memory (ROM) for storing software for executing the operations described below, and a random access memory (R) for storing operation results of the DSP.
AM). Very large scale integration (VLSI) hardware or a combination of custom VLSI circuits and general purpose DSP circuits can also be used.

FIG. 1 shows a system capable of performing UEP-DS-CDMA coding. This system includes a base station 100 and a public switched telephone network 102 (PSTN10).
2), a plurality of mobile units 104a and 104b,
It includes a plurality of stationary units 106a and 106b and the like.

The base station 100 uses UEP-DS-CDMA.
A transmitter 108, a UEP-DS-CDMA receiver 110,
And an antenna 112. Mobile unit 104a
Are UEP-DS-CDMA transmitters 108a, UEP-
DS-CDMA receiver 110a and antenna 114
including. Mobile unit 104b is UEP-DS-C
It includes a DMA transmitter 108b, a UEP-DS-CDMA receiver 110b, and an antenna 116. For example, mobile units 104a and 104b may include base station 100,
A link 118 between the base station 100 and the PSTN 102,
And the stationary unit 106a via the PSTN 102
And 106b.

In FIG. 1, if a first person in mobile unit 104a desires to talk to a second person at the location of stationary unit 106a, the first person makes a call.
The UEP-DS-CDMA transmitter 108a encodes and transmits a signal representing the first person's voice. The UEP-DS-CDMA receiver 110 of the base station 100 receives and decodes the signal representing the first person's voice. Then UE
The P-DS-CDMA receiver 110 sends the decoded speech to the stationary unit 106a. A voice signal from the second person to the first person is also sent via the PSTN 102 and the base station 100. Therefore, the first person and the second
Can communicate with other people.

Although shown only one type of communication, there are many other communication methods in which the present invention can be used. For example, the mobile unit 104a may be replaced by another mobile unit 104b.
You may wish to communicate with. For example, if the mobile units are far apart, more than one base station is needed. Further, the present invention can be used to send / receive satellite based communications. In addition, the present invention can be used in a system in which information other than a signal representing voice is transmitted / received. For example, a system that can send / receive data for other audio signals, video signals, audio-video signals, and other types of signals. Next, UEP-DS-for voice communication
How UEP is applied in a CDMA system is described.

FIG. 2 shows a UEP-DS-CDMA transmitter 1
08 is shown. The UEP-DS-CDMA transmitter 108
It includes a pre-processor 200, a UEP processor 202 and a post-processor 204.

The UEP-DS-CDMA transmitter 10 of FIG.
8 can be configured in various ways. For example, the UEP of FIG.
-DS-CDMA transmitter 108 has variable time (VT) U
It can also be configured using the EP method, the variable code (VC) UEP method, or the variable power (VP) UEP method. The UEP-DS-CDMA transmitter 108 of FIG. 2 can also be configured using a combination of these three methods. However, what these methods have in common is that they all provide a first error protection process to the set of relatively significant portions of the signal and a second error to the set of relatively insignificant portions of the signal. To provide a protection process. Unequal error protection, or UEP, is achieved in DS-CDMA coding because the first error protection provides a greater amount of error protection than the second error protection.

After describing the VT method that can be used within the framework of the UEP-DS-CDMA transmitter 108 shown in FIG. 2, the corresponding UEP-DS-CDMA using the VT method is described.
The receiver will be described. Finally, a combination of the VT, VP and VC methods will be briefly described.

1. UEP-DS-CDMA transmitter: VT
UEP Method and Device FIG. 3 shows a UEP-DS-CD that can be used in the VT method.
Details of the MA transmitter 108 are shown. Hereinafter, the pre-processor 200, the UEP processor 202, and the post processor 204 will be described in this order.

The pre-processor 200 includes an input voice data interface 300 and a first channel decoder 30.
2 and a second channel decoder 304. The input audio data interface 300 can use any one of many audio compression techniques. The input voice data interface 300 inputs voice data.
The input audio data interface 300 separates audio data into two data streams with non-uniform significance. For a heterogeneous significance association for UEP,
It will be described later. The first data stream (eg, a relatively significant data stream) is the first channel decoder 3
02, a second data stream (eg, a relatively insignificant data stream) is input to the second channel decoder 304.

The first channel decoder 302 and the second
Channel decoder 304 of each essentially serves to provide redundancy to the first data stream 306 and the second data stream 308, respectively, the first channel encoded data stream 310 and the second channel encoding. A data stream 312 that has been processed. First channel encoded data stream 310 and second channel encoded data stream 312
Are input to the UEP processor 202.

The UEP processor 202 inputs a first channel encoded data stream 310 and a second channel encoded data stream 312,
The first variable time modulator 313 and the second variable time modulator 315 are used. Variable time modulators 313 and 31
5 is the encoded data stream 3 of the first channel
A first time modulated signal 314 and a second time modulated signal 316 are generated from the 10 and second channel encoded data streams 312, respectively. The first time modulated signal 314 and the second time modulated signal 316 are further processed by post processor 204.

The post-processor 204 inputs the first time-modulated signal 314 and the second time-modulated signal 316 and outputs an RF signal representing the audio data input by the input audio data interface 300. Post processor 204 includes multiplexer 318, interleaver 320, spreader 322, modulator 324, radio frequency (RF) transmitter 32 connected together as shown.
6 and an antenna 328.

