2008-ASAP - Configurable and Scalable High Throughput Turbo...

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Unformatted text preview: Configurable and Scalable High Throughput Turbo Decoder Architecture for Multiple 4G Wireless Standards * Yang Sun , Yuming Zhu , Manish Goel , and Joseph R. Cavallaro ECE Department, Rice University. 6100 Main, Houston, TX 77005 DSPS R&D Center, Texas Instruments. 12500 TI Blvd MS 8649, Dallas, TX 75243 Email: ysun@rice.edu, y-zhu@ti.com, goel@ti.com, cavallar@rice.edu Abstract In this paper, we propose a novel multi-code turbo de- coder architecture for 4G wireless systems. To support var- ious 4G standards, a configurable multi-mode MAP (max- imum a posteriori) decoder is designed for both binary and duo-binary turbo codes with small resource overhead (less than 10%) compared to the single-mode architecture. To achieve high data rates in 4G, we present a parallel turbo decoder architecture with scalable parallelism tai- lored to the given throughput requirements. High-level parallelism is achieved by employing contention-free inter- leavers. Multi-banked memory structure and routing net- work among memories and MAP decoders are designed to operate at full speed with parallel interleavers. We designed a very low-complexity recursive on-line address generator supporting multiple interleaving patterns, which avoids the interleaver address memory. Design trade-offs in terms of area and power efficiency are explored to find the optimal architectures. A 711 Mbps data rate is feasible with 32 Radix-4 MAP decoders running at 200 MHz clock rate. 1. Introduction The approaching fourth-generation (4G) wireless sys- tems are projected to provide 100 Mbps to 1 Gbps speeds by 2010, which consequently leads to orders of magnitude increases in the expenditure of the computing resources. The high throughput turbo codes [1] are required in many 4G communication applications. 3GPP Long Term Evo- lution (LTE) and IEEE 802.16e WiMax are two examples. As some 4G systems use different types of turbo coding schemes (e.g. binary codes in 3GPP LTE and duo-binary codes in WiMax), a general solution to supporting multiple code types is to use programmable processors. For exam- * This work was supported by the Summer Student Program 2007, Texas Instrument Incorporated. ple, a 2 Mbps turbo decoder implemented on a DSP proces- sor is proposed in [2]. Also, authors in [3] and [4] develop a multi-code turbo decoder based on SIMD processors, where a 5.48 Mbps data rate is achieved in [3] and a 100 Mbps data rate is achieved in [4] at a cost of 16 processors. While these programmable SIMD/VLIW processors offer great flexibil- ities, they have several disadvantages notably higher power consumption and less throughput than ASIC solutions. A turbo decoder is typically one of the most computation- intensive parts in a 4G receiver, therefore it is essential to design an area and power efficient turbo decoder in ASIC....
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This note was uploaded on 10/15/2009 for the course COMMUNICAR IEE 126 taught by Professor M.j.liu during the Spring '09 term at The School of the Art Institute of Chicago.

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2008-ASAP - Configurable and Scalable High Throughput Turbo...

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