User's Manual

WiN7000 cBST Product Description | 20
Or in another example, a mobile network that offers just Internet access and voice may wish
to abrogate responsibility for data encryption and use session initiation protocol (SIP)
signaling for its VoIP and WiMAX native authentication tools.
Referring to encryption, clearly an AES supported data encryption system gives WiMAX
excellent security in this regard. However, additional solutions that meet customer needs
such as virtual private networks may enhance the business model and provide additional
source of revenue.
In the following two clauses, two revolutionary applications targeted at specific market
segments are described. These applications of WiMAX for DBS & DVB-T operators and
WiMAX for Cable operators distinguish WiNetworks from other players in the WiMAX
industry.
Network Access Providers can easily provide fast Internet and advanced data service to their
deployed network by using the WiNetworks WiMAX-based technology solution.
2.4.3 Time Division Duplexing (TDD)
The WiN7000 base station uses time division duplexing (TDD) to transmit and receive on the
same RF channel. This is a non-contention based method for providing an efficient and
predictable two-way PMP cell deployment. All uplink and downlink transmission scheduling
is managed by the base station. The base station sends data traffic to subscribers, polls for
grant requests, and sends grant acknowledgements based on the total of all traffic to all
subscribers.
2.4.4 Coding Rate
Each burst of data transmitted over the wireless interface is padded with redundant
information, making it more resistant to potential over-the-air errors. The coding rate is the
ratio of user data to the total data transmitted including the redundant error correction data.
The base station supports coding rates of 1/2, 2/3, and 3/4.
2.4.5 Modulation
The modulation technique specifies how the data is coded within the OFDMA carriers. The
base station supports QPSK, 16 Quadarature Amplitude Modulation (QAM), and 64 QAM
modulations.
2.4.6 Error Code Correction
Error correction techniques have been incorporated into WiMAX to reduce the system signal
to noise ratio requirements. Strong Reed Solomon FEC, convolutional encoding, and
interleaving algorithms are used to detect and correct errors to improve throughput. These
robust error correction techniques help to recover erroneous frames that may have been lost
due to frequency selective fading or burst errors. Automatic repeat request (ARQ) is used to