KR100819124B1 - Apparatus and method for detecting frame preamble in wireless broadband system - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to an apparatus and method for detecting a frame preamble in a portable internet system.

2. The technical problem to be solved by the invention

According to the present invention, a first correlation value in which a first predetermined number (for example, 256 samples) and a last predetermined number (for example, 256 samples) of the received samples are correlated in reverse order, the first predetermined number of samples, and the last predetermined number By detecting the frame preamble using the ratio of the second correlation value which is automatically summed after the number of samples, the frame preamble detection of the portable Internet system enables frame synchronization to be obtained even in the no-signal transmission interval. To provide a device and a method thereof.

3. Summary of Solution to Invention

According to an aspect of the present invention, there is provided a frame preamble detection apparatus of a portable Internet system, comprising: storage means for storing a predetermined number of samples received; The first correlation value and the first predetermined number of samples and the last predetermined number of samples, which are correlated in the reverse order of the first predetermined number of samples and the last predetermined number of samples stored in the storage means, are sequentially added. Correlation ratio calculating means for calculating a correlation ratio of the correlated second correlation values; And preamble detection means for detecting a frame preamble as a correlation ratio (value) calculated by the correlation ratio calculation means is located within a threshold section.

4. Important uses of the invention

The present invention is used in the portable Internet system.

Portable Internet, Preamble Detection, Correlation, Correlation Rate, Threshold Interval, Synchronization

Description

Apparatus and method for detecting frame preamble in wireless broadband system for portable internet system             

1 is an exemplary view showing a result of IFFT processing of a received signal in a conventional portable Internet system;

2 is a configuration diagram of an apparatus for detecting a frame preamble in a conventional portable Internet system;

3 is a flowchart illustrating a method of detecting a frame preamble in a frame preamble detection apparatus of a conventional portable Internet system;

4 is an exemplary view illustrating a signal-free transmission interval existing between uplink and downlink in a conventional portable Internet system;

5 is an exemplary view illustrating a preamble detection result in a preamble detection apparatus of a conventional portable Internet system.

FIG. 6 is a diagram illustrating an embodiment of a preamble symbol except for a CP (Cylic Prefix) used in the present invention. FIG.

7 is a configuration diagram of an embodiment of a preamble detection apparatus for a portable Internet system according to the present invention;                 

8 is a detailed configuration diagram of an embodiment of a correlation ratio calculator of a preamble detection apparatus according to the present invention;

9 is a diagram illustrating an example of a correlation process of a first correlator of a correlation ratio calculator according to the present invention;

10 is a flowchart illustrating a method of detecting a frame preamble in a preamble detection apparatus of a portable Internet system according to the present invention;

11 to 14 are diagrams illustrating output characteristics of a frame preamble detection apparatus of a portable Internet system according to the present invention.

* Explanation of symbols for the main parts of the drawings

70: transceiver unit 71: storage unit

72: correlation ratio calculation unit 73: preamble detection unit

74: switch control unit 75: switch

81: first correlator 82: adder

83: second correlator 84: correlation ratio operator

The present invention relates to an apparatus and method for detecting a frame preamble in a mobile Internet system. More particularly, the present invention relates to a first predetermined number (for example, 256) samples and a final predetermined number (for example, 256) samples of input samples. For detecting the frame preamble using a ratio of the first correlation value correlated in the reverse order, the first predetermined number of samples and the last predetermined number of samples, and then the second correlation value correlated with each other. An apparatus and method for detecting frame preamble in a system are provided.

In the present invention, the portable Internet system will be described with an example of an Orthogonal Frequency Division Modulation / Multiplexing Access (OFDMA) / TDD (Time Division duplex) scheme.

With the integration of wired and wireless networks, the demand for services that require video services, internet broadcasting services, and large database access technologies is increasing with the increase of personal mobility and the emergence of various application services.

Therefore, in the next generation mobile communication system, it is possible to transmit / receive hundreds of Mbps ultra high speed data using 2 ~ 60GHz band, effectively adapt to the time-varying wireless channel, and provide data symmetrically and asymmetrically according to the characteristics of traffic. There is a demand for high-quality, high-capacity, high-speed multimedia communication technology.

In addition, as an initial model for the next generation of mobile communication, wireless internet services that can provide services to anyone, anywhere at any time, are attracting attention. Existing mobile communication systems have high limitations in providing high-speed wireless Internet due to various problems such as high base station construction cost, high usage rate of wireless Internet, and small screens of terminals, resulting in limitation of contents that can be provided.                         

