KR101702243B1 - Differential Spatial Modulation with Gray Coded Antenna Activation Order and MIMO system applying the same - Google Patents

Abstract

Provided are a differential spatial modulation method and an MIMO system applying the same. According to the differential spatial modulation method, an antenna activation order by a permutation can be determined by applying a gray code order, thereby improving the bit error rate (BER) performance of differential spatial modulation (DSM) compared to the BER performance applying a lexicographic order and a lexi-gray order. The DSM method comprises the following steps: a transmitter divides an information bit of a transmission signal into a plurality of transmission blocks; the transmitter maps a permutation representing an antenna activation order to a specific bit of each of the transmission blocks; and the transmitter transmits the transmission block according to the antenna activation order mapped to the permutation.

Description

(Differential Spatial Modulation with Gray Coded Antenna Activation Order and MIMO system Applying the Same)

The present invention relates to a signal modulation method and a MIMO system, and more particularly, to a differential space modulation method to which a gray code antenna activation sequence is applied and a MIMO system using the same.

Spatial Modulation (SM) is an attractive and special transmission structure in a multi-input multi-output (MIMO) system. In Spatial Modulation (SM), information bits are conveyed not only by the transmitted modulation symbols but also by the transmit antenna index. Since the extra information bits are transmitted by selecting the transmit antenna, the spectral efficiency of the system is increased. In addition, since only one antenna is active for transmission, it is possible to avoid inter-channel interference and inter-antenna synchronization.

However, optimum maximum likelihood (ML) decoding in spatial modulation (SM) requires channel state information (CSI) to create a decoding complex.

타임 슬롯(time slots) 동안 대응되는 안테나 인덱스 행렬에 의해 전달되며, 여기에서

는 송신 안테나의 수를 나타낸다. 따라서, 안테나 인덱스 행렬들 간의 차이는 비트 에러율(BER : Bit Error Rate) 성능과 관련하여 중요한 역할을 하게 된다.In order to solve such a problem, differential spatial modulation (DSM), which provides channel state information (CSI), is provided. In differential space modulation (DSM), an antenna index matrix is applied, transmitted symbols

Is delivered by the corresponding antenna index matrix during time slots, where

Represents the number of transmit antennas. Therefore, the difference between the antenna index matrices plays an important role in relation to the bit error rate (BER) performance.

타임 슬롯에서 안테나 액티베이션 순서(antenna activation order)에 의해 결정된다. 집합

의 퍼뮤테이션(permutation)으로써 특정되는 안테나 인덱스 행렬은 사전식 순서(lexicographic order)를 따르는 집합이다.The antenna index matrix, mapped from a portion of the information bits,

Lt; / RTI > is determined by the antenna activation order in the time slot. set

The antenna index matrix specified by the permutation of the antenna index matrix is a set following the lexicographic order.

As is well known, the maximum likelihood error detection occurs between very similar permutations in a high signal-to-noise ratio (SNR) environment. However, in the lexicographic order, the pseudo-permutation creates a large bit difference between the corresponding information bits, which degrades bit error rate (BER) performance in differential spatial modulation (DSM).

Accordingly, a search for a method for improving the bit error rate performance in the differential space modulation is sought.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a differential space modulation method for determining an antenna activation order according to a permutation by applying a gray code order and a MIMO system using the same .

According to an aspect of the present invention, there is provided a method of differential differential spatial modulation (DSM) of a multi-input multi-output (MIMO) system, Dividing the received blocks into transmitted blocks; The transmitter mapping a permutation indicating an antenna activation order to a specific bit of each transport block; And transmitting, by the transmitter, the transmission block according to an antenna activation sequence mapped to the permutation. The order of antenna activation according to the permutation may be a gray code order.

개의 송신 안테나를 포함하고, 상기 전송 블록은,

개의 비트로 구성되는 것을 특징으로 할 수도 있다. In addition,

Wherein the transmission block comprises:

Bit bits.

개의 비트에 안테나 액티베이션 순서(activation order)를 나타내는 퍼뮤테이션을 맵핑할 수도 있다. In the mapping step,

Mapped to permutation indicating an antenna activation order.

