KR100354471B1 - Wireless mobile communication system for recovering pilot bit from pilot signal including supplementary information bit - Google Patents

Abstract

The present invention includes a plurality of transmitters for transmitting a pilot signal generated by inserting a sub information bit at a predetermined position of a pilot bit sequence on a pilot channel and a receiver for receiving a plurality of the pilot signals transmitted from the plurality of transmitters The receiver identifies the inserted sub information bits in each of the received plurality of pilot signals, stores data indicating the presence or absence of additional information for later use, and restores the data with the pilot bits, And extracting means for extracting a predetermined characteristic of the recovered plurality of pilot signals and processing means for performing a predetermined process using the characteristic.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a wireless mobile communication system for recovering a pilot bit from a pilot signal in which an additional information bit is inserted.

More particularly, the present invention relates to a wireless mobile communication system, and more particularly, to a wireless mobile communication system in which additional information bits are inserted in a pilot bit stream on a pilot channel and transmitted in a pilot signal transmitter, Channel estimation and idle handoff performance by restoring the bits with pilot bits prior to pilot channel acquisition.

In general, a forward link of a CDMA mobile communication system is multiplexed by Walsh codes orthogonal to each other as forward channels transmitted from a base station to a mobile station. For example, in an IS-95 CDMA mobile communication system, a forward channel includes a pilot channel, a sync channel, a paging channel, and a traffic channel.

In a CDMA mobile communication system, a mobile station applies a Walsh code 0 to a pilot bit and transmits a pilot signal on a pilot channel spread by the same PN (pseudo noise) code to all base stations at a time offset The mobile station finds the time offset of the pilot signal having the highest power among the received pilot signals and finds the nearest base station.

The pilot signal is, for example, a bit sequence obtained by multiplying a PN sequence and a Walsh code 0 by a bit sequence that is periodically repeated, or a signal already known by the receiver, having a logic value of 0.

The mobile station finds the nearest base station through the pilot channel, receives the time synchronization information from the synchronization channel, and searches for the paging channel by monitoring the paging channel after matching with the system time. When the call information of the mobile station is received through the paging channel, the call is started via the call channel.

Recently, a method of transmitting a pilot signal including not only a pilot bit but also an additional information bit to a pilot channel has been proposed. As an example of this, Korean Patent Application No. 10-1999-0033546 filed on August 14, 1999 by the same person as the applicant of the present application discloses a method in which a forward link pilot channel is transmitted in a predetermined manner (for example, a hash ) Function), and when a corresponding mobile station of each slot is to be called, a paging indicator is inserted in the corresponding slot, and after the channel acquisition and channel estimation in the mobile station, the mobile station determines the call indicator A wireless communication system is disclosed.

As another example, according to Korean Patent Laid-Open Publication No. 2000-0001049, filed on June 8, 1998 and published on Jan. 15, 2000 by LG Information Communication Co., Ltd., in addition to the pilot bit inserted in the received pilot signal A channel estimation apparatus and a method of a CDMA cellular mobile communication system in which the additional information bits of the additional information bits are also used for channel estimation.

However, conventionally, in the case of generating and transmitting a pilot signal by inserting additional information bits into the pilot bits, the performance of channel acquisition is lowered because the pilot information is obtained using the pilot signal inserted in the pilot bit . That is, in comparing the power obtained by despreading the pilot signal to the PN code at the receiver, the power of the pilot channel is not compared with the pilot signal due to the additional information bit inserted in the pilot bit.

Therefore, when a pilot indicator other than pilot bits, system information, general call data bits, or additional information bits such as a power control bit are transmitted together on a pilot channel, it is difficult to acquire a pilot channel and estimate a channel .

In addition, since the power of the pilot signal can not be accurately measured as described above, there is a possibility that an error occurs during idle handoff.

It is an object of the present invention to provide a wireless mobile communication system for recovering pilot bits from a pilot signal inserted with supplementary information bits that improve channel acquisition performance by restoring supplementary information bits included in a pilot signal with pilot bits before channel acquisition .