In addition, wireless LAN (Local Area Network) technology using the Industrial Scientific and Medical Equipment (ISM) band is possible for a home LAN, but also has limitations in providing public services due to radio interference and narrow coverage. For this purpose, there is an urgent need for a high-speed portable Internet system capable of providing a seamless service while supporting a cell size larger than a wireless LAN and supporting low to medium speed mobility.

In order to meet these demands, the proposed mobile Internet is located in the middle of WLAN and mobile communication-based wireless Internet, and has the advantages of both services. It means a service that can access and obtain various information and contents at high speed through access.

The portable Internet is expected to play a role as a catalyst to form a new market other than the market formed by each wireless LAN and mobile communication according to service characteristics or to lead convergence of wired and wireless communication services toward the ubiquitous era in the future.

In Korea, the 2.3GHz band used for the wireless subscriber network (WLL) will be used for the mobile Internet service. Accordingly, the Korea Information and Communication Technology Association (TTA) has standardized the 2.3GHz mobile Internet service.

On the other hand, it is a concept that enables high-speed data transmission by accessing the wireless internet anytime and anywhere even in the state of stopping and moving, and aims to support the transmission speed of up to 3Mbps or more per subscriber regardless of indoor or outdoor. The research and development trends of core technologies required by the system are as follows.

First, in the duplex method, the frequency division duplex (FDD) method requires a guard band of about 30 to 40 MHz between the uplink band and the downlink band, and the time division duplex (TDD) method reduces link budget corresponding to 3 dB and There is a need for a guard time that can absorb round trip delay between uplink (UL) and downlink (DL). In addition, since the TDD scheme uses the same frequency for uplink and downlink, the uplink and downlink channels are reversible, so that the concept of MIMO (Multi Input Multi Output), smart antenna, etc. can be effectively introduced to increase the frequency usage efficiency. There is an advantage that can be efficiently used in the up and down asymmetric traffic according to the amount of data required in.

In the modulation and coding coding scheme, an OFDM (Othogonal Frequency Division Modulation) scheme suitable for wideband transmission, which can simplify the equalizer by eliminating interference between adjacent symbols of a signal, and a multi-coding scheme for each subcarrier constituting the OFDM signal. Detailed techniques for applying modulation schemes such as Binary Phase Shift Keying (BPSK) / Quadrature Phase Shift Keying (QPSK) / 16 Quadrature Amplitude Modulation (16QAM) / 64 Quadrature Amplitude Modulation (64QAM) have been proposed. This means an adaptive modulation scheme in which a modulation scheme is applied differently according to channel conditions.

In addition, in the multiple access technology, time division multiplexing access (TDMA), frequency division multiplexing access (FDMA), orthogonal frequency division multiplexing access (OFDMA) employing frequency hopping is compared and studied and implemented. OFDMA is known to have an advantage over TDMA in terms of budget and granularity. In addition to improving the frequency usage efficiency by using a smart antenna, a method of using both Space Division Multiplexing Access (SDMA), TDMA, and FDMA has been proposed, and a cell plan using a multi-access technology such as frequency hopping OFDMA and TDMA is proposed. The way to make it easy and easy is also researched and suggested.

In addition, in the channel encoding for reliable data transmission, a hybrid ARQ that can improve the performance of the system by combining coding schemes such as low density parity check (LDPC) and convolutional turbo code (CTC), modulation and coding schemes. We are researching and suggesting methods such as (Automatic Repeat reQuest).

In addition, researches and proposals have been made on a system architecture for fast and accurate channel estimation and compensation in the physical layer, power control, and fast handoff support in a high-speed Internet service in a high-speed terminal mobility state.

In addition, in service quality, a link budget improvement method for supporting a transmission speed of a portable Internet service in a hot spot area and a suburban area outside the city center has been researched and proposed. In addition, various types of IP-based wireless data services provided by the wired Internet can be used to express streaming video, FTP, mail, and chat in a multi-cell environment while guaranteeing a specified quality of service (QoS). A method for supporting system throughput and QoS has been researched and proposed.

In addition, in system technology, the aim is to provide broadband packet data service at a much lower price than existing cellular systems, and to reduce the cost of base station and wireless network construction in consideration of IP-based service. Design is also researched and proposed.

