Second-Generation Broadband Systems
Second-generation broadband wireless systems were able to overcome the LOS issue and to provide more capacity. This was done through the use of a cellular architecture and implementation of advanced-signal processing techniques to improve the link and system performance under multipath conditions.
Several start-up companies developed advanced proprietary solutions that provided significant performance gains over first-generation systems. Most of these new systems could perform well under non-line-of-sight conditions, with customer-premise antennas typically mounted under the eaves or lower.
Many solved the NLOS problem by using such techniques as orthogonal frequency division multiplexing (OFDM), code division multiple access (CDMA), and multiantenna processing. Some systems, such as those developed by SOMA Networks and Navini Networks, demonstrated satisfactory link performance over a few miles to desktop subscriber terminals without the need for an antenna mounted outside.
A few megabits per second throughput over cell ranges of a few miles had become possible with secondgeneration fixed wireless broadband systems.