KR20000040469A - Method for detecting optimal signal of multipath in mobile communication system - Google Patents

Abstract

PURPOSE: A method for detecting an optimal signal of a multipath in a mobile communication system is provided to detect the optimal signal of a multipath by determining the lock states of fingers after getting a received signal strength indicator of each of the fingers, using the power of a dedicated channel as well as a pilot channel. CONSTITUTION: A searching part(10) searches an optimum signal path according to the synchronization of a PN code of a channel received from a transmitting device of a CDMA communication system. A plurality of finger parts(200,300) are allocated on signal paths according to the searched result of the searching part(10) and executes demodulation. A control part(400) allocates the finger parts on an optimum signal path, based on the searched result of the searching part(10). A noise estimation part(500) estimates the noise of the channel.

Description

Optimal Signal Detection Method for Multipath in Mobile Communication System

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for optimal signal detection of multipaths in a mobile communication system. In particular, the present invention relates to a pilot channel as well as power of a dedicated channel in a code division multiple access (CDMA) communication system. The present invention relates to a method of detecting an optimal signal of a multipath by determining a locked state of a finger after obtaining a RSSI (Received Signal Strength Indicator) value of each finger using power. .

In the forward link of the existing IS-95 CDMA communication system, the RSSI value of the finger is obtained by using the received energy of the pilot channel and the lock state is determined. Here, RSSI represents the strength of the radio wave as energy, and is an important index that influences the operation of various demodulation algorithms such as a RAKE receiver, time-tracking, and frequency error correction. In the reverse link, since a pilot channel does not exist, orthogonal energy detection is performed to determine a lock state of a finger. In general, signals passing through each finger are combined and then decoded. At this time, the finger whose lock state is determined among the plurality of fingers is not coupled with other fingers.

On the other hand, new CDMA standards after IS-95 recommend that the reverse link transmit a pilot channel or a pilot symbol as well as the forward link. Therefore, the receiving apparatus of the CDMA communication system based on the new standard can obtain the RSSI value of the finger and determine the locked state by using the energy of the pilot signal in the reverse link as in the forward link. Here, since the mobile communication system is one-to-N communication, the pilot channel of the forward link is transmitted at high power because it is common to all terminals in the cell area of the base station. However, since the dedicated pilot channel of the reverse link is dedicated for each terminal, it is transmitted at low power. Of course, depending on the standard or the data rate, the power strength of the dedicated pilot channel of the reverse link may vary slightly. For reference, types of dedicated channels include a fundamental channel, a supplemental channel, a dedicated control channel, and a dedicated pilot channel.

1 is a block diagram showing the configuration of a receiving apparatus of a conventional CDMA communication system.

Referring to FIG. 1, in a receiver of a conventional CDMA communication system, a signal input through an antenna is separated into an I channel and a Q channel in the first multiplier 1, respectively, and filtered by the filter unit 2. The filtered signal is input to the searcher 10 to search for an optimal signal path in a multipath environment. In addition, the filtered signal is input to each finger unit 20 and 30, and assigned to the signal path according to the search result of the search unit 10 to be demodulated. A process of processing a signal in the first finger unit 20 among the finger units 20 and 30 is as follows. The PN code generated by the PN (Pseudo Noise) code generator 29 is multiplied by the second multiplier 21, and the PN despreading is output. In the PN despread signal, a pilot channel is filtered by the pilot filter 22, energy is detected by the energy detector 23, and an RSSI value is filtered by the RSSI filter 24 to control the controller 40. ) Is entered. The lock state determination unit 41 of the controller 40 determines the lock state of the first finger unit 20 according to the received RSSI value. Therefore, the lock state of the first finger portion 20 is determined by using a pilot channel. At this time, when the finger portion is locked, the output of the finger portion is not combined with the output of the other finger portion, and determining the lock state of the finger portion determines the reliability and time tracking operation of the demodulated data. Is an important factor.

In addition, the PN despread signal is Walsh code generated by the Walsh Code Generator 28 and Walsh code generated by the Walsh code generated by the third multiplier 25. Accumulation at 26. The accumulated signal is multiplied by the filtered pilot channel and the fourth multiplier 27 to extract data di and dq.

In the conventional CDMA communication system receiving apparatus, an optimal signal detection method of multipath uses a pilot channel power having a low power strength in a reverse link to obtain RSSI value of a finger and makes a lock state decision. There was a problem in not detecting the signal.