In addition, in supporting mobile Internet services, OFDMA can efficiently and variably allocate radio link resources of granular OFDMA based on a channel structure, and provide multiple states (on, hold, sleep) and Fast transitions based on QoS state, optimization to support non-conflict between multiple users, fast ARQ and low latency to support interactive application services (game, VoIP, etc.) In addition, researches and proposals for supporting multiple scheduling that can easily execute QoS, and research on media access control for various multiple access channels other than OFDMA have been conducted.

In addition, in order to support mobile Internet service, it is smart to increase high spectral efficiency and capacity, and to increase system capacity efficiency by frequency reuse in a multi-input multi output (MIMO) system and adjacent cells. A system that combines the use of an antenna (Smart ANT) has been researched and suggested.

On the other hand, the domestic portable Internet technology is the wireless access system standard, and the multiplexing method adopts the TDD method, and the channel bandwidth is 10MHz, and the OFDMA method is selected as the multiple access method. In addition, as a prerequisite, the transmission rate per subscriber was set at a maximum of 1 Mbps for a minimum of 128 kbps and a maximum of 3 Mbps for a lower 512 kbps. The frequency reuse factor was 1 and the maximum frequency efficiency was defined as 6bps / Hz / Cell and 2bps / Hz / Cell, respectively. In addition, handoff set the maximum travel speed to 60km / h and 150ms or less for the time when packet transmission was interrupted. In addition, service coverage is divided into 100m picocell, 400m microcell, and 1km macrocell in urban areas.

The time division duplex (TDD) technology supports bidirectional transmission using the same frequency band, unlike the FDD scheme that uses different frequency bands for uplink and downlink for bidirectional communication. Theoretically, the same data rate support is possible using fewer timeslots than Frequency Division Duplex (FDD), and the dynamic allocation of timeslots is suitable for the transmission of asymmetric or bursty applications. In addition to its characteristics, TDD technology has become a very attractive technology for service providers who want to provide inexpensive wireless Internet service because it can provide service at 1/2 frequency and eventually at 1/2 price compared to FDD.

Meanwhile, in the preamble mapping method set in the portable Internet standard, an inverse fast fourier transform (IFFT) is performed by inserting a preamble signal into an even subcarrier among all subcarriers and inserting a null signal into an odd subcarrier. do. At this time, the result shows that two repeating patterns occur as shown in FIG. 1.

Here, referring to FIG. 2, the frame preamble detection apparatus of the conventional portable Internet system, the frame preamble detection apparatus of the conventional portable Internet system, has a predetermined number (for example, 1024 received from the transceiver 20). Storage unit 21 for storing samples), and a first correlation value of the first 512 samples and the last 512 samples of the 1024 samples from the storage unit 21 and the last 512 samples autocorrelate A correlation ratio calculator 22 for calculating a ratio of the second correlation value, a signal / noise detector 23 for detecting whether a sample calculated by the correlation ratio calculator 22 is a signal or noise, and the signal / noise And a preamble detection unit 24 for detecting the preamble using the correlation ratio (value) calculated by the correlation ratio calculation unit 22 as the detection result from the detection unit 23 is a signal.

Here, the switch control unit 25 controls the switch 26 to synchronize the frame according to the preamble detection signal from the preamble detection unit 24.

In addition, the switch control unit 25 further performs a function of resetting the frame preamble detection device when the preamble detection signal is not received from the preamble detection unit 24 at a predetermined time interval.

Meanwhile, referring to FIG. 3, the preamble detection method in the frame preamble detection apparatus of the conventional portable Internet system will first store a predetermined number (1024) of samples sequentially (301).

Subsequently, a first correlation value is calculated by correlating the first 512 samples and the last 512 samples among the 1024 samples using Equation 1 below (S302).

Subsequently, a second correlation value is calculated by autocorrelating the last 512 samples using Equation 2 below (303).

Thereafter, the ratio of the first correlation value and the second correlation value is calculated using Equation 3 below (304).

Thereafter, the frame preamble is detected using the calculated correlation ratio (value) (305). At this time, the preamble detection result is as shown in FIG. Here, the flat portion on the graph is generated by CP (Cyclic Prefix), the end portion of the flat portion is the point where the preamble ends.

Where n is an arbitrary integer and R (n) is a signal received at any time n.

The apparatus for detecting a frame preamble of the conventional portable Internet system, as shown in FIG. 4, can detect the frame preamble normally even if there is a repetitive pattern when a signalless transmission interval is included between the uplink and the downlink. There was no problem.

In addition, the frame preamble detection apparatus of the conventional portable Internet system detects the frame preamble using a plurality of adders and multipliers as shown in [Table 1], and thus has a problem of increasing complexity.