In order to achieve the object of the present invention, in the wireless communication system according to the present invention,

A plurality of transmitters for transmitting a pilot signal generated by inserting a sub information bit at a predetermined position of a pilot bit train on a pilot channel,

And a receiver for receiving a plurality of the pilot signals transmitted from the plurality of transmitters,

The receiver

The method comprising the steps of: recognizing the inserted sub information bits in each of the plurality of received pilot signals, storing data for indicating presence / absence of additional information insertion for subsequent use, recovering the pilot bits, Sudan,

Extracting means for extracting predetermined characteristics of the recovered plurality of pilot signals,

Processing means for performing a predetermined process using the characteristic

The present invention provides a wireless mobile communication system.

1 illustrates a base station and a mobile station of a wireless mobile communication system according to the present invention.

2 is a diagram showing an example of call processing in a wireless mobile communication system for inserting a call indicator into a pilot according to an embodiment of the present invention;

3 shows a pilot channel transmitter according to the present invention.

4 shows a pilot channel receiver according to the invention;

5 is a detailed view of the pilot bit recoverer of FIG. 4;

6 is a detailed view of the call indicator pre-processor of FIG. 5;

FIG. 7 is a diagram showing an example of a pilot signal, a PN code and integrated values thereof in which a call indicator is inserted; FIG.

Description of the Related Art

1: mobile station

2-8:

41: Pilot bit recoverer

56-59: Call indicator preprocessor

60-63: Call indicator discriminator

64-67: Call indicator discrimination code adder

Embodiments of a wireless mobile communication system according to the present invention will be described in detail below with reference to the drawings.

1 is a diagram showing a radio connection between a mobile station 1 and a base station 2-8 in a wireless mobile communication system according to the present invention. In FIG. 1, the mobile station 1 wirelessly connects with the base station 2 to 8, which is closest to the base station, that is, the base station having the largest pilot signal power. Each of the base stations 2 to 8 transmits a pilot signal generated by applying the same PN code (pseudo noise code) having a certain length to the pilot bits and the additional information bits in different offsets. In FIG. 1, only the base station 2-8 that generates the pilot signal using the corresponding offset from the PN 0 offset to the PN 6 offset is illustrated, and the other base stations are omitted for simplicity of explanation.

Such as information on system information or paging information inserted in the pilot bits, such as information on paging zone, call indication, command, channel assignment, etc. Hereinafter, paging indicators are used as additional information bits I will explain.

2 is a diagram illustrating an example of a call processing procedure of the mobile station 1 in a mobile communication system in which a call indicator is inserted into a pilot as additional information bits according to an embodiment of the present invention. When the mobile station 1 is powered on (step S100), the mobile station 1 determines the additional information bits embedded in the pilot signal and stores the additional information bits in the buffer. If the additional information bits are inserted, the mobile station 1 restores the pilot bits (step S110). Then, the PN code offset of the nearest base station is determined using the strength of the pilot signal received on the pilot channel (step S120). After acquiring the pilot channel, a synchronization channel is acquired to obtain time synchronization information, and its timing is adjusted to match the system time (step S130). The mobile station 1 monitors the paging channel to obtain information necessary for the call (step S150) and starts the call through the communication channel (step S140) (Step S160).

3 is a diagram illustrating a pilot channel transmitter according to the present invention. In the embodiment of the present invention, the additional information bits are inserted into the pilot bits using an on-off keying scheme. That is, the bits into which the additional information bits are inserted are PN Is inserted by reversing the polarity of the code chips.

In FIG. 3, bits determined in a predetermined manner to a position at which a call indicator in a pilot bit string, which is a bit string having a logic value of all 0, are inserted are stored in the accumulator 31 in such a manner that the polarity reversal code do. For example, assuming a bit transfer rate of 9.6 kilobits per second (Kbps) and a chip transfer rate of 1.2288 Mcps (Mega chip per second), the polarity reversal code is a code that contains 128 PN code chips per bit. The pilot bit sequence including the polarity reversal code and the accumulated bits is spread by adding Walsh code 0 and modulo 2 in the modulo 2 adder 32. The pilot bit sequence diffused by Walsh code 0 is spread by 1.2288 Mcps, two 15-squared PN codes and 2 modulo 2 in the modulo 2 adders 33 and 34 and then spread in baseband filters 35 and 36 Filtered. The signals passed through the baseband filters 35 and 36 are respectively integrated with the sinusoidal signals in the integrators 37 and 38 to produce an in-phase component signal I (t) and a quadrature component signal Q (t) (39) to finally generate a QPSK modulation transmission pilot signal P _T (t).

