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.

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Error Performance of Chaotic Digital Code-Divison Multiple Access (CDMA) Systems

International Journal of Bifurcation and Chaos ◽

10.1142/s0218127498001704 ◽

1998 ◽

Vol 08 (10) ◽

pp. 2047-2059 ◽

Cited By ~ 13

Author(s):

Tao Yang ◽

Leon O. Chua

Keyword(s):

Channel Capacity ◽

Code Division Multiple Access ◽

Communication Systems ◽

Multiple Access ◽

Digital Code ◽

Error Performance ◽

Interference Level ◽

Wireless Environments ◽

Cdma Systems ◽

Code Division Multiple

Chaotic digital code-division multiple access ((CD)2MA) systems are new types of communication systems using chaotic carriers. (CD)2MA had found applications in both wireless and other communication systems. In this paper we study the error performance of chaotic digical code-division multiple access ((CD)2MA) systems used in both wireless environment and cable networks. We present first the details of the interleave mode of the (CD)2MA. When a (CD)2MA system works in the interleave mode, each of its transmitters only transmits signals during a portion of the bit duration of the message signal. The total interference level is thus reduced which in turn increases the channel capacity. The relationship between the bit error rate (BER) and the interleave rate is studied in both the synchronous (CD)2MA system used in cable systems, and the asynchronous (CD)2MA system used in wireless environments. Our simulation results show that in a cable system the synchronous (CD)2MA system can support 1.5 times more channel capacity than synchronous CDMA systems, and double the channel capacity of CDMA systems in wireless environments.

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