Subcarrier and Power Allocation for LDS-OFDM System

Low Density Signature-Orthogonal Frequency Division Multiplexing (LDS-OFDM) has been introduced recently as an efficient multiple access technique. In this paper, we focus on the subcarrier and power allocation scheme for uplink LDS-OFDM system. Since the resource allocation problem is not convex due to the discrete nature of subcarrier allocation, the complexity of finding the optimal solutions is extremely high. We propose a heuristic subcarrier and power allocation algorithm to maximize the weighted sum-rate. The simulation results show that the proposed algorithm can significantly increase the spectral efficiency of the system. Furthermore, it is shown that LDS-OFDM system can achieve an outage probability much less than that for OFDMA system

Performance Evaluation of Low Density Spreading Multiple Access

In this paper, we evaluate the performance of Multicarrier-Low Density Spreading Multiple Access (MC-LDSMA) as a multiple access technique for mobile communication systems. The MC-LDSMA technique is compared with current multiple access techniques, OFDMA and SC-FDMA. The performance is evaluated in terms of cubic metric, block error rate, spectral efficiency and fairness. The aim is to investigate the expected gains of using MC-LDSMA in the uplink for next generation cellular systems. The simulation results of the link and system-level performance evaluation show that MC-LDSMA has significant performance improvements over SC-FDMA and OFDMA. It is shown that using MC-LDSMA can considerably reduce the required transmission power and increase the spectral efficiency and fairness among the users

On receiver design for low density signature OFDM (LDS-OFDM)

Low density signature orthogonal frequency division multiplexing (LDS-OFDM) is an uplink multi-carrier multiple access scheme that uses low density signatures (LDS) for spreading the symbols in the frequency domain. In this paper, we introduce an effective receiver for the LDS-OFDM scheme. We propose a framework to analyze and design this iterative receiver using extrinsic information transfer (EXIT) charts. Furthermore, a turbo multi-user detector/decoder (MUDD) is proposed for the LDS-OFDM receiver. We show how the turbo MUDD is tuned using EXIT charts analysis. By tuning the turbo-style processing, the turbo MUDD can approach the performance of optimum MUDD with a smaller number of inner iterations. Using the suggested design guidelines in this paper, we show that the proposed structure brings about 2.3 dB performance improvement at a bit error rate (BER) equal to 10-5 over conventional LDS-OFDM while keeping the complexity affordable. Simulations for different scenarios also show that the LDS-OFDM outperforms similar well-known multiple access techniques such as multi-carrier code division multiple access (MC-CDMA) and group-orthogonal MC-CDMA

Impact of factor graph on average sum rate for uplink sparse code multiple access systems

In this paper, we first study the average sum rate of sparse code multiple access (SCMA) systems, where a general scenario is considered under the assumption that the distances between the mobile users and the base station are not necessarily identical. Closed-form analytical results are derived for the average sum rate based on which an optimal factor graph matrix is designed for maximizing the capacity of the SCMA systems. Moreover, we propose a low-complexity iterative algorithm to facilitate the design of the optimal graph matrix. Finally, Monte Carlo simulations are provided to corroborate the accuracy of the theoretical results and the efficiency of the proposed iterative algorithm

Method and Apparatus for Allocating Device-To-Device (D2D) Communications Resource

Embodiments of the present invention provide a method and an apparatus for allocating a device-to-device (D2D) communications resource. The method for allocating a device-to-device (D2D) communications resource in the present invention comprises: a first network device receiving device-to-device (D2D) communications capabilities sent by user equipments in coverage; the first network device sending, according to the communications capabilities, a resource identification to each of the user equipments in the coverage of the first network device in a D2D group, the D2D group comprising at least two user equipments; and the first network device sending a resource allocation message, the resource allocation message carrying D2D communication resource allocation information corresponding to the resource identification. In the embodiments of the present invention, by allocating a same resource identification to user equipments in a D2D communications group, and using a same resource allocation message to carry resource allocation information corresponding to the resource identification, signaling overheads are reduced and the allocation efficiency is improved in a process of allocating resources used in a discovery stage and resources used in a communication stage to the user equipments in the D2D group

Cooperative Communication Method, Apparatus and System for User Equipment

Provided are a cooperative communication method, apparatus and system for a user equipment. The cooperative communication method for the user equipment comprises: a network device receiving a cooperation request sent by a first user equipment; determining at least one second user equipment which receives first downlink data cooperatively with the first user equipment according to the cooperation request; and sending a first instruction message to the first user equipment, wherein the first instruction message is used for instructing the first user equipment to receive a first part of the first downlink data from the network device, and receive a second part of the first downlink data from the second user equipment. The embodiments of the present invention can realize that a user equipment obtains a diversity gain or a multiplexing gain

Terminal Coordination Communications Method and User Terminal

Embodiments of the present invention disclose a terminal coordination communications method, comprising: a benefit-receiving user terminal broadcasting a coordination request of transmitting target data in a coordinated manner, and receiving a signal quality parameter of the target data returned by each supporting user terminal receiving the coordination request; the benefit-receiving user terminal separately calculating a service quality increment of the target data according to the signal quality parameter corresponding to each supporting user terminal; and the benefit-receiving user terminal sending a control instruction of participating in coordination or quitting coordination to a corresponding supporting user terminal according to the service quality increment, so that the supporting user terminal executes a corresponding operation according to an indication of the control instruction. The present invention further discloses a user terminal. By means of the present invention, service quality of service data of a terminal can be effectively improved

Terminal Cooperation Communication Method, Device and System

Provided are a terminal cooperation communication method, device and system. Since a second terminal acquires equivalent channel feature information according to a channel parameter of at least one first channel sent by at least one first terminal and a channel parameter of a second channel of the second terminal, a signal sent by a base station to the second terminal according to downlink sending configuration information determined by means of equivalent channel feature information will increase the overall gain of received signals of the at least one first terminal and the second terminal, wherein the first terminal is a support terminal of the second terminal, and the second terminal is a benefited terminal, thereby increasing the gain of ultimately received signals of the benefited terminal

Elucidating the role of RBM5 in osteoclastogenesis: a novel potential therapeutic target for osteoporosis

Abstract Osteoporosis is a prevalent bone disease with multigene involved, and the molecular mechanisms of its pathogenesis are not entirely understood. This study aims to identify novel key genes involved in osteoporosis to discover potential pharmacological targets. We analyzed three microarray datasets and identified four differentially expressed genes. The LASSO model indicated that RNA-binding motif protein 5 (RBM5) is associated with osteoporosis and is a potential drug target. We conducted the Spearman correlation analysis and found 52 genes that were significantly related to RBM5. Enrichment analysis showed that these genes were primarily involved in RNA splicing and osteoclast differentiation pathways. By using lentivirus-based shRNA, we successfully knocked down RBM5 expression in RAW264.7 cell line, which showed that RBM5 knockdown significantly impaired their differentiation potential to mature osteoclasts and significantly inhibited bone-resorbing activity. RT-qPCR analyses revealed the expression of osteoclastogenesis marker genes was downregulated along with RBM5 expression. These findings suggest that RBM5 plays a crucial role in the pathogenesis of osteoporosis and provides a new potential pharmacological target