As far as the PHY layer is concerned, CR can communicate with various radio-access technologies in the environment, or it can improve the quality of communication depending on the environmental characteristics, by simply changing the configuration parameters of the
GMSK system and the SDR interface.
EDGE improved GPRS rates by using a modulation scheme of higher spectral efficiency, 8-PSK (phase-shift keying), which transmits three bits per symbol, while
GMSK transmits only one bit per symbol.
Figure 15 shows the transmitter output constellation for
GMSK. The root-mean-square (rms) and peak phase errors are [4.sup.[degrees].sub.rms] and [8.5.sup.[degrees].sub.peak], respectively, meeting error vector magnitude (EVM) requirements [16] of
GMSK.
Within the 824 to 849 MHz region for CEL Tx-band operation the unit features a typical output power in
GMSK mode of 35 dBm with an input power of 3 dBm.
Both the model ranges offer a 5 Watt RF modem with FSK as standard and FFSK and
GMSK options.
Typical applications for the RF2485 include digital and spread spectrum systems;
GMSK, QPSK, DQPSK and QAM modulation; private mobile radio and TETRA systems; AM, SSB, DSB modulation and image-reject up-converters.
The European Telecommunications Standards Institute has developed the HIPERLAN (High Performance Radio LAN) standard, which operates in the 5-GHz band and delivers rates to 24 Mbps using
GMSK (Gaussian minimum shift keying) modulation.
Ramalingam, "Cross layer analysis of queuing with AMC through
GMSK modulation over wireless links," in Proceedings of the 16th International Conference on Advanced Computing and Communications (ADCOM '08), pp.