Multiplexer 318 functions to combine first time modulated signal 314 and second time modulated signal 316. The combined signal is interleaved by interleaver 320. Multiplexer 3
18, spreader 322, modulator 324, RF transmitter 3
The processing performed in 26 is a typical D known to those skilled in the art.
This is a process of the S-CDMA system. For example, the spreader 322 inputs the spreading sequence 323. The processing performed in the interleaver 320 will be described later.

In FIG. 3, an input audio data interface 300 provides a signal, eg audio data, to a first data stream 306 and a second data stream 308.
To separate. The first data stream 306 includes a relatively significant portion of at least one audio data and a second data stream 306
Data stream 308 includes at least one relatively insignificant portion of audio data. This at least 1
The two relatively significant parts are also referred to as the first segment. At least one relatively insignificant portion is also referred to as the second segment.

The input voice data interface 300 is
This separation is performed based on the significance of the time part of the audio data. For example, a first segment of a signal is said to be more significant than a second segment of the signal if the first segment is relatively sensitive to transmission errors. The first segment and the second segment can be either digital or analog. Thus, for example, the first data stream 306 is the second data stream 308.
It may include information bits that are considered more significant than. In this case, the first segment and the second segment may be referred to as a set of relatively significant bits and a set of relatively insignificant bits, respectively.

4a-4f and 4h show that the signals are variable time modulators 313 and 3 by the encoder shown in FIG.
It shows how it is processed via 15. 4a and 4b each show a first data stream 306 and a second data stream 308 that are two bits long. The first channel coder 302 and the second channel coder 304 are each rate 1/2 coders.

Therefore, when processed by the first channel coder 302 and the second channel coder 304, the number of bits of the first data stream 306 and the second data stream 308 is determined by the first channel coder 302.
And at the output of the second channel coder 304 (see FIGS. 4c, 4d). First channel coder 3
02 and the second channel coder 304 have the same rate, but two separate channel coders are used in order to make a clear distinction between relatively significant and relatively insignificant portions. . To maintain this distinction,
Two channel decoders are used at receiver 110.

In the time domain (FIGS. 4a, 4b), the first data stream 306 and the second data stream are each 8 basic time units long.
The “fundamental time unit” is the longest such that the stretched bits representing the first segment (see FIG. 4e) and the compressed bits representing the second segment (see FIG. 4f) are integer products of T0. The time interval is T0. Therefore, if the UEP is not used, the information shown in Figures 4a and 4b shows that 16 basic time units of bits are 8 relatively important basic time units of bits and 8 basic bits of bits.
For four relatively unimportant base time units, there will be a total of 16 base time unit lengths.

More generally, a first data stream 306 containing a set of relatively significant bits is represented in a first time portion 350 (eg, 8 basic time units). A second data stream 308 that includes a set of relatively insignificant bits is represented in a second time portion 352 (eg, 8 basic time units). At least one of these time portions 350 and / or 35
2 is time modulated.

When processed by the first channel coder 302 and the second channel coder 304, the set of relatively significant bits is time modulated to increase (eg, stretch) the first time portion, The set of relatively insignificant bits is time modulated to reduce (eg, compress) the first time portion. The result of the time modulation is called modulation frame 354 (Fig. 4h). The modulation frame 354 is shown as being generated from a 4-bit frame (see FIGS. 4a and 4b) for simplicity, but typically:
One of ordinary skill in the art will appreciate that a frame contains significantly more than four bits.

4c and 4d, a first channel encoded data stream 310 and a second channel encoded data stream 312 are shown, respectively. In this example, a first channel coder 302 and a second channel coder 304 input a first data stream 306 and a second data stream 308, respectively, with two bits to represent each information bit therein. use. Therefore, both FIGS. 4c and 4d are shown to have 4 bits each.

If twice as many bits as the first and second data streams 306 and 308 occur in the first channel encoded data stream 310 and the second channel encoded data stream 312, the The first and second channel coders 302 and 304 are
Called "rate 1/2 coder". Another example is where the encoded data streams of the first and second channels have three times as many bits as the first and second data streams. In this example, the first and second channel coders are "rate 1/3 coders".

The effect of time modulation is shown in FIGS. 4e-4h. 4e and 4f show a first time modulated signal 314 and a second time modulated signal 316, respectively. The first and second time modulated signals 314, 316 are
Although representing two original bits (see FIGS. 4a and 4b), the first time-modulated signal 314 and the second time-modulated signal 316 each have 12 bases instead of being shown in FIG. 4g with 8 time bits each. It is shown in Figure 4h as a time unit length and 4 basic time unit lengths.

If no time modulation were performed, the input to spreader 322 would be similar to that of FIG. 4g,
First channel encoded data stream 310 and second channel encoded data stream 31
Two are combined. In this case, in fact, only one channel coder is needed instead of two, and the multiplexer 31
No need for 8. Further, even though the bits of Figure 4a are more significant than the bits of Figure 4b (which the channel coder does not know), the two bits shown in Figure 4a were applied to them before they were input to the spreader 322. Will have a basic time unit. Also, the 2 bits shown in FIG. 4b will also have 8 basic time units assigned to them before they are input to the spreader 322.

