KR102263034B1 - Method for transmitting down-link signal of wireless communication system - Google Patents

Abstract

The present invention relates to a method for transmitting a downlink signal of a wireless communication system, which comprises the following steps: allocating, by each base station, each local user and a first remote user as a non-orthogonal multiple access (NOMA) user while applying joint transmission cooperative multipoint-based non-orthogonal multiple access (JT-CoMP NOMA) and spatial modulation (SM) in a plurality of cells including a base station, a local user, and a remote user; allocating, by each base station, each remote user except the first remote user as an SM user; allocating a second remote user among the remote users as a coordinated spatial modulation (CoSM) user; and transmitting a downlink signal to the NOMA user, the SM user, and the CoSM user. According to the present invention, a user transmission capacity for multiple cells and multiple users can be increased.

Description

Downlink signal transmission method of a wireless communication system {METHOD FOR TRANSMITTING DOWN-LINK SIGNAL OF WIRELESS COMMUNICATION SYSTEM}

The present invention is a joint transmission coordinated multi-point (JT-CoMP) based non-orthogonal multiple access (JT-CoMP NOMA) that improves transmission capacity by mitigating inter-cell interference (ICI) ) and an antenna as an index to provide a wireless communication system to which spatial modulation (SM) is applied to improve the spectral efficiency of radio signals, thereby improving user transmission capacity for multiple cells and multiple users. It relates to a downlink signal transmission method of a system.

As is well known, mobile communication systems have been developed to provide voice services while ensuring user activity. However, the mobile communication system has expanded its scope to not only voice but also data service, and now, due to the explosive increase in traffic, a resource shortage is caused and users demand a higher speed service, so a more advanced mobile communication system is required. .

The requirements of these next-generation mobile communication systems are largely to accommodate explosive data traffic, a dramatic increase in the transmission rate per user, a significantly increased number of connected devices, very low end-to-end latency, and high energy efficiency. should be able to support

To this end, in a wireless communication system, dual connectivity, massive multiple input multiple output (MIMO), in-band full duplex, non-orthogonal multiple access (NOMA), Various technologies such as support for super wideband and device networking are being studied.

Here, the non-orthogonal multiple access (NOMA) is a multiple access technique that is considered to further improve a spectrum gap compared to orthogonal multiple access (OMA). When a plurality of multiplexed users can be supported through a specific resource that is allocated different power according to each user, and each user requires the same quality of service (QoS), the power allocation can be determined based on their channel gain, and the channel gain This good user can use successive interference cancellation (SIC) to decode their own signal by canceling other signals.

On the other hand, in a downlink multi-cell network, since inter-cell interference (ICI) may degrade system performance such as user throughput and cell capacity, in order to solve this, non-orthogonal multiple access (ICI) ( Joint transmission coordinated multi-point (JT-CoMP) is being introduced as an inter-cell interference (ICI) mitigation technology that can increase the transmission capacity of NOMA). have.

1. Korea Patent Publication No. 10-2017-0106376 (published on Sep. 20, 2017) 2. Korea Registered Patent No. 10-1596543 (Registered on Feb. 16, 2016)

The present invention uses non-orthogonal multiple access (JT-CoMP NOMA) based on joint transmission cooperative multipoint (JT-CoMP) to improve transmission capacity by mitigating inter-cell interference (ICI) and an antenna as an index for spectrum of radio signals An object of the present invention is to provide a downlink signal transmission method of a wireless communication system capable of improving user transmission capacity for multiple cells and multiple users by providing a wireless communication system to which spatial modulation (SM) is applied to improve efficiency.

In addition, the present invention applies non-orthogonal multiple access (JT-CoMP NOMA) and spatial modulation (SM) based on joint transmission cooperative multipoint in a plurality of cells including a base station, a local user, and a remote user, respectively, but each base station assigns each local user and the first remote user as a non-orthogonal multiple access (NOMA) user, and assigns each remote user except the first remote user as a spatial modulation (SM) user, 2 By allocating a distant user as a CoSM (JT-CoMP NOMA-SM) user and transmitting a downlink signal, a downlink signal of a wireless communication system that can increase user transmission capacity and effectively mitigate inter-cell interference We want to provide a method of transmission.

The purpose of the embodiments of the present invention is not limited to the above-mentioned purpose, and other objects not mentioned will be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. .

According to an embodiment of the present invention, non-orthogonal multiple access (JT-CoMP NOMA) and spatial modulation (SM) based on joint transmission cooperative multipoint are applied in a plurality of cells including a base station, a local user and a remote user, respectively, Allocating each local user and the first remote user as a non-orthogonal multiple access (NOMA) user at each base station, and spatial modulation (SM) of each remote user except the first remote user at each base station assigning to a user; assigning a second remote user from among the respective remote users to a coordinated SM (CoSM) user; and to the non-orthogonal multiple access (NOMA) user, spatial modulation (SM) user and CoSM user. to provide a method for transmitting a downlink signal in a wireless communication system including transmitting a downlink signal.

In addition, according to an embodiment of the present invention, the step of allocating to the CoSM user is a wireless communication system for allocating a plurality of remote users excluding the first remote user and the second remote user as non-CoSM (non-CoSM) users. A downlink signal transmission method of may be provided.

In addition, according to an embodiment of the present invention, the first base station corresponding to the first remote user and the second base station corresponding to the second remote user use a spatial modulation (SM) index to provide the CoSM user with the downlink. A method for transmitting a downlink signal of a wireless communication system adjusted to transmit a link signal may be provided.

In addition, according to an embodiment of the present invention, the CoSM user may be provided with a downlink signal transmission method in a wireless communication system using a joint ML detector to decode the downlink signal.

In addition, according to an embodiment of the present invention, the non-CoSM (non-CoSM) user obtains information for decoding the downlink signal using the spatial modulation (SM) index of a downlink signal of a wireless communication system. A transmission method may be provided.