The mapping step may include mapping a permutation indicating an antenna activation order to a specific bit of each transport block using a lookup table containing information bits and corresponding permutations in a predetermined gray code order, You may.

The mapping step may map a permutation indicating an antenna activation order to a specific bit of each transport block using a ranking method.

The mapping step may map a permutation indicating an antenna activation order to a specific bit of each transport block using an unranking method.

The method may further include demapping the received signal to a permutation of the antenna activation order and demodulating the received signal to recover the information bit.

Meanwhile, a multi-input multi-output (MIMO) system to which differential signaling spatial modulation (DSM) is applied according to an embodiment of the present invention includes transmitting information bits of a transmission signal to a plurality of transmitted blocks A transmitter for mapping a permutation indicating an antenna activation order to a specific bit of each transport block and transmitting the transport block according to an antenna activation sequence mapped to the permutation; And a receiver for demapping a signal received from the transmitter to a permutation of the antenna activation order and demodulating the demodulated signal to recover the information bit. The antenna activation sequence according to the permutation includes a Gray code A gray code order may be applied.

According to various embodiments of the present invention, it is possible to perform differential space modulation that determines an antenna activation sequence according to a permutation by applying a Gray code order so that bit error rate (BER) performance of differential space modulation (DSM) It can be improved than when the lexi-gray order is applied.

= 4 및 6을 가지는 그레이 코드 순서, 사전식 순서, 및 렉시-그레이 순서에 대한 비트에러율(BER) 성능을 각각 도시한 도면,
도 3은

= 3,4,5 및 6인 경우의 코딩 게인의 이론적 결과치를 도시한 도면, 그리고,
도 4는 본 발명의 실시예에 따른 MIMO 시스템의 신호 차등 공간 변조 방법의 설명에 제공되는 흐름도이다.1 shows a MIMO system to which the present invention is applicable,
2 is a graph showing the relationship between the spectral efficiency at 1 bps / Hz and 1.5 bps / Hz

= 4 and 6, bit error rate (BER) performance for the lexico-gray order, respectively,
3,

= 3, 4, 5, and 6, and FIG.
4 is a flowchart provided in the description of a signal differential space modulation method of a MIMO system according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings.

Differential spatial modulation (DSM) is intended to overcome channel estimation problems in spatial modulation (SM).

An embodiment of the present invention provides a gray code order of antenna index matrices in differential spatial modulation. According to an embodiment of the present invention, the information bits represent the antenna index matrix and the corresponding permutations of the active antenna indices follow the gray code order.

To facilitate the implementation of the method according to an embodiment of the present invention, a ranking and unranking algorithm is proposed for linking the relationship between information bits and corresponding permutations.

The method according to embodiments of the present invention is able to achieve a coding gain of 1.2 dB with respect to the currently applied lexicographic order while representing a very similar performance complexity. The bit error rate can be verified using the Monte-Carlo simulation.

One. Gray  Differential space modulation method applying code sequence

Gray code represents a similar object with only one bit difference, so that the above-described problem can be solved. Therefore, in the embodiment of the present invention, a gray code order is applied for information bits and corresponding permutations. Then, each information bit sequence has only one bit difference from the previous or next one.

On the other hand, the corresponding antenna index permutation has two antenna index differences from the previous one or the next one. For easier application, we propose a one-to-one correspondence between the permutation and the corresponding information bit sequence, which is referred to as an unranking algorithm. Ranking and un-ranking algorithms require only a simple operation and have computational complexity that is almost the same as the lexicographic order.

In the simulation, the bit error rate (BER) performance of Differential Spatial Modulation (DSM) in Gray code order is compared to the case of lexicographic and lexi-gray order where the lexi- A sequence follows a lexicographic order while a corresponding permutation follows a gray code order. Simulation results show that the gray code order is better than the lexicograph order or the lexico-gray order.

는 Hermitian 전치(transpose)를 나타낸다. 복소수는

로 표시한다.

는

사이즈의 단위행렬(identity matrix)을 나타낸다.

