Limitations of current 4G systems and its substitute schemes with TDD/TDMA

  • Authors:
  • Lu Zhaogan;Zhang Taiyi;Shen Xiaodong;Li Xiaohe

  • Affiliations:
  • School of Electronic & Information Engineering, Xi'an Jiaotong University, China;School of Electronic & Information Engineering, Xi'an Jiaotong University, China;School of Electronic & Information Engineering, Xi'an Jiaotong University, China;School of Electronic & Information Engineering, Xi'an Jiaotong University, China

  • Venue:
  • WSEAS TRANSACTIONS on COMMUNICATIONS
  • Year:
  • 2007

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Abstract

In current 4G system given in recent literatures, channel estimation overhead and complexity of multi-user detectors (MUD), may lead to bad performance in fast fading channel scenarios when large number of users exists. So, a novel 4G system with TDD/TDMA as duplex and wireless access is designed to reduce channel estimation spending and avoid MUD, as only one user can be active to communicate with base station. Under the requirement of 4G systems, radio frame structure is elaborately designed to fit for fast fading channel scenarios. Construction of training sequences for channel estimation is also detailed together with a novel eigenmodes coupled universal space-time codes. The system architecture with consideration of link adaptations is given and evaluated for performance of TDD/TDMA 4G systems. Results show the proposed TDD/TDMA 4G can meet the requirement of 4G system under the classical ITU channel profiles.