Showing papers on "Cyclic delay diversity published in 2020"

Secrecy Performance Analysis of Distributed Asynchronous Cyclic Delay Diversity-Based Cooperative Single Carrier Systems

Abstract: A joint data and interference transmission scheme based on a new distributed asynchronous cyclic delay diversity (dACDD) technique is proposed for cooperative communication systems. Without any perfect channel state information from a legitimate user (LU) and an eavesdropping user (EU), joint remote radio head (RRH) selection for the data and jamming signal transmissions is proposed for dACDD to achieve the maximum diversity gain at the LU, while degrading the receive signal-to-interference-plus-noise ratio at the EU. The proposed dACDD is the extension of distributed cyclic delay diversity, which requires a tight synchronization among the central control unit and RRHs. Thus, processing at each RRH causing no intersymbol interference at the LU is developed. Then, the selection scheme for a data RRH is proposed, which selects a single RRH connected with the channel having the greatest channel magnitude as the data RRH to transmit a desired confidential message and controls the remaining RRHs to transmit an artificial interference sequence to the LU and EU. For the proposed distributed system, the marginal secrecy outage probability and marginal probability of non-zero achievable secrecy rate are analyzed by deriving closed-form expressions, whose correctness is verified via link-level simulations over non-identically distributed frequency selective fading channels.

Diversity Gain Analysis of Distributed CDD Systems in Non-Identical Fading Channels

Abstract: This paper investigates the diversity gain of a distributed cyclic delay diversity (dCDD) scheme for cyclic-prefixed single carrier systems in non-identical fading channels. Non-identical small-scale fading is assumed in the environment, in which non-identical line-of-sight and non-line-of-sight fading coexist. A condition for dCDD resulting in intersymbol interference free reception at the receiver, is extended to this new channel environment. For an overpopulated system setup, a generalized performance analysis, is not available from existing works, is conducted after developing closed-form expressions for the distribution of the signal-to-noise ratio (SNR) realized at the receiver. Since the order statistics are involved in the statistical properties of the SNR, the corresponding spacing statistics are utilized to derive feasible closed-form expressions. The finalized closed-form expressions are shown to provide very reliable outage probability and spectral efficiency of dCDD for underpopulated and overpopulated systems. An asymptotic performance analysis verifies the maximum achievable diversity of the dCDD even in the overpopulated case within the considered channel environment. Link-level simulations are conducted and these verify the maximum achievable diversity gain.

Backhaul Reliability Analysis on Cluster-Based Transmit Diversity Schemes in Private Networks

Abstract: For a multi-cluster-based transmit diversity scheme that supports joint transmissions (JT) in private networks, a distributed remote radio unit system (dRRUS) is deployed in each of the clusters to increase the spectral efficiency and coverage, and to achieve flexible spatial degrees of freedom. Due to its distributed structure, the dRRUS relies on backhaul communications between the private network server (PNS) and cluster master (CM), which is the main backhaul communication, and between the CM to remote radio units (RRUs), which is the secondary backhaul communication. Thus, this paper mainly investigates the reliability of main and secondary backhaul connections for cluster-based transmit diversity schemes in private networks. Employing a Bernoulli process to model each backhaul reliability, a composite backhaul connection is modeled by an independent product of Bernoulli processes. By employing the distributed cyclic delay diversity scheme over the dRRUS and precision time protocol for clock synchronization, the multicluster-based JT can be achieved without full channel state information of the private network environment at the PNS and CMs. Having developed necessary distributions for the signal-tonoise ratio realized at the receiver, the closed-form expressions for the outage probability and spectral efficiency are derived. To verify their accuracy, the analytical performances are compared with link-level simulations.

Method for performing, by terminal, communication according to cyclic delay diversity (cdd) using multiple antennas in wireless communication system and apparatus therefor

Abstract: Provided, according to various embodiments, are a method for performing, by a terminal, communication according to cyclic delay diversity (CDD) using multiple antennas in a wireless communication system and an apparatus therefor. Disclosed are a method for performing communication according to cyclic delay diversity (CDD) and an apparatus therefor, the method comprising the steps of: determining a delay range of a delay value for CDD on the basis of a moving speed of a terminal; determining the delay value of the CDD within a set delay range; and transmitting a cyclically delayed signal to a target terminal, according to the determined delay value, wherein the preset delay range is determined on the basis of the moving speed of the terminal.

A dCDD-Based Transmit Diversity for NOMA Systems

Abstract: In this paper, a new transmit diversity scheme for cooperative non-orthogonal multiple access (NOMA) is proposed without perfect channel state information at the transmitter (CSIT). To support two users under a near-far user pairing constraint, a distributed cyclic delay diversity (dCDD) scheme is adjusted into NOMA by dividing a set of remote radio heads (RRHs) into two groups for multiple cyclic-prefixed single carrier transmissions. Using only a limited channel relevant information needed to make dCDD work, a new RRH assignment and power allocation mechanism is proposed. After then, closed-form expressions for the rates of two users achieved by the proposed RRH assignment and power allocation mechanism are derived. For various scenarios, link-level simulations verify that superior rates can be achieved by NOMA with dCDD over the traditional orthogonal multiple access with dCDD.

Method of two-layer uplink transmission with cyclic delay diversity

Abstract: A method of applying rank two transmission from a plurality of sets of coherent antennas of a user equipment (UE) in a wireless communication system includes: transmitting two information streams using a first set from the plurality of sets of coherent antennas of the UE; and transmitting the two information streams using a second set from the plurality of sets of the coherent antennas of the UE. The first set and the second set are incoherent with respect to each other. The two information streams are common to the first set and the second set.

Method for transmitting and receiving signal in wireless communication system, and apparatus therefor

Abstract: The present specification provides a method for transmitting, by a terminal, an uplink signal in a wireless communication system More specifically, the method performed by the terminal comprises the steps of: receiving, from a base station, first control information related to a delay value applied to precoding for small-delay cyclic delay diversity (CDD); layer mapping a complex-valued modulation symbol onto one or more transport layers; precoding, on the basis of a precoding matrix and a diagonal matrix, the complex-valued modulation symbols on each transport layer to transmit same on an antenna port; and transmitting an uplink signal to the base station