Performance of a TDMA portable radio link with a switching frequency synthesizer

The authors present the performance of an experimental TDMA (time division multiple access) portable radio link with a switching single loop frequency synthesizer. The synthesizer, used as a local oscillator (LO), operates around 2 GHz with a 400 kHz step size and can switch over 20 MHz in less than 400 μs. Performance of the TDMA radio link using WER (word error ratio) as a criterion was measured with the synthesizer switching frequencies between bursts at the transmitter. WER versus SNR (signal-to-noise ratio) shows small degradation, only 0.5 dB at WER of 10^-3, due to the phase noise of the synthesizer signal. The phase noise values for an offset of 10 kHz and 100 kHz were -70 dBc/Hz and -90 dBc/Hz, respectively. Measurements indicated that the radio link performance showed only minor degradation when the synthesizer was switched 20 MHz only 400 μs before transmitting a data burst. This permits a handset to switch to different channels than the channel of operation to measure signal quality for possible call-transfer once every 2 ms frame