In addition, according to an embodiment of the present invention, each of the base stations may provide a method for transmitting a downlink signal in a wireless communication system in which an overall bandwidth and a total transmission power are normalized.

In addition, according to an embodiment of the present invention, each of the base stations may provide a method for transmitting a downlink signal in a wireless communication system including a plurality of transmission antennas.

The present invention uses non-orthogonal multiple access (JT-CoMP NOMA) based on joint transmission cooperative multipoint (JT-CoMP) to improve transmission capacity by mitigating inter-cell interference (ICI) and an antenna as an index for spectrum of radio signals By providing a wireless communication system to which spatial modulation (SM) is applied to improve efficiency, it is possible to improve user transmission capacity for multiple cells and multiple users.

In addition, the present invention applies non-orthogonal multiple access (JT-CoMP NOMA) and spatial modulation (SM) based on joint transmission cooperative multipoint in a plurality of cells including a base station, a local user, and a remote user, respectively, but each base station assigns each local user and the first remote user as a non-orthogonal multiple access (NOMA) user, and assigns each remote user except the first remote user as a spatial modulation (SM) user, 2 By allocating a distant user as a CoSM user and transmitting a downlink signal, user transmission capacity can be increased and inter-cell interference can be effectively mitigated.

In particular, the present invention provides joint transmission cooperative multi-point (JT-CoMP VP-NOMA) combined with orthogonal multi-point (OMA), non-orthogonal multiple access (NOMA) and virtual user pairing-based non-orthogonal multiple access (JT-CoMP VP-NOMA: joint When compared with transmission coordinated multi-point combined with virtual user pairing based non-orthogonal multiple access), it has the same short-range user (CCU) capacity as JT-CoMP VP-NOMA, and high far-end user (CEU) capacity compared to other techniques. , and ergodic sum capacity (ESC) has superior performance than other techniques by increasing the remote user (CEU) capacity, and when the number of cells increases, more remote users (CEU) than other techniques Capacity can be better maintained and inter-cell interference (ICI) can be mitigated.

1 is a flowchart illustrating a process of transmitting a downlink signal in a wireless communication system according to an embodiment of the present invention;
2 is a diagram illustrating a network configuration to which a downlink signal transmission method of a wireless communication system according to an embodiment of the present invention is applied;
3 is a diagram illustrating a system configuration diagram of a wireless communication system according to an embodiment of the present invention;
4 to 13 are diagrams for explaining simulation results of a wireless communication system to which joint transmission cooperative multipoint-based non-orthogonal multiple access (JT-CoMP NOMA) and spatial modulation (SM) are applied according to an embodiment of the present invention. .

Advantages and features of embodiments of the present invention, and methods of achieving them, will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

In describing the embodiments of the present invention, if it is determined that a detailed description of a well-known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms to be described later are terms defined in consideration of functions in an embodiment of the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

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

1 is a flowchart illustrating a process of transmitting a downlink signal in a wireless communication system according to an embodiment of the present invention, and FIG. 2 is a network to which a downlink signal transmission method of a wireless communication system according to an embodiment of the present invention is applied. It is a diagram illustrating a configuration diagram, and FIG. 3 is a diagram illustrating a system configuration diagram of a wireless communication system according to an embodiment of the present invention, and FIGS. 4 to 13 are multi-point based joint transmission cooperation according to an embodiment of the present invention. It is a diagram for explaining the simulation results of a wireless communication system to which non-orthogonal multiple access (JT-CoMP NOMA) and spatial modulation (SM) are applied. Here, the full name of JT-COMP NOMA-SM is 'joint transmission coordinated multi-point based non-orthogonal multiple access', and JT-CoMP NOMA (JT-CoMP NOMA) and spatial modulation (SM) ) is applied to a wireless communication system, CoSM represents 'coordinated spatial modulation', reference numeral 10 means each base station, reference numeral 20 means each local user (CCU: cell center user), and reference numeral 30 denotes each remote user (CEU: cell edge user).

When the downlink signal transmission method of the wireless communication system is described with reference to FIGS. 1 to 13 , the base station 10 , the local user 20 and the remote user 30 are jointly transmitted in a plurality of cells including each multi-point cooperative transmission. Non-orthogonal multiple access (JT-CoMP NOMA) and spatial modulation (SM) based on non-orthogonal multiple access (SM) are applied to each local user 20 and the first remote user 30 in each base station 10. NOMA) can be assigned as a user (step 110).

Then, each remote user 30 except for the first remote user 30 in each base station 10 may be assigned as a spatial modulation (SM) user (step 120).

In addition, a second remote user 30 among each remote user 30 may be assigned as a coordinated SM (CoSM) user (step 130).

Here, in the step of allocating CoSM users, a plurality of remote users 30 except for the first remote user 30 and the second remote user 30 may be allocated as non-CoSM (non-CoSM) users.

In addition, the first base station 10 corresponding to the first remote user 30 and the second base station 10 corresponding to the second remote user 30 are downlinked to the CoSM user using a spatial modulation (SM) index. It can be adapted to transmit link signals.

Specifically describing steps 110 to 130 as described above, as shown in FIGS. 2 and 3 , the N cells include K cooperative multipoint base stations (CoMP BSs), and each cooperative cell includes one base station. (BS), one local user (CCU), and one remote user (CEU) may be included.

Here, each i ^th cell represents the coverage of each i ^th BS (i∈1, 2, ..., K, K+1, ..., N), in this case K cells (2≤K≤ N and K⊂N) can be adjusted to each central unit (CU), other cells are not adjusted, and the local user (CCU) and the far user (CEU) located in the ^{i th} _{cell are U i,} It can be denoted as ₁ and U _{i,2 .}

These users can be divided into a system to which JT-CoMP NOMA is applied and a system to which spatial modulation (SM) is applied. In a system to which (JT-CoMP NOMA) is applied, K CCUs (U _i,1 for 1≤i≤K) and CEUs (U _i,2 for i=1) may be assigned as NOMA users. _{Here, CEUs (U 1,2} ) located in the first cell are allocated as CoMP users, but all CCUs do not apply the CoMP technique.