However, when time-modulated, it has the effect of stretching the relatively significant bits and compressing the relatively insignificant bits, as determined by the input voice data interface 300. Time modulators 313, 3
15 can be configured in software according to the normal time-index scaling procedure. For example, the number of basic time units used to represent relatively significant bits is greater than the number of basic time units to represent relatively insignificant bits.

Those skilled in the art will appreciate that the signal processing shown in FIG. 4 is merely an example, and the following is possible. (A) Using a single channel decoder time-allocated between relatively significant bits and relatively insignificant bits. (B) do not use a channel decoder when relatively significant bits and relatively insignificant bits are input directly to the first variable time modulator 313 and the second variable time modulator 315, for example. thing. ;

(C) A level of significance greater than 2. For example, first, second and third levels of significance. Note that each level has a different amount of error protection. (D) The first channel coder 302 has a predetermined rate and the second channel coder 304 has the same rate. However, each channel coder does not necessarily have to be a rate 1/2 coder. (E) Consider any percentage of bits as "relatively significant", which is 50% in FIG. 4, but depending on the application and the capabilities of the interface 300. ;

(F) Stretching the relatively significant bits while leaving the relatively insignificant bits unchanged, or compressing the relatively insignificant bits while leaving the relatively significant bits unchanged. And / or (g) A combination of the above, such as (e) and (f), which are not inconsistent.

Preferably, the symbol length of interleaver 320 is a basic time unit, and interleaver 320
Operates with each basic time unit shown in FIG. 4h. However, one of ordinary skill in the art will appreciate that the symbol lengths of the symbols on which interleaver 320 operates may be:

(A) Chip. A chip is defined here as the time associated with one symbol unit of a direct spreading sequence. The interleaving process performed by interleaver 320 is performed subsequent to the spreading function of spreader 322. (B) An integral multiple of the chip or the basic time unit. And / or (c) a non-integer multiple of a chip or basic time unit.

The interleaver 320 also includes a variable symbol of the individual stretched and compressed bits represented by FIGS. 4e and 4f, regardless of whether the stretched and compressed bits have a common base time unit. The input signals can be interleaved while maintaining the time length. Although interleaving may not be needed if the channel coder is not used, interleaving to the basic time unit is
Provides extra protection against fading.

The output of the interleaver 320 is input to the spreader 322. The spreader 322 is a DS-CD
Typical spreader for MA applications, KSGilhousen, IMJacobs, R.Padovani, AJViterb
i, LAWeaver, Jr., and CEWheatley III, "On the Capa
city of a Cellular CDMA System, "IEEETransactions
of Vehicular Technology, Vol.40, No.2, 303-312 (May,
1991) (hereinafter referred to as "Gilhousen et al." Paper). The modulator 324, RF transmitter 326, and antenna 328 are also "Gilhousen et a.
l. "is a typical element as described in the paper.

Preferably, the Walsh function ("Gilhousen
In the case of quadrature transmission using E. et al. (see paper), for example, a Walsh modulator based on the fundamental time unit T0 is an interleaver 320 of the UEP DS-CDMA transmitter.
And the spreader 322. Also, the first channel coder 302 and the second channel coder 30
4 may be a spiral coder or a block coder.

The interleaver 320 may be a spiral interleaver or a block interleaver. The reference timing signal is provided within the transmitter (eg, 108) of FIG. 1 for the unit concerned. The quadrature transmission and the reference timing signal are VCs described in detail in Sections 3 and 5 of the detailed description of the invention, respectively.
It can be used with transmitters and VP transmitters.

2. UEP-DS-CDMA receiver: VT
UEP Method and Apparatus In Figures 5A and 5B, a UEP-DS-CDMA receiver 110 is shown. UEP-DS-CDMA receiver 110 consists of pre-processor 500, UEP processor 502, and post-processor 504. Pre-processor 500, UEP processor 502, and post-processor 504 are described in order with reference to FIG. 5B, which shows a receiver that can be used with the transmitter of FIG.

In FIG. 5B, the pre-processor 500
Consists of an antenna 506, an RF receiver 508, and a demodulator 510 connected as shown. Demodulator 510
Is output to the UEP processor 502.

The UEP processor 502 comprises a despreader 512 and a deinterleaver 51 connected as shown.
4, demultiplexer 516, first accumulator 5
18 and a second accumulator 520. Those skilled in the art are well aware of how to achieve the normal synchronization and timing associated with DS-CDMA systems. See the "Gilhousen et al." Paper.
These synchronizations and timings have already been provided in the pre-processor 500 and the UEP processor 50
2 receives a properly timed and synchronized signal (timed signal).

Despreader 512 receives signal 528 and outputs despread signal 530. Despreader 512 performs this function by associating signal 528 with spreading sequence 532 for each elementary time unit. The despread signal 530 represents an analog value that, when properly combined, forms a series of soft decision values. Next, a method of combining these analog values will be described.

Deinterleaver 514 receives despread signal 530 and deinterleaves signal 534.
Is output. Accordingly, deinterleaver 514 functions to perform the inverse of the operations performed by interleaver 320 of transmitter 108. The order of the basic time units of the signal input to the interleaver 320 is restored. However, in general, the amplitude of the signal in receiver 110 is
It is analog and the deinterleaver 514 is "soft"
Deinterleaver operation is performed.