The present invention has been proposed to solve the above problems, and includes a first correlation value in which the first predetermined number (for example, 256 samples) and the last predetermined number (for example, 256 samples) of the received samples are correlated in reverse order. The frame preamble is detected by using the ratio of the second correlation value that is auto-correlated after the first predetermined number of samples and the last predetermined number of samples are sequentially added, thereby enabling frame synchronization to be obtained even in a no-signal transmission interval. An object of the present invention is to provide an apparatus and method for detecting a frame preamble in a portable Internet system.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

According to an aspect of the present invention, there is provided a frame preamble detection apparatus of a portable Internet system, comprising: storage means for storing a predetermined number of samples received; The first correlation value and the first predetermined number of samples and the last predetermined number of samples, which are correlated in the reverse order of the first predetermined number of samples and the last predetermined number of samples stored in the storage means, are sequentially added. Correlation ratio calculating means for calculating a correlation ratio of the correlated second correlation values; And preamble detection means for detecting a frame preamble as the correlation ratio (value) calculated by the correlation ratio calculation means is located within a threshold section.

On the other hand, the method of the present invention, frame preamble detection method in a preamble detection device of a portable Internet system, the method comprising: a sample storing step of sequentially storing a predetermined number of samples; Calculating a first correlation value by correlating a first predetermined number of samples and a last predetermined number of samples from each other in reverse order; A sample summing step of sequentially summing the first predetermined number of samples and the last predetermined number of samples; Calculating a second correlation value by autocorrelating the sum of the predetermined number of samples; Calculating a ratio of the first correlation value and the second correlation value; And a frame preamble detection step of detecting a frame preamble as the calculated correlation ratio (value) is located within a threshold section.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

7 is a configuration diagram of an apparatus for detecting frame preamble in the portable Internet system according to the present invention.

As shown in FIG. 7, the frame preamble detection apparatus of the portable Internet system according to the present invention includes a storage unit 71 for storing a predetermined number (for example, 1024) samples received from the transceiver unit 70. The first correlation value and the first 256 samples and the last 256 samples in the reverse order of the first 256 samples and the last 256 samples of the 1024 samples from the storage unit 71, and then auto-correlation Preamble for detecting the frame preamble as the correlation ratio calculation unit 72 for calculating the correlation ratio of the second correlation value, and the correlation ratio (value) calculated by the correlation ratio calculation unit 72 are located within the threshold section. The detector 73 is included.

를 포함한다.Here, the threshold interval X is an example.

It includes.

In addition, the switch control unit 74 controls the switch 75 to synchronize frame according to the preamble detection signal from the preamble detection unit 73.

In addition, the switch control unit 74 further performs a function of resetting the frame preamble detection device when the preamble detection signal is not received from the preamble detection unit 73 at a predetermined time interval.

On the other hand, the preamble detection unit 73 is the third ratio (value) of the ratio (value) in the threshold interval generated six per frame as the correlation calculation ratio (value) from the correlation ratio calculation unit 72 is located in the threshold interval ) May be determined as the start point of the preamble, and the preamble may be detected by determining the sixth ratio (value) as the end point of the preamble.                     

8 is a detailed block diagram of an embodiment of a correlation ratio calculator of a frame preamble detection apparatus according to the present invention.

As shown in FIG. 8, the correlation ratio calculating unit 72 of the frame preamble detection apparatus according to the present invention uses the following [Equation 4] to select the first 256 samples and the last 256 samples of 1024 samples. A first correlator 81 for correlating each other in reverse order to calculate a first correlation value, and an adder 82 for sequentially summing the first 256 samples and the last 256 samples using Equation 5 below. Using a second correlator 83 for calculating a second correlation value by autocorrelating 256 samples added by the adder 82 using Equation 6 below, and using Equation 7 below. And a correlation ratio calculator 84 for calculating a ratio of the first correlation value and the second correlation value.

Here, the adder 82 prevents Equation 6 below from being mathematically 'disabled', that is, zero, when calculating a correlation ratio in Equation 7 below.

는 1024를 의미한다.
Where

Means 1024.

In addition, the complexity of the frame preamble detection apparatus of the portable Internet system according to the present invention is shown in Table 2 below.                     

6 and 9, a process in which the first correlator 81 correlates the first 256 samples and the last 512 samples of the 1024 samples in reverse order to calculate a first correlation value will be described in more detail. Let's do it.

