KR20100085762A - Receiver of mobile communications system and receiving method thereof - Google Patents

Abstract

PURPOSE: A receiver of a mobile communications system and a receiving method thereof are provided to implement the efficiency of a system and reduce power consumption by configuring equalizers and lake fingers in serial. CONSTITUTION: A channel searcher and channel estimator(100) detects the reception signals of multiple paths according to each lake finger, and estimates a first channel of the detected reception signal, and second and third signals adjacent to the first channel. Equalizers(300) equalizes the first, second and third channels, and an equalizer controller(400) controls the on or off operation of the equalizers according to the channel state.

Description

Hybrid receiver and reception method in mobile communication system {RECEIVER OF MOBILE COMMUNICATIONS SYSTEM AND RECEIVING METHOD THEREOF}

The present invention relates to a receiver of a mobile communication system, and more particularly, to a hybrid receiver using an equalizer and a rake receiver in a mobile communication system.

1 is a block diagram of a conventional hybrid receiver.

In a conventional hybrid receiver, an equalizer and a rake finger are coupled in parallel. Referring to Figure 1, the operation of the conventional hybrid receiver will be described. The signal from the receiver 10 enters the equalizer 20 and the rake finger 30 and is processed respectively. Equalizer 20 may be configured to equalize the received stream and despread the PN code in 'post processor 40' and perform decovering on one or more channelization codes. The rake finger 30 is designed with a finger processor to process one or more multipaths to recover the received signal into a symbol. Each finger processor performs PN (Pseudo Noise) despreading and channel decovering on the sample stream to perform coherent demodulation for multipath. The rake then combines the demodulated symbols for all multipaths of the received signal to produce recovered symbols for the received signals. The rake allows to combine the recovered symbols for all signals to provide the full recovered symbols provided from the rake receiver. The symbols recovered from the processor 40 and the rake are then picked up by the switch 50 and provided to the deinterleaver 70 and decoded by the decoder 80. The controller 60 operates the switch 50 to calculate a S / N ratio of the signals received at the equalizer 20 or the rake finger 30 to select a better symbol.

On the other hand, in the conventional hybrid receiver, the equalizer does not always operate, but operates when the equalizer 20 is expected to perform better than the rake 30, thereby reducing the power of the hybrid receiver system. Hybrid equalizers generally perform better at slow fading conditions or at high SINR. Therefore, the operation of the equalizer is to operate in a slow fading environment by evaluating the correlation statistics of received pilot symbols, or to operate when the received signal is a high SINR.

2 is a state diagram illustrating an operation of implementing a rake and a hybrid equalizer in a conventional hybrid receiver. As shown in Fig. 2, there are two modes, a rake mode, an equalizer and a rake mode (hybrid mode). The two modes consist of rake mode only or rake and equalizer mode (hybrid mode). Initial operation starts only in rake mode. Remain in rake mode until the equalizer is further activated to gain sufficient gain. Two conditions are considered in order to transition from rake mode to hybrid mode. First, when the SINR is above a certain threshold, a transition occurs in hybrid mode. In hybrid mode, the receiver SINR of the rake and equalizer is continuously measured. When the SINR of the rake is greater than the SINR of the equalizer, the receiver shifts back to the rake mode. The second method measures the cross-correlation between pilot bursts to determine the speed of the channel, ie how fast the mobile station is moving, so that the equalizer mode is activated at low cross-correlation.

In the conventional hybrid receiver, a rake and an equalizer are configured in parallel. In this configuration, in the hybrid mode, the equalizer and the rake finger operate simultaneously. In this case, that is, when operating in the equalizer and the rake mode, the receiver always operates the equalizer and the rake together and measures each SINR to select the one having the best reception performance (equalizer or rake finger). That is, by selecting an equalizer or a rake finger that works together with the equalizer and the rake finger, the unselected one consumes unnecessary power. Thus, the conventional receiver not only increases the complexity of the system, but also greatly increases the power consumption. On the other hand, in the low SINR it is possible to operate only the rake mode, there is a technical limitation that the system operating choices are small and the benefits of the efficiency of the system is not large.