_{In addition, in a system to which spatial modulation (SM) is applied, other CEUs (U i,2} for 2≤i≤K) not included in the system to which joint transmission cooperative multipoint based non-orthogonal multiple access (JT-CoMP NOMA) is applied ) may be assigned as an SM user, U _2,2 may be assigned as a CoSM user, and U _i,2 may be assigned as a non-CoSM user for 3≤i≤K.

On the other hand, as shown in FIG. 3 , each i ^th base station (BS) has a plurality of antennas, can be connected through a backhaul, and K cooperative multipoint base stations (CoMPs) controlled using each central unit (CU) BS) can be considered.

Here, the central unit (CU) may design a transmission parameter by collecting channel state information (CSI) from a cooperative multi-point base station (CoMP BS) through a backhaul.

In this case, the central unit (CU) may provide an additional function for controlling the antenna selector at each base station (BS), and on the receiver side, the user can use a joint maximum likelihood (ML) detector to It is possible to estimate which transmitter is transmitting based on the received signal. Here, a joint minimum distance detector may be used to reduce the complexity approximation of the maximum likelihood detector.

Next, as a non-orthogonal multiple access (NOMA) user, a spatial modulation (SM) user, and a CoSM user, the base station 10 may transmit a downlink signal to a local user (CCU) and a far user (CEU) (step 140). ).

For the downlink signal transmission of the base station 10, the CoSM user may use a joint ML detector to decode the downlink signal after receiving the downlink signal transmitted from the base station 10. and a non-CoSM (non-CoSM) user may obtain information for decoding a downlink signal using a spatial modulation (SM) index.

In the wireless communication system as described above, each base station 10 in a plurality of cells including the base station 10, the local user 20, and the remote user 30, respectively, the total bandwidth and the total transmission power to be normalized. and may include a plurality of transmission antennas.

Specifically, the total bandwidth of each base station (BS) is normalized to B = 1, and the total transmission power of each base station (BS) can be normalized to P = 1, and a near user (CCU) and a far user (CEU) are normalized. ) can be assigned as _{α 1} and α _{2 , respectively. For example, assuming α 1} =0.1, α ₂ can be calculated as 1-α _{1 , and P i,1} =α ₁ P and P _i,2 =α ₂ P may be allocated as power to a near user (CCU) and a far user (CEU) located in the i ^{th cell.}

And, the user location can be generated based on a random user algorithm and distributed to the adjusted cell, i ^th the distance between the near user (CCU) and the far user (CEU) from the base station (BS) ground of the cell is r _{i ,1} and r _i,2 , when the maximum cell radius from the base station (BS) ground is normalized to R=1, the base station (BS) antenna height and other base station (BS) distances are 0,01R and 2R, respectively can be assigned, and d _i,1 and d _i,2 can be calculated as the distances of the local user (CCU) and the far user (CEU) from the base station (BS) antenna of ^{the i th} cell, respectively, using the concept of trigonometry. have.

On the other hand, in the present invention, incomplete SIC (successive interference cancellation) and incomplete CSI (channel state information) can be considered in the simulation parameters. On the other hand, a fixed value assumed to be -25 dB for incomplete SIC is considered, Incomplete CSI can be modeled as a channel estimation error.

에 의해 모델링될 수 있고, i^th 셀의 기지국(BS)과 원거리 사용자(CEU) 사이의 링크에 대한 채널 추정 오류는

로 나타낼 수 있다.Here, the priority of the variance of the error estimation is known, and the channel estimation error for the link between the local user (CCU) in the base station (BS) of the ^{i th cell is}

can be modeled by , and the channel estimation error for the link between the base station (BS) and the remote user (CEU) of the ^{i th cell is}

can be expressed as

로 페이딩될 경우 독립적인 레일리가 있다고 가정될 수 있다. 여기에서,

및

는 각각 근거리 사용자(CCU) 및 원거리 사용자(CEU)에 대한 각 채널 추정 오차의 분산을 나타낸다.Through each link, the channel counts

When fading to , it can be assumed that there are independent Rayleighs. From here,

and

denotes the variance of each channel estimation error for a near user (CCU) and a far user (CEU), respectively.

및

을 고려할 필요가 있기 때문에, 근거리 사용자(CCU) 및 원거리 사용자(CEU)의 채널 추정 특성은 평균 0과 독립적으로 분포된다고 가정하고, 이는 각각

및

으로 모델링될 수 있다.In addition, the received signals for the local user (CCU) and the far user (CEU) from the base station (BS) of the ^{i th cell are channel estimation gains, respectively.}

and

Since it is necessary to consider , it is assumed that the channel estimation characteristics of the near user (CCU) and the far user (CEU) are distributed independently of the mean 0, which is each

and

can be modeled as

및

는 i^th 셀의 기지국(BS) 안테나에서 근거리 사용자(CCU) 및 원거리 사용자(CEU)까지의 링크에 대한 추정 분산을 각각 나타내며, v는 경로 손실 지수를 나타내고, 단순성을 위해 기지국(BS)에서 사용자와 각 안테나 사이의 링크는

로 표시되는 동일한 채널 추정 오류를 가지고 있다고 가정할 수 있으며,

=0,01을 가정할 수 있다.in this case,

and

denotes the estimated variance for the links from the base station (BS) antenna of the i ^th cell to the near user (CCU) and far user (CEU), respectively, v denotes the path loss index, and for simplicity, and the link between each antenna is

We can assume that we have the same channel estimation error denoted by

=0,01 can be assumed.

In the present invention, it can be assumed that each cooperative multipoint base station (CoMP BS) has two antennas (T _Xi =2), where T _Xi represents the number of base station (BS) antennas in i ^{th cell, and each user} For this, a single antenna can be applied. Here, spatial modulation (SM) may use multiple transmit antennas while a single transmit antenna is used to transmit some symbols at a specific time.