A demultiplexer 516 receives the deinterleaved signal 534 and a first set of time domain portions corresponding to the relatively significant bit set and a second set corresponding to the relatively insignificant bit set. Output the time domain part of. The first and second sets of time domain portions consist of analog values represented by despread signal 530.

The first accumulator 518 receives the first set of time domain portions. First accumulator 51
8 operates based on the analog value associated with each elementary time unit for each stretched bit.
For example, in FIG. 4e, each stretched bit has 3
Since it occupies a basic time unit, there are three analog values for each stretched bit. These analog values are added together to provide a soft decision value for each stretched bit. When this is done for all stretched bits, it results in a series of soft decision values representing the first set of time domain portions.

The second accumulator 520 receives the second set of time domain portions. Second accumulator 52
0 operates based on the analog value associated with each basic time unit for each compressed bit. For example, in FIG. 4f, there is one analog value for each compressed bit because each compressed bit occupies one basic time unit. Generally, the analog values are added together as described for FIG. 4e, but in the special case where there is only one analog value per compressed bit as shown in FIG. 4f, the addition is not necessary. This will be the soft decision value for each compressed bit.
When this is done for all compressed bits, it results in a series of soft decision values representing the second set of time domain portions.

Post processor 504 includes a first channel decoder 522, a second channel decoder 524,
And an output voice data interface 526.
Preferably, the first channel decoder 522 and the second channel decoder 522
The channel decoder 524 of is a Viterbi decoder like other channel decoders. Also preferably these decoders, eg 522, are the memories 6, 7,
Or 8 coder.

The first channel decoder 522 decodes the soft decision values representing the first set of time domain portions to restore the representation of the first data stream 306. The second channel decoder 524 decodes the soft decision values representing the second set of time domain portions and restores the representation of the second data stream 308. A representation of the first data stream 306 and the second data stream 308 is output audio data interface 526.
Is input to

Those skilled in the art will appreciate that, depending on the variations made in transmitter 108 (discussed in Section 1), variations must also be made in receiver 110. For example, if the channel coder is not used, then the channel decoder is also gone. A decision will be made for each symbol. Also, for example, if one channel coder is used, then one channel decoder can be used that changes the symbol timing from the first time portion to the second time portion.

3. UEP-DS-CDMA transmitter: VC
UEP Method and Equipment FIG. 6 shows a UEP-DS-C that can be used with the VC method.
DMA transmitter 108 is shown. Referring to FIG.
Pre-processor 200, UEP processor 202, and post-processor 204 will be described in sequence.

In FIG. 6, the pre-processor 200
Includes an input voice data interface 600. The interface 600 converts the encoded audio data into a first
Data stream 606 and a second data stream 608. For example, first data stream 606 and second data stream 608 can be represented by a series of bits.

The UEP processor 202 comprises a first channel coder 602 and a second channel coder 604. The first data stream 606 is input to the first channel coder 602 and the second data stream 6
08 is input to the second channel coder 604. First channel coder 602 and second channel coder 604 operate to form a first channel encoded data stream 610 and a second channel encoded data stream 612, respectively.

In the preferred VC method embodiment, first channel coder 602 and second channel coder 60 are provided.
4 is a coder with a different rate. This is because each bit in the first channel encoded data stream 610 is represented in the first time portion and each bit in the second channel encoded data stream 612 is in the second time portion. Ensure that it is represented in the part. Each bit in the first channel coded data stream 610 and the second channel coded data stream 612 is of the same length. Each bit is also equal to the length of the basic time unit T0. Accordingly, the first channel encoded data stream 610 and the second channel encoded data stream 612 are the first data stream 606 and the second data stream 6.
It is represented by the same number of basic time units as 08.

The above example shows the first encoded signal 60.
Using half of the bits in 6 (eg, the set of relatively significant bits), the second encoded signal 608 (eg,
Half of the bits (relatively insignificant bit set) are used. A regular rate 1/4 coder is used to generate the first channel encoded data stream 610 and a regular rate 1/2 coder is used to generate the second channel encoded data stream 612. Used for. Therefore, the entire signal (consisting of the first data stream 606 and the second data stream 608)
The average rate for is 1/3.

The post-processor 204 inputs a first channel encoded data stream 610 and a second channel encoded data stream 612 and represents an RF representing audio data input by the input audio data interface 600. Output a signal. Post processor 204 includes multiplexer 614, interleaver 616, spreader 61 connected as shown.
8, modulator 620, RF transmitter 622, and antenna 624.

The multiplexer 614 functions to combine the first channel encoded data stream 610 and the second channel encoded data stream 612. The combined signal is interleaved by interleaver 616 and spread by spreader 618. The spread signal is modulated and modulator 62
0, RF transmitter 622, and antenna 624 for conventional transmission.

