Changes between Version 5 and Version 6 of OFDM
- Timestamp:
- Jun 27, 2006, 2:47:45 PM (18 years ago)
Legend:
- Unmodified
- Added
- Removed
- Modified
-
OFDM
v5 v6 1 1 = OFDM Physical Layer = 2 We have chosen OFDM as the underlying physical layer for our research. Currently a SISO OFDM transceiver is fully implemented and tested in hardware. This model is available via the [source:ResearchApps/PHY/SISO_OFDM repository].2 We have chosen OFDM as the underlying physical layer for our research. Currently a SISO OFDM transceiver is fully implemented and tested in hardware. 3 3 4 4 == OFDM Models Overview == 5 Our SISO OFDM transceiver is implemented as two Simulink models built using Xilinx's System Generator for DSP. Both models are designed from scratch for real-time, wideband operation on the WARP hardware. The models have top-level interfaces to the WARP radio board's Tx/Rx analog converters. They also utilize an OPB interface for data exchange and control by the embedded PowerPC in the WARP FPGA. 5 Our SISO OFDM transceiver is implemented as two Simulink models built using Xilinx's System Generator for DSP. Both models are designed from scratch for real-time, wideband operation on the WARP hardware. The models have top-level interfaces to the WARP radio board's Tx/Rx analog converters. They also utilize an OPB interface for data exchange and control by the embedded PowerPC in the WARP FPGA. Both models are available in the [source:ResearchApps/PHY/SISO_OFDM repository]. 6 6 7 == Performance ==7 == Features & Performance == 8 8 Some basic performance paramters are listed below. This page will be updated as we further verify and extend the models in hardware. 9 10 '''Moduation:''' 11 Both models support flexible modulation schemes, allowing individual subcarriers to carry [0, 1, 2, 4, 6, 8] bits. In other words, any combination of 0, BPSK, QPSK, 16/64/256 QAM can be used per packet. We have fully tested a QPSK-only system in hardware, loading 48 of 64 subcarriers with user data. 9 12 10 13 '''Bandwidth:''' 11 14 The effective bandwidth is currently 10 MHz. The ADC/DAC sampling rate is actually 50 MHz; interpolation/decimation filters are included in the models to achieve this rate change. 12 15 13 '''Moduation:'''14 Both models support flexible modulation schemes, allowing individual subcarriers to carry [0, 1, 2, 4, 6, 8] bits. In other words, any combination of 0, BPSK, QPSK, 16/64/256 QAM can be used per packet. We have fully tested a QPSK-only system in hardware, loading 48 of 64 subcarriers with user data.15 16 16 '''Data rate:''' 17 17 We have tested a 12 Mbps PHY configuration over-the-air (10 MHz bandwidth with 48 data-bearing subcarriers using QPSK modulation). We have also tested a 16 QAM system in hardware (running at 24 Mbps) and are in the process of fully verifying its operation now. 18 19 '''Checksum calculation:''' 20 Both the Tx and Rx models include hardware checksum calculation blocks. These blocks calculate a 32-bit CRC over each packet's payload in real-time. The Tx model appends the 4-byte checksum to each transmitted packet. The Rx model automatically notifies user code of a received packet's checksum status.