mple, f = fIGHz X 10°. Problem 4.9 The approximate distance between an Earth station and a geostationary satel- lite is 40,000 km. (a) What is the attenuation of the uplink radio section at the 6-GHz frequency? (b) What is the attenuation in the downlink direction at 4 GHz? Problem 4.10 Consider a cell in a GSM cellular network operating at 900 MHz and a cell in a DCS-1800 network operating at 1.8 GHz. The DCS-1800 base station is installed in the same site as the GSM base station. Assume that all system parameters except frequency are equal and use the free-space loss formula. What would be the radius of the DCS-1800 cell if the radius of the GSM cell is 1 km? Problem 4.11 How much higher transmission power is needed, according to the free-space loss formula, if the radio transmission distance is doubled (for the same performance)? Transmission Problem 4.12 A telecommunications network operator is aiming to update a GSM network with DCS-1800 base stations. The cells of GSM (900 MHz) are designed for a maximum transmission power of 1W. What should be the maximum transmission power of DCS-1800 (1.8-GHz) base stations with the same cell structure? Assume here a free-space environment and that the only difference between systems is the frequency. Problem 4.13 What is the approximate gain of the satellite TV antenna when the diameter of the dish is 0.6m and the frequency is 10 GHz? How much better is the S/N ratio if the antenna is changed to a larger one with diameter of 1m? Problem 4.14 What is the received power level (dBm) and power (W) when transmitted power is 1W, frequency 1 GHz, distance 1 km, and transmitter and receiver antenna gains are 14 and 2 dB, respectively? Assume a free-space loss approximation for link loss. Problem 4.15 What are the theoretical maximum symbol rate r and the maximum binary bit rate C through the following baseband channels: (a) bandwidth B = 3 kHz and S/N = 20 dB (degraded speech channel); and (b) bandwidth B = 5 MHz and S/N = 48 dB (typical video channel)? Problem 4.16 How many bi