Block Floating Point Arithmetic for Low-Energy GNSS-Receiver PVT-Estimation

E. Tasdemir, G. Kappen, T.G. Noll

Abstract:	Block Floating Point Arithmetic (BFPA) combines the ideas of integer arithmetic and classical floating point arithmetic by using a common exponent for a set of val-ues, which have to be processed [1]. While integer arithmetic has the benefit that it can be implemented on a simple ALU it suffers from lower accu-racy. Floating point arithmetic [2] in general has to be implemented in additional libraries or specific hardware but achieves high accuracy and allows for larger dynamic of the processed values [1] and [3]. In general, algorithms for position estimation rely on this floating point arithmet-ic since they are developed in MATLAB and are subse-quently translated to C/C++. A BFPA-based realization allows the processing of the respective algorithm using a simple integer-based arith-metic logical unit (ALU), thus increasing the efficiency of the implementation. The paper analyses the feasibility of BFPA for the im-plementation of GNSS-receiver algorithms to reduce area and energy requirements for low-cost applications. As a main part this paper focuses on the application of BFPA for the position, velocity, and time estimation in a GNSS-receiver. Required processing cycles and energy consumption are derived for standard embedded micro-processors (e.g. ARM7) and an application specific pro-cessor (i.e. GNSS-ASIP [4], [5]). The derived results show an improvement of 55% (ARM7TDMI) and 72% (GNSS ASIP) compared to a realization of the position estimation using standard floating point arithmetic in terms of performance and area and energy requirements.
Published in:	Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010) September 21 - 24, 2010 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	2933 - 2940
Cite this article:	Tasdemir, E., Kappen, G., Noll, T.G., "Block Floating Point Arithmetic for Low-Energy GNSS-Receiver PVT-Estimation," Proceedings of the 23rd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2010), Portland, OR, September 2010, pp. 2933-2940.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In