An object of the present invention has been made in view of the above-mentioned problems of the prior art, using the power of the dedicated channel as well as the pilot channel to obtain the RSSI value of the finger and determine the locked state to determine a stable optimal signal To provide a multipath optimal signal detection method in a CDMA communication system to be detected.

According to an aspect of the present invention for achieving the above object, the step of detecting the power for the input dedicated channel, and the intensity of the relative power between the intensity of the detected dedicated channel and the intensity of noise power Obtaining, comparing the relative power intensity with the threshold power intensity, and determining whether to combine the strength of the dedicated channel with the strength of the pilot channel according to the comparison result. It is made, including.

Preferably, after determining whether the coupling is performed, the step of filtering the RRSI value to determine the lock state of the finger part by the RSSI value is added. Detecting power intensity of the input dedicated channel includes despreading the input dedicated channel, decovering the PN despread signal with a Walsh code, and the Walsh code. Accumulating a signal that is decovered into a second channel is added. Determining whether or not to combine the power of the dedicated channel combines the power of the dedicated channel with the power of the pilot channel when the relative power is greater than the threshold power. .

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing the configuration of a receiving apparatus of a conventional CDMA communication system.

Fig. 2A is a block diagram showing the configuration of a receiving apparatus of a CDMA communication system according to the present invention.

2b is a partial detailed view of a receiving apparatus according to the present invention;

Explanation of symbols on the main parts of the drawings

1: first multiplication unit 2: filter unit

10: search unit 20: first finger part

21,202: second multiplier 22,203: pilot filter

23: energy detector 24,218: RSSI filter unit

25,207: third multiplier 26: accumulator

27,209: fourth multiplier 28,206: Walsh code generator

29, 201: PN code generation unit 30: n-th finger unit

40: control unit 41: lock state determination unit

200: first finger 201: PN code generation unit

204: First energy detector 205: First power measurer

208: first accumulator 210: second energy detector

215: second power measurement unit 216: selection unit

217: second accumulating part 300: n-th finger part

400: control unit 401: threshold comparison unit

402: lock state determination unit 500: noise estimation unit

Hereinafter, the configuration and operation according to an embodiment of the present invention will be described with reference to the accompanying drawings.

2A is a block diagram showing the configuration of a receiving apparatus of a CDMA communication system according to the present invention. Partial detail of this receiver is Fig. 2B.

Referring to FIG. 2A, a receiver of a CDMA communication system according to the present invention searches for an optimal signal path in a multipath environment by matching synchronization of PN codes of channels received from a transmitter of a CDMA communication system 10. And a plurality of fingers 200 and 300 that are assigned to a signal path according to the search result of the searcher to perform demodulation, and a controller that allocates the finger to an optimal signal path based on the search result of the searcher. 400, and a noise estimator 500 for measuring the strength of the power of the noise of the input channel (500).

The plurality of fingers 200 and 300 may include branches for measuring the intensity of power of a pilot channel including a pilot filter 203, a first energy detector 204, and a first power measurer 205. Intensity of power of a dedicated channel including a third multiplier 21, a Walsh code generator 206, an accumulator 208, a second energy detector 210, and a second power measurer 215. A branch for demodulating data comprising a third multiplier 21, a Walsh code generator 206, a first accumulator 208, and a fourth multiplier 209. And a selection unit 216 for selecting whether to combine the intensity of the relative power between the strength of the dedicated channel with the strength of the relative power between the strength of the noise power and the strength of the dedicated channel. ) And the power of the noise relative to the power of the pilot channel. A second accumulator 217 that combines the relative power intensity between the relative power intensity of the period and the intensity of the noise power with respect to the power of the dedicated channel; and filtering RSSI values for the output of the second accumulator. RSSI filter unit 218 is configured to include. At this time, the branch for measuring the strength of the power of the dedicated channel may be allocated by increasing the number of dedicated channel types. In addition, the dedicated channel has a different characteristic according to the type. The Fundamental Channel is always loaded with a predetermined value or more until the call is released once the call is set up. A supplemental channel may or may not be powered depending on the presence or absence of transmission data even when a call is established. Therefore, it is necessary to determine whether to use the strength of the power of the dedicated channel in the RSSI of the finger unit.

