KR102114796B1 - Wireless communication system considering multi-user based on ship and yard area network and method thereof - Google Patents

Abstract

The present invention relates to a system and a method for wireless communication considering a multi-user based on a ship and yard area network (SYAN). The method includes: a step in which a unique and mutually orthogonal N-bit code set (N: subcarrier count) is allocated from a server to each of a plurality of user terminals in the SYAN; a step in which the user terminal modulates data to be transmitted; a step in which the modulated data is spread into N-bit data by the modulated data being multiplied by the code set allocated to itself; a step in which the spread N-bit data is classified by bit, each bit is matched with and multiplied by one among N CI codes having different phase components, and then the results are added up; and a step in which the added data is allocated for each of N subcarriers and simultaneous transmission is performed through the N subcarriers. According to the present invention, a CI-OFCDM-type wireless communication technique is used that uses a CI matching technique for frequency diversity and a code matching technique for multi-user classification in a SYAN environment that is high in diffused radio wave reflection and radio wave transmission path uncertainty, and thus wireless communication performance improvement can be achieved along with bit error rate improvement.

Description

Wireless communication system considering multi-user based on ship and yard area network and method thereof

The present invention relates to a wireless communication system and a method for considering a multi-user based on SYAN, and more particularly, to multiple users in a Ship and Yard Area Network (SYAN) with multiple devices (users) and a very poor radio wave environment. The present invention relates to a wireless communication system considering a multi-user and a method for improving communication performance using a CI-OFCDM wireless communication technique.

The channel environment in the ship interior (Sihp) and the ship building area (Yard) has a very poor propagation environment because there are many enclosed areas and numerous steel structures, unlike the general channel environment.

The interior of the ship is entangled like a complicated maze, and each space in the ship is designed to be shielded in consideration of an emergency, so it is very difficult to smoothly penetrate the radio waves. Also, in the shipbuilding area, there are a number of pre-made steel blocks for shipbuilding and steel materials for making blocks. These structures are very likely to maximize the diffuse reflection of radio waves and the uncertainty of the radio transmission path.

However, it is difficult to consider that special and poor radio environment such as Ship and Yard Area Network (SYAN) has been sufficiently considered because wireless communication standards that are currently commercialized have been developed in consideration of services in a general radio environment.

Moreover, extreme signal attenuation and very long multipath delays are major obstacles to constructing a reliable wireless communication system. In particular, in order to derive the reception performance in a poor radio environment, various diversity needs to be utilized, and efforts to improve performance without wasting frequency resources are also required.

In addition, a very long multipath signal delay may cause inter symbol interference, which may result in an inability to increase the transmission rate to a desired level.

Most current wireless communication systems are based on Orthogonal Frequency Division Multiplexing (OFDM). In OFDM, a guard interval equal to a multipath delay of radio waves is applied to avoid intersymbol interference.

However, there is a limit to eliciting a desired performance in an environment where there is a large amount of diffuse reflection or a signal is very poor, such as a shaded area. In addition, the OFDM signal is transmitted while maintaining orthogonality by each subcarrier, and each subcarrier represents an unstable envelope in the time domain. Will occur.

In order to overcome the above problems, various communication methods based on OFDM have been proposed. Among them, OFCDM (Orthogonal Frequency Code Division Multiplexing), which combines OFDM and Direct Sequence Spread Spectrum (DSSS), utilizes the advantages of a direct code frequency spreading method that converts a multipath signal into a received signal rather than an interference signal. It is designed to be suitable. However, this method has a limitation in throughput, and has a disadvantage in that the throughput limit is severe when there are multiple devices (multi-user).

Accordingly, there is a need for a new communication technique that can reduce PAPR and improve wireless communication performance when multiple devices are present in a poor propagation environment such as SYAN.

The technology underlying the present invention is disclosed in Korean Patent Publication No. 2006-0022674 (published on March 10, 2006).

The present invention, SYAN (Ship and Yard Area Network) using a CI-OFCDM wireless communication method considering multiple users in a wireless communication system considering the SYAN-based multi-user that can improve the communication performance and its method The purpose is to provide.

In the present invention, in a wireless communication method considering a multi-user based on a SYAN (Ship and Yard Area Network), each of the plurality of user terminals in the SYAN is unique to each other consisting of N bits (N: the number of subcarriers) from the server. Receiving a code set of, the user terminal modulating the data to be transmitted, and multiplying the modulated data by the code set assigned to it to spread the modulated data into N-bit data; Matching, multiplying, and summing one of the N CI codes having different phase components for each bit of the spread N-bit data, and allocating the summed data for each of the N sub-carriers to the N sub-carriers It provides a wireless communication method in consideration of multiple users including the step of simultaneously transmitting through.