The transmit pilot signal P _T (t) of FIG. 3 may include only pilot bits and may include inserted call indicator bits to reverse the polarity of the pilot bits in addition to the pilot bits. One bit of the pilot bit sequence corresponds to 128 PN code chips. When there is a call, the bit where the call indicator is inserted is 128. The phase of the PN code chip is reversed so that the mobile station 1 corresponding to the bit reverses the polarity of the PN code chip It is possible to know that the user is being called.

4 is a diagram illustrating a pilot channel receiver according to the present invention.

In FIG. 4, the received signal R (t) at the receiver includes a received pilot signal P _R (t), a synchronization channel signal, a paging channel signal, a call channel Signal and noise.

The pilot bit recoverer 41 determines whether a call indicator is inserted in each of a plurality of component pilot signals included in the received pilot signal P _R (t). The pilot bit recoverer 41 directly applies the component pilot signal whose call indicator is not determined to the pilot channel acquisition processor 42 as it is. The pilot bit recoverer 41 stores a component pilot signal obtained by restoring the call indicator to the pilot bit while storing the presence or absence of the call indicator discrimination in the buffer 43 for the discriminated component pilot signal when the call indicator is discriminated, .

The pilot channel acquisition processor 42 compares the power of the component pilot signal and / or the recovered component signals applied from the pilot bit recoverer 41 and outputs a PN offset of the highest power component pilot signal to a PN offset .

The buffer 43 stores the presence or absence of call indicator discrimination for each of a plurality of component pilot signals. When the PN offset is determined in the pilot channel acquisition processor 42, the buffer 43 transmits a signal indicating whether a call indicator is present to the corresponding component pilot signal, To a processor (not shown).

That is, in the present invention, the additional information bits included in each transmission pilot signal P _T (t) included in the received signal R (t) are recovered as pilot bits before processing the pilot signal in the IS-95 environment The pilot signal is processed in the same manner as in the IS-95 environment. Therefore, according to the present invention, pilot channel acquisition, channel estimation performance degradation and idle handoff error problems due to inserting additional information bits on the pilot channel can be prevented.

FIG. 5 is a detailed view of the pilot bit recoverer 41 of FIG. The pilot bit recoverer 41 discriminates whether or not to insert the call indicator by one bit of 128 PN chips.

5, the pilot bit recoverer 41 includes a modulo 2 adder 51-55, a call indicator preprocessor 56-59, a call indicator discriminator 60-63, a call indicator discrimination code An adder 64-67, a delay 68, and a summer 69. [

First, the received signal R (t) is modulo-2 added to the Walsh code 0 signal in the modulo 2 adder 51 and is output as the received pilot signal P _R (t).

The received pilot signal P _R (t) is added to the PN code chip having a corresponding one of the PN_offset_0 to PN_offset_511 by the modulo 2 adders 52 to 55 as modules.

The output of each of the modulo 2 adders 52 to 55 is input to the corresponding call indicator preprocessor 56-59 and is a signal Z_n (T) for judging the presence or absence of a call indicator insertion, 0? N? 511, .

FIG. 6 shows the call instruction preprocessor 56-59 of FIG. 5 in detail. The signal output from the corresponding one of the modulo two adders 52-55 is then passed through the in-phase reference signal and the quadrature reference signal as shown to move to the baseband at the two integrators 71 and 72 of the call indicator preprocessor Respectively. The outputs of the integrators 71 and 72 are applied to integrators 73 and 74, respectively.

Integrators 73 and 74 integrate the outputs of integrators 71 and 72 for one bit time T _b and then apply them to corresponding squarers 75 and 76. The result squared in the squarer 75 is squared in the squarer 76 and subtracted in the subtractor 77 to generate a call indicator decision signal Z_n (T). Z_n (T) are input to the corresponding call indicator discriminators 60-63, respectively.

5, the call indicator discriminator 60-63, which has received the Z_n (T), compares it with a predetermined threshold value to determine whether a call indicator has been inserted.

The calling indicator determination signal Z_n (T) corresponding to each PN offset is generated by adding the chips of the PN code received in the currently determined bit to the corresponding module and the chip of the PN code added by the module 2 in the 2-adder 52-55 Represents a matching number.

