%0 Journal Article
%T Energy-Efficient Hardware Architectures for the Packet Data Convergence Protocol in LTE-Advanced Mobile Terminals
%A Shadi Traboulsi
%A Valerio Frascolla
%A Nils Pohl
%A Josef Hausner
%A Attila Bilgic
%J VLSI Design
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/369627
%X In this paper, we present and compare efficient low-power hardware architectures for accelerating the Packet Data Convergence Protocol (PDCP) in LTE and LTE-Advanced mobile terminals. Specifically, our work proposes the design of two cores: a crypto engine for the Evolved Packet System Encryption Algorithm (128-EEA2) that is based on the AES cipher and a coprocessor for the Least Significant Bit (LSB) encoding mechanism of the Robust Header Compression (ROHC) algorithm. With respect to the former, first we propose a reference architecture, which reflects a basic implementation of the algorithm, then we identify area and power bottle-necks in the design and finally we introduce and compare several architectures targeting the most power-consuming operations. With respect to the LSB coprocessor, we propose a novel implementation based on a one-hot encoding, thereby reducing hardware¡¯s logic switching rate. Architectural hardware analysis is performed using Faraday¡¯s 90£¿nm standard-cell library. The obtained results, when compared against the reference architecture, show that these novel architectures achieve significant improvements, namely, 25% in area and 35% in power consumption for the 128-EEA2 crypto-core, and even more important reductions are seen for the LSB coprocessor, that is, 36% in area and 50% in power consumption. 1. Introduction New data-demanding mobile applications, such as video streaming and online gaming, are the main drivers for higher mobile data rates. New standards improve the mobile Internet experience by providing downlink data rates starting from 100£¿Mbit/s in LTE up to 1£¿Gbit/s for LTE-Advanced [1]. This huge increase in data rates imposes new challenges on the design of mobile devices, where computational power and battery lifetime are strictly limited. A recent uplink/downlink performance analysis of an LTE protocol stack on a representative virtual mobile platform [2, 3] has identified the Protocol Data Convergence Protocol (PDCP) as the most time-critical component within the Layer 2 software architecture. PDCP incorporates two computationally expensive tasks: the Robust Header Compression (ROHC) algorithm, which compresses IP packet headers in order to improve the spectral efficiency of radio links, and the ciphering algorithm, responsible for user data protection and for providing a secure communication towards the core network. While both protocol functions show long processing times, ciphering comes in the first place followed by ROHC. Apart from performance requirements, PDCP algorithms must be designed for low-power
%U http://www.hindawi.com/journals/vlsi/2013/369627/