Accordingly, an object of the present invention is to provide a hybrid receiver capable of lowering the efficiency and power consumption of a system by configuring an equalizer and a rake finger in series to implement an efficient hybrid receiver.

In order to achieve the above object, a hybrid receiver according to the present invention is a hybrid receiver of a mobile communication system,

A channel search and channel estimator for detecting a multipath received signal for each rake finger and estimating a first channel of the received signal detected for each rake finger and a second channel and a third channel adjacent to the first channel; An equalizer for equalizing the first channel, the second channel, and the third channel detected and estimated by the channel search and channel estimator; An equalizer controller for controlling the equalizer on or off according to a channel state according to a channel state; And a finger processor for processing the received signal in a rake mode or a hybrid mode according to the on or off of the equalizer under the control of the equalizer controller.

Preferably, the first channel is a main path channel,

The second channel is an adjacent channel that is one-half chip ahead of the first channel,

The third channel may be an adjacent channel behind 1/2 chip of the first channel.

Advantageously, said channel search and estimator

An energy detector which calculates energy of a symbol obtained by processing the received signal; A phase detector for calculating a phase value of the symbol; And determining a multipath of the received signal and sending a multipath signal H Set to the equalizer.

Preferably, when the equalizer is On,

The equalizer calculates an inverse of a channel from the H set received from the multipath selector, and inputs it as an FIR filter coefficient to equalize RX data.

Preferably, when the equalizer is On,

The finger processor performs PN despreading, and channel estimation and phase compensation do not operate.

Preferably, when the equalizer is Off,

The equalizer sends only the h value corresponding to the first channel to the finger processor, and the equalizer does not operate.

Preferably, when the equalizer is Off,

The pinker processor may perform channel compensation after performing PN despreading.

Preferably, the equalizer and the finger processor are connected in series,

And a set comprising at least one of the equalizer and the finger processor for processing the multi-path received signal.

Preferably, when the equalizer is On, the hybrid mode,

When the equalizer is Off, it is characterized in that the rake mode.

Preferably, the equalizer controller

Calculating a sum of powers of the first channel and each channel of the second channel and the third channel, which are adjacent to the first channel,

Comparing the channel power sum of the first channel to the third channel with the value of the channel power of the first channel,

If the sum of the channel power is greater than the predetermined value compared to the value of the first channel power, the equalizer is controlled to On.

The equalizer may be controlled to be off when the sum of the channel powers is smaller than a preset value compared to the value of the first channel power.

In addition, the reception method of the mobile communication system according to the present invention in order to achieve the above object,

(A) Receiving a received signal received in a multipath via radio for each rake finger and estimating a first channel of the received signal detected for each rake finger and a second channel and a third channel adjacent to the first channel Making a step; (B) calculating power of the received first to third channels, and controlling the equalizer on or off for each rake finger based on the calculated result; (C) processing the received signal through the equalizer and the rake finger according to whether the equalizer is on or off; wherein the equalizer and the rake finger are connected in series.

Preferably, step (B) is

Calculating a sum of powers of the first channel and each channel of the second channel and the third channel, which are adjacent to the first channel;

Comparing a channel power sum of the first channel to the third channel with a value of the channel power of the first channel;

If the sum of the channel power is greater than the predetermined value compared to the value of the first channel power, the equalizer is controlled to On.

And controlling the equalizer to Off when the sum of the channel powers is smaller than a preset value relative to the value of the first channel power.

Preferably, in the step (B)

If the equalizer is On,

First to third channels, which are the received signals, are equalized by the equalizer and sent to the rake finger; And performing the PN despreading of the received signal at the Rake finger.

Preferably, in the step (B)

If the equalizer is Off,

Sending the first channel to the rake finger without the equalizer operating; The rake finger may further include performing PN despreading and channel compensation by receiving the first channel.

In the hybrid receiver according to the present invention, since the equalizer and the rake fingers are coupled in series, only the rake may be operated or the equalizer and the rake may be operated according to the channel environment to improve reception performance. This solves the performance degradation problem in the multipath environment of the vertical rake receiver and provides a way to reduce the total power consumption by operating the equalizer separately for each finger.