The control unit 400 receives a threshold comparison unit 401 for comparing the intensity of the relative power between the intensity of the dedicated channel and the intensity of the noise power with the intensity of the threshold power, and the filtered RSSI value to be locked. It includes a lock state determination unit 402 for determining whether or not. Similarly, the threshold comparison unit may be allocated in proportion to the number of dedicated channels.

In the CDMA communication system according to the present invention configured as described above, in the multi-path optimal signal detection method, a signal input through an antenna is separated into an I channel and a Q channel in the first multiplier 1, respectively. Is filtered). The filtered signal is used by the search unit 10 to synchronize the PN (Pseudo Noise) code and to find an optimal signal path in a multipath environment.

In addition, the filtered signal is input to the plurality of fingers 200 and 300, and the PN code generated by the PN code generator 201 is multiplied by the second multiplier 202 to inverse the PN. It is output by spreading.

Subsequently, the PN despread and output signal is divided into a branch for measuring the power of the pilot channel and a branch for measuring the power of the dedicated channel. When the PN despread signal is input to a branch for measuring the strength of the pilot channel power, the PN despread signal is filtered by the pilot filter 203 and the first energy detector 204. The energy of the filtered pilot channel is detected at. The detected energy is measured by the first power measurement unit 205 of the intensity of the relative energy with the intensity of the noise energy measured by the noise estimator 500. Here, energy is power, i.e., the intensity of relative energy is the intensity of relative power and is obtained by the formula 10 x log (the intensity of the power of the pilot channel / the intensity of the noise power).

On the other hand, when the PN despread signal is input to a branch for measuring the strength of the power of the dedicated channel, the PN despread signal is generated by the Walsh code of the dedicated channel generated by the Walsh code generator 206. After Walsh decovering is performed in the third multiplier 207, it is accumulated in the first accumulator 208, and then energy is detected in the second energy detector 210. The detected energy is measured by the second power measurement unit 215 in the intensity of the relative power with the intensity of the noise energy measured by the noise estimator 300. Similarly, the relative power intensity is obtained by 10 x log (intensity of dedicated channel power / noise power). The signal accumulated by the first accumulator 208 is multiplied by the filtered pilot channel by the fourth multiplier 209 to extract data di and dq. The noise estimator 300 may use RSSI (Received Signal Strength Indicator) of the input signal depending on the configuration, or Walsh code the PN despread signal with a Walsh code different from the Walsh code of the dedicated channel. By decovering, the power strength of the noise can be obtained.

In addition, the measured intensity of the relative power for the dedicated channel is compared with the strength of the threshold power in the threshold comparison unit 401 of the controller 400 to determine whether the power is loaded on the dedicated channel.

In this case, when the intensity of the relative power is less than the intensity of the threshold power, since the power is not loaded in the dedicated channel, the strength of the relative power of the dedicated channel is not combined with the strength of the relative channel of the pilot channel. If the relative power of the power is greater than the threshold power, the power is carried in the dedicated channel, so that the strength of the relative power of the dedicated channel is combined with the strength of the pilot channel.

The signal accumulated by the second accumulator 217 according to the combined strength of the relative power of the dedicated channel is filtered by the RSSI filter unit 218 to the lock state determiner 402 of the controller 400. Is entered. The lock state determination unit 402 determines the lock state of the finger unit according to the RSSI value.

As described above, the present invention obtains the RRSI value of the finger part by using not only the pilot channel but also the power of the dedicated channel, and determines the locked state of the finger part from the locked state. Since it can be determined that the optimal signal of the multi-path more stably.

Claims (4)

Detecting power for an input dedicated channel; Obtaining an intensity of relative power between the intensity of the detected dedicated channel and the intensity of noise power; Comparing the strength of the relative power with the strength of the threshold power; And determining whether to combine the power of the dedicated channel with the power of the pilot channel according to the result of the comparison. The method of claim 1, wherein after determining whether to combine, filtering the RRSI value to determine a lock state of the finger part based on the RSSI value is added. Way. The method of claim 1, wherein the detecting of the power intensity of the input dedicated channel comprises: PN despreading the input dedicated channel, and decovering the PN despread signal with a Walsh code. And accumulating the signal decovered by the Walsh code. 2. The method of claim 1, wherein determining whether to combine the strengths of the powers of the dedicated channels is based on the strengths of the pilot channels when the relative powers are greater than the threshold powers. A method for multipath searching in a mobile communication system characterized by combining the strength of power.