In addition, the server supports up to N code sets orthogonal to each other corresponding to the number of subcarriers, and one of M code sets orthogonal to each other corresponding to M (M≤N) user terminals in the SYAN. Can be randomly assigned.

Further, the N code sets may be Walsh codes.

In addition, when the BPSK modulation scheme is used, the user terminal may multiply the 1 bit modulation data including the value of 0 or 1 by the code set to spread the 1 bit modulation data into the N bit data.

And, the present invention, in a wireless communication system considering a multi-user based on SYAN (Ship and Yard Area Network), each of the plurality of user terminals in the SYAN, each of N bits (N: the number of subcarriers) from the server A storage unit that receives and stores an orthogonal unique code set, a modulator that modulates data to be transmitted, and a code that multiplies the modulated data with the code set that is allocated to spread the modulated data into N-bit data. A matching unit, a CI matching unit for matching and multiplying one of N CI codes having different phase components for each bit of the spread N bits of data, and summing the data, and for each N subcarriers of the summed data It provides a wireless communication system including a transmission unit that is assigned to each and transmits simultaneously through the N subcarriers.

According to the present invention, a CI-OFCDM method using a code matching technology for distinguishing multiple users in a SYAN (Ship and Yard Area Network) environment with high scattering of radio waves and uncertainty of a radio transmission path and a CI matching technology for frequency diversity By using the wireless communication technique of, the wireless communication performance is improved, and the bit error rate is improved.

1 is a diagram illustrating a wireless communication system considering multiple users based on SYAN according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a signal processing configuration between a transmitting end and a receiving end for the wireless communication system of FIG. 1.
3 is a diagram showing the configuration of a user terminal operating in a SYAN environment according to an embodiment of the present invention.
4 is a diagram illustrating a wireless communication method using the user terminal of FIG. 3.
5 is a diagram illustrating a code set allocated for each user in an embodiment of the present invention.
6 is a diagram for explaining the principle of code spreading through code matching in an embodiment of the present invention.
7 is a diagram illustrating a frequency spreading principle through CI matching in an embodiment of the present invention.
8 is a diagram illustrating a signal processing process at a receiving end according to an embodiment of the present invention.
9 is a view showing a result of performance comparison between a wireless communication system and an existing system according to an embodiment of the present invention.

Then, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily practice.

1 is a diagram illustrating a SYAN-based wireless communication system according to an embodiment of the present invention.

The SYAN (Ship and Yard Area Network) shown in FIG. 1 is a network applied to a ship interior or a ship construction area (Yard), and generally has characteristics of a poor propagation environment with severe diffuse reflection and high uncertainty in a transmission path. .

A plurality of user terminals 100 communicating in SYAN corresponds to M multiple users. Each user terminal 100 includes a transmission / reception terminal, and has a structure capable of transmitting / receiving data. Accordingly, the user terminal 100 performs the role of a transmitting end when entering the transmitting terminal to transmit data, and serves as a receiving end when entering the receiving terminal receiving data.

FIG. 2 is a diagram illustrating a signal processing configuration between a transmitting end and a receiving end for the wireless communication system of FIG. 1.

The transmitting end includes a modulation block, a code matching block, a carrier interferometry (CI) matching block, an inverse FFT (IFFT) block, and a guard interval (GI) insertion block. The remaining blocks except for the code matching block and the CI matching block in the transmitting end are the same as the structure of the transmitting end of the conventional OFDM system.

In FIG. 2, the code matching block serves to distinguish M multiple users, and the CI matching block serves to improve wireless communication performance by spreading frequencies to obtain a frequency diversity effect. As described above, this embodiment performs a total of two matches including code matching and CI matching in consideration of multi-user and poor propagation environment.

The transmitter spreads data by modulating the bit stream to be transmitted and performing code matching to multiply the modulated data by a user-specific code set. Then, CI matching is performed by multiplying CI codes of different phases for each bit of data spread through code matching, and then converted to a signal in a time domain through IFFT processing, and then a GI is inserted and transmitted through a wireless channel. do.

The other blocks except the CI correlation block and the code correlation block are the same as those of the normal OFDM system. The receiving end, in contrast to the transmitting end, includes a GI removal block, an FFT block, a CI correlation block, a code correlation block, and a demodulation block. The receiving end removes the GI from the data received from the transmitting end, performs FFT processing, converts it into a signal in the frequency domain, and then performs CI correlation, code correlation (CI correlation), and then transmits bits through demodulation (signal detection). The stream is detected.