는 인수(argument)의 실수 성분을 나타낸다. tr{·} 및 rank{·}는 각각 트레이스(trace) 및 랭크(rank) 연산을 나타낸다. A(i,j)는 행렬 A의 (i,j)번째 성분을 나타낸다.

및

는 각각 floor 및 ceil 연산을 나타낸다. Notation: Capital letters in boldface represent matrices.

Represents a Hermitian transpose. The complex number is

.

The

Size identity matrix.

Represents the real component of the argument. tr {·} and rank {·} represent the trace and rank operations, respectively. A (i, j) represents the (i, j) th component of the matrix A.

And

Denote the floor and ceil operations, respectively.

2. System model for differential space modulation method

의 MIMO 시스템을 고려한다. 도 1에 도시된 송신기(100)와 수신기(200)로 구성되는 MIMO 시스템이 그러한 예이다.The phase shift keying (M-PSK) constellation set S

Lt; / RTI > system. An example of such a MIMO system is a transmitter 100 and a receiver 200 shown in FIG.

는 송신 안테나 개수를 나타내고,

과 M은 각각 수신 안테나 개수 및 성상도 차수(constellation order)를 나타낸다. 구체적으로, 차등 공간 변조(DSM)은 다음과 같은 역할을 하게 된다. 송신기에서, 정보 비트는 전송 블록(transmitted blocks)으로 나눠지고, 각 블록은

비트로 구성되며, 개의 타임 슬롯(time slots)에 걸쳐 전송된다. From here,

Denotes the number of transmission antennas,

And M denote the number of receive antennas and the constellation order, respectively. Specifically, differential space modulation (DSM) plays a role as follows. At the transmitter, the information bits are divided into transmitted blocks,

Bits, RTI ID = 0.0 > time slots. ≪ / RTI >

Specifically, the transmitter divides the information bits of the transmission signal into a plurality of transmitted blocks. Then, the transmitter maps specific bits of each transport block to a permutation indicating an antenna activation order. Then, the transmitter transmits the transmission block using the activation antenna according to the antenna activation sequence mapped to the permutation. Here, the antenna activation sequence according to the permutation is a gray code order.

비트는 퍼뮤테이션으로 맵핑되며, 이는 안테나 액티베이션 순서(activation order)를 나타낸다. 즉, 송신기는 전송 블록의 최초

개의 비트에 안테나 액티베이션 순서(activation order)를 나타내는 퍼뮤테이션을 맵핑하게 되는 것이다. For each transport block, the first

The bits are mapped to permutations, which represent the antenna activation order. That is, the transmitter transmits the first

And the permutation indicating the antenna activation order is mapped to the bits.

비트는 집합 S로부터 송신 신호

를 선택하는데 이용된다. t번째 전송 블록에는, 송신행렬(transmitted matrix)

가 다음과 같이 주어진다. On the other hand,

Bit from the set S to the transmit signal

. In the tth transport block, a transmitted matrix

Is given as follows.

(1)

(One)

는 정보 행렬(information matrix)이고, 이는 정보 비트에 의해 결정된다. 단순화를 위해,

라고 정의한다. 그러면,

가 만족함은 명백하며, 여기에서

와

는 정수 파라미터

에 대응되는 안테나 액티베이션 순서의 퍼뮤테이션을 나타낸다. From here,

Is an information matrix, which is determined by information bits. For simplicity,

. then,

Is satisfactory, and here

Wow

Is an integer parameter

And the permutation of the antenna activation sequence corresponding to the antenna activation sequence.

는 공분산(covariance)

를 가지는 채널 행렬(channel matrix)을 나타낸다. 그러면, 수신 신호 행렬

은 다음과 같이 표현된다.

(Covariance)

≪ / RTI > Then, the received signal matrix

Is expressed as follows.

(2)

(2)

은 제로 평균(zero mean)이고 공분산 행렬이

인 가산성 백색 가오시안 노이즈 행렬(additive white Gaussian noise matrix)을 나타낸다. 마찬가지로,

번째 전송 블록의 수신 신호 행렬인

는 다음과 같이 주어진다. From here,

Is the zero mean and the covariance matrix is

(Additive white Gaussian noise matrix). Likewise,

Lt; th > transmission block

Is given as follows.

