Frequency Hopping

GSM and DCS both employ frequency hopping technique for two main advantages:

• To reduce Mulitpath Fading effect which is dependent in carrier frequency
• To randomize Co-Channel Interference (CCI)

The hopping algorithm is continuously broadcast on BCCH and MS/BTS transmits TDMA frames on different hopping carriers during a call on hopping TRX. Hopping is used on TCH, SDCCH and all Packet Data channels while BCCH and common control channels are not allowed to hop. Frequency hopping types are:

• Baseband Hopping (BBH)
• Synthesizer Hopping (SFH)
• Discrete Hopping

Power Control RxLev for GSM and DCS

The upper and lower bounds of Power Control RxLev for Downlink should be set such as signal strength is maintained slightly above the threshold of noise floor. This would provide for enough signal strength to maintain a good voice quality and keeping the interference level to the minimum. Thus, these values are kept more aggressive for DCS, being a clearer band than GSM, for instance, the upper and lower bounds for DCS are generally set to -80dBm and -90dBm as compared to GSM values of -75 dBm and -85 dBm.