7a-4d show a first data stream 606, a second data stream 608, a first channel encoded data stream 610, and a second channel encoded data stream 612.
In this example, the first channel coder 602 is a rate 1/4 coder and the second channel coder 604
Is a rate 1/2 coder. The outputs of these coders are shown in Figures 7c and 7d, respectively. Note that the overall duration of the signals in Figures 7c and 7d is equal to the overall duration of the signals in Figures 7a and 7b. Therefore, a VC UEP system such as the VT UEP system described above may also be used in DS-CDMA.
Achieve UEP in the environment. In particular, this example achieves "stretching" and "compressing" bits in a different way than the VT system described above.

The signal processing shown in FIG. 7 is merely exemplary. First channel coder 6 having the same code rate but different error correction capabilities (eg complexity)
02 and the second channel coder 604 may perform UEP. Those skilled in the art will also recognize that the following is possible. (A) A level of significance greater than 2. For example, first, second and third levels of significance. Note that each level has a different amount of error protection. (B) having a first channel coder 602 and a second channel coder 604 that are a combination of suitable coders with different rates. Each is not necessarily rate 1
It does not have to be a / 4 coder and a rate 1/2 coder. ;

(C) Consider 50% in FIG. 7, but any percentage of bits as "relatively significant" depending on the application and the capabilities of the interface 600. (D) stretching relatively significant bits (eg, by the rate of the first channel coder) without changing relatively insignificant bits, or relatively insignificant without changing relatively significant bits. Bit (eg, second
Compression (depending on the channel coder rate). And / or (e) A combination of the above, such as (c) and (d), which are not inconsistent.

Preferably, the symbol length of interleaver 616 is a basic time unit, and interleaver 616
Operates with each basic time unit of the signal shown in FIG. However, those skilled in the art will appreciate that the symbol length of the symbols on which interleaver 616 operates may be: (A) Chip. Here, the interleaving process performed by the interleaver 616 is based on the spreader 61.
8 spreading function is performed subsequently. And / or (b) an integral multiple of chips or basic time units.

The output of interleaver 616 is input to spreader 618. Spreader 618 is a "Gilhousen
Modulator 62 is a typical spreader for DS-CDMA applications described in the et al.
0, RF transmitter 622, and antenna 624 are also "Gilho
It is a typical element as described in the "usen et al." paper.

Preferably, the first channel coder 602
And the second channel coder 604 is according to J. Hagenauer, N.
Seshadri, and CE.W.Sundberg, "The performance of ra
tecompatible punctured convolutional codes for dig
ital mobil radio, "IEEE Transactions on Communicati
ons, 38 (7), 966-980 (July, 1990). A coder based on a rate compatible perforated spiral (RCPC) code. In this case, the corresponding decoder also
It is based on the RCPC code.

4. UEP-DS-CDMA receiver: VC
UEP Method and Apparatus In FIG. 8, a UEP-DS-CDMA receiver 110 is shown. UEP-DS-CDMA receiver 110 consists of pre-processor 800, UEP processor 802, and post-processor 804.

In FIG. 9, the pre-processor 800
Consists of an antenna 900, an RF receiver 902, a demodulator 904, a despreader 906, a deinterleaver 908, and a demultiplexer 910 connected as shown. The output of the demultiplexer 910 is input to the UEP processor 802. These are the demultiplexers 9
With the exception of 10, it is conventional in DS-CDMA coding techniques, as shown in the "Gilhousen et al." Paper. In the example above, the demultiplexer 910
Operates to separate a set of relatively significant time portions of the deinterleaved signal from a set of relatively insignificant time portions of the deinterleaved signal. The result is an analog value that forms a series of soft decision values input to the UEP processor 802.

The UEP processor 802 has a first channel decoder 912 and a second channel decoder 914.
Consists of These decoders 912, 914 each include a set of soft decision values associated with a set of relatively significant portions of the deinterleaved signal and a set of soft decision values associated with a set of relatively insignificant portions of the deinterleaved signal. Receives the soft decision value of. Preferably, this series of soft decision values is Viterb.
It is processed by the i decoder.

Post processor 804 comprises an output voice data interface 916. The output audio data interface 916 includes a first channel decoder 912.
And receives an input from the second channel decoder 914 and outputs a signal representative of audio.

Those skilled in the art will recognize that, depending on the variations made in transmitter 108 (described in Section 3), variations must also be made in receiver 110.

5. UEP-DS-CDMA transmitter: VP
The UEP method and the device VP transmission method can be implemented in at least two basic embodiments. The first embodiment is shown in FIG. 10 and the second embodiment is described as a variation thereof.

In FIG. 10, input voice data interface 1000, first channel coder 1002, second channel coder 1004, multiplexer 1006, interleaver 1008, spreader 1010, modulator 1012, variable power connected as shown. Modulator 10
14, an RF transmitter 1016, and an antenna 1018. Essentially, the first channel coder 1002, the second channel coder 1004, and the multiplexer 1
006 helps the signal from interface 1000 to receive the UEP provided by variable power modulator 1014.

The variable power modulator 1014 has a standard D signal.
When processed using S-CDMA technology, each part inputs a signal transmitted with the same amount of power. However, the variable power modulator 1014 may adjust the signal such that the power used to transmit the relatively significant portion of the signal is greater than the power used to transmit the relatively insignificant portion of the signal. Adjust the amplitude level of the relatively significant portion of the signal (eg, providing amplitude modulation) with respect to the amplitude level of the relatively insignificant portion of

Preferably, the average transmit power of the signal is conserved and the power required to transmit the signal is UE
It is equal to the average power required without P. This is preferable because the average co-channel interference associated with the average transmit power of the interfering users remains the same. The required power control operates at the average transmit power for VP technology.