Hereinafter, a configuration of a user terminal wirelessly communicating in a SYAN network will be described in more detail. In addition, for convenience of description, the transmitting end of the transmitting / receiving end built in the user terminal will be mainly described.

3 is a diagram illustrating a configuration of a user terminal operating in a SYAN environment according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating a wireless communication method using the user terminal of FIG. 3. As shown in FIG. 3, each user terminal 100 in the SYAN network includes a storage unit 110, a modulation unit 120, a code matching unit 130, a CI matching unit 140, and a transmission unit 150 do.

First, the storage unit 110 receives and stores unique code sets orthogonal to each other composed of N bits from a server (not shown) of the network (S410).

Here, N corresponds to the number of subcarriers in OFDM. This N is equal to the length of one symbol. If N = 64, one code set consists of 64 bits.

The server (not shown) supports up to N code sets corresponding to the number of subcarriers (N). Of course, each code set is composed of N bits, and the N code sets are orthogonal to each other. For example, when the number of subcarriers N = 64, up to 64 code sets are supported, and each code set has a length of 64 bits. Each of the 64 code sets has orthogonal characteristics.

In this case, N code sets orthogonal to each other may correspond to a Walsh code, which is an orthogonal code used in CDMA communication. Since there are various types of Walsh codes, they can be selectively used among known ones.

In addition, if there are N user terminals in this network (here, M≤N), the server (not shown) randomly allocates one of M code sets orthogonal to each other corresponding to M user terminals that are multiple users. Do it.

For example, when the number of subcarriers is N = 64, if the number of users is M = 10, 10 code sets that are a part of 64 code sets supported are selected to correspond one to one to 10 user terminals, and when the number of users is M = 64, supported Allocating 64 code sets is one-to-one correspondence to 64 user terminals.

Accordingly, one code set unique to each user in the network may be allocated. This code set serves to differentiate multiple users in a poor propagation environment.

Of course, in this embodiment, the server shares the codeset table that records the codeset information allocated for each user to all users in the network, so that when a certain user in the network receives and detects a signal from the outside, the received signal is detected by the user. It is possible to know whether it is a signal transmitted from.

5 is a diagram illustrating a code set allocated for each user in an embodiment of the present invention. FIG. 5 (a) will be described on the assumption that for convenience of description, the number of subcarriers is 4 (N = 4) and there are 4 users in the network.

In this case, the server supports four code sets orthogonal to each other (Walsh code = 4), and each code set is composed of a length of 4 bits. One of the four codes is assigned to each of the four users to match 1: 1. In other words, it can be seen that four codes are divided and used by four users.

FIG. 5 (b) assumes a situation in which the number of subcarriers is 64 and there are 64 users in the network. In this case, up to 64 code sets (Walsh code = 64) are supported, and each code set is composed of 64 bits. In the case of N = 64, it is difficult to express all the information in the code set in the drawing. In this way, each user is given a unique code set.

The modulator 120 modulates data to be transmitted (S420). At this time, the modulation method can be selectively used among BPSK, QPSK, 16-QAM, and 64-QAM. Of course, the modulation method may be changed according to the communication environment.

The code matching unit 130 multiplies the modulated data by a code set allocated to it and spreads the modulated data into N bits (N: number of subcarriers) data (S430).

6 is a diagram illustrating a code spreading process through code matching in an embodiment of the present invention.

FIG. 6 (a) shows that 1-bit modulation data is increased to 64-bit by multiplying the 64-bit code set by 1 bit modulation data through the BPSK method. Of course, FIG. 6 (b) shows that a 64-bit signal is detected as 1-bit data of a corresponding user through code correlation using a code set for each user, as opposed to a receiving end.

As described above, when the BPSK modulation method is used, the code matching unit 130 multiplies the N-bit code set by 1 bit modulation data including a value of '0' or '1', and modulates data of 1 bit length. Spreads to N bit length data. That is, 1 bit is extended by N bits (OFDM one symbol length).

Of course, since the number of used bits is 1 for BPSK, the number of used bits is 2 for QPSK, the number of used bits is 4 for 16-QAM, and the number of used bits is 6 for 64-QAM, so depending on the modulation method, 1 The modulated signal of a bit can be increased to N bits, or the modulated signal of 2, 4 or 6 bits can be increased to an N bit length.