(3)

(3)

이면, 수식 (2)를 다음과 같이 표현할 수 있다. Quasi-static fading, i. E.

, Equation (2) can be expressed as follows.

(4)

(4)

Therefore, the optimal maximum likelihood (ML) detection is derived as follows.

(5)

(5)

는 모든 가능한 정보 행렬으로 구성된 집합을 나타낸다. From here,

Represents a set of all possible information matrices.

에서 안테나 액티베이션 순서의 퍼뮤테이션의 디맵핑(demapping) 및 송신 신호의 복조(demodulation)에 의해 복구될 수 있게 된다. 즉, 수신기가 수신된 신호를 안테나 액티베이션 순서의 퍼뮤테이션으로 디맵핑(demapping)하고 복조(demodulation)하여 정보 비트를 복구할 수 있게 된다. As a result,

Demapping of the permutation of the antenna activation sequence and demodulation of the transmission signal. That is, the receiver can demap the received signal to the permutation of the antenna activation order and demodulate the demodulated signal to recover the information bit.

정보비트와 관련이 있다. 본 발명의 실시예에 따른 그레이 코드 순서의 효과를 구분시키기 위해, 차등 공간 변조(DSM)의 특별한 경우인 차등 공간 쉬프트 키잉(DSSK : differential space shift keying)의 경우 만을 고려하며, 이는

비트 중에

비트가 폐기되고, 그 결과

는 모든 시간에 대해 1s로 세팅이 된다. Hereinafter, gray coding for the antenna activation procedure will be described,

It is related to information bits. In order to distinguish the effect of the gray code order according to an embodiment of the present invention, only the case of differential space shift keying (DSSK), which is a special case of differential space modulation (DSM), is considered,

Among the bits

Bits are discarded, and the result

Is set to 1s for all times.

3. Gray  Index in code order Mapping (INDEX-MAPPING IN GRAY CODE ORDER)

In the following, an antenna index mapping method will be described by providing corresponding permutations in a gray code order for differential space shift keying (DSSK). The index mapping procedure in the gray code order according to the embodiment of the present invention may use a look-up table method and a ranking / un-ranking method.

A. Lookup  table

= 3에 대한 사전식 순서 및 그레이 코드 순서에서의 정보 비트와 대응 퍼뮤테이션을 나타내고 있다. 여기에서, 총 6개의 퍼뮤테이션 중 2개가 제거된 것을 알 수 있다. 그레이 코드 순서에서 제거된 퍼뮤테이션은 사전식 순서에서 제거된 퍼뮤테이션과 다른 것을 확인할 수 있다. The lookup table represents a table in which all possible information bits in a predetermined gray code order and corresponding permutations are stored. Table 1 shows an example of a look-up table. Table 1

= 3, and the information bits and corresponding permutations in the gray code order. It can be seen here that two of the six permutations in total were removed. The permutation removed from the gray code sequence is different from the permutation removed in the lexicographic order.

[Table 1]

= 3에 대한 사전식 순서 및 그레이 코드 순서의 룩업 테이블

= 3 < / RTI > look-up table of the gray code order

1. LO = lexicographic order.

2. GCO = gray code order

B. ranking  And Unranked  Ranking and Unranking  Methods)

값을 가지는 경우에 대해서는 실용적이지 않다. 따라서, 저장공간 낭비(leakage) 문제를 피하기 위해 각각의 퍼뮤테이션과 유일한 정수간의 관계를 생성하는 방법을 이용한다. 이러한 목적을 위해, 다음과 같은 랭킹 및 언랭킹 알고리즘(ranking and unranking algorithms)을 제안한다. 우선, 그레이 코드에서 퍼뮤테이션 생성의 규칙을 설명한다. Since the look-up table method requires storage of all possible permutations for both the transmitter and the receiver,

But it is not practical when it has a value. Therefore, we use a method to create a relation between each permutation and unique integer in order to avoid storage space leakage problem. For this purpose, the following ranking and unranking algorithms are proposed. First, the rule of permutation generation in gray code is explained.

