Hybrid Spread Spectrum Techniques for Cell Phone Essay -- Technology

In addition to the frequency hopped and direct sequence, spread spectrum multiple access technique, there are certain other hybrid combinations that provide the advantage in the area of cellular mobile communication system. The available wideband spectrum is divided in to a number of subspectras with smaller bandwidth. Frequency Hopped Multiple Access Technique (FHMAT) consists of a direct sequence modulated signal whose center frequency is made to hop periodically in a pseudorandom fashion. In this paper we provide a Hybrid Spread Spectrum Techniques using Time Division Code Division Multiple Access (TDCDMA) system in which different spreading codes are assigned to different cell within each cell, only one user per cell is allotted a particular time slot. Time Division Frequency Hopping Multiple Access (TDFHMA) Technique has an advantage in severe multipath or when severe co-channel interference occurs. The subscriber can hop to new frequency at the subscriber can hope to new freque ncy at the start of a new time division multiple access frame. These different areas covered by the antenna beam may be served by the same frequency or difference frequency. Keywords: Frequency Hopped Multiple Access, Time Division Code Division Multiple Access, Time Division Frequency Hopping, Space Division Multiple Access 1 Introduction Spread spectrum techniques spread information over a very large bandwidth specifically, a bandwidth that is much larger than the inverse of the data rate. In this paper we are discussing various ways of providing multiple access by spreading the spectrum. We start out with the conceptually simplest approach, Frequency Hopping (FH). We then proceed to the most popular form of spread spectrum, Direct Sequence-Code D... ... Hybrid Wireless Networks Using Autonomic Computing Principles† IEEE, CNSR, 2005 [4] C. Lo, E. Masry, and L. B. Milstein, â€Å"Design and Analysis of a Fast Frequency-Hopped DBPSK Communication System, Part I,† IEEE Trans. Commun., Vol. COM-41, pp. 1552-1564, 1993 [5] Masato Mizoguchi and Kazuhiko Seki ,† In-Chip Fast Frequency Hopped and Direct Sequence CDMA Systems for Indoor Wireless Communications†,IEEE Trans. Commun, pp.1508-1512, 1996 [6] Andreas F. Molsch, â€Å"Spread Spectrum Systems†, publisher by Wiley India Edition, pp. 469-471,2005. [7] Theodore S. Rappaport, â€Å"Multiple Access Technique for Wireless communications†, Second Edition pp. 451- 463, 1996. [8] Q. Chen, Q. Wang and V. K. Bhargava, â€Å"Error Performance of Coded SFHiDPSK in Tone Interference and AWGN,† IEEE Confrence Milcom, pp. 63-67, 1992.