KR20120071920A - Method and apparatus for processing single for initial ranging - Google Patents

Abstract

The transmitting end down-samples and transmits an initial ranging signal processed using a K-size fast fourier transform (FFT) engine for transmitting a data signal, and the receiving end demultiplexes the received signal to even-numbered initial ranging signals. Split into the first initial ranging signal. Each separated initial ranging signal is processed using a K-size FFT engine.

Description

An apparatus and method for initial ranging signal processing in a wireless communication system {method and apparatus for processing single for initial ranging}

The present invention relates to a signal processing device, and more particularly, to an apparatus and a method for processing an initial ranging signal in a wireless communication system.

The orthogonal frequency division modulation access / time division duplexing (OFDMA / TDD) scheme converts a high speed data signal into a low speed data signal and transmits and receives data through a subchannel composed of a plurality of subcarriers. In the OFDMA / TDD scheme, the downlink transmits a signal to a plurality of users at the base station at the same time. Each user data signal is allocated to several subchannels and processed as a downlink signal. At this time, all subcarriers of the signals transmitted from the base station undergo the same time delay and reach each user terminal simultaneously, thereby maintaining orthogonality between the subcarriers.

However, in the case of uplink, due to independent propagation delay time and relative position difference between each terminal, absolute time synchronization does not coincide with data signals from each terminal reaching the base station, which may possibly break orthogonality between subcarriers. have. Therefore, if the absolute time synchronization between the uplink signals transmitted from the terminals do not match, signal orthogonality is broken between subcarriers coming from a plurality of terminals, so that the data cannot be recovered when demodulating the signal received at the base station. This can lead to loss of data signal. In order to solve this problem, the base station measures a time error based on a ranging signal transmitted from each terminal and informs the terminal through an uplink ranging procedure, so that the terminal transmits a signal according to the base station reference time. It is possible to offset the propagation time error between each terminal.

In order to measure an uplink time error between the terminal and the base station, each terminal generates a random ranging code and transmits it to the base station through a ranging channel, and the signals received at the base station through the lasing channel have independent time delays. Undergoing phase appears in a modulated form. The base station measures a correlation value of all random ranging codes provided from the terminals and finds a maximum value, thereby searching for a time error with respect to the base station reference time of each terminal and a corresponding ranging code.

과 데이터 부반송파 스페이싱

이 동일하기 때문에, 동일한 사이즈의 FFT(fast fourier transform) 엔진을 사용하여 초기 레인징 수신 검출을 할 수 있었지만, 802.16m 기반 초기 레인징 신호는 종래의 사용되던 방식과 다르게 초기 레인징 부반송파 스페이싱

과 데이터 부반송파 스페이싱

의 차이로 인해 동일한 사이즈의 FFT 엔진을 함께 사용하기 어렵다는 단점이 있다.However, when the initial ranging signal is detected in the conventional ranging procedure, the initial ranging subcarrier spacing

And data subcarrier spacing

Since this is the same, initial ranging reception detection can be performed using a fast fourier transform (FFT) engine of the same size, but the initial ranging subcarrier spacing is different from that of the conventional 802.16m-based initial ranging signal.

And data subcarrier spacing

Due to this difference, it is difficult to use the same size FFT engine together.

SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus and method capable of processing both an initial ranging channel signal and a data channel signal having different subcarrier spacings in a wireless communication system.

Another object of the present invention is to provide an apparatus and a method capable of processing both an initial ranging channel signal and a data channel signal using an FFT engine having the same size.

According to an aspect of the present invention for the above object, in the method for receiving and processing the initial ranging signal, the received initial ranging signal--the initial ranging signal is the down-sampled and sampled values of the transmitter Receiving a signal formed based on an average value; Demultiplexing the received signal and separating the first signal into a first ranging reception value corresponding to an odd initial ranging signal and a second ranging reception value corresponding to an even initial initial ranging signal; FFT processing and outputting the first ranging reception value and the second ranging reception value using a fast fourier transform (FFT) engine of size K, and performing correlation with the generated ranging codes to output correlation values. step; And detecting a maximum value among the correlation values and finding a time error value corresponding to the detected maximum value and a ranging code value at that time.

