Three dimensional diversity for closed proximity MIMO systems

The problem that needs to be consider in a multi user distributive and decentralized network is the interception of transmitted signals by an undesirable node. A decentralized system is nothing but a data processing system in which all information is processed locally without the need for a Central Processing Facility where various effects like multipath and scattering causes non- orthogonality of the symbols. To overcome these problems spatial, time and frequency diversity can be used. This paper proposes a three dimensional (Space, Time and Frequency) diversity involving frequency hopping and space time coding technique. A three dimensional system is demonstrated to support heterogeneous networks in LTE advanced standards. Because of limited spectrum and absence of a protected physical boundary, wireless systems face much more serious challenges in capacity and security than wired networks. When transmitted through the air link, wireless signals are more prone to jamming and interception. The main purpose of Frequency hopping (FH) technique is to avoid the interference which is likely to happen in wireless systems. To improve system performance against malicious nodes a space-time coded frequency hopping (STC-FH) based on the orthogonal frequency division multiple access (OFDMA) is proposed. The system considers Almouti block codes and Trellis codes to achieve diversity. The results considers orthogonal frequency division multiplexing which uses cyclic prefix in a space time block coding (STBC) transmission scheme.