A Time Reversal Based Time Division Duplex IDMA Communication System

The explosive demands for mobile broadband service bring a major challenge to 5G wireless networks. Device-to-device communication, adopting side links for user-direct communication, is regarded as a main technical source for offloading large volume of mobile traffic from cellular base station. This article investigates the joint power and subcarrier allocation scheme for device-to-device communication in 5G time division duplex systems. In time division duplex system, instead of utilizing an exclusive portion of the precious cellular spectrum, device-to-device pairs reuse the subcarriers occupied by cellular users, thus producing harmful interference to cellular users in both uplink and downlink communication, and strongly limiting the spectrum efficiency of the system. To this end, we focus on the maximization of device-to-device throughput while guaranteeing both uplink and downlink channel quality of service of cellular users as well as device-to-device pairs. The problem is formulated as a mixed integer non-linear programming (MINLP) problem. To make it tractable, we separate the original MINLP problem into two sub problems: power allocation and sub-carrier reusing. The former is to develop optimal power allocation for each device-to-device pair and each cellular user, with the constraints of maximum power and quality of service. It is solved by geometric programming technique in convex optimization method. The latter is derived as a one-to-many matching problem for scheduling multiple subcarriers occupied by cellulars to device-to-device pairs. It is solved by Hungarian method. Simulation results show that the proposed scheme significantly improves system capacity of the device-to-device underlay network, with quality of service of both device-to-device users and cellular users guaranteed.

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Low‐complexity channel estimation for time division duplex massive multi‐user multi‐input multi‐output systems

IET Communications ◽

10.1049/cmu2.12053 ◽

2020 ◽

Author(s):

Muamer Hawej ◽

Yousef R. Shayan

Keyword(s):

Channel Estimation ◽

Low Complexity ◽

Time Division Duplex ◽

Time Division

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Analysis of the Possibilities of Using the Means of Tropospheric cm-Wave Radio Communication with a Time Division Duplex in Telecommunication Systems

Developments in Language Theory - Lecture Notes in Computer Science ◽

10.1007/978-3-319-99447-5_44 ◽

2018 ◽

pp. 514-524

Author(s):

V. G. Anisimov ◽

V. N. Perelomov ◽

L. O. Myrova ◽

D. A. Aminev

Keyword(s):

Radio Communication ◽

Time Division Duplex ◽

Telecommunication Systems ◽

Wave Radio ◽

Time Division

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Study of Full-Duplex Communication with Excellent Security by 3-Level Communication Method

Electronics ◽

10.3390/electronics8101186 ◽

2019 ◽

Vol 8 (10) ◽

pp. 1186

Author(s):

Seong-Mi Park ◽

Sung-Jun Park ◽

Sang-Kil Lim

Keyword(s):

Communication System ◽

Full Duplex ◽

Communication Security ◽

Communication Line ◽

Network Construction ◽

Communication Signal ◽

Half Duplex ◽

Current Transmission ◽

Communication Method ◽

Time Division

Currently, the industry is using the MODBUS communication method, utilizing RS485 for the distributed equipment and network construction. This method has a rather good transmission and reception distance but has a disadvantage in that it is a half-duplex communication method that cannot simultaneously transmit and receive. Therefore, there is a great need for a full-duplex communication system that can simultaneously transmit and receive two-wire communications. Therefore, in this paper, we propose new communication hardware equipment that can implement a full-duplex communication method by communication signal level in order to overcome the disadvantage of communication speed when using a full-duplex communication method by time division method. The proposed communication hardware is a structure that can transmit and receive at the same time in such a way that two pieces of equipment communicating by two-wire communication can apply the outgoing signal to the same communication line and detect the received signal at the same time. Therefore, the receiving side can analyze the received signal based on the information on the current transmission signal. This signal can only be analyzed by the two communicating devices, indicating that communication security is very good.

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