In this spatial modulation (SM), information can be conveyed by antenna index as well as IQ domain, and SM users require more capacity or increase the number of SM users, while generalized SM utilizing more BS antennas. (Generalized SM) is required.

In this case, the first base station (BS) and the second base station (BS) may be coordinated to transmit information to the CoSM user using the SM index. Considering this problem, the CoSM user decodes information from multiple base stations (BS). To do this, a joint maximum likelihood (ML) detector can be used, and a joint minimum distance (MD) detector can be used to reduce the complexity approximation of the ML detector.

On the other hand, each non-CoSM can obtain information from a base station (BS) ^{of an i th} cell with 3≤i≤K using an SM index (eg, a transmission symbol and an antenna index). Binary Phase Shift Keying (BPSK) : Assuming that binary phase-shift keying) is used, the number of SM index combinations increases when the first base station (BS) and the second base station (BS) perform cooperative multipoint (CoSM) as shown in FIG. As a result of the combination, a CoSM user may receive 4 input bits, and a non-CoSM user may receive only 2 input bits. Here, as the modulation increases, the combination may increase.

Specifically, the ergodic sum capacity (ESC) in the case of transmitting a downlink signal in the wireless communication system as described above, in the case of the ergodic sum capacity (ESC) of the JT-CoMP NOMA system, the Shannon formula It can be determined through mathematical analysis based on If it is considered that the cooperative multi-point base station (CoMP BS) transmits the same data to the CoMP user, the i-th base station (BS) may transmit the signal information of Equation 1 below.

Here, S _i,1 and S _i,2 represent desired signals for a near user (CCU) and a far user (CEU) located in the i ^{th cell, respectively.}

And, when considering the point of view of the short-range user (CCU), the total received signal of the short-range user (CCU) located in the ^{i th cell may be given as in Equation 2 below.}

을 고려할 경우 근거리 사용자(CCU)의 수신된 신호 대 잡음비(SINR)는 다음의 수학식 3과 같이 나타낼 수 있다.Here, n _i,1 is expressed as the noise received by the near-field user (CCU) located in the ^{i th} cell during transmission,

When , the received signal-to-noise ratio (SINR) of the short-range user (CCU) can be expressed as Equation 3 below.

은 i^th 셀에 위치하는 근거리 사용자(CCU)에 대한 추가 백색 가우시안 노이즈(AWGN)를 나타내며, 근거리 사용자(CCU)는 연속적인 간섭 제거(SIC)를 이용하여 각 협력 다중포인트 기지국(CoMP BS)으로부터의 CoMP 사용자 신호를 상쇄시킬 수 있지만, CoMP 사용자 신호에 의해 야기되는 잔여 간섭의 경우 근거리 사용자(CCU)는 이를 완벽하게 상쇄시킬 수 없다.From here,

represents the additional white Gaussian noise (AWGN) for the near user (CCU) located in the i ^th cell, the near user (CCU) from each cooperating multipoint base station (CoMP BS) using successive interference cancellation (SIC) Although it can cancel the CoMP user signal, in the case of residual interference caused by the CoMP user signal, the near user (CCU) cannot completely cancel it.

을 고려할 경우, i^th 셀에 위치하는 근거리 사용자(CCU)의 신호 대 잡음비(SINR)는 다음의 수학식 4와 같이 유도될 수 있다.And,

In consideration of , the signal-to-noise ratio (SINR) of the short-range user (CCU) located in the ^{i th cell can be derived as in Equation 4 below.}

는 SIC 프로세스 중 근거리 사용자(CCU)에서 불완전한 디코딩으로 인한 잔여 간섭을 나타내며, 상기 수학식 4에서 근거리 사용자(CCU)는 비협력 다중포인트 기지국(non-CoMP BS)으로부터 셀 간 간섭(ICI : inter-cell interference)을 겪게 되고, 근거리 사용자(CCU)에 할당된 전력에 의해 야기되는 협력 다중포인트 기지국(CoMP BS)으로부터 셀 간 간섭(ICI)를 겪게 되는데, 단순성을 위해 근거리 사용자(CCU)에 대한 오류 매개 변수의 모든 분산은 동일한 값을 갖는 것으로 가정할 경우, 상기 수학식 4는 다음의 수학식 5와 같이 다시 나타낼 수 있다.From here,

denotes residual interference due to incomplete decoding in a short-range user (CCU) during the SIC process, and in Equation 4, the short-range user (CCU) receives inter-cell interference (ICI) from a non-cooperative multipoint base station (non-CoMP BS). cell interference), and inter-cell interference (ICI) from a cooperating multipoint base station (CoMP BS) caused by the power allocated to the near user (CCU), which for simplicity is an error for the near user (CCU). If it is assumed that all variances of the parameters have the same value, Equation 4 can be expressed again as Equation 5 below.

는 각 채널 추정 오류에 대한 분산을 나타내며, i^th 셀에 위치한 근거리 사용자(CCU)의 달성 가능한 데이터 전송률은 다음의 수학식 6과 같이 나타낼 수 있다.From here,

represents the variance for each channel estimation error, and the achievable data rate of a near user (CCU) located in the ^{i th cell can be expressed as in Equation 6 below.}

On the other hand, the total received signal of the CoMP user may be given by Equation 7 below.

Here, n _1,2 is represented by the noise received by the CoMP user during transmission, and in Equation 7, the CoMP user directly performs decoding without successive interference cancellation (SIC), so it is assigned to a short-range user (CCU). Cooperative multipoint inter-cell interference (ICI CoMP) is received from the received power.

And, the received signal-to-noise ratio (SINR) for the CoMP user can be expressed as in Equation 8 below.