The present invention is applied to a hybrid receiver in a mobile communication system. However, the present invention is not limited thereto and may be applied to a receiver of wired and wireless communication to which the technical idea of the present invention can be applied.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms including ordinal numbers such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes any item of a plurality of related listed items or a plurality of related listed yields.

When an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may be present in between. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present disclosure does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and, unless expressly defined in this application, are construed in ideal or excessively formal meanings. It doesn't work.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The description will be omitted.

The basic concept of the present invention is a design technique for a hybrid receiver using an equalizer and a rake receiver, and equalizes a received signal of each path received in a multipath and front and rear adjacent signals of adjacent 1/2 chips according to channel conditions. PN despreading and channel compensation. In particular, the present invention does not equalize the entire band by connecting an equalizer and rake fingers in series, but equalizes each rake finger, i.e., a channel of each path and two adjacent channels (channels with the most interference) to receive in a hybrid mode. Alternatively, or by selectively operating as a conventional rake receiver, the performance of a mobile communication (eg WCDMA HSDPA) receiver is improved.

In addition, according to the present invention, the channel searcher used in the conventional rake receiver may serve as a half chip channel estimator as well as multipath detection so that the channel searcher may be used in the chip level equalizer. The chip-level equalizer operates independently for each rake finger and is designed so that the equalizer controller can choose rake mode or equalizer + rake mode (aka hybrid mode) based on channel conditions.

3 is a block diagram of a hybrid receiver in which an equalizer and a rake finger are coupled in series according to an embodiment of the present invention. Meanwhile, hereinafter, the channel searcher and the channel estimator 100 will be described as a channel searcher or a channel estimator according to their functions. In addition, the series of finger processors 300 performs the same function as the rake finger and at the same time receives and processes the equalized signal from each chip level equalizer. Therefore, the pinker processor may be described as a lake finger. In the embodiment of the present invention, for convenience of description, a description will be made based on a signal processed through one chip level equalizer and a corresponding finger processor.

Referring to FIG. 3, unlike the channel searcher of the conventional rake receiver, the channel searcher and the channel estimator 100 according to the present invention not only multipath detection but also serve as a 1/2 chip channel estimator, thereby providing a chip level equalizer 200. To be used in. The chip level equalizer operates independently of each rake finger 300 and is designed to allow the equalizer controller 400 to select a rake mode or an equalizer + a rake mode (hereinafter referred to as 'hybrid mode' for convenience) according to channel conditions. As shown in FIG. 3, signals through multipath detection and 1/2 chip channel estimation of a received signal received by the hybrid receiver of the present invention are input to each chip level equalizer 200. The equalized signal through each chip level equalizer 200 is processed (operated) independently in each finger processor 300.

4 is a diagram illustrating a channel searcher and a channel estimator according to an embodiment of the present invention. 4 is a block diagram illustrating in more detail the channel finder and the channel estimator 100 in FIG. 3.

Referring to FIG. 4, the channel search operates at half chip intervals for the maximum delay time and performs despreading using the CPICH channel. The SCICH generator generates a CPICH scramble code, descrambles the RX data, accumulates in a buffer for N symbols, and then calculates energy and phase values of the symbol in the channel estimator 100. In this case, the energy of the symbol is calculated by the energy detector 101, and the phase value of the symbol is calculated by the phase detector 102, respectively. The multipath selector 103 selects only paths of any size or more to determine the multipath. At this time, the equalizer controller 400 controls the on / off of the equalizer as it is determined to be multipath or not multipath. In more detail, the equalizer controller 400 includes two channels before and after the main path channel coming from the channel estimator 100 and 1/2 chip of the main path channel (that is, two channels before and after 1/2 chip). Is the channel with the greatest interference effect on the main path), plus the magnitude of the power (i.e., the value of the three channel powers) is greater than the random value relative to the main path (this value is determined by the experiment depending on the network environment). If it is large, it operates.