의 모든 퍼뮤테이션은

의 퍼뮤테이션의 모든 가능한 위치에 원소

를 삽입함으로써 생성된다. 예를 들어,

로부터

개의 퍼뮤테이션을 다음과 같이 구할 수 있다. set

All permutations of

At every possible position of the permutation of element

Lt; / RTI > E.g,

from

The permutation of the two can be obtained as follows.

를

퍼뮤테이션의 한쪽 끝에서 다른쪽으로 인접한 두개의 원소를 바꿔감으로써, 새로운

개의 퍼뮤테이션을 생성할 수 있게 된다.

가 한쪽 끝에 도달하면 새로운

퍼뮤테이션으로 업데이트 된다. 그러면,

퍼뮤테이션은

퍼뮤테이션에서 가능한 각각의 위치에

를 위치시킴으로써 생성될 수 있다. 따라서,

개의 원소의 모든 퍼뮤테이션은

개의 원소의 모든 퍼뮤테이션으로부터 반복 생성될 수 있게 된다. 이와 같은 규칙을 더욱 쉽게 이해하기 위해,

의 방향을

와

로 정의하고, 이는 각각 그레이 코드 순서에서 왼쪽 방향 및 오른쪽 방향을 나타낸다.

To

By switching two adjacent elements from one end of the permutation to the other,

Quot; permutation "

Is reached at one end,

It is updated to the permutation. then,

Permutation

At each possible position in the permutation

Lt; / RTI > therefore,

All permutations of the

Lt; RTI ID = 0.0 > permutation < / RTI > To make this rule easier to understand,

The direction of

Wow

, Which respectively represent the left direction and the right direction in the gray code order.

와 {1,2,...,

} 집합의 인접 원소 사이의 교환(swap) 전체는

에 대한 하나의 라운드(round)로 정의된다. 분명히, 퍼뮤테이션에서

의 라운드들의 수인

은

이다.

= 4인 예제 1(example 1)에서, 원소 4는 반대 방향으로 변경하기 전에 인접한 숫자들과 4번 스위칭할 수 있음을 확인할 수 있다. 그리고,

= 4!/4 = 6 임을 알 수 있다. 4의 방향은 라운드 4의 진행에 따라 달라진다.

가 첫번째, 세번째, 다섯번째(홀수번째) 라운드에 발생하는 반면,

는 두번째, 네번째, 여섯번째(짝수번째) 라운드에 발생하는 것을 확인할 수 있다. Generally, for the same direction

And {1,2, ...,

} The entire swap between adjacent elements of the set is

As shown in FIG. Obviously, in permutation

Of rounds of

silver

to be.

In example 1 with 4 = 4, we can see that element 4 can switch 4 times with adjacent numbers before changing to the opposite direction. And,

= 4! / 4 = 6. The direction of 4 changes according to the progress of round 4.

Occurs in the first, third and fifth (odd-numbered) rounds,

Can occur in the second, fourth, and sixth (even-numbered) rounds.

에 대한 방향 지시자를

로 정의하고,

= 1은

인 경우를 나타내고,

= 0은

인 경우를 나타내는 것으로 한다. 위에서 보인 예제에서,

가 홀수이면

= 1이고,

가 짝수이면

= 0인 것을 쉽게 확인할 수 있다. 여기에서,

는

가 전체 퍼뮤테이션 중에서

번째에 있다는 점을 나타내는 숫자이다. For simplicity,

Direction indicator for

Respectively,

= 1

, ≪ / RTI >

= 0

, Respectively. In the example shown above,

Is odd

= 1,

Is an even number

= 0 can be easily confirmed. From here,

The

Of the total permutations

In the second column.

≥ 3 인 경우에 대한 랭킹과 언랭킹 알고리즘(ranking and unranking algorithms)을 설명한다. to the next,

≥ 3, ranking and unranking algorithms are described.

i) ranking Ranking method

가 있고,

및

라고 가정하자.

에서 원소

의 위치를

로 정의하고, 여기에서

는

보다 큰 원소를 제거한

의 서브 퍼뮤테이션(sub-permutation)을 나타낸다. 일단,

를 얻기 위해

가 퍼뮤테이션 {1,2} 또는 {2,1} 중 어느 것에서 생성될지 결정한다. 만약,

= 2인 경우,

가 {1,2}로부터 생성되며

가 된다. 반면,

= 1인 경우,

는 {2,1}로부터 생성되고

가 된다.

