5.2 Wireless Backhaul Technology
Wireless in transport has long been synonymous with microwave point-to-point (PtP) radio link. For decades microwave radios (MWR) have been used in all levels of transport networks, for short and long hauls. In the digital era main data structures have been PDH and SDH, today it is Ethernet. The majority of MW radios use frequency bands allocated for fixed services between 2 ... 15 GHz, while newer urban installations use frequency bands 18...38 GHz. Typical capacities used to be 2...16 × 2 Mbit/s in access section and 140 Mbit/s, STM-1 or even STM-4 in national trunk lines. The backbone network installations used to be huge in size: long and stabile masts, large parabolic dish antennas, heavy radio and baseband rack installation in air-conditioned special premises.
In the upper level of (core) networks the radios are yielding to optical fiber transmission due to a huge increase of transmission rates. Wireless transport systems, however, have their benefits and are widely used in the access part of the mobile backhaul networks. Mobile and fixed network convergence is reality and this is true also in mobile backhaul.
Over 55% of all MBH physical connections worldwide are on microwave, and a total of 64% of MBH equipment revenue in 2010 was from TDM, dual TDM/Ethernet and packet microwave (Chapter 02). Due to increasing mobile data rates in LTE/LTE-A era the mobile hand-sets' distance to the BTS (eNB) will shorten. Much more capacity is needed per ...