According to an embodiment of the present invention, it is possible to process both an initial ranging channel signal and a data channel signal having different subcarrier spacings, and in particular, an initial ranging channel signal and a data channel using an FFT engine of the same size. It can process all signals of.

Therefore, the FFT engine size difference caused by the subcarrier spacing difference can be overcome, thereby preventing unnecessary waste of hardware system resources and reducing the complexity of the system design.

1 is a diagram illustrating a frame structure of an initial ranging signal according to an embodiment of the present invention.
2 is a diagram illustrating a structure of a general processing apparatus for uplink initial ranging transmission and reception processing.
3 is a structural diagram of an initial ranging signal processing apparatus according to an embodiment of the present invention.
4 is a diagram illustrating an example of a signal processed by a signal interpolator according to an exemplary embodiment of the present invention.
5 is a diagram illustrating an initial ranging signal processing method according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, except to exclude other components unless specifically stated otherwise.

Hereinafter, an initial ranging signal processing apparatus and method thereof of a wireless communication system according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

According to an embodiment of the present invention, a signal of an initial ranging channel and a signal of a data channel are different from each other (for example, in an 802.16m based wireless communication system, a signal of an initial ranging channel, that is, an initial ranging signal, Although an example of processing a signal of a data channel, that is, a data signal, will be described as an example, the present invention is not necessarily limited thereto, and the present invention can be applied to the case where the initial ranging signal and the data signal have the same subcarrier spacing.

A method and apparatus for measuring a time error and a ranging code by processing an uplink initial ranging signal in an orthogonal frequency division multiplexing access (OFDMA) / time division duplex (TDD) scheme.

1 is a diagram illustrating a frame of an uplink initial ranging signal in a wireless communication system according to an exemplary embodiment of the present invention.

을 포함하고, 초기 레인징 심볼 구간

앞에 레인징 사이클릭 프리픽스(Cyclic Prefix) 구간

이; 위치되는 형태로 이루어진다. As shown in FIG. 1, the frame of the uplink initial ranging signal includes two initial ranging symbol intervals in which the initial ranging signal is transmitted.

Including, the initial ranging symbol interval

Ranged before Cyclic Prefix section

this; In the form of being located.

동안 레인징 사이클릭 프리픽스가 전송되고 이어서 두개의 초기 레인징 심볼 구간

동안 초기 레인징 신호가 반복되어 전송된다. Ranging cyclic prefix interval

Ranging cyclic prefix is transmitted followed by two initial ranging symbol intervals.

During the initial ranging signal is repeatedly transmitted.

구간은 하나의 데이터 심볼 구간

의 2배이며, 레인징 사이클릭 프리픽스 구간

은 다음과 같이 나타낼 수 있다. Initial ranging symbol interval

Interval is one data symbol interval

Is twice the ranging cyclic prefix interval

Can be written as

[Equation 1]

은 (N_sym+1)/2이고

는 (N_sym-4)/2이다. N_sym은 하나의 서브 프레임을 구성하는 OFDMA 심볼 개수를 나타낸다. Where T _g represents the data cyclic prefix interval,

Is (N _sym +1) / 2

Is (N _sym -4) / 2. N _sym represents the number of OFDMA symbols constituting one subframe.

과 데이터 신호들간의 데이터 부반송파 스페이싱

이 다르다. 예를 들어, 초기 레인징 부반송파 스페이싱

이 데이터 부반송파 스페이싱

의 0.5배이다. 이것은 OFDM 변조를 위해 사용되는 FFT 엔진의 사이즈가 다르다는 것을 의미한다.Initial ranging subcarrier spacing between initial ranging signals transmitted from each terminal

Data subcarrier spacing between data and data signals

This is different. For example, initial ranging subcarrier spacing

Spacing this data subcarrier

0.5 times This means that the size of the FFT engine used for OFDM modulation is different.

2 is a diagram illustrating a structure of a general processing apparatus for uplink initial ranging transmission and reception processing.

