Cross‐layer optimization for CDMA/TDD wireless mesh networks

Abstract

This paper proposes a new cross-layer optimization algorithm for wireless mesh networks (WMNs). CDMA/TDD (code division multiple access/time division duplex) is utilized and a couple of TDD timeslot scheduling schemes are proposed for the mesh network backbone. Cross-layer optimization involves simultaneous consideration of the signal to interferenceplus-noise ratio (SINR) at the physical layer, traffic load estimation and allocation at medium access control (MAC) layer, and routing decision at the network layer. Adaptive antennas are utilized by the wireless mesh routers to take advantage of directional beamforming. The optimization formulation is subject to routing constraints and can be solved by general nonlinear optimization techniques. Comparisons are made with respect to the classic shortest-path routing algorithm in the network layer. The results reveal that the average end-to-end successful packet rate (SPR) can be significantly improved by the cross-layer approach. The corresponding optimized routing decisions are able to reduce the traffic congestion. Copyright

Nested and interleaved direct sequence spread spectrum to enhance CDMA security and bit error rate performance

“…CDMA systems can be implemented by employing Direct Sequence Spread Spectrum (DSSS). On the other hand, the performance of a digital communications network, which is mostly measured by Bit Error Rate (BER), is also of prime importance [3][4][5][6][7]. The effects of these two are only mitigated when the spreading code is not determined by an eavesdropper, else the system is not secure at all, because the eavesdropper can correlate and de-spread the received signal by the given code [2].…”

“…This fact implies the importance of security in a CDMA system. On the other hand, the performance of a digital communications network, which is mostly measured by Bit Error Rate (BER), is also of prime importance [3][4][5][6][7]. In a CDMA system, the reduction in BER performance is caused by some sources of signal interference.…”

Random Network Coding Effects on CDMA/TDD Mesh Networks

“…Recently, research efforts have extended the CDMA/TDD technique to backbone mesh networks [3], [4]. In [3], the transmitter and receiver structure of a CDMA/TDD system for mesh networks was introduced and the delay and delay jitter were computed.…”