For example, if 128 PN code chips per bit of the pilot signal corresponds to a bit with a call indicator, assuming that the chip value included in the bit is opposite to the chip value of the PN code, (T) will have a value of -128. On the other hand, in the case of a bit without a call indicator, Z_n (t) will have a value of +128 because the chip value included in the bit is the same as the chip value of the PN code.

However, it will not have only -128 and +128 values due to fading and noise in a wireless channel environment. Therefore, the call indicator discriminator 60-63 compares each input Z_1 (T) to Z_512 (T) with 0, which is an intermediate value between -128 and +128. If the value is equal to or larger than 0, the call indicator discriminator 60-63 determines that the call indicator is not inserted, , It is determined that the call indicator is inserted.

The output signals of the respective call indicator discriminators 60 to 63 are input to the buffer 43 and the corresponding call indicator discriminator code adder 64-67. A signal obtained by delaying the output of the modulo 2 adder 51 by one bit in the delay unit 68 is input as one input to all the call indicator discrimination code adders 64-67.

If it is determined in the call indicator discriminator 60-63 that there is a call indicator in the current bit, the call indicator code adder 64-67 generates a call indicator code that inverts the polarity of the PN code chip corresponding to the current bit And adds modulo 2 to the signal input from the delay 68. [ That is, the call indicator code adder 64-67 restores the polarity of the pilot bit whose polarity is inverted by the call indicator by adding it to the PN code chip whose polarity is inverted.

On the other hand, when it is determined in the call indicator discriminator 60-63 that there is no call indicator in the corresponding bit, the call indicator code adder 64-67 adds the signal input from the delay 68 to the adder 69).

The summer 69 adds the outputs of the call indicator code adders 64-67 and applies them to the pilot despreader 42 of FIG.

FIG. 5 shows an example in which the receiver initially discriminates the call indicator for all pilot offsets (PN_Offset_0 to PN_Offset_512). Once the mobile station 1 successfully establishes a radio connection with a neighboring base station (for example, the base station 2) of the base station 2 - 8, the pilot offset included in the search pilot list determined by a predetermined method instead of all pilot offsets The call indicator may be discriminated.

That is, only the pilot offsets used by the base station closest to the mobile station 1 other than PN_Offset_0 to PN_Offset_511 in FIG. 5 may be processed according to the above procedure.

FIG. 7 is a diagram showing an example of a pilot signal, a PN code, and an integrated value thereof, into which a call indicator is inserted when it is assumed that a pilot signal of a base station closest to the mobile station 1 is received through a channel free of noise and fading.

In FIG. 7, (a) is a signal representing a received pilot signal as a chip, and chips marked in the drawing correspond to bits into which a call indicator is inserted. One bit corresponds to 128 chips and the length of the PN code corresponds to 256 bits. (b) The signal is a PN code that matches the PN offset of the received pilot signal except for the interval in which the call indicator is inserted. The chips indicated in the figure are opposite to the chips in the part where the call indicator shown above is inserted to be. (c) The signal represents a signal obtained by integrating the pilot signal and the PN code.

As described above, when the additional information is inserted in the received pilot signal, the polarity of the chips is opposite to the pilot bit in the bit in which the additional information is inserted when the received pilot signal is integrated with the PN code of the offset used in transmission. So that the bit in which the additional information is inserted can be found.

According to the present invention, it is possible to improve channel acquisition, channel estimation, and idle handoff performance by restoring the additional information bits included in the pilot signal with the pilot bits before acquiring the channel.

Although the present invention has been particularly shown and described with reference to the above detailed description, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the essence and scope of the invention as defined by the appended claims. It is self-evident.

Claims (23)

