User's Manual

from which more sophisticated uplink processing techniques (such as interference mitigation)
are built.
On the downlink (Base Station to Subscriber Station), sophisticated digital signal processing
algorithms exploit information gathered during the uplink beamforming process to concentrate
the transmitted RF energy from the antenna array to the exact subscriber stations locations,
improving gain, efficiency, and signal to noise ratio (SNR), resulting in greater range and
throughput.
MIMO Matrix A utilizes a technique called space-time coding (STC), which exploits the spatial
diversity of the channel to improve downlink performance. By improving data reception, it can
increase range and maximize the utilization of available sector capacity.
MIMO Matrix B utilizes a technique called spatial multiplexing (SM), in which multiple streams
of data are simultaneously transmitted through multiple antennas and effectively separated by
the receiving device. This technique can actually increase the spectral efficiency and, hence,
the capacity of a system.
The effectiveness of MIMO relies upon the spatial diversity inherent within the channel as well
as other factors, and therefore a given technique may be more appropriate for certain users or
deployments. Fortunately, PureWave Quantum Base Stations make these decisions
automatically, maximizing the efficiency of your valuable spectrum.
Cyclic Delay Diversity (CDD) is a technique employed by PureWave Quantum base stations to
allow the power of multiple antennas to be combined in transmitting a single stream of data
even when MIMO or beamforming cannot be supported (e.g., when transmitting the MAP).
Spatial Division Multiple Access (SDMA) is SDMA is an advanced form of beam-forming in
which multiple distinct beams are transmitted (or received) at the same time on the same
frequency to (or from) multiple users. Whereas FDMA separates users in frequency (e.g., sub-
channelization) and TDMA separates users in time, SDMA separates users in space. With SDMA
different signals are simultaneously sent on the same frequency to different physical locations.
Collaborative MIMO, also known as Collaborative Spatial Multiplexing (CSM), is a technique
that, similar to uplink SDMA, allows multiple subscriber stations to transmit at the same time
on the same frequency.
A key difference between CSM and SDMA is, however, that CSM transmissions are specially
coded and require specific support in the subscriber stations. In contrast, SDMA does not
require specific support from the subscriber station.