KR20000040468A - Method for searching multipath in mobile communication system - Google Patents

Abstract

PURPOSE: A method for searching a multipath in the mobile communication system is provided to search a multipath by using the power of a dedicated channel as well as a pilot channel. CONSTITUTION: A searching part(100) searches an optimum signal path by according the synchronization of the PN code of a channel received from a transmitting device of the CDMA communication system. A plurality of finger parts(11,12) are allocated on signal paths according to the searched result of the searching part(100) and executes demodulation. A control part(200) allocates the finger parts on an optimum signal path, based on the searched result of the searching part(100). A noise estimation part(300) estimates the noise of the channel. The searching part(100) is composed of one branch to measure the power strength of a pilot channel comprising a third division part(15), a first energy detection part(16), a fourth division part(17) and a first power measurement part(20) and the other branch to measure the power strength of a dedicated channel comprising a third multiplication part(21), a walsh code generation part(40), a fifth division part(25), a second energy detection part(26), a sixth division part(27) and a second power measurement part(30).

Description

Multipath Search Method in Mobile Communication System

The present invention relates to a multipath search method in a mobile communication system, and more particularly to a pilot channel as well as a dedicated channel in a code division multiple access (CDMA) communication system. The present invention relates to a method for searching for multipaths for finger assignment using power.

In the forward link of the existing IS-95 CDMA communication system, the discovery is performed using the received energy of the pilot channel. In the reverse link, the preamble search uses a preamble signal that replaces the pilot channel of the forward link. In the case of multipath search, orthogonal energy is detected because there is no pilot channel. Perform discovery by detecting).

In addition, new CDMA standards after IS-95 recommend that a pilot channel or a pilot symbol be transmitted on the reverse link as well as the forward link. Therefore, the receiving apparatus of the CDMA communication system based on the new standard can perform the search 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 the receiver of the 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 PN code generated by the PN code generator 8 of the searcher 3 is multiplied by the second multiplier 4 to output the filtered signal. The complex output signal is accumulated in synchronization with a coherent accumulator 5, energy is detected by the energy detector 6, and a noncoherent accumulator ( In 7) the detected energy is accumulated. This accumulation and energy detection process is performed in a branch for measuring the strength of the power of the pilot channel. The threshold comparator 10 of the controller 9 compares the signal accumulated in the noncoherent accumulator 7 of the searcher 3 with a threshold value to determine an optimal signal path. Allocate a finger. In addition, each of the fingers 11 and 12 is assigned to an optimal signal path from the control unit 9 to perform demodulation.

In the conventional CDMA communication system receiving apparatus, the multipath searching method uses only a branch for measuring the strength of the pilot channel power.

Therefore, the performance is good in the forward link with a large power strength of the pilot channel, but the performance is degraded in the reverse link with a low power strength of the pilot channel.

Disclosure of Invention An object of the present invention has been made in view of the above-mentioned problems of the prior art, and in a CDMA communication system for performing a multipath search using power of a dedicated channel as well as a pilot channel to search for a stable optimal signal path It is to provide a multipath searching method.

According to an aspect of the present invention for achieving the above object, the step of measuring the strength of the power for the input dedicated channel, and calculating the relative power strength of the intensity of the measured power and the intensity of the noise power Comparing the intensity of the relative power with the intensity of the threshold power, and determining whether to combine the strength of the power of the dedicated channel with the strength of the pilot channel according to the comparison result. It is made to include.

Preferably, the step of measuring the strength of the power for the input dedicated channel comprises: despreading the input dedicated channel, decovering the PN despread signal with a Walsh code; Performing coherent accumulation of the signal decovered with the Walsh code, detecting energy of the coherent accumulated signal, and performing noncoherent accumulation of the detected energy. It comprises a step. In addition, determining whether to combine the strength of the power of the dedicated channel, the strength of the power of the dedicated channel to the strength of the pilot channel when the strength of the relative power is greater than the threshold power. To combine.

