Capacity of a cellular time division duplex CDMA system

The power control in CDMA systems, grant numerous users to share resources of the system uniformly between each other, leading to expand capacity. With convenient power control, capacity of CDMA system is immense in contrast of frequency division multiple access (FDMA) and time division multiple access (TDMA). If power control is not achieved numerous problems such as the near-far effect will start to monopolize and consequently will reduce the capacity of the CDMA system. However, when the power control in CDMA systems is implemented, it allows numerous users to share resources of the system uniformly between themselves, leading to increased capacity For power control in CDMA system optimization algorithms i.e. genetic algorithm & particle swarm algorithm can be used which regulate a convenient power vector. These power vector or power levels are dogged at the base station and announce to mobile units to alter their transmitting power in accordance to these levels. The performances of the algorithms are inspected through both analysis and computer simulations, and compared with well-known algorithms from the literature.

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Pre-equalisation, transmitter precoding and joint transmission techniques for time division duplex CDMA

Second International Conference on 3G Mobile Communication Technologies (3G 2001) ◽

10.1049/cp:20010052 ◽

2001 ◽

Author(s):

S. Georgoulis

Keyword(s):

Time Division Duplex ◽

Transmitter Precoding ◽

Time Division ◽

Joint Transmission

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Centralized Dynamic-Time Division Duplex Utilizing Interference Alignment

IEEE Transactions on Wireless Communications ◽

10.1109/twc.2021.3077250 ◽

2021 ◽

pp. 1-1

Author(s):

Mojtaba Ghermezcheshmeh ◽

Mohsen Mohammadkhani Razlighi ◽

Vahid Shah-Mansouri ◽

Nikola Zlatanov

Keyword(s):

Interference Alignment ◽

Time Division Duplex ◽

Dynamic Time ◽

Time Division

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Joint power allocation and subcarrier assignment for device to device in 5G time division duplex networks

International Journal of Distributed Sensor Networks ◽

10.1177/1550147718811094 ◽

2018 ◽

Vol 14 (11) ◽

pp. 155014771881109 ◽

Cited By ~ 1

Author(s):

Pan Zhao ◽

Lei Feng ◽

Peng Yu ◽

Wenjing Li ◽

Xuesong Qiu

Keyword(s):

Quality Of Service ◽

Power Allocation ◽

Base Station ◽

Joint Power ◽

Time Division Duplex ◽

Device To Device ◽

Minlp Problem ◽

Device To Device Communication ◽

Time Division

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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