That is, when the equalizer 200 does not operate according to the command of the equalizer controller 400, the path h2 (that is, the main path) of one selected position is transferred to the rake finger 300, and when the equalizer operates. A total of three (h1 to h3) values are passed to the chip level equalizer 200 up to the path before and after the path (that is, the path before and after the 1/2 chip of the main path) to remove the interference between adjacent channels.

The chip level equalizer 200 performs a total channel response H received from the channel estimator 100 separately for each rake finger. When the entire received signal from the channel estimator is expressed in a matrix, Equation (1) is given.

When the received signal is divided into channel H set units, it can be expressed as in Equation (2). This method divides the matrix by allocating all three H channels and calculates the inverse matrix separately. In this case, the center h (e.g., h2 in one row of the H matrix in Equation (1)) is the main path and both h (e.g., h1 and one row in the H matrix in the Equation (1). h3 ) is a channel that is half a chip apart and is the most influential channel in the main path.

This allows the inverse and equalizer to be performed using only three adjacent channels. When the inverse matrix is obtained in this manner, the inverse matrix operation must be performed separately, which is different from the method of obtaining the inverse matrix for all channels at once. However, since the inverse is obtained by selecting only three h's, the total length of N may be made small. In addition, since the equalizer can be selected on and off for each rake finger according to the channel state, the amount of computation can be reduced overall. The equalizer may use any method such as zero forcing or LMMSE. Equation (4) shows an example of performing an equalizer for each rake finger using zero forcing.

5 illustrates an embodiment of a chip level equalizer according to the present invention. Hereinafter, the operation of the chip level equalizer in the on mode and the off mode will be described.

First, when the equalizer is in the on mode, the inverse matrix of the channel is calculated from the H set received from the multipath selector and inputted as an FIR filter coefficient to equalize the RX data. In the Rake finger, only PN despreading is performed and channel estimation and phase compensation do not operate.

Second, when the equalizer is in the Off mode, only the h value is passed to the rake finger, the equalizer is not operated, and channel compensation is performed after despreading at the rake finger and operates like the conventional rake receiver. Such a receiver is configured by the number of rake fingers and the equalizer controller 400 manages each ON or Off operation according to the channel state.

6 is an operational state diagram of the hybrid receiver according to the present invention. Referring to FIG. 6, the equalizer turns on or off the equalizer 200 according to a channel state from a channel coming from the channel estimator 100. When multipath channels such as ITU (International Telegraph Union) PA3 and PB3 channels exist within 1/2 chip and cannot be distinguished by rake fingers, the equalizer can be effectively compensated for. In the present invention, the equalizer operation method operates when the sum of the channel power magnitudes before and after the main path 1/2 chip is larger than an arbitrary value (this value is determined by experiment according to the network environment) compared to the main path. to be.

As an example of operation, a hybrid receiver in accordance with the present invention starts operation in an initial rake mode. In the H set made by the channel detector 100, when h2 is the main path of the channel and h1 and h3 are adjacent channels, when the power of h1 and h3 is measured to be α times greater than the h2 power, the equalizer + rake mode ( The equalizer is turned on to operate in so-called hybrid mode, and the hybrid mode state is maintained if the measured value is the same as above. On the other hand, when the power of the received adjacent channel drops below α times, the equalizer is turned off and operates only in the rake mode. The channel controller 400 operates each receiver independently to stop the equalizer 200 when the channel state is good, thereby reducing unnecessary power consumption. Here, the value of α is determined by experiment according to the network environment.

On the other hand, the method according to the invention described so far may be implemented in software, hardware, or a combination thereof. For example, the method according to the present invention may be stored in a storage medium (eg, mobile terminal internal memory, flash memory, hard disk, etc.) and may be stored in a processor (eg, mobile terminal internal microprocessor). It may be implemented as codes or instructions in a software program that can be executed by.

In the above, the present invention has been described with reference to the embodiments shown in the drawings, but this is merely exemplary, and those skilled in the art may realize various modifications and other equivalent embodiments therefrom. I will understand. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a block diagram of a conventional hybrid receiver.

