The OFDM Baseband Processor is a custom baseband processor, which implements the physical layer of an OFDM, time division duplexing (TDD) system. The baseband processor includes both transmission and reception bit-level and symbol-level processing chains including a sophisticated synchronization unit. The host interface is based on SPI protocol as well as with handshaking/interrupt ports. This custom system implements a subset of 802.16d standard functional options/features and is highly configurable via the integrated register file. An RF interface module is also included, compatible with Analog Devices AD9361 RF transceiver.
The Bit-level processing block (BLPB) transmission chain implements the following functional units : randomization, FEC encoding, interleaving and symbol mapping. In BLPB reception chain the following operations are implemented: soft symbol demapping, deinterleaving, FEC decoding and derandomization. The FEC module is based on the implementation of the Reed Solomon algorithm.
The Symbol-level processing block (SLPB) transmission chain implements the following functional units: OFDM symbol transmitter, IFFT , CP insertion. In reception chain the SLPB module is preceded by the synchronization unit, which is searching for known preamble values in order to locate the start an incoming wimax sub-frame. Once the sub-frame is located, frequency offset compensation is applied and received information is propagated down to SLPB reception chain. In SLPB reception chain the following operations take place: CP removal, FFT, OFDM symbol receiver, channel estimation, phase offset compensation and channel equalization.
- Customized transmit and receive physical layer chains.
- Fully synchronous design enabling high throughput TDD operation.
- BLPB and SLPB processing blocks.
- Implements a sophisticated synchronization algorithm to efficiently detect and isolate received modulated payload information.
- Configurable as either downlink (DL) baseband station or uplink (UL) baseband station.
- Configurable data randomization, modulation level and code rate.
- Host interface based on SPI protocol.
- RF interfacing supporting Analog Devices AD9361 RF Transceiver.
- Configurable dynamic range scaling (1x, 2x or 4x) providing robust operation in channels with lower SNR value.
- Fully synchronous design.
- Silicon proven in FPGA technologies.
- Fully commented synthesizable VHDL or Verilog source code or FPGA netlist.
- VHDL or Verilog test benches and example configuration files.
- Comprehensive technical documentation.
- Technical support.
- The ntOFDM_BBP core implements a custom, OFDM, TDD based baseband processor which can be used in a variety of wireless broadband applications.
Block Diagram of the OFDM Baseband Processor