Based on Equation 8, when the number of cooperative multi-point base stations (CoMP BSs) increases, a desired signal of a CoMP user may increase. Since the CoMP user directly performs decoding, continuous interference cancellation (SIC) is performed. may not be used. This means that CoMP users cannot override or use the SIC process.

Similarly, if it is assumed that all variances of error parameters for CoMP users have the same value, Equation 8 can be expressed again as Equation 9 below.

And, the achievable data rate of the CoMP user can be expressed as in Equation 10 below.

In addition, the ergodic sum capacity (ESC) of the JT-CoMP NOMA system can be expressed as in Equation 11 below.

을 상기 수학식 6을 기반으로 결정할 수 있으며,

과

을 사용함으로써, 상기 수학식 6은 다음의 수학식 12와 같이 단순화하여 나타낼 수 있다.In the present invention, accurate near user (CCU) capacity, that is,

can be determined based on Equation 6 above,

and

By using , Equation 6 can be simplified as Equation 12 below.

에 대한 상기 수학식 12는 다음의 수학식 13과 같이 나타낼 수 있다.Also,

Equation 12 can be expressed as Equation 13 below.

는 기대 연산자로,

로 표시되며, 상기 수학식 13에서의

및

은 후술하는 [참조] A.1에서 수학식 27 및 수학식 28을 사용하여 유도할 수 있다. 따라서, 상기 수학식 13은 다음의 수학식 14와 같이 결정될 수 있다.From here,

is the expectation operator,

It is represented by , and in Equation 13

and

can be derived using Equations 27 and 28 in [Reference] A.1 to be described later. Accordingly, Equation 13 can be determined as Equation 14 below.

은 다음의 수학식 15와 같이 나타낼 수 있다.Next, by substituting Equations 25 and 26 in [Reference] A.1 to be described later with Equation 14,

can be expressed as in Equation 15 below.

와

를 이용하여 달성 가능한 데이터 전송률

은 다음의 수학식 16과 같이 나타낼 수 있다.Also,

Wow

Data rates achievable using

can be expressed as in Equation 16 below.

On the other hand, the correct CoMP user capacity in Equation (10) can be given as Equation (17) below.

이다.From here,

to be.

및

는 후술하는 [참조] A.2에서의 수학식 32 및 수학식 33을 사용하여 결정될 수 있다.Similarly, in Equation 17 above

and

may be determined using Equations 32 and 33 in [Reference] A.2, which will be described later.

And, a probability density function (PDF) for each exponential random variable of the remote user (CEU) may be derived from Equations 30 and 31 of [Reference] A.2, which will be described later.

에 대한 달성 가능한 데이터 전송률은 다음의 수학식 18과 같이 나타낼 수 있다.therefore,

The achievable data rate for ? can be expressed as Equation 18 below.

Accordingly, the ergodic sum capacity (ESC) of the JT-CoMP NOMA system can be expressed as Equation 19 below.

)와 하나의 원거리 사용자(CEU,

)에 이미 적용된 JT-CoMP NOMA를 고려할 경우, 다른 사용자들은 기지국(BS)에 의해 자원을 할당받지 않으며, SM 사용자(

)는 공간 변조(SM)를 사용하여 처리될 수 있다.Next, if the ergodic sum capacity (ESC) of the SM system is described, the ergodic sum capacity (ESC) of the SM system can be determined in K cooperative multi-point base stations (CoMP BSs), and all short-range users (CCU,

) and one remote user (CEU,

), when considering JT-CoMP NOMA already applied to, other users are not allocated resources by the base station (BS), and SM users (

) can be processed using spatial modulation (SM).

In such spatial modulation (SM), sometimes users cannot perfectly estimate modulated information through an antenna index, which may reduce user capacity expressed by probability of error (PE).

, )은 SM 사용자들이 수신한 오류 정보의 수와 기지국(BS)으로부터 전송된 원본 정보의 수를 비교함으로써 계산될 수 있다.In the present invention, when it is assumed that SM users can perfectly detect the antenna index, and the error probability (PE) occurs only in error estimation of the BPSK constellation symbol, the error probability per SM user (that is,

, ) can be calculated by comparing the number of error information received by SM users with the number of original information transmitted from the base station (BS).

_{When considering PE i.2} and SM capacity of [Reference] A.3, which will be described later in consideration of the table shown in FIG. 4, the achievable data rate for the SM user in consideration of perfect antenna detection is calculated by the following equation 20 can be determined.

Here, M represents an M-ary modulation constellation order.

Accordingly, the ergodic sum capacity (ESC) for the SM system can be expressed as Equation 21 below.

And, by substituting Equations 54 and 55 in [Reference] A.3 to be described later with Equation 20, the correct ergodic sum capacity (ESC) of the SM system of Equation 21 is obtained by Equation 22 and can be assigned together.

On the other hand, in the case of the ergodic sum capacity (ESC) of the JT-CoMP NOMA-SM system according to the embodiment of the present invention, when considering N cells, the ergodic sum capacity for K cooperative multipoint base stations (CoMP BSs) ( ESC), and other base stations (BS) may not apply the adjustment.

Therefore, the ergodic sum capacity (ESC) of the JT-CoMP NOMA-SM system according to the embodiment of the present invention is obtained by adding the sum of the capacities of the near user (CCU) and the far user (CEU) as in Equation 23 below. can decide

Similarly, the exact ergodic sum capacity (ESC) of the JT-CoMP NOMA-SM system according to an embodiment of the present invention can be expressed as Equation 24 below.

Meanwhile, the performance of the JT-CoMP NOMA-SM system as described above is compared and simulated with OMA, NOMA, and JT-COMP VP-NOMA to analyze the performance such as CCU capacity, CEU capacity, and ESC below.

For simplicity of comparative analysis, it is simulated and analyzed based on a simplified 3-CoMP BS (K=3) within 12 cells (N=12), in which case Rayleigh flat fading is applied between the user and the BS antenna. It can be simulated with v=4 for the path loss exponent in the link of . For example, it is possible to compare and analyze the simulation parameters as shown in FIG. 5 and the scenario shown in FIG. 6 .

