next up previous contents
Next: 9 Current Solutions Up: Stream Processors and their Previous: 7 4G   Contents

8 Computational Complexity and Power Consumption

The computational requirements imposed by cellular standards has increased exponentially from 1G to 4G. This is due to the increased complexity of algorithms introduced to reduce the bit-error rate use of the wireless spectrum more efficiently. These algorithms have been shown to require more performance than is currently available in embedded processors. Table 1, shows the computation requirements to handle 384 Kbits/s transmission rate on a 3G WCDMA receiver[3]. The problem will persist in the future since the computation requirements are growing faster than Moore's law[3]. Power dissipation is also a major problem in battery powered mobile computing and communication devices. While the computational requirements are increasing exponentially, battery capacity is only improving at the rate of 1.03 times per year[15]. Flexibility and low time to market require the use of programmable processors for the implementation of the increasingly sophisticated digital signal processing algorithms. Power efficiency on the other hand, requires the use of a customized solution. To make 4G systems usable, the performance per unit power consumption of processors needs to improve significantly - an area in which stream processors have a significant advantage.


Table 1: Computation Requirements for 3G WCDMA Receiver
Algorithm Approximate MIPS
Digital Filter (RRC, Channelization) 3000
Searcher 1500
Rake 650
Maximal-ratio combining 24
Channel estimator 12
AGC, AFC 10
De-interleaving, rate matching 14
Turbo decoding 52
Sum 5262



next up previous contents
Next: 9 Current Solutions Up: Stream Processors and their Previous: 7 4G   Contents
Binu K. Mathew, Ali Ibrahim