World Applied Sciences
Journal 12 (3): 330-335, 2011 ISSN 1818-4952 © IDOSI Publications, 2011
Multi-band Carrier Code Division Multiple Access for 4G Mobile System with Improved Signal Quality Jalal J. Hamad Ameen and Widad Binti Ismail School of Electrical and Electronics, Universiti Sains Malaysia, Pulau Penang, 11800, Malaysia Abstract: The proposed frequency band for a 4G mobile system is 2 to 8 GHz, while the proposed access for the system is MC-CDMA / OFDM. In this paper, a new access technique has been proposed, with the bandwidth of the system divided into ten sub-bands. Each sub-band has40 channels and the access is a multiband of the carrier CDMA (MBC-CDMA). The proposed access provides more flexibility for the base stations to re-use the frequency than MC-CDMA because of the use of frequency hopping between the channels as well as the sub-bands. The hopping sequence depends on the spreading code. A comparison of the performance of the proposed access technique with MC-CDMA showed that there is an improvement in signal quality and BER performance, as an application, this proposed multiple access technique suitable for 4G mobile air interface for further interference reduction and in improvement in signal quality. Key words: 4G mobile system % MC-CDMA % Frequency Hopping % MBC-CDMA INTRODUCTION There are a number of multiple access techniques to transmit several user signals simultaneously through one channel. In general, what are used are three-dimensional time, frequency and code. The use of multiple frequencies at the same time and one code, if digital, is referred to as frequency division multiple access (FDMA). On the other hand, the use of different time slots in one frame with the same frequency is referred to as time division multiple access (TDMA). Finally, the transmission of signals at the same time using the same frequency with different spreading codes is referred to as code division multiple access (CDMA). Each of the multiple access techniques mentioned above has advantages and disadvantages. In the case of FDMA, a band of frequency is shared among users, which can cause interference. On the other hand, in TDMA, there must be synchronization in the number of users using time slots; otherwise, there is inter symbol interference (ISI). In the case of CDMA, the technique requires more complex receivers, such as the Rake receiver and synchronization between the transmitter and the receiver. Moreover, some systems also use hybrid techniques, including TDMA+FDMA-like GSM or TDMA+CDMA-like UMTS systems. Therefore, Multi-Carriers CDMA (MCDMA) and Orthogonal FDMA (OFDMA) have been designed to improve signal quality, especially for next-generation wireless systems, such as the 4G mobile system, which will provide higher data rates of up to 200Mbps. In this paper, the proposed multiple access technique was introduced using multiple bands for each band of multiple carriers with the CDMA system (MBC CDMA).In the next sections, further details on the proposed multiple access technique are provided, along with a comparison of the performance results of the proposed technique and the Multi Carrier CDMA (MC CDMA) technique. 4g Mobile System: The 4G mobile system is the future mobile system through which a higher data rate service will be provided. It is the integration of other wireless systems, including GSM, UMTS and WiMAX. With a higher frequency band, the cell radius of base stations will be smaller, about one third of that in the 3G mobile system. Some 4G specifications are converged data and voice over IP, hybrid Integration of Wireless LAN (WiFi, Bluetooth) and wide area as network architecture, 20 to 100 Mbps speed in mobile mode, Higher frequency bands (2–8 GHz), 100 MHz (or more) bandwidth, all digital with packetized voice of switching design, OFDM and MCCDMA as access technology, forward Error Correction is
Corresponding Author: Jalal J. Hamad Ameen, School of Electrical and Electronics,...
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