Crest Factor Reduction Reference Design for OFDM Systems
from Altera Corporation
Please contact your local Altera sales representative for a copy of this reference design.
Overview
Orthogonal frequency division multiplexing (OFDM) is widely regarded as the key underlying air interface technology for future wireless systems such as WiMAX, 3GPP long term evolution (LTE) and 3GPP2 ultra mobile broadband (UMB). Due to their inherent nature, OFDM signals have high peak-to-average power ratio (PAR) that adversely impacts the efficiency of power amplifiers (PAs) used in wireless basestations.
Crest factor reduction (CFR) schemes help reduce PAR and have been widely implemented for code division multiple access (CDMA) systems. But CFR schemes developed primarily for CDMA signals exhibit poor performance when used in conjunction with OFDM signals, given the stringent error vector magnitude (EVM) requirements specified in standards such as WiMAX.
Altera’s CFR reference design has been developed primarily for OFDM systems and demonstrates how such algorithms can be efficiently implemented using Stratix® III FPGAs. The resulting low latency, high performance design significantly reduces the PAR of the output signal while being standards compliant, leading to improved power amplifier efficiency and reduced cost.
Altera supplies the reference design as clear-text VHDL, including a MATLAB bit-accurate simulation model.
Features
- Support for OFDM-based systems including WiMAX and LTE
- Additional functionality includes OFDMA symbol modulation, DUC (4x interpolation), and cyclic prefix insertion
- Programmable mask for any environment
- Programmable EVM budget
- Programmable channel bandwidths including 10 and 20 MHz
- Up to 5db PAPR improvement
- No receiver-side modification required
Demonstrated Altera Technology
Block Diagram
Figure 1 shows the CFR for OFDM reference design blocks.
Figure 1. CFR for OFDM Reference Design Blocks
Related Links
Reference Designs Disclaimer
These reference design illustrations may be used within Altera Corporation devices only and remain the copyrighted property of Altera. They are being provided on an "as-is" basis and as an accommodation, and therefore all warranties, representations, or guarantees of any kind (whether express, implied, or statutory) including, without limitation, warranties of merchantability, non-infringement, or fitness for a particular purpose, are specifically disclaimed. Altera expressly does not recommend, suggest, or require that these examples be used in combination with any other product not provided by Altera.
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