Having described the preferred form of the VP apparatus and technique, one of ordinary skill in the art will recognize that the following variations are possible. (A) Instead of the variable power modulator 1014, a first variable power modulator inserted between the first channel coder 1002 and the multiplexer 1006, and between the second channel coder 1004 and the multiplexer 1006. Use the inserted second variable power modulator. (B) Instead of the first channel coder 1002, the second channel coder 1004 and the multiplexer 1006, only one channel coder is used. ;

(C) First channel coder 1002, second channel coder 1004 and multiplexer 10
No channel coder is used instead of 06. And / or (d) A combination of compatible ones, such as (a) and (b).

6. UEP-DS-CDMA receiver: VP
UEP Method and Apparatus In FIG. 11, the VP receiver is an antenna 1100, an RF receiver 1102, a demodulator 11 connected as shown.
04, despreader 1106, deinterleaver 110
8, a demultiplexer 1110, a first channel decoder 1112, a second channel decoder 1114, and an output audio data interface 916.

Since there is no transmission deterioration, the demodulator 1104
Inputs a signal whose first and second segments have high and low power levels, respectively. This is due to the method of transmitting the signal from the transmitter 108 described in Section 5. UEP is the result of the variable power introduced by the variable power modulator 1014 of transmitter 108.

Demultiplexer 1110, first channel decoder 1112, and second channel decoder 1
The operation of 114 provides a clear distinction between relatively significant bits and relatively insignificant bits. This should be understood by those skilled in the art. Those skilled in the art will also recognize that variations must be made in the receiver 110, depending on the variations made in the transmitter 108 (described in Section 5).

7. UEP-DS-CDMA: VT method, V
A number of examples of achieving UEP in a combined C- and VP-method DS-CDMA system have been described. These examples include VT,
Includes VC and VP modulation / demodulation methods. Those skilled in the art will also understand that these techniques can be combined in a single system to achieve UEP in a DS-CDMA system. For example, the VP and VT methods can be combined in a single system. Also, the VP and VC methods can be combined in a single system. It is also possible to combine the VC and VT methods in a single system. It is also possible to combine the VP method, the VC method and the VT method.

[0092]

As described above, according to the present invention, it is an object of the present invention to provide a spread spectrum communication technique capable of increasing system capacity and / or improving signal quality.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating an example configuration of a system in which a UEP DS-CDMA coding process is executed.

FIG. 2 is a UEP DS-C according to the first embodiment of the present invention.
The block diagram which shows the structure of a DMA encoder.

FIG. 3 is a block diagram showing a detailed configuration of the UEP DS-CDMA encoder shown in FIG.

FIG. 4 shows a comparison with a CDMA encoder without UEP,
4 is a timing diagram showing signal processing by the UEP DS-CDMA encoder shown in FIG. 3. FIG.

FIG. 5A is a UEP DS- according to the first embodiment of the present invention.
FIG. 3 is a block diagram showing the configuration of a CDMA decoder.

5B is a block diagram illustrating a detailed configuration of the UEP DS-CDMA decoder shown in FIG. 5A.

FIG. 6 is a UEP DS-C according to a second embodiment of the present invention.
The block diagram which shows the structure of a DMA encoder.

7 is a timing diagram illustrating signal processing by the UEP DS-CDMA encoder shown in FIG.

FIG. 8 is a UEP DS-C according to a second embodiment of the present invention.
FIG. 3 is a block diagram showing the configuration of a DMA decoder.

9 is a block diagram showing a detailed configuration of the UEP DS-CDMA decoder shown in FIG.

FIG. 10 shows a UEP DS- according to the third embodiment of the present invention.
The block diagram which shows the structure of a CDMA encoder.

FIG. 11 shows a UEP DS- according to the third embodiment of the present invention.
FIG. 3 is a block diagram showing the configuration of a CDMA decoder.

[Explanation of symbols]

 300 Input Audio Data Interface 302 First Channel Decoder 304 Second Channel Decoder 306 First Data Stream 308 Second Data Stream 310 First Channel Coded Data Stream 312 First Channel Coded Data Stream 313 First variable time modulator 315 Second variable time modulator 314 First time modulated signal 316 Second time modulated signal 204 Multiplexer 320 Interleaver 322 Spreader 324 Modulator 326 RF transmitter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication H04J 13/00 F (72) Inventor Karl-Eric Wilhelm Sandberg United States, 07928 New Jersey, Chatham, Hickory Place A-11 25

Claims (33)