인 경우에 대해서는,

는 다음과 같이 재귀적으로(recursively) 계산될 수 있다. Permutation

There,

And

.

In element

The location of

, And here

The

Removing larger elements

(Sub-permutation). First,

To get

To be generated from the permutation {1,2} or {2,1}. if,

= 2,

Is generated from {1,2}

. On the other hand,

= 1,

Is generated from {2, 1}

.

In the case of "

Can be computed recursively as follows.

(6)

(6)

이다. From here

to be.

에 대응되는 정수

은 다음과 같이 계산된다. finally,

An integer corresponding to

Is calculated as follows.

(7)

(7)

는

으로부터 직접 구할 수 있게 된다. Then, in the gray code sequence, the information bit sequence

The

. ≪ / RTI >

The ranking algorithm described above is summarized in algorithm 1 below.

= 4 이고

= {3,1,2,4} 라고 가정한다. 랭킹 알고리즘에 따르면, 3에 대한 파라미터는

및

로 계산된다. 그리고,

,

및

임을 더 얻을 수 있다. 마지막으로,

= 9이고 그레이 코드 순서에서 대응되는 정보 비트는 0100이 된다. Example 2:

= 4

= {3,1,2,4}. According to the ranking algorithm, the parameter for 3 is

And

. And,

,

And

Can be obtained. Finally,

= 9 and the corresponding information bit in the gray code order is 0100.

ii) Unranked ( Unranking ) Way

으로 전환된다. 그 후에,

및

는 다음과 같이 유도 된다.The unranked method is the opposite of the ranking method. First, the information bit sequence in the gray code sequence is an integer

. After that,

And

Is derived as follows.

(8)

(8)

And

(9)

(9)

는 모듈러스(modulus)

연산을 나타낸다. 예를 들어,

> 3인 경우에 대해,

인

및

는 다음과 같이 계산된다. From here,

Modulus < / RTI >

Operation. E.g,

≫ 3,

sign

And

Is calculated as follows.

(10)

(10)

And

(11)

(11)

로 설정하고, 수식 (10) 및 (11)로부터

및

를 얻을 수 있게 된다.

까지,

및

는 모두 얻어진다.

는

에 의해 결정된다는 것은 명백하다. 마지막으로, 알고리즘 1로부터 퍼뮤테이션을 리빌드(rebuild)할 수 있다. 언랭크 방법에 대한 전체적인 프로세스는 아래의 알고리즘 2에 요약되어 있다. After that,

(10) and (11) to

And

.

Till,

And

Are all obtained.

The

Lt; / RTI > Finally, permutations can be rebuilt from Algorithm 1. The overall process for the un-ranking method is summarized in algorithm 2 below.

= 4 및 n = 18인 것으로 가정한다. 우선,

및

은 쉽게 얻을 수 있다. 그 후,

및

를 얻을 수 있다. 알고리즘 1에 따르면, 서브 퍼큐테이션 {2,3,1}은

및

로부터 얻어진다. 마지막으로, 대응 퍼뮤테이션 {2,3,4,1}을 구할 수 있게 된다.Example 3:

= 4 and n = 18. first,

And

Can be easily obtained. After that,

And

Can be obtained. According to Algorithm 1, the sub-function {2,3,1}

And

Lt; / RTI > Finally, the corresponding permutation {2,3,4,1} can be found.