에서 124.2%, 258.7%, 590.2% 증가하였음을 알 수 있으며, JT-CoMP VP-NOMA 시스템이 가장 낮은 CEU 용량을 보인다는 점을 알 수 있다.Referring to the simulation results as described above, FIG. 7 shows that the CEU capacity of the JT-CoMP NOMA-SM system of the present invention is higher than that of other techniques, and the CEU capacity of the JT-CoMP NOMA-SM system of the present invention is NOMA , OMA, JT-CoMP compared to VP-NOMA, respectively

124.2%, 258.7%, and 590.2% in , and it can be seen that the JT-CoMP VP-NOMA system shows the lowest CEU capacity.

을 할당하고, CEU에는

을 할당할 수 있다.In this case, we can simulate a 3-CoMP BS (K = 3) model with two users (CCU and CEU) in each cell. In JT-CoMP VP-NOMA, each CoMP BS is located in a coordinated cell. Transmits one CCU paired with all CEUs, which means that CCUs are allocated full bandwidth B=1 paired with three CEUs in a non-overlapping frequency band with bandwidth B=3, and each CoMP BS has a CCU power factor in

is assigned, and the CEU has

can be assigned.

와 짝을 이루는 CCU에 전력계수

을 할당할 수 있고, 다른 CEU는 SM 인덱스를 통해 정보가 전달되기 때문에 BS에 의해 자원이 할당되지 않기 때문에, JT-CoMP VP-NOMA의 열화 CEU 용량은 각 CoMP BS가 3개의 CEU에 전력과 대역폭을 모두 할당해야 하는 원인이 되는 것을 알 수 있다.On the other hand, in the case of the JT-CoMP NOMA-SM system of the present invention, each CoMP BS is connected to the CEU through the same resource.

Power factor in the CCU paired with

Since resources are not allocated by the BS because other CEUs transmit information through the SM index, the degraded CEU capacity of JT-CoMP VP-NOMA means that each CoMP BS provides power and bandwidth to three CEUs. It can be seen that it is the cause of allocating .

과 대역폭 B=1의 두 가지 방식에 대해 비교를 통해 할당되기 때문이다.It can be seen that the JT-CoMP NOMA-SM system of the present invention has the same CCU capacity as that of the JT-CoMP VP-NOMA as shown in FIG.

This is because it is allocated through comparison for two schemes of and bandwidth B=1.

In addition, it can be seen that the CCU of the JT-CoMP NOMA-SM system of the present invention has the same interference pattern as that of the JT-CoMP VP-NOMA. While SIC can be used to mitigate most CoMP user signals.

9 shows that the JT-CoMP NOMA-SM system of the present invention has 77.3%, 103.2%, and 132.7% higher ESCs at 20 dB than NOMA, JT-CoMP VP-NOMA, and OMA, respectively, the JT-CoMP of the present invention It is clear that the ESC increase in the CoMP NOMA-SM system is due to the increase in the CEU capacity, and the CCU capacity can be maintained.

와

를 고려하면 완벽한 SIC에 비해 각각

에서 2.12%와 0.22%의 ESC를 저하시킬 수 있음을 나타내는데, 실제로 불완전한 SIC 효과는 디코딩과정 동안 SIC에 의해 삭제될 수 없는 잔여 CEU 또는 CoMP 사용자 신호에 의존하는 이산 랜덤 변수로 판명되었다.10 is an ESC of the JT-CoMP NOMA-SM system of the present invention.

Wow

Considering that compared to a perfect SIC, each

In fact, the incomplete SIC effect turned out to be a discrete random variable dependent on residual CEU or CoMP user signals that could not be deleted by SIC during the decoding process.

과

을 고려하여 본 발명의 JT-CoMP NOMA-SM 시스템의 ESC는 도 11에 도시한 바와 같이 완벽한 SIC에 비해 각각

에서 5.33%와 13.42%로 저하될 수 있으며, 도 10과 도 11은 불완전한 SIC와 불완전한 CSI가 추가 간섭으로 인해 용량이 저하될 수 있음을 증명합니다.However, while it can be seen that more modeling and analysis is needed given the incomplete SIC,

and

In consideration of the ESC of the JT-CoMP NOMA-SM system of the present invention, as shown in FIG. 11, compared to the perfect SIC, each

can be degraded to 5.33% and 13.42%, and Fig. 10 and Fig. 11 prove that incomplete SIC and incomplete CSI can degrade capacity due to additional interference.

와

를 고려할 경우, CCU에 대한 최적 전력 할당 계수는 도 12에 도시된 바와 같이 각각

와

일 때 달성될 수 있고, 이는 전송 신호대 잡음비가 감소하면 CCU에 할당된 전력이 증가함을 나타낸다.On the other hand, if it is assumed that the CCU and the CEU require the same QoS, optimal performance can be obtained when the CCU has the same capacity as the CEU.

Wow

When considering , the optimal power allocation coefficient for the CCU is

Wow

can be achieved when , indicating that the power allocated to the CCU increases as the transmit signal-to-noise ratio decreases.

의 경우, 본 발명의 JT-CoMP NOMA-SM 시스템의 CEU 용량은 9.72% 감소하였고, NOMA, OMA 및 JT-CoMP VP-NOMA는 도 13에 도시한 바와 같이 각각 16.5%, 21.1% 및 33.03% 감소하였음을 알 수 있는데, 이는 셀 수가 증가하면 본 발명의 JT-CoMP NOMA-SM 시스템이 다른 기법보다 CEU 용량을 더 잘 유지할 수 있음을 증명한다.Also,

In the case of , the CEU capacity of the JT-CoMP NOMA-SM system of the present invention was reduced by 9.72%, and NOMA, OMA and JT-CoMP VP-NOMA were reduced by 16.5%, 21.1% and 33.03%, respectively, as shown in FIG. 13 . This proves that the JT-CoMP NOMA-SM system of the present invention can better maintain CEU capacity than other techniques when the number of cells increases.