[Claims] 1. A device for processing a signal in a spread spectrum communication system including means for using a spread spectrum coding process, wherein the signal is a function of time, the signal including power modulating means for generating a power modulated signal, Includes a first segment and a second segment, the first segment being more significant than the second segment, the first segment and the second segment being respectively the first time portion and the second portion of the signal. And the power modulation means increases the average power of the signal in the first time portion as compared with the average power of the signal in the second time portion. apparatus. 2. The spread spectrum of claim 1 including means for spreading the power modulated signal to produce a spread spectrum signal, the spreading means combining the power modulated signal and the spread signal. Communication system signal processing device. 3. The average power of the first segment is less than the average power of the power modulated signal in the first time portion by a first amount, and the average power of the second segment is less than the average power of the power modulated signal. The first amount and the second amount are equal to each other and are larger by the second amount.
A signal processing device of the spread spectrum communication system described. 4. A spread spectrum communication signal processing apparatus including means for using a spread spectrum decoding process, wherein the signal is a function of time, and (a) demultiplexes the signal to obtain a first segment of the signal. And means for generating a second segment of the signal, (b) means for decoding the first segment with a first channel decoder, and (c) means for decoding the second segment with a second channel decoder. A signal processing device of a spread spectrum communication system characterized by including. 5. A spread spectrum communication signal processing apparatus including means for using a spread spectrum coding process, wherein the signal is a function of time, and (a) a first segment of the signal operating at a first rate. Means for encoding with a first channel decoder to produce a first encoded segment; and (b) a second segment of the signal with a second channel decoder operating at a second rate, the second encoding And a second rate different from the first rate, the signal processing apparatus of the spread spectrum communication system. 6. A spread spectrum communication signal processing apparatus including means for using a spread spectrum coding process, comprising: (a) combining a first encoded segment and a second encoded segment to form a third encoded segment; Means for producing an encoded segment; (b) means for interleaving a third encoded segment to produce an interleaved segment; (c) spreading the interleaved segment to produce a spread spectrum signal 6. The spread spectrum communication system signal processing apparatus according to claim 5, wherein the spreading means combines the interleaved segment with the spread signal. 7. The spread spectrum communication according to claim 5, wherein the signal is generated by (a) means for receiving an analog voice signal at the transmitter and (b) means for coding the analog voice signal. System signal processing equipment. 8. The first encoded segment is a first amount longer than the first segment and the second encoded segment is a second amount shorter than the second segment. 6. The quantity and the second quantity are equal.
A signal processing device of the spread spectrum communication system described. 9. A signal processing apparatus for a spread spectrum communication system including means for using a spread spectrum multiple access decoding process, wherein the signal is a function of time, and (a) a first received segment of the signal is Means for decoding at a first channel decoder operating at a rate of 1 to produce a first decoded segment; and (b) a second received segment of a signal for operating at a second rate. And a means for generating a second decoded segment by the channel decoder of (1), wherein the second rate is different from the first rate. 10. (a) means for despreading the demodulated signal to produce a despread signal, and (b) the despread signal for a first received segment and a second received segment. 10. A spread spectrum communication system signal processing apparatus according to claim 9, further comprising: a separating unit. 11. A method comprising: (a) means for receiving a modulated radio frequency signal; and (b) means for demodulating the modulated radio frequency signal to generate a demodulated signal. Item 10. A signal processing device of the spread spectrum communication system according to Item 10. 12. (a) means for deinterleaving the despread signal to produce a deinterleaved signal, and (b) demultiplexing the deinterleaved signal for a first received signal. 11. The spread spectrum communication signal processing apparatus according to claim 10, further comprising a segment and a means for generating a second received segment. 13. A spread spectrum communication signal processing apparatus including means for using a spread spectrum encoding process, wherein a first error protection process is applied to at least one relatively significant part, and a second error protection process. Of at least one relatively insignificant part, the first error protection process providing a greater amount of error protection than the second error protection process. Signal processing device. 14. A device for processing a signal in a spread spectrum communication system comprising means for using a spread spectrum decoding process, wherein at least one relatively significant part of the signal is decoded using a first error protection decoding process. And a means for decoding at least one relatively insignificant portion of the signal using a second error protection decoding process. 15. A device for processing a signal in a spread spectrum communication system including means for using a spread spectrum coding process, wherein the signal is a function of time, has means for modulating the signal and generating a modulated signal, and the signal is , A first segment and a second segment, the first segment being more significant than the second segment and including the first time portion of the signal, the second segment being the second segment of the signal. The signal processing apparatus of the spread spectrum communication system, wherein the modulating means includes means for increasing the duration of the first time portion with respect to the duration of the second time portion. 16. Spread spectrum according to claim 15, comprising means for spreading the modulated signal and generating a spread spectrum signal, the spreading means comprising combining the modulated signal and the spread signal. Communication system signal processor 17. The modulating means modulates both the first segment and the second segment, wherein an increase during the first time portion is equal to a decrease during the second time portion. 15. A spread spectrum communication system signal processing device according to item 15. 18. A method comprising: (a) means for modulating a radio frequency carrier with a spread spectrum signal to generate a modulated radio frequency signal; and (b) means for transmitting the radio frequency modulated signal. A signal processing apparatus for a spread spectrum communication system according to claim 2, 6 or 16. 19. A signal comprising: (a) means for receiving an analog voice signal at a transmitter; (b) means for coding the analog voice signal to produce a digitized voice signal; (c) this digital. By applying a forward error correction code to the encoded speech signal to generate an intermediate signal, and (d) interleaving the intermediate signal to generate a signal. 16. A signal processing device of the spread spectrum communication system according to claim 1 or 15. 20. The spread spectrum communication signal processing apparatus according to claim 19, wherein the interleaving means includes means for interleaving an intermediate signal based on a fundamental time unit of the signal. 21. A spread spectrum communication system signal processing apparatus including means for using a spread spectrum decoding process, wherein the signal is a function of time, and means for performing variable time demodulation of the signal to generate a variable time demodulated signal. And the signal has a first segment and a second segment, the first segment being more significant than the second segment, including the first time portion of the signal, and the second segment being , A second time portion of the signal, the variable time demodulation means includes a first time duration of the second time portion