4. ANALYSIS OF THE CODING GAIN

Hereinafter, the coding gain ratio of the gray code order and the lexical order is derived in a high signal-to-noise ratio (SNR) environment. The upper bound of the average bit error ratio (ABER) is given by union bound as:

(12)

(12)

는

가 전송될 때 신호행렬

에서 검출되는 쌍 오류 확률(PEP : pairwise error probability)을 나타내며,

및

는

와

사이의 에러 있는 비트 수(the number of bits in error)를 나타낸다. 높은 신호대잡음비(SNR) 환경에서, 상한 경계(upper bound)는 다음과 같이 표현될 수도 있다. From here,

The

Lt; RTI ID = 0.0 >

(PEP) detected at the base station,

And

The

Wow

(The number of bits in error). In a high signal-to-noise ratio (SNR) environment, the upper bound may be expressed as:

(13)

(13)

Here, c is a constant and r = 1. The average of the number of bits in error for the lexicographic order and the gray code order can be defined as:

(14)

(14)

And

(15)

(15)

및

는 각각 사전식 순서 및 그레이 코드 순서에 대한 에러 있는 비트 수(the number of bits in error)를 나타낸다. 수식 (13)에서, 사전식 순서와 그레이 코드 순서에 대한 코딩 게인(coding gain)은 오직

와

에 의해서만 차이가 발생한다는 것을 확인할 수 있다. 코딩 게인 비율(coding gain ratio)는 데시벨(dB)로 다음과 같이 계산될 수 있다. From here,

And

Denote the number of bits in error for the lexicographic order and the gray code order, respectively. In equation (13), the coding gain for the lexicographic order and gray code order is only

Wow

It can be confirmed that the difference occurs only by The coding gain ratio can be calculated in decibels (dB) as follows.

(16)

(16)

5. Simulation results

= 1 및 2를 가지는 경우를 고려하였다. 또한, 이론적 코딩 게인도 계산하였다. Hereinafter, a simulation for testing a bit error rate performance (BER performance) of a differential space shift keying (DSSK) to which a gray code order according to an embodiment of the present invention is applied will be described, and a lexicographic order ) And the lexi-gray order. In the simulation, slow-varying Rayleigh flat fading channels

= 1 and 2, respectively. The theoretical coding gain was also calculated.

= 4 및 6을 가지는 그레이 코드 순서, 사전식 순서, 및 렉시-그레이 순서에 대한 비트에러율(BER) 성능을 각각 도시한 도면이다. 비트에러율(BER) =

일 때, 본 발명의 실시예에 따른 그레이 코드 순서는

= 4 및 6에 대해 사전식 순서의 경우와 비교했을 때 각각 1.2dB 및 0.3dB의 성능 게인(performance gains)을 얻을 수 있는 것으로 확인된다. 렉시-그레이 순서와 비교했을 때에도, 본 발명의 실시예에 따른 그레이 코드 순서 방법이 거의 같은 성능 게인을 가지는 것으로 확인된다. 도 3은

= 3,4,5 및 6인 경우의 코딩 게인의 이론적 결과치를 도시한 도면이다.

= 3인 경우, 그레이 코드 순서에 대한 에러 있는 비트의 합은 사전식 순서의 경우와 같으므로 0의 코딩게인을 가지게 된다. 하지만, 코딩게인은

= 4에서 큰 성능 게인 차이를 가지게 되고,

= 5 및 6에서는 약간의 성능 강화가 있게 된다.

= 4 및 6의 경우에 대해 코딩 게인의 이론적 결과 시뮬레이션 결과가 일치하는 것을 확인할 수 있다. 2 is a graph showing the relationship between the spectral efficiency at 1 bps / Hz and 1.5 bps / Hz

= 4 and 6, bit error rate (BER) performance for the lexicograph order, and lexico-gray order, respectively. Bit error rate (BER) =

, The gray code sequence according to the embodiment of the present invention is

= 4 and 6, respectively, the performance gains of 1.2 dB and 0.3 dB are obtained, respectively, as compared with the case of the lexicographic order. Even when compared with the lexi-gray order, it is confirmed that the gray code order method according to the embodiment of the present invention has almost the same performance gain. 3,

= 3, 4, 5, and 6, respectively.

= 3, the sum of erroneous bits in the gray code order is the same as in the case of the lexicographic order, so that it has a coding gain of zero. However, the coding gain

= 4, a large performance gain difference is obtained,

= 5 and 6 have some performance enhancements.

= 4 and 6, it can be confirmed that the simulation result of the theoretical result of the coding gain coincides.

