User's Manual

16 4Motion System Manual
Chapter 1 - System Description
the backhaul implements a layer-2 connection toward the NPUs in the cascaded
shelves. Bearer, control and management traffic is sent over the cascade
connection. Synchronization and GPS backup power are sent toward the NPUs in
the cascaded shelves through the GPS/SYNC ports.
GPS synchronization cascading will be implemented in a future release.
1.3.3 AU
The Access Unit module performs the WiMAX/IEEE 802.16e BS function
according to the NWG Profile C definitions via digital signal processors (DSPs) and
field-programmable gate array (FPGA) technology. The AU module is designed to
support high-traffic throughput and enable diversity, MIMO and AAS, thereby
extending capacity and range.
The AU implements the following functionality:
 802.16e multi-channel OFDMA PHY
 Up to four-channel support (Tx/Rx)
 Diversity and future AAS
 Flexible channel bandwidth - up to 20 MHz
 Flexible FFT size - up to 2048 points
 Wide variety of reuse patterns
 Advanced channel coding (CTC)
 HARQ
 Rate adaptation
 High-performance CDMA detector
 IF interface to RF ODU
 MAC-PHY interface
 Link management (network entry, basic capabilities negotiation,
authentication and registration, connection management)