In a wireless communication system, A plurality of transmitters for transmitting a pilot signal generated by inserting a sub information bit at a predetermined position of a pilot bit train on a pilot channel, And a receiver for receiving a plurality of the pilot signals transmitted from the plurality of transmitters, The receiver The method comprising the steps of: recognizing the inserted sub information bits in each of the plurality of received pilot signals, storing data for indicating presence / absence of additional information insertion for subsequent use, recovering the pilot bits, Sudan, Extracting means for extracting predetermined characteristics of the recovered plurality of pilot signals, Processing means for performing a predetermined process using the characteristic And a radio base station. 2. The wireless mobile communication system according to claim 1, wherein the predetermined characteristic is power and the predetermined process is a process of determining a pilot signal having the highest power by comparing power of the recovered plurality of pilot signals. 3. The wireless mobile communication system according to claim 2, wherein the additional information bits are system information bits. The wireless mobile communication system according to claim 2, wherein the additional information bits are paging information bits. The wireless mobile communication system according to any one of claims 1 to 4, wherein the additional information bits are inserted by modifying the pilot bits of the predetermined position among the pilot bit sequences. 6. The wireless mobile communication system of claim 5, wherein the additional information bits are inserted in an on-off keying manner. 7. The apparatus of claim 6, A plurality of discrimination means for discriminating whether to insert additional information bits for each of the plurality of received pilot signals in a predetermined time interval; Storage means for storing the determined additional information bits; For each of the plurality of received pilot signals, polarities of the received plurality of pilot signals are inverted and applied to the extracting means during a time interval determined to insert the additional information bits, And a plurality of selective polarity reversing means for respectively applying a plurality of pilot signals to the extracting means. The wireless mobile communication system of claim 7, wherein the predetermined time interval is a time interval corresponding to one bit of the pilot bit sequence. A wireless communication method, Transmitting a plurality of pilot signals generated by inserting a sub information bit at a predetermined position of a pilot bit train on a pilot channel; Receiving the transmitted plurality of pilot signals, Determining the inserted sub information bits in each of the plurality of received pilot signals, storing data indicating the presence or absence of additional information for later use, recovering the inserted pilot information with the pilot bits, and generating a recovered plurality of pilot signals Wow, Extracting a predetermined characteristic of the recovered plurality of pilot signals; Performing a predetermined process using the characteristic And transmitting the radio signal. 10. The method of claim 9, wherein the predetermined characteristic is power, and the predetermined process is a process of determining a pilot signal having the highest power by comparing power of the recovered plurality of pilot signals. 11. The method of claim 10, wherein the additional information bits are system information bits. 11. The method of claim 10, wherein the additional information bits are paging information bits. The method of any one of claims 9 to 12, wherein the additional information bits are inserted by modifying the pilot bits of the predetermined position among the pilot bit sequences. 14. The method of claim 13, wherein the additional information bits are inserted in an on-off keying manner. 15. The method of claim 14, Determining whether to insert additional information bits for each of the plurality of pilot signals in a predetermined time interval; Storing the determined additional information bits, For each of the plurality of received pilot signals, polarities of the received plurality of pilot signals are inverted and applied to the extracting means during a time interval determined to insert the additional information bits, And applying a plurality of pilot signals to the extracting means. 16. The method of claim 15, wherein the predetermined time interval is a time interval corresponding to one bit of the pilot bit sequence. A receiving apparatus for use in a mobile communication system for transmitting a pilot signal generated by inserting a sub information bit at a predetermined position in a pilot bit sequence in each of a plurality of pilot channels, The method comprising the steps of: recognizing the inserted sub information bits in each of the plurality of received pilot signals, storing data for indicating presence / absence of additional information insertion for subsequent use, recovering the pilot bits, Sudan, Extracting means for extracting predetermined characteristics of the recovered plurality of pilot signals, Processing means for performing a predetermined process using the characteristic . 18. The receiving apparatus according to claim 17, wherein the predetermined characteristic is power and the predetermined process is a process of determining a pilot signal having the highest power by comparing power of the recovered plurality of pilot signals. 19. The apparatus of claim 18, wherein the additional information bits are system information bits. 19. The apparatus of claim 18, wherein the additional information bits are paging information bits. The receiving apparatus according to any one of claims 17 to 20, wherein the additional information bits are inserted in an on-off keying manner. 22. The apparatus of claim 21, wherein the recovery means A plurality of discrimination means for discriminating whether to insert additional information bits for each of the plurality of received pilot signals in a predetermined time interval; Storage means for storing the determined additional information bits; For each of the plurality of received pilot signals, polarities of the received plurality of pilot signals are inverted and applied to the extracting means during a time interval determined to insert the additional information bits, And a plurality of selective polarity reversing means for respectively applying a plurality of pilot signals to said extracting means. 24. The apparatus of claim 22, wherein the predetermined time interval is a time interval corresponding to one bit of the pilot bit sequence.