6. Conclusion

값에 대한 일대일 대응을 구하기 위해, 그레이 코드 순서에 대한 랭킹 및 언랭킹 알고리즘을 제안하였다.Up to now, it has been confirmed that the gray code order improves the performance of differential space modulation (DSM). A method according to an embodiment of the present invention is to use a gray code sequence for both information bits and corresponding permutations. Also,

To obtain a one-to-one correspondence to the values, we proposed a ranking and un-ranking algorithm for the gray code sequence.

4 is a flowchart provided in the description of a signal differential space modulation method of a MIMO system according to an embodiment of the present invention.

4, the transmitter 100 divides the information bits of a transmission signal into a plurality of transmitted blocks (S310), adds an antenna activation order ) Are mapped (S320).

Next, the transmitter 100 transmits the transmission block to the receiver 200 according to the antenna activation sequence mapped to the permutation (S330).

At this time, gray code order is applied to the order of antenna activation according to the permutation.

It is to be understood that the technical idea of the present invention can also be applied to a computer-readable recording medium having a computer program for performing the functions of the MIMO system and the differential spatial modulation method according to the embodiment of the present invention. In addition, the technical idea according to various embodiments of the present invention may be realized in the form of a computer-readable programming language code recorded on a computer-readable recording medium. The computer-readable recording medium is any data storage device that can be read by a computer and can store data. For example, the computer-readable recording medium may be a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical disk, a hard disk drive, a flash memory, a solid state disk (SSD), or the like. In addition, the computer readable code or program stored in the computer readable recording medium may be transmitted through a network connected between the computers.

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, but, on the contrary, It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention.

100: MIMO transmitter
200: MIMO receiver

Claims (8)

In a signal differential space modulation (DSM) method of a multi-input multi-output (MIMO) system,
A transmitter comprising: dividing information bits of a transmission signal into a plurality of transmitted blocks;
The transmitter mapping a permutation indicating an antenna activation order to a specific bit of each transport block; And
The transmitter transmitting the transport block according to an antenna activation sequence mapped to the permutation,
The antenna activation sequence according to the permutation is applied with a gray code order,
Wherein the mapping step comprises:
Mapping a permutation indicating an antenna activation order to a specific bit of each transport block using a lookup table containing information bits and permutations in a predetermined gray code order,
The transmitter includes N _T transmit antennas,
N _T is a permutation, the N _T (N _T -1), but generated by changing the other end adjacent to the sense element in one end of the permutation, the second odd-numbered and even-numbered traveling direction of the N _T N _T in the second round Wherein the direction of travel of the differential space modulation is different.
The method according to claim 1,
The transmission block includes:

Gt; bits, < / RTI >
The method of claim 2,
Wherein the mapping step comprises:
The first

And mapping the permutation indicating an antenna activation order to the bits.
delete The method according to claim 1,
Wherein the mapping step comprises:
Wherein a permutation indicating an antenna activation order is mapped to a specific bit of each of the transport blocks using a ranking method.
The method according to claim 1,
Wherein the mapping step comprises:
Wherein a permutation indicating an antenna activation order is mapped to a specific bit of each of the transport blocks using an unranking method.
The method according to claim 1,
Further comprising demapping the received signal to a permutation of the antenna activation sequence and demodulating the received signal to recover the information bit.
In a multi-input multi-output (MIMO) system to which differential signal spatial modulation (DSM) is applied,
The information bits of the transmission signal are divided into a plurality of transmitted blocks, a permutation indicating an antenna activation order is mapped to a specific bit of each transmission block, and an antenna activation sequence mapped to the permutation A transmitter for transmitting the transport block; And
And a receiver for demapping a signal received from the transmitter to a permutation of the antenna activation order and demodulating the signal to recover the information bit,
The antenna activation sequence according to the permutation is applied with a gray code order,
The transmitter includes:
Group using a look-up table contained the information bits with permutation of the Gray code sequence set, and maps a permutation of an antenna activation sequence (activation order) a specific bit of each transport block, N the _T transmit antennas Including,
N _T permutation,
The N _T (N _T -1), but generated by changing the other end adjacent to the sense element in one end of the permutation, an odd number N _T of travel direction in the second moving direction and even the N _T in the second round is the different MIMO system characterized by.

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