과 데이터 부반송파 스페이싱

의 차이로 인해, 초기 레인징 신호를 OFDM 변조하기 위해서는 데이터 신호를 OFDM 변조하기 위해 사용되는 K 사이즈의 IFFT 엔진보다 2배 더 큰 2K 사이즈의 IFFT(2)을 이용하여 초기 레인징 코드 생성기(1)에서 생성되는 초기 레인징 신호를 변조하여 송신한다. 그리고 수신 측에서도 초기 레인징 신호를 복조하기 위해 2K 사이즈 FFT(3)을 이용하여 복조를 한다. 초기 레인징 신호는 FFT(3)에 의하여 처리된 다음에 상관기(5)에 의하여 초기 레인징 코드 생성기(4)로부터의 레인징 코드와 상관 처리되어 출력된다. 이는 송수신 장치에서 초기 레인징 처리를 위해 2K 사이즈의 FFT 엔진과 데이터 신호 처리를 위해 K 사이즈의 FFT 엔진을 모두 갖추고 있어야 한다는 것을 의미한다. 이러한 경우에는 하드웨어 구현 시 불필요한 시스템 자원의 낭비를 초래하고, 각 엔진을 운용하기 위하여 좀 더 복잡한 구성이 요구된다. Initial ranging subcarrier spacing

And data subcarrier spacing

Due to the difference, the initial ranging code generator 1 using the 2K size IFFT 2, which is twice as large as the K size IFFT engine used for OFDM modulation of the initial ranging signal, is used for OFDM modulation. Modulates and transmits an initial ranging signal. The receiver also demodulates using the 2K size FFT 3 to demodulate the initial ranging signal. The initial ranging signal is processed by the FFT 3 and then correlated with the ranging code from the initial ranging code generator 4 by the correlator 5 to be output. This means that the transceiver should have both a 2K size FFT engine for initial ranging and a K size FFT engine for data signal processing. In this case, hardware implementation wastes unnecessary system resources, and a more complicated configuration is required to operate each engine.

In an embodiment of the present invention, a K-size FFT engine used for data signal processing is also used for initial ranging signal processing.

3 is a structural diagram of an initial ranging signal processing apparatus according to an embodiment of the present invention.

As shown in FIG. 3, an initial ranging signal processing apparatus according to an embodiment of the present invention includes a ranging signal transmission processor 10 and a ranging signal reception processor 20. Here, although the initial ranging signal processing apparatus is illustrated as including the ranging signal transmission processing unit 10 and the ranging signal receiving processing unit 20, the ranging signal transmission processing unit 10 or the ranging signal reception is different. The processor 20 may be implemented in a form including one.

The ranging signal transmission processor 10 includes a ranging signal generator 11, an FFT unit 12, and a signal interpolation unit 13 that generate a ranging signal.

The signal generator 11 generates an initial ranging code, and the generated initial ranging code is modulated and then serial-to-parallel converted to be input to the IFFT unit 12.

The IFFT unit 12 performs an IFFT operation on the initial ranging code and outputs it. The IFFT section 12 has a size of K, which indicates that the number of input points is K.

The signal interpolator 13 performs signal interpolation on the signal output from the IFFT unit 12. Specifically, the signal interpolated by double down sampling the signals output from the IFFT unit 12 and sampling The average value is taken and output as the final signal.

)을 구하여 최종 신호로 출력한다. 4 is a diagram illustrating an example of a signal processed by the signal interpolator 13 according to an exemplary embodiment. As shown in FIG. 4, the signal interpolation unit 13 inputs x (t ₁ ), x (t ₂ ),. 2 times down sampling at x (t _n ), for example, x (t ₁ ), x (t ₃ ),. The average value of the signals obtained according to the acquisition and sampling (e.g.,

) Is output as the final signal.

On the other hand, the ranging signal receiving processing unit 20 is the demultiplexer 21, the K size FFTs 22 and 23, the correlators 24 and 25, the initial ranging code generator 26, and the K size FFTs 27, 28) and a peak detector 29.