2 is a state diagram illustrating an operation of implementing a rake and a hybrid equalizer in a conventional hybrid receiver.

3 is a block diagram of a hybrid receiver in which an equalizer and a rake finger are coupled in series according to an embodiment of the present invention.

4 is a diagram illustrating a channel searcher and a channel estimator according to an embodiment of the present invention.

5 illustrates an embodiment of a chip level equalizer according to the present invention.

6 is an operational state diagram of the hybrid receiver according to the present invention.

Claims (14)

In a hybrid receiver of a mobile communication system, A channel search and channel estimator for detecting a multipath received signal for each rake finger and estimating a first channel of the received signal detected for each rake finger and a second channel and a third channel adjacent to the first channel; An equalizer for equalizing the first channel, the second channel, and the third channel detected and estimated by the channel search and channel estimator; An equalizer controller for controlling the equalizer on or off according to a channel state according to a channel state; And a finger processor for processing the received signal in a rake mode or a hybrid mode according to the equalizer on or off under the control of the equalizer controller. The method of claim 1, The first channel is a main path channel, The second channel is an adjacent channel one-half chip ahead of the first channel, And the third channel is an adjacent channel behind one-half chip of the first channel. The channel search and estimator of claim 1, wherein the channel search and estimator An energy detector which calculates energy of a symbol obtained by processing the received signal; A phase detector for calculating a phase value of the symbol; And a multipath selector for determining the multipath of the received signal and sending the multipath signal H Set to the equalizer. The method of claim 3, If the equalizer is On, And the equalizer calculates an inverse of a channel from the H set received from the multipath selector, and inputs it as an FIR filter coefficient to equalize RX data. The method of claim 4, wherein If the equalizer is On, And the finger processor performs PN despreading and channel estimation and phase compensation do not operate. The method of claim 3, If the equalizer is Off, And the equalizer sends only the h value corresponding to the first channel to the finger processor, and the equalizer does not operate. The method of claim 6, If the equalizer is Off, The pinker processor performs channel compensation after performing PN despreading. The method of claim 1, The equalizer and the finger processor are connected in series, And a set comprising at least one of the equalizer and the finger processor for processing the multi-path received signal. The method of claim 1, If the equalizer is On, the hybrid mode, And if the equalizer is Off, it is in a rake mode. The method of claim 1, wherein the equalizer controller Calculating a sum of powers of the first channel and each channel of the second channel and the third channel, which are adjacent to the first channel, Comparing the channel power sum of the first channel to the third channel with the value of the channel power of the first channel, If the sum of the channel power is greater than the predetermined value compared to the value of the first channel power, the equalizer is controlled to On. And if the sum of the channel powers is smaller than a predetermined value compared to the value of the first channel power, controlling the equalizer to Off. (A) Receiving a received signal received in a multipath via radio for each rake finger and estimating a first channel of the received signal detected for each rake finger and a second channel and a third channel adjacent to the first channel Making a step; (B) calculating power of the received first to third channels, and controlling the equalizer on or off for each rake finger based on the calculated result; (C) processing the received signal through the equalizer and the rake finger according to the on or off of the equalizer; And the equalizer and the rake finger are connected in series. The method of claim 11, wherein step (B) Calculating a sum of powers of the first channel and each channel of the second channel and the third channel, which are adjacent to the first channel; Comparing a channel power sum of the first channel to the third channel with a value of the channel power of the first channel; If the sum of the channel power is greater than the predetermined value compared to the value of the first channel power, the equalizer is controlled to On. And controlling the equalizer to be off when the sum of the channel powers is smaller than a predetermined value compared to the value of the first channel power. The method of claim 11, wherein in the step (B) If the equalizer is On, First to third channels, which are the received signals, are equalized by the equalizer and sent to the rake finger; And performing the PN despreading of the received signal at the rake finger. The method of claim 11, wherein in the step (B) If the equalizer is Off, Sending the first channel to the rake finger without the equalizer operating; And receiving the first channel to despread the PN and perform channel compensation.

Images