In other words, it is because SM users do not suffer ICI because SM users operate beyond the upper limit of SM, and by using CoSM with BPSK and two transmitter antennas, about 2 bits/s/Hz high CEU capacity without using CoSM is achieved. can be improved Here, if the number of transmit antennas or modulation symbols increases, the CEU capacity may increase.

를 고려할 경우 NOMA, OMA, JT-CoMP VP-NOMA에 비해 각각 124.2%, 258.7%, 590.2% 높은 CEU 용량을 가진다는 것을 알 수 있다.As described above, in the present invention, the capacity can be improved by using JT-CoMP NOMA-SM, and the 255 results show that the JT-CoMP NOMA-SM system of the present invention has the same CCU capacity as that of the JT-CoMP VP-NOMA. It indicates that there is, and the JT-CoMP NOMA-SM system of the present invention is

When considering NOMA, OMA, and JT-CoMP, it can be seen that CEU capacity is 124.2%, 258.7%, and 590.2% higher than that of VP-NOMA, respectively.

In addition, it was found that the ESC of the JT-CoMP NOMA-SM system of the present invention is superior to other techniques by increasing the ESC capacity, and the CCU capacity can be maintained, and incomplete SIC and incomplete CSI can lower the capacity. , it can be seen that the JT-CoMP NOMA-SM system of the present invention can better maintain CEU capacity than other techniques when the number of cells increases.

와

를 고려할 경우, CCU에 대한 최적 전력 할당 계수는 각각

와

일 때 달성됨을 알 수 있었고, CoSM을 활용함으로써 CEU 용량은 CoSM을 사용하지 않고도 약 2비트/s/Hz 더 높아진다는 것을 알 수 있었으며,본 발명의 JT-CoMP NOMA-SM 시스템은 다른 방법들보다 성능이 뛰어남을 확인할 수 있었다.And, in the JT-CoMP NOMA-SM system of the present invention

Wow

Considering that, the optimal power allocation factor for the CCU is

Wow

It was found that this was achieved when , and by using CoSM, it was found that the CEU capacity was increased by about 2 bits/s/Hz without using CoSM, and the JT-CoMP NOMA-SM system of the present invention is superior to other methods. It was confirmed that the performance was excellent.

Therefore, the present invention uses a joint transmission cooperative multipoint (JT-CoMP) based non-orthogonal multiple access (JT-CoMP NOMA) and an antenna to improve transmission capacity by mitigating inter-cell interference (ICI) as an index for radio signals By providing a wireless communication system to which spatial modulation (SM) is applied to improve the spectral efficiency of , it is possible to improve user transmission capacity for multiple cells and multiple users.

In addition, the present invention applies non-orthogonal multiple access (JT-CoMP NOMA) and spatial modulation (SM) based on joint transmission cooperative multipoint in a plurality of cells including a base station, a local user, and a remote user, respectively, but each base station assigns each local user and the first remote user as a non-orthogonal multiple access (NOMA) user, and assigns each remote user except the first remote user as a spatial modulation (SM) user, 2 By allocating a distant user as a CoSM user and transmitting a downlink signal, user transmission capacity can be increased and inter-cell interference can be effectively mitigated.

Meanwhile, the derivation of the equation used to determine the ergodic sum capacity (ESC) as described above will be described in [Reference] below.

[Reference]

및

의 유도A.1. For Ergodic CCU capacity

and

induction of

를 가정한다.

assume

The PDF of X _i,1 can be determined using the sum of the number of cells, in which case the random variables assume independent and equally distributed exponents with different parameters.

Y _i,1 can be determined using the sum of neighboring cells, and the parameter of the ^{exponential random variable is assumed to be different because the distance from each i th} BS to the CCU is different, and the PDF for each exponential random variable is It can be determined as in Equations 25 and 26 of

Here, w _i,1 denotes each parameter of the exponential random variable for the CCU. Then, _{the PDFs of X i,1} and Y _i,1 can be expressed as the following Equations 27 and 28 for the K number of CoMP BSs in N cells.

And, considering the K number of CoMP BSs in N cells, w _i,1 can be assigned as shown in Equation 29 below.

와

의 유도A.2. For Ergodic CEU capacity

Wow

induction of

를 가정한다. 마찬가지로, 각 지수 랜덤 변수에 대한 PDF는 다음의 수학식 30 및 수학식 31과 같이 결정할 수 있다.

assume Similarly, the PDF for each exponential random variable can be determined as shown in Equations 30 and 31 below.

및 m_i,2는 CoMP BS의 수에 따라 달라지며, X_i,2 및 Y_i,2의 PDF는 각각 다음의 수학식 32 및 수학식 33으로 표기될 수 있다.From here,

and m _i,2 depend on the number of CoMP BSs _{, and PDFs of X i,2} and Y _i,2 may be expressed by Equations 32 and 33, respectively.

And, considering the K number of CoMP BSs in N cells, m _i,2 may be allocated as in Equation 34 below.

A.3. Induction probability of error

In this case, the BS transmits a signal for the SM user mapped to the BPSK constellation symbol, and considering that the SM user information is superimposed through the P power, the transmitted signal is given by Equation 35 below.

는 i번째 BS에서 SM 사용자에게 전송 신호를 나타내며, 이 경우, 제1 BS(BS1) 및 제2 BS(BS2)는 서로 협조하여 CoSM 사용자에게 정보를 전송하고, 전송 중에, CoMP 사용자는 불완전한 CSI를 고려하여 레일리(Rayleigh) 채널을 통해 전송되는 데이터를 수신하며, 불완전한 CSI를 고려하여 CoSM 사용자(U_2,2)에 대한 수신 신호를 다음의 수학식 36과 같이 부여할 수 있다.From here,

indicates a transmission signal from the i-th BS to the SM user, in this case, the first BS (BS1) and the second BS (BS2) cooperate with each other to transmit information to the CoSM user, and during transmission, the CoMP user receives incomplete CSI Considering that, data transmitted through a Rayleigh channel is received, and _{a reception signal for the CoSM user (U 2,2} ) may be given as in Equation 36 below in consideration of incomplete CSI.