The demultiplexer 21 separates and outputs a reception value corresponding to an odd initial ranging signal and a reception value corresponding to an even initial initial ranging signal. Hereinafter, for convenience of description, a reception value corresponding to an odd initial ranging signal is referred to as a “first ranging reception value”, and a reception value corresponding to an even initial initial ranging signal is referred to as a “second ranging reception value”. Name it.

The FFTs 22 and 23 have a size of K, and FFT processes and outputs the first ranging reception value and the second ranging reception value, respectively. Here, the FFTs 22 and 23 are K size FFT engines used for existing data modulation.

The initial ranging code generator 26 generates ranging codes, and the correlators 24 and 25 correlate and output the ranging codes and the values output from the FFTs 22 and 23, respectively, and the FFTs 27 and 28. ) FFT processes the values output from the correlators 24 and 25 and outputs correlation values of random ranging codes.

The peak detector 29 detects a maximum value among the correlation values of the random ranging codes, and finds a time error value corresponding to the detected maximum value and a ranging code value at that time.

Next, a signal processing method according to an embodiment of the present invention will be described based on such a structure.

5 is a diagram illustrating an initial ranging signal processing method according to an embodiment of the present invention.

The base station generates a predetermined number of initial ranging codes and assigns them to the terminals for ranging, and the terminal selects one of the allocated ranging codes and transmits the same to the base station.

The terminal modulates and transmits the selected ranging code, and the initial ranging signal is transmitted over two consecutive symbol intervals, as shown in FIG. 1. That is, the terminal transmits an initial ranging signal during two consecutive symbol intervals, and the base station measures how much time error has occurred with respect to the base station reference time for the signal transmitted from the terminal during the two symbol intervals.

That is, the ranging signal transmission processing unit 10 of the terminal interpolates the ranging signal output by the IFFT process to double downsampling, takes the average value of the sampled values, and outputs the final signal as the final signals (S100 and S110).

The ranging signal transmitted as described above is received by the ranging signal receiving processing unit 20 of the base station, and the ranging signal receiving processing unit 20 receives the ranging code and the code of the ranging code generated by the base station itself. Find the correlation value.

In detail, the ranging signal receiving processor 20 demultiplexes the received signal to generate a first ranging reception value corresponding to an odd initial ranging signal and a reception value corresponding to an even initial initial ranging signal. It is separated into two ranging reception values (S120, S130).

In addition, the first ranging reception value and the second ranging reception value are output by FFT using a K-size FFT engines 22, 23, 27, and 28, and the random ranging is performed by performing correlation with the generated ranging code. The correlation values of the ranging codes are output (S140).

Next, the ranging signal receiving processor 20 detects a maximum value among the correlation values of the random ranging codes (S150), and finds a time error value corresponding to the detected maximum value and the ranging code value at that time (S160). .

As described above, although the initial ranging signal received for the time error measurement of the initial ranging signal was separated and processed in parallel, since the initial ranging measurement does not require real time, the initial ranging signal is sequentially received in series. It can also be processed in turn. In the case of serial processing in this way, hardware resources can be used more effectively.

In addition, the transmitter may transmit the initial ranging signal using the K-size FFT engine as described above, but may transmit the initial ranging signal using the existing 2 X K-size FFT engine. In this case, there is no change in the initial ranging signal processing method and apparatus at the receiving side.

The embodiments of the present invention are not limited to the above-described apparatuses and / or methods, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention, a recording medium on which the program is recorded And such an embodiment can be easily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims (1)

In the method for receiving and processing the initial ranging signal,
Receiving a received initial ranging signal, wherein the initial ranging signal is a signal formed based on an average of downsampled and sampled values at a transmitting end;
Demultiplexing the received signal and separating the first signal into a first ranging reception value corresponding to an odd initial ranging signal and a second ranging reception value corresponding to an even initial initial ranging signal;
FFT processing and outputting the first ranging reception value and the second ranging reception value using a fast fourier transform (FFT) engine of size K, and performing correlation with the generated ranging codes to output correlation values. step; And
Detecting a maximum value among the correlation values and finding a time error value corresponding to the detected maximum value and a ranging code value at that time
Including, the initial ranging signal processing method.

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