uplink and downlink in cellular communication

Beam width (measure if directional property) of the antenna is directly proportional to wavelength. The earth station antenna must direct the beam towards the satellite with as little spill over as possible i.e.However for the satellite this will result in higher power consumption, which results in avoidable inefficiency. This will increase the weight and power supply ratings will not make any difference. Higher power requirements involve the use of high power amplifiers with high ratings and heat sinks. At higher frequency attenuation is more hence more power will be required for signal transmission to ensure that it reaches the destination with the required minimum power.Uplink frequency is kept higher than Downlink frequency for the following reasons: So, Uplink frequency is different from downlink frequency. To overcome the above-mention difficulties satellite repeaters must involve some form of frequency translation before power amplification.Frequency band separation allows the same antenna to be used for both receiving and transmitting, simplifying the satellite hardware.Trying to receive and transmit an amplified version of the same uplink waveform at same satellite will cause unwanted feedback or ring around from the downlink antenna back into the receiver. In 900 MHz band: 890-915 MHz Uplink band, 935-960 MHz Downlink Radio carrier is a 200kHz channel > 125 pairs of radio channels Called Absolute Radio Frequency Channel Number (ARFCN) ARFCN numbers given by f(n) 890 +. LTE-Advanced supports Single-User MIMO (SU-MIMO) schemes up to 8-layer downlink MIMO (8x8 MIMO) and 4-layer uplink MIMO (4x4 MIMO).The satellite transmitter generates a signal that would jam its own receiver if both uplink and downlink shared the same frequency.Uplink frequency is different from downlink frequency for following reason:.The downlink frequency is the frequency which is used for transmission of signals from the satellite to the earth station receiver.

The uplink frequency is the frequency which is used for transmission of signals from earth station transmitter to the satellite.

Uplink and downlink in cellular communication