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

3,100: search unit 4: second multiplier

5: coherent accumulation part 6: energy detection part

7: noncoherent accumulator 8 PN code generator

9,200 control unit 10 threshold comparison unit

11: first finger portion 12: n-th finger portion

15: third accumulator 16: first energy detector

17: fourth accumulator 20: first power measurer

21: third multiplier 25: fifth accumulator

26: second energy detector 27: sixth accumulator

30: second power measurement unit 40: Walsh code generation unit

50 switch unit 51 adder

60: first threshold comparison unit 70: second threshold comparison unit

300: 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. 2B is a detailed view of each part of this receiving apparatus.

Referring to FIG. 2A, the receiving apparatus of the 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 transmitting apparatus of the CDMA communication system. A plurality of fingers 11 and 12 which are assigned to the signal path according to the search result of the search unit to perform demodulation, and a control unit which assigns the finger part to the optimal signal path based on the search result of the search unit. 200, and a noise estimator 300 for estimating noise of the channel.

The searcher 100 measures the power intensity of the pilot channel including the third accumulator 15, the first energy detector 16, the fourth accumulator 17, and the first power measurer 20. Branch, third multiplier 21, Walsh code generator 40, fifth accumulator 25, second energy detector 26, and six accumulator ( 27) and another branch for measuring the strength of the power of the dedicated channel composed of the second power measurement unit 30. 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, a step is needed to determine whether to add the power of the dedicated channel to the power of the pilot channel.

The control unit 200 includes a first threshold comparison unit 60 for comparing the intensity of the relative power between the strength of the pilot channel and the noise power combined with the power of the dedicated channel with the intensity of the threshold power; And a second threshold comparator 70 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. Similarly, the threshold comparison unit may be allocated in proportion to the number of dedicated channels.

In the multi-path searching method in the receiving apparatus of the CDMA communication system according to the present invention configured as described above, the signal input through the antenna is separated into the I channel and the Q channel in the first multiplier 1, respectively, and filtered in the filter unit 2. do. The PN code generated by the PN (Pseudo Noise) code generator 8 of the searcher 100 is multiplied by the second multiplier 4 to output PN despreading. . In this case, the PN despreading is performed by obtaining a correlation while sliding the received data to a local PN code aligned with a Walsh symbol boundary.

Subsequently, the PN despread and output signal is divided into a branch for measuring the power of the pilot channel and another 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 coherent accumulated in the third accumulator 15, Subsequently, energy is detected by the first energy detector 16, and the detected energy is accumulated by the fourth accumulator 17. The accumulated energy is measured by the first power measurement unit 20 in terms of intensity of energy relative to the intensity of noise energy measured by the noise estimator 300. 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 another branch for measuring the strength of the power of the dedicated channel, the PN despread signal is a Walsh code of the dedicated channel generated by the Walsh code generator 40. Is Walsh decovered by the third multiplier 21 and then coherent accumulates in the fifth accumulator 25, and then energy (or energy) is absorbed by the first energy detector 26. Energy is detected, and the detected energy is accumulated in the fourth accumulator 27. The accumulated energy is measured by the second power measurement unit 30 in the strength 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 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.

The measured relative power of the dedicated channel is compared with the strength of the threshold power in the second threshold comparator 70 of the controller 200 to determine whether the dedicated channel is loaded with power.

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 strengths of the combined pilot channel and the dedicated channel are compared by the first threshold comparator 60 to determine whether the acquisition is performed. When the acquisition is determined, the control unit 200 assigns a finger unit to an optimal signal path.

Each of the fingers 11 and 12 is assigned to an optimal signal path from the controller 200 to perform demodulation.

As described above, the present invention uses not only the pilot channel but also the power of the dedicated channel, so that the optimal signal path can be more stably searched by using the received energy more than the conventional method. It has an effect.

Claims (4)

Measuring an intensity of power for an input dedicated channel; Obtaining an intensity of relative power between the measured intensity of power 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 the measuring the power intensity of the input dedicated channel comprises: despreading the input dedicated channel and decovering the PN despread signal with a Walsh code. Performing coherent accumulation of the signal decovered by the Walsh code, detecting energy of the coherent accumulated signal, and noncoherent detection of the detected energy. Multipath searching method in a mobile communication system, characterized in that comprising the step of accumulating. 3. The method of claim 2, wherein the despreading of the input dedicated channel comprises: taking a sliding correlation while sliding the input dedicated channel data into a PN code aligned with a period of the Walsh code. Multipath search method in a mobile communication system, characterized in that comprises a. 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.