If, if N = 64, and BPSK modulation is used, a 1-bit modulation signal including a value of '0' or '1' can be increased to 64 bits. When using QPSK modulation, '00', '01' , A 2-bit modulated signal including a value of '10' or '11' can be increased to 64 bits.

As such, in the case of N = 64, each code set is given to up to 64 multi-users, so even if radio signals from each device (user terminal) are mixed in the same band, signals from multiple users can be transmitted and received with minimal loss. have.

Subsequently, the CI matching unit 140 divides the spread N-bit data into units of 1 bit, multiplies and multiplies and matches one of N carrier interferometry (CI) codes having different phase components for each bit, and then adds them together. (S440).

Here, N CI codes are used corresponding to the total number of bits of the spread data, and N CI codes of different phase components have orthogonality to each other.

Then, the transmitting unit 150 allocates the summed data for each N subcarriers, and simultaneously transmits them through the N subcarriers (S450).

7 is a diagram illustrating a frequency spreading principle through CI matching in an embodiment of the present invention. 7 shows a CI matching process of multiplying extended data by CI phase codes orthogonal to all subcarriers.

For convenience of explanation, it is assumed that N = 4 by reducing 64 people to 4 people. In this case, the spread data is 4 bits, and the CI matching unit 140 receives 4 bits of data, matches and multiplies different CI codes per bit, and then adds them together. The summed result is assigned to each of N subcarriers.

블록 참조), 곱해진 결과들이 모두 합산(

블록 참조)된 후 N개의 부반송파 마다 실리게 된다. That is, the first bit of the 4-bit data (Bit 1) is a CI ₁ is multiplied, the second bit (Bit 2), the CI ₂ are multiplied, and the third bit (Bit 3), the CI ₃ are multiplied, and the fourth bit (Bit 4) is multiplied by CI ₄ (

Block), and the multiplied results are all added (

Block), and is loaded on every N subcarriers.

As a simple example, it is assumed that the number of subcarriers is 4 (N = 4), there are 4 users, and each user uses a BSPK modulation method for signal transmission.

At this time, the code set assigned to the first user (user 1) is' 1100 ', and if the data modulated by the user 1 by the BSPK method is' 1', the principle of FIG. 6 is applied to the data set '1' to code set '1100. 'Is multiplied by' to expand to 4 bits of data called '1100'.

블록 참조), 각각의 부반송파에서 이 신호의 합이 부반송파의 입력으로 들어간다(

블록 참조). Subsequently, according to the principle of FIG. 7, '1100' is divided by 1 bit, '1' for Bit 1, '1' for Bit 2, '0' for Bit 3, and '0' for Bit 4, respectively, and then After multiplying each orthogonal CI code (

Block), the sum of these signals on each subcarrier goes into the input of the subcarrier (

Block).

Then, four subcarriers corresponding to the input of the IFFT are transmitted by combining four subcarriers and different CI phase components orthogonal to each subcarrier, and include all data having a constant phase offset in one subcarrier to cancel each other's power. The effect of reducing the PAPR can be obtained by removing the 둣 value.

As such, an embodiment of the present invention proposes a CI-OFCDM-based wireless communication method using code matching for distinguishing multiple users and CI matching for frequency diversity, thereby improving wireless communication performance and increasing bit error rate (BER) To improve.

In particular, as shown in FIG. 7, since the frequency spreading effect is obtained by having the structure of spreading the frequency by dividing it into N subcarriers by applying the quadrature CI spreading code to the data spread primarily through the code set, The BER performance loss due to the change of the channel environment can be reduced, and it shows very good performance for the frequency selective fading channel.

In addition, the proposed CI-OFCDM method transmits one data by combining all CI phase components orthogonal to all subcarriers, and thus, one subcarrier includes all data having a constant phase offset, thereby canceling power between each other. By removing the 둣 value, an effect of reducing the PAPR (Peak to Average Power Raid) can be obtained.

Moreover, in case of using the OFCDM method, the transmission speed is very low in the frequency spreading process in order to overcome a very long multipath signal delay. In this case, when there are multiple users, the transmission speed problem cannot be overcome and performance is also deteriorated.

However, in the present embodiment, when only one user exists, the transmission speed decreases as in the normal OFCDM method, but when 64 multiple users exist, 64 times than the existing OFCDM method through the code set of each independent user (64 people). You can get the throughput of.

As described above, the present invention can improve wireless communication performance and transmission rate in a SYAN environment by using a CI-OFCDM type wireless communication technique suitable for a very poor propagation environment in which multiple devices (multi-users) exist. Of course, the present invention can be applied to a network having a very poor propagation environment, in addition to a SYAN network, which is highly diffused or has high uncertainty in a transmission path on the same principle.

