Titus I. Eneh

Power Control and Performance Comparison of AODV and DSR Ad Hoc Routing Protocols

A technique is proposed to evaluate the effect of ambient noise and path loss have on received signal strength of mobile node in a mobile ad hoc network environment using optimized network (OPNET) simulator while comparing the performance of Ad-Hoc on demand distance vector (AODV) and dynamic source routing (DSR) protocols. Numerical and simulation results presented illustrate how the performance of an ad hoc network protocol drastically changes as a result of changing the mobility model and power control system of the network. The simulation result for DSR and AODV showed a significant improvement with 86.8% decrease in end-to-end delay (sec), while AODV also showed 68.5% drop in end-to-end delay. The network load simulation result revealed that DSR protocol maintained a constant load while there was a 75%drop in routing load for AODV protocol. The simulation results of AODV and DSR routing protocols showed 99%and 98%confidence intervals respectively.

Minimum Cell Size for Information Capacity Increase in Cellular Wireless Network

In this paper results of mathematical analysis supported by simulation are used to find a theoretical limit for cell size reduction in mobile communication systems. Information capacity approach is used for the analysis. Attention is given to the active co-channel interfering cells. Because at microwave frequencies beyond 2 GHz, co-channel interfering cells beyond the first tier becomes dominant as the cell size reduces. We show that when the cell size limit is reached any further reduction in cell size will not increase the information capacity of the cellular network. A formula is derived for calculating the number of co-channel cells in subsequent tiers.

CELLULAR SYSTEM INFORMATION CAPACITY CHANGE AT HIGHER FREQUENCIES DUE TO PROPAGATION LOSS AND SYSTEM PARAMETERS

In this paper, mathematical analysis supported by computer simulation is used to study cellular system information capacity change due to propagation loss and system parameters (such as path loss exponent, shadowing and antenna height) at microwave carrier frequencies greater than 2 GHz and smaller cell size radius. An improved co-channel interference model, which includes the second tier co-channel interfering cells is used for the analysis. The system performance is measured in terms of the uplink information capacity of a time-division multiple access (TDMA) based cellular wireless system. The analysis and simulation results show that the second tier co-channel interfering cells become active at higher microwave carrier frequencies and smaller cell size radius. The results show that for both distance-dependent: path loss, shadowing and effective road height the uplink information capacity of the cellular wireless system decreases as carrier frequency increases and cell size radius R decreases. For example at a carrier frequency fc = 15.75 GHz, basic path loss exponent α = 2 and cell size radius R = 100, 500 and 1000m the decrease in information capacity was 20, 5.29 and 2.68%.

Adaptive MMSE multiuser receivers in MIMO OFDM wireless communication

This paper presents a novel adaptive multiuser detection scheme for MIMO OFDM, which we refer to as AMUD MIMO OFDM. It combines the adaptive minimum mean square error multiuser detection scheme with prior information of the channel and interference cancelation in the spatial domain. Simulation results show that joint channel parameters estimation has good performance compared to individual parameter estimation. The developed algorithm sum rate capacity is close to MIMO theoretical upper bound (21.5 bits/s/Hz at an SNR of 20dB) which indicates its applicability to the uplink channel, where power transmission at the mobile station is a constraint. The BER performance shows that an 8 x 8 AMUD MIMO OFDM provides a 2dB SNR gain as compared to non adaptive MIMO OFDM.

Sensitivity of information capacity of land mobile cellular system to propagation loss parameters at higher microwave frequencies

In this paper, results of mathematical analysis supported by simulation are used to investigate the impact of propagation loss on the performance and information capacity of cellular wireless network at higher microwave carrier frequencies (beyond 2 GHz). At higher microwave carrier frequencies co-channel interfering cells beyond the first six co-channel cell becomes active as the cell size reduces. It is shown that the second tier co-channel interfering cell is more dominant at lower (below 2.5) path loss exponent.

The performance of dynamic source routing protocol to path loss models at carrier frequencies above 2 GHz

In this paper, we describe a simulation study of the impact of wireless channel on Dynamic Source Routing (DSR) protocol performance at microwave carrier frequencies above 2 GHz. Simulation results show that at microwave carrier frequencies above 2 GHz, when the two-slope path loss model is used for channel modelling, the breakpoint distance affect the end-to-end throughput of the DSR protocol in Mobile Wireless Ad Hoc Network (MANET), whilst at frequencies below 2 GHz the end-to-end throughput for the free space and the two-slope path loss model was the same.

Impact of Vehicular Traffic on Information Capacity of Cellular Wireless Network at Carrier Frequencies Greater Than 3 GHz

In this paper we describe a simulation study of the impact of vehicular traffic on the performance of cellular wireless network at microwave carrier frequencies above 3 GHz and up to 15 GHz, where the first and subsequent tiers co-channel interfering cells are active. The uplink information capacity of the cellular wireless network is used for the performance analysis. The simulation results show that vehicular traffic causes a decrease in the information apacity of a cellular wireless network. Results also show that for both light and heavy vehicular traffic environment, the nclusion of subsequent tier co-channel interferences caused a decrease of between 3 - 12

The Smearing Filter Design Techniques for Data Transmission

\%

Adaptive MMSE multiuser detection for MIMO OFDM over Turbo-Equalization for Single-Carrier Transmission wireless channel

in the information capacity of the cellular wireless network as compared to the case, when only the first tier co-channel interferences are active.

Performance of iterative decoding with imperfect MMSE DFE

Reducing Impulse noise is a very active research area in communication systems. This paper presents a digital smear-desmear technique (SDT) applied to data transmission over band limited channels. A generalized set of filter design criteria based on minimizing the average bit error probability is introduced. The design criteria were applied to a practical digital filter implementing SDT techniques. The SDT is simulated and combined with coded communication systems for high data transmission rate. Simulation results show that the SDT yields a significant improvement in bit error rates for coded systems subject to impulse noise, relative to the systems with no SDT. The technique also completely removes the error floor caused by the impulse noise.