)는 비 CoSM 사용자 (

)에게 독립적으로 정보 심볼을 전송하며, 각각의 비CoSM 사용자에 대한 수신 신호는 다음의 수학식 37과 같이 주어질 수 있다.On the other hand, other BSs (

) for non-CoSM users (

) independently, and a received signal for each non-CoSM user can be given as in Equation 37 below.

는 SM 사용자에서 원하는 신호를 나타내며,

의 디코딩된 정보는 오류 전송으로 인해 y_i,2와 차이가 날 수 있는데, 복호화된 신호가 주어지면, SM 사용자에 대한 에러 검출은 다음의 수학식 38과 같이 나타낼 수 있다.From here,

indicates the signal desired by the SM user,

The decoded information of _{may be different from y i,2} due to error transmission. Given a decoded signal, error detection for an SM user can be expressed as Equation 38 below.

)은 다음의 수학식 39를 통해 계산할 수 있다.And, the exact error probability of the CoSM user (i.e.,

) can be calculated through the following Equation 39.

및

는 각각 제1 BS 및 제2 BS로부터 전송되는 BPSK 심볼의 상이한 신호 성상점들에 대해 CoSM 사용자의 SNR을 나타내며,

및

는 각각 다음과 같이 수학식 40과 수학식41로 표기할 수 있다.From here,

and

represents the SNR of the CoSM user for different signal constellation points of the BPSK symbol transmitted from the first BS and the second BS, respectively,

and

can be expressed by Equations 40 and 41, respectively, as follows.

의 PDF는 다음의 수학식 42와 같이 유도될 수 있다.And, when each random variable of the Rayleigh fading channel is independently distributed,

The PDF of can be derived as in Equation 42 below.

에서 g_i는 다음의 수학식 43과 같이 주어질 수 있다.where Q is the function defined in [52-54],

, g _i can be given as in Equation 43 below.

은 모든 채널에 대해 가정될 수 있고,

는 가정될 수 있으며, 상기 수학식 42와 수학적 재배열을 사용함으로써,

는 다음의 수학식 44와 같이 얻을 수 있다.From here,

can be assumed for all channels,

can be assumed, and by using Equation 42 and the mathematical rearrangement above,

can be obtained as in Equation 44 below.

Here, Equation 44 can be expressed as Equation 45 to Equation 53 below, respectively.

은 일반화된 초기하함수이며, 상기 수학식 39에서 CoSM 사용자에 대한 정확한 오류 확률은 다음의 수학식 54와 같이 다시 쓸 수 있다.From here,

is a generalized hypergeometric function, and the correct error probability for the CoSM user in Equation 39 can be rewritten as Equation 54 below.

)는 다음의 수학식 55와 같이 나타낼 수 있다.Similarly, the correct probability of error for non-CoSM users (i.e.,

) can be expressed as in Equation 55 below.

In the above description, various embodiments of the present invention have been presented and described, but the present invention is not necessarily limited thereto. It will be readily appreciated that branch substitutions, transformations and alterations are possible.

10: base station
20: near user
30: remote user

Claims (7)

Non-orthogonal multiple access (JT-CoMP NOMA) and spatial modulation (SM) based on joint transmission cooperative multipoint are applied in a plurality of cells each including a base station, a local user, and a remote user, but each local user at each base station and assigning the first remote user as a non-orthogonal multiple access (NOMA) user;
allocating, at each base station, each remote user except the first remote user as a spatial modulation (SM) user;
allocating a second remote user from among the respective remote users as a coordinated spatial modulation (CoSM) user;
Transmitting a downlink signal to the non-orthogonal multiple access (NOMA) user, the spatial modulation (SM) user, and the CoSM user,
The allocating to the CoSM user may include allocating a plurality of remote users excluding the first remote user and the second remote user as non-CoSM (non-CoSM) users,
A first base station corresponding to the first remote user and a second base station corresponding to the second remote user are coordinated to transmit the downlink signal to the CoSM user by using a spatial modulation (SM) index,
The non-CoSM (non-CoSM) user obtains information for decoding the downlink signal using the spatial modulation (SM) index,
Analyze ESCs for NOMA users provided by K cooperative multipoint base stations (CoMP BSs) considering N cells, other base stations (BSs) do not apply coordination, and cooperative multipoint base stations (CoMP BSs) have the same When considering sending data to cooperative multipoint (CoMP) users,
The ergodic sum capacity (ESC) of the JT-CoMP NOMA-SM system can be determined through mathematical analysis based on the Shannon formula, and the ergodic sum capacity (ESC) is the sum of the local user (CCU) and the far user (CEU). A method for transmitting a downlink signal in a wireless communication system, characterized in that it can be determined by summing the sum of capacities as shown in Equation 1 below.
[Equation 1]

Here, in consideration of N cells, NOMA users provided by K cooperative multi-point base stations (CoMP BSs) are divided into short-range users and remote users, and C _i,1 is the achievement of a short-range user (CCU) located in the i ^{th cell.} Corresponds to the possible data rate, and C _i,2 corresponds to the achievable data rate of the remote user (CCU) located in the i ^{th cell.}
delete delete The method of claim 1,
The CoSM user, a method for transmitting a downlink signal in a wireless communication system using a joint ML detector to decode the downlink signal.
delete 5. The method of claim 1 or 4,
Each of the base stations is a downlink signal transmission method of a wireless communication system in which the total bandwidth and the total transmission power are normalized.
7. The method of claim 6,
Each of the base stations is a downlink signal transmission method of a wireless communication system having a plurality of transmission antennas.

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