6 and 9, it can be seen that the first 512 samples are repeated for the input 1024 samples. Accordingly, the first correlator 81 correlates the first input of the first 256 samples (a) and the first input of the 256 samples (c '), and the second of the first 256 samples. The inputted sample b is correlated with the 255th input sample b 'of the last 256 samples.

The first correlation value is calculated by adding up all 256 results correlated in this manner.

10 is a flowchart illustrating a method for detecting a frame preamble in the apparatus for detecting a frame preamble in the portable Internet system according to the present invention.

First, a predetermined number (1024) of samples are sequentially stored (1001).

Thereafter, a first correlation value is calculated by correlating the first 256 samples and the last 256 samples of the 1024 samples in reverse order to each other (1002).

Thereafter, the first 256 samples and the last 256 samples are sequentially added (1003).

Thereafter, the sum of the 256 samples is autocorrelated to calculate a second correlation value (1004).

Thereafter, a ratio of the first correlation value and the second correlation value is calculated (1005).

Thereafter, the frame preamble is detected as the calculated correlation ratio (value) is located within the threshold section (1006).

11 to 14 are diagrams illustrating output characteristics of a frame preamble detection apparatus of a portable Internet system according to the present invention.                     

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

In the present invention as described above, the first correlation value of the first 256 samples and the last 256 samples in the reverse order of the 1024 samples received, the first 256 samples and the last 256 samples are sequentially summed and then autocorrelated By detecting the frame preamble using the ratio of the second correlation value, the frame synchronization can be obtained even in the no signal transmission interval.

In addition, since the present invention detects the frame preamble using a few adders and multipliers, there is an effect of detecting the frame preamble with little complexity.

Claims (9)

In the frame preamble detection device of a portable internet system, Storage means for storing a predetermined number of samples received; The first correlation value and the first predetermined number of samples and the last predetermined number of samples, which are correlated in the reverse order of the first predetermined number of samples and the last predetermined number of samples stored in the storage means, are sequentially added. Correlation ratio calculating means for calculating a correlation ratio of the correlated second correlation values; And Preamble detection means for detecting a frame preamble as the correlation ratio (value) calculated by the correlation ratio calculation means is located within a threshold section Frame preamble detection device of a mobile Internet system comprising a. The method of claim 1, The correlation ratio calculating means, A first correlator for calculating the first correlation value by correlating the first predetermined number of samples and the last predetermined number of samples among the samples stored in the storage means in reverse order; An adder for sequentially summing the first predetermined number of samples and the last predetermined number of samples; A second correlator for autocorrelating a predetermined number of samples summed by the adder to calculate the second correlation value; And A correlation ratio calculator for calculating a ratio of the first correlation value and the second correlation value Frame preamble detection device of a mobile Internet system comprising a. The method according to claim 1 or 2, The preamble detection means, As the correlation calculation ratio (value) from the correlation ratio calculation means is located in the threshold interval, the third ratio (value) of the ratio (value) in the threshold interval that occurs six times per frame is determined as the start point of the preamble, and 6 And detecting the preamble by determining the second ratio (value) as the end point of the preamble. The method according to claim 1 or 2, The storage means, An apparatus for detecting frame preamble in a portable internet system, characterized by storing 1024 samples. The method according to claim 1 or 2, The predetermined number is Frame preamble detection device of the portable Internet system, characterized in that 256. A frame preamble detection method in a preamble detection apparatus of a portable internet system, A sample storing step of sequentially storing a predetermined number of samples; Calculating a first correlation value by correlating a first predetermined number of samples and a last predetermined number of samples from each other in reverse order; A sample summing step of sequentially summing the first predetermined number of samples and the last predetermined number of samples; Calculating a second correlation value by autocorrelating the sum of the predetermined number of samples; Calculating a ratio of the first correlation value and the second correlation value; And A frame preamble detection step of detecting a frame preamble as the calculated correlation ratio (value) is located within a threshold section; Frame preamble detection method in a preamble detection device of a portable Internet system comprising a. The method of claim 6, The frame preamble detection step, As the calculated ratio (value) is located within the threshold interval, the third ratio (value) is determined as the starting point of the preamble among the ratios (values) generated in the six intervals per frame, and the sixth ratio (value) is determined. And detecting the preamble by determining the end point of the preamble. The method according to claim 6 or 7, The sample storage step, A frame preamble detection method in a portable internet system, characterized by sequentially storing 1024 samples. The method according to claim 6 or 7, The predetermined number is Frame preamble detection method in a portable Internet system, characterized in that 256.

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