Wireless Point-to-Point (P2P) Microwave Backhaul Systems are network extensions or traffic overflow management devices in cellular and broadband networks. P2P microwave backhaul systems are deployed in two stages: outdoor and indoor units connected to each other by a coaxial cable (includes RF signal and DC power). The outdoor unit contains an antenna and microwave compatible components used to down or up convert RF signals within 7 – 38 GHz. The major components of the indoor unit include the processor, modem unit, and power section.
The P2P system processor unit routes high speed signals, monitors system status, and performs baseband processing. High speed performance and low power consumption are key attributes for the P2P processor as seen in TI’s TMS320TCI64x DSP family. The DSPs also support several interfaces and wireless protocols including GSM, CDMA, and WiMax for faster development and time-to-market. For example, TI’s TCI6482 features Gigabit Ethernet connectivity for direct connectivity to the network, a DDR2 memory external interface, and CDMA enhanced software toolkits.
The modem unit employs complex demodulation/modulation to suppress the carrier and sidebands for a cost effective, low noise (phase) solution as seen in the TI’s TRF37xx family. Furthermore, ultra-low jitter clocking enables accurate sampling in the modem unit’s data converters. The local oscillator into the demodulator/modulator requires low phase noise as shown in the TRF3750 (please see TSW3000: RF Transmit Signal Chain evaluation module for complete transmit solution). The modem unit’s Digital-to-Analog Converter and Analog-to-Digital Converter support high SNR and high SFDR at P2P application frequencies (i.e. TI’s DAC5662 & ADS62P15). For integrated solutions in the modem, TI can provide a cost effective, low power ASIC versus power hungry FPGAs.
P2P indoor units are typically powered by a -48V bus which is routed to the outdoor unit. Secondary voltages can be accomplished with traditional system power, digital power, or power modules depending on the design preference. The key power attributes of the indoor units include electronic soft start and short circuit protection (i.e TPS40021), under voltage protection (i.e. TPS545x family), and the ability to withstand transients (i.e TPS74x family.)