Implementation Of The Frequency-hopped Receiver With A Pilot Signal

Abstract

In this paper, we propose a new frequency-hopped receiver configuration without correlator. By introducing a pilot signal in the forward link, the proposed system can obtain symbol timing with faster tracking time and great simplib the necessary synchronization process along with a simple hardware complaity. Therefore, the proposed system has the advantages of being strong in the frequency selective fading channel. I. Introduction The wireless multimedia services and FPLMTS following the AMPS and digital mobile phone systems based on IS-95 will provide such services as voice, data, video communications and so forth. Also, the future communication services will be in the form of multimedia and the required data rates for providing such services will be in the range from a numbers of kbps to a numbers of Mbps. In this paper, we analyzed Frequency-Hopping(FH)[ 13 multiple access scheme, one of the methods of providing variable and high speed services. FH system[2] is a kind of spread spectrum communication systems, where the carrier frequency of the transmitter varies depending on the code pattern, and has a strong immunity to frequency selective fading environments. It has applications in the fields of military and commercial wireless LAN and also the GSM using the slow FH technique[3]. The proposed HF system introduces pilot channel, control channel and traffic channel. The purpose of pilot channel is to identify the base station and to inform the position of traffic channel to the mobile station in the frequency domain and the purpose of control channel is to set up calls. The mobile does not transmit pilot but can be synchronized to the received pilot from the base station. Because the linearity between the phase of hopping carriers is hard to get, the GMSK modulator, which is strong to phase nonlinearity, is adopted. The pilot channel transmitting the hopping pattem in the forward link uses the fixed carrier and the bandwidth for pilot is nothing but a number of tens kHz since real hopping speed is a few msec.