This paper deals with the outdoor path loss behavior. The study has been conducted in Mosul city Iraq to fit a suitable propagation model to measured data at 900 MHz and 1800 MHz in urban and suburban environment. The empirical models dealt which are Hata, Cost-231 Hata, international Telecommunication Union (ITU-R), Ericsson and Stanford University Interm (SUI). Path loss accuracy of the fitting of the empirical models to the measured data is estimated using Root Mean Square (RMS) error.

No abstract

Mobility is the distinct feature of wireless mobile cellular system. Usually, continuous services is achieved by supporting handoff which is the transfer of an ongoing call from the current cell to the next adjacent cell as the mobile moves through the coverage area. usually handoff calls are given higher priority than new calls since it has a significant impact on the network performance. Simulation study of the relative signal strength with hysteresis and threshold (RSS-HT) algorithm for varying hysteresis and threshold are studies to evaluate the mean number of cell handoffs, mean number of wrong cell handoffs and expected average signal strength.

Long terms evolution (LTE) allows using new and wider spectrum up to 20MHz with high data rates and lower latency. This paper provides analysis of the concept of heterogeneous networks as compared to homogenous networks on a realistic scenario of Mosul city and discusses the need for an alternative deployment model and topology to enhance the performance of network. It is clearly demonstrating the need for using inter-cell interference coordination (ICIC) methods to achieve a good performance for network especially at the cell edge. Heterogeneous network enables flexible and low-cost deployments and it has attractive solution for non-uniform traffic distribution or needed a special service in hot-spot.

No abstract

This paper investigates three different empirical propagation models for the next 4 th generation known Long Term Evolution (LTE) in the (2-3) GHz band in urban and suburban areas. The suitability of these models are compared with actual field measurement at 2.6 GHz in Erbil city-Iraq. Tuning method is suggested to fit the experimental results of path loss with the propagation models.

In this paper, capacity analysis for mobile WiMAX working in distributed subcarrier permutation modes is investigated mathematically depending on the physical layer simulation results. These simulation results of physical layer dispose exact values for the number of best burst profiles that candidate to carry Medium Access Control (MAC) payload in a proposed ITU-R mixed user channel. The complete simulation model for physical and MAC layers has been made using OPNET 14.5 to validate the analytical results of the obtained capacity. This approach for capacity analysis based on simulation results is proposed to overcome the lack of interests by other researches in the significant influence of the physical layer constraints on the MAC layer capacity calculations. As well as in this paper, a proposed ITU-R mixed user channel is performed to suit the high mobility users involved under distributed subcarrier permutation modes. Moreover, this paper focused on the exact overhead calculations by taking into account all the significant overhead parameters in the MAC layer frame structure that affects the overall system capacity. KeywordsIEEE802.16e-2005, OFDMA, PUSC, FUSC, QoS, proposed ITU-R mixed user channel model, PER.

Mobile WiMAX is one of the candidate technologies for 4G wireless systems, promising high data rates and affluent multimedia services. The mobile WiMAX standard (IEEE802.16e-2005)is based on Orthogonal Frequency Division Multiple Access (OFDMA), which allows a very efficient use of bandwidth in a wide frequency range, this is due to the fact that OFDMA uses multi-channel OFDM approach and provides subcarrier access in the time and the frequency domains. In this paper the impact of downlink distributed (FUSC, PUSC) and adjacent (AMC) subcarrier permutation modes used in mobile WiMAX system are investigated using simulation under various modulation and coding schemes (link speeds)with the support of optimum value of the Cyclic Prefix (CP) for the OFDMA symbol duration. The results are expressed in terms of the maximum achievable throughput and operating distance from base station in pedestrian multipath fading channel (ITU-R Ped. B at 3Km/h speed) under a UDP-based application (video streaming), which is the proper application for multimedia services. The results show the optimum cyclic prefix valve for the FUSC, PUSC and AMC subcarrier permutation modes to achieve the best system performance, also the results show differences in PER performance atvarious modulation and coding schemes for the three subcarrier permutation modes (FUSC, PUSC and AMC). These differences in performance are exploited in the present work to show the best threshold SNR to switch from link speed to another link speed in terms of throughput and operating distance.