A signal processing apparatus of spread spectrum communication system, comprising means for increasing the duration of the time portion of. 22. The variable time demodulation means includes (a) means for despreading a signal to generate a despread signal, and (b) deinterleaving the despread signal to generate a deinterleaved signal. 22. A spread spectrum communication system signal according to claim 21, further comprising: and (b) means for demultiplexing the deinterleaved signal to generate a first signal and a second signal. Processing equipment. 23. (a) means for generating a first series of soft decision values based on the first signal; and (b) a second series of soft decision values based on the second signal. 23. The spread spectrum communication system signal processing apparatus according to claim 22, further comprising: generating means. 24. The variable time demodulation means demodulates both the first segment and the second segment, the increase during the second time portion being equal to the decrease during the first time portion. 22. A signal processing device for a spread spectrum communication system according to claim 21. 25. The signal processing apparatus according to claim 22, wherein the means for deinterleaving includes means for deinterleaving an intermediate signal based on a basic time unit of the signal. . 26. A spread spectrum communication system signal processing apparatus including means for using a spread spectrum encoding process, wherein a first error protection process is applied to at least one relatively significant part, and a second error protection process. To at least one relatively insignificant part, the first error protection process providing a greater amount of error protection than the second error protection process, the applying means comprising: (a) varying A signal processing apparatus for a spread spectrum communication system, comprising: a unit using a power modulator; and (b) a unit using a variable time modulator. 27. A spread spectrum communication signal processing apparatus including means for using a spread spectrum encoding process, wherein the first error protection process is applied to at least one relatively significant portion, and the second error protection process is applied. To at least one relatively insignificant part, the first error protection process providing a greater amount of error protection than the second error protection process, the applying means comprising: (a) varying A signal processing apparatus for a spread spectrum communication system, comprising: a unit using a power modulator; and (b) a unit using a variable rate coder. 28. A spread spectrum communication signal processing apparatus including means for using a spread spectrum encoding process, wherein the first error protection process is applied to at least one relatively significant portion, and the second error protection process is applied. To at least one relatively insignificant part, the first error protection process providing a greater amount of error protection than the second error protection process, the applying means comprising: (a) varying A spread spectrum communication system signal processing apparatus comprising: a means using a time modulator; and (b) means using a variable rate coder. 29. A spread spectrum communication system signal processing apparatus including means for using a spread spectrum encoding process, wherein the first error protection process is applied to at least one relatively significant portion, and the second error protection process is applied. To at least one relatively insignificant part, the first error protection process providing a greater amount of error protection than the second error protection process, the applying means comprising: (a) varying A spread spectrum communication signal processing apparatus comprising: a unit using a power modulator; (b) a unit using a variable time modulator; and (c) a unit using a variable rate coder. 30. A spread spectrum communication signal processing apparatus, comprising means for using a spread spectrum decoding process, wherein at least one of the signals is processed using a first error protection process.
And a means for decoding at least one relatively insignificant portion of the signal using a second error protection process, the means for decoding comprising: (a) demultiplexing the signal. Means for plexing and generating a first segment of the signal and a second segment of the signal, means for decoding the first segment with a first channel decoder, and decoding the second segment with a second channel decoder And (b) means for using a variable time demodulator. 31. A spread spectrum communication signal processing apparatus comprising means for using a spread spectrum decoding process for decoding at least one relatively significant portion of a signal using a first error protection process, Having means for decoding at least one relatively insignificant part of the signal using a second error protection process, the means for decoding comprising: (a) demultiplexing the signal, the first segment of the signal and Means for generating a second segment of the signal, means for decoding the first segment at the first channel decoder, and means for decoding the second segment at the second channel decoder, and (b) a variable rate coder. A signal processing device of a spread spectrum communication system characterized by including means for using. 32. A spread spectrum communication signal processing apparatus including means for using a spread spectrum decoding process, wherein at least one of the signals is processed using a first error protection process.
Means for decoding at least one relatively insignificant portion of the signal using the second error protection process, the means for decoding comprising: (a) a variable time modulator. And a means for using a variable rate coder. (B) A signal processing apparatus for a spread spectrum communication system, characterized by including: 33. A spread spectrum communication signal processing apparatus including means for using a spread spectrum decoding process, wherein at least one of the signals using the first error protection process is used.
And a means for decoding at least one relatively insignificant portion of the signal using a second error protection process, the means for decoding comprising: (a) demultiplexing the signal. Means for plexing and generating a first segment of the signal and a second segment of the signal, means for decoding the first segment with a first channel decoder, and decoding the second segment with a second channel decoder A signal processing apparatus for a spread spectrum communication system, comprising: (b) means using a variable time modulator; and (c) means using a variable rate coder.