Abstract—Orthogonal Frequency Division Multiplexing(OFDM) has been increasingly used in wireless broadbandcommunication systems. Guard interval (GI) is used inOFDM system to reduce inter-symbol interference (ISI). Asselection of the length of guard interval depends on thechannel condition, the length of guard interval will changedynamically. Thus there must be a way to synchronize thisparameter between the transmitter and the receivers.Traditional OFDM systems require a transmitter to notifyits receivers using additional signal and thus resultadditional bandwidth. In addition, this complicates theinitiation process for an OFDM receiver as it has to searchthrough all the possible values of GI length to find theparameter used by the transmitter. To address this problem,this paper gives a low-complexity method, which can detectthe length of guard interval at the receiver without anyguard interval length information from the transmitter. Theintroduction of this method will reduce the additionalsignaling and simplifies OFDM systems. Both theoreticalanalysis and simulation results show that the proposedmethod has good performance. The proposed method cangive accurate measure of GI length under both AWGN andRayleigh Channel even when SNR is as low as 3dB.

Index Terms—OFDM, Guard Interval

Cite: Li Zou, "Automatic Detection of the Guard Interval Length in OFDM System," Journal of Communications, vol. 1, no. 6, pp. 28-32, 2006.