Study of Uplink Interference in UMTS Network: ASIACELL Company, Iraq

Universal Mobile Telecommunications System (UMTS), is the third generation (3G) of mobile communication which is based on the wideband code division multiple access (W-CDMA) radio access to provide bandwidth and spectral efficiency. Interference in 3G system is significantly lower compared to the preceded generations. However, it does not mean 3G is free from the issues associated with interferences, such as low signal quality and call drop. The interference level in UMTS can be measured by using the well-known parameter Received Total Wideband Power (RTWP). This parameter is affected by many factors such as number of the users connected to the system, combining second generation (2G) and 3G frequencies within the same geographical area, geographical causes (difference of Altitude), and hardware impairment. In this paper we intensively study how these factors affect the uplink interference level (i.e. RTWP value) in 3G system used by a particular telecommunications company, Asiacell company, Iraq. The obtained data shows that call drop is the most serious issue raised due to high value of RTWP in 3G system. We demonstrate that system enhancement, in terms of lower RTWP level, are obtained by adding second carrier to the sites, separating 2G band from 3G band using special filter, and optimizing the hardware components.

High Isolation Superwideband Monopole Antenna with Mitigation of Dual Interfering Bands (WiMAX/C and Satellite Communication System in X Band) for Wireless Applications

In this manuscript, a dual notched superwideband Multiple-Input-Multiple-Output (MIMO) monopole antenna is verified in frequency, time and spatial domain. Antenna occupies space of 18340.787 mm3 and is printed on (Rogers RT Duroid5880) microwave substrate. Proposed antenna is capable of covering bandwidth 2.66 GHz–22.31 GHz with bandwidth ratio > 10:1. Proposed antenna rejects WiMAX/C band (3.28 GHz–4.36 GHz) which is obtained by using L-shaped stub connected with ground and X-band satellite downlink/uplink interference is removed by etching inverted U-shaped slit in microstrip feedline. Also, antenna offers maximum gain of and radiation efficiency of 5.30 dBi and 96.20% respectively in operating band. Proposed antenna also shows good diversity performance in terms of ECC (Envelope Correlation Coefficient), DG (Directive Gain) and TARC (Total Active Reflection Coefficient).