The processing at the receiving end of the signal transmitted from the transmitting end may be configured in reverse to correspond to the processing method of the transmitting end.

8 is a diagram illustrating a signal processing process at a receiving end according to an embodiment of the present invention. As shown in FIG. 8, the signal processing order of the receiver is in reverse order with the transmitter, and sequentially input signals are made in parallel and put into Bit 1, Bit 2, ..., Bit N digits. This signal is demodulated through the FFT and then through the next block diagram process.

9 is a view showing a result of performance comparison between a wireless communication system and an existing system according to an embodiment of the present invention. FIG. 9 compares three methods including an existing OFDM method, a CI-OFDMM method, and a proposed CI-OFCDM method in an AWGN environment, and verifies performance by dividing the user into one case and two cases.

As a result of the verification, it can be seen that the performance of CI-OFDM and CI-OFCDM is significantly improved compared to the existing OFDM. However, when comparing the case of 1 user and the case of 2 users, it can be seen that in the case of the existing CI-OFDM, the performance deteriorates significantly as the user increases. On the other hand, in the case of the proposed CI-OFCDM method, it can be confirmed that even if the number of users increases, the performance is the same as when the number of users is one.

In general, in the environment of a ship, various communication systems such as LTE, Wi-Fi, and internal communication systems exist in a mixed manner due to the presence of several workers. The proposed CI-OFCDM method is expected to be a good alternative in such a poor propagation environment.

According to the present invention as described above, the wireless communication technique of CI-OFCDM method using the code matching technique for distinguishing multiple users and the CI matching technique for frequency diversity in a SYAN environment in which radio wave diffuse reflection and radio wave transmission path uncertainty are high. Using provides an advantage of improving the wireless communication performance as well as improving the bit error rate.

The present invention has been described with reference to the embodiments shown in the drawings, but these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

100: user terminal 110: storage unit
120: modulation unit 130: code matching unit
140: CI matching unit 150: transmission unit

Claims (8)

In the wireless communication method considering a multi-user based on SYAN (Ship and Yard Area Network),
Each of the plurality of user terminals in the SYAN is assigned a unique code set orthogonal to each other composed of N bits (N: the number of subcarriers) from the server;
The user terminal modulating data to be transmitted;
Spreading the modulated data into N-bit data by multiplying the modulated data by the code set allocated thereto;
Matching and multiplying one of N CI codes having a different phase component for each bit of the spread N-bit data, and then summing them; And
A wireless communication method in consideration of multiple users, comprising allocating the summed data for each N subcarriers and simultaneously transmitting the N subcarriers. The method according to claim 1,
The server,
Supports up to N code sets orthogonal to each other corresponding to the number of subcarriers,
A wireless communication method considering multiple users randomly allocating one of M code sets orthogonal to each other corresponding to M (M≤N) user terminals in the SYAN. The method according to claim 2,
The N code set is a wireless communication method considering a multi-user that is a Walsh code. The method according to claim 1,
The user terminal,
When using the BPSK modulation method, a wireless communication method considering multi-user spreading 1-bit modulation data into the N-bit data by multiplying the code set by 1-bit modulation data including a value of 0 or 1. In a wireless communication system considering multiple users based on SYAN (Ship and Yard Area Network),
Each of the plurality of user terminals in the SYAN,
A storage unit that receives and stores unique code sets orthogonal to each other composed of N bits (N: the number of subcarriers) from the server;
A modulator for modulating data to be transmitted;
A code matching unit for multiplying the modulated data by the code set allocated by the user and spreading the modulated data into N-bit data;
A CI matching unit that matches, multiplies, and sums one of N CI codes having different phase components for each bit of the spread N-bit data; And
And a transmission unit that allocates the summed data to each of the N subcarriers and transmits them simultaneously through the N subcarriers. The method according to claim 5,
The server,
Supports up to N code sets orthogonal to each other corresponding to the number of subcarriers,
A wireless communication system considering multiple users randomly allocating one of M code sets orthogonal to each other corresponding to M (M≤N) user terminals in the SYAN. The method according to claim 6,
The N code set is a wireless communication system considering multiple users that are Walsh codes. The method according to claim 5,
The user terminal,
When using the BPSK modulation method, a wireless communication system considering multi-user spreading 1-bit modulation data into the N-bit data by multiplying the code set by 1-bit modulation data including a value of 0 or 1.

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