TITLE:
On Ultra Extended Cyclic Prefix in Orthogonal Frequency Division Multiplexing (OFDM) Systems: The Case of LTE Downlink
AUTHORS:
Abayomi M. Ajofoyinbo
KEYWORDS:
OFDM; Normal; Extended; Ultra Extended; Cyclic Prefix; LTE
JOURNAL NAME:
Communications and Network,
Vol.5 No.4,
November
14,
2013
ABSTRACT: Orthogonal Frequency Division Multiplexing (OFDM) is a
multi-carrier scheme used in modern broadband wireless communication systems to transmit data over a number of
orthogonal subcarriers. When transmitted signals arrive at the receiver by more
than one path of different length, the received signals are staggered in time;
this is multipath propagation. To mitigate the effect of dispersed channel
distortion caused by random channel delay spread, Cyclic Prefix (CP) is
introduced to eliminate Inter-Symbol Interference (ISI). In the literature,
researchers have focused on carrying out investigations (or studies) mainly on
the two existing CP insertions, namely: normal and extended CPs. Both CPs have
limitations with respect to handling channel delay spreads. In the current
work, a new CP, herein referred to as “ultra extended” CP is proposed to
address delay spreads beyond the limits of the normal and extended CPs. The efficacy
of the proposed ultra extended CP is tested via simulation under different
scenarios. It is shown by the results obtained that the proposed CP can
efficiently handle delay spreads beyond the limits of the existing normal and extended
CP, and can indeed be implemented in the design of future telecommunication
systems to accommodate higher channel delay spreads and it ensures
wider cell coverage.