A new reconfigurable Linear FeedBack Shift Register organization to improve SDR design

In the context of Software Defined Radio (SDR), parametrization is an interesting approach in the design of multi-standard terminals. Compared to Software based approaches, the Techniques of Parameterization limit the size of the software to a limited set of parameters thereby decreasing the radio reconfiguration time. Many current functions such as Scrambling, Convolutional Coding, CRC and even Cordic or Fast Fourier Transform can be derived as Linear Feedback Shift Registers (LFSR). We have already defined four LFSR architectures to execute such operations [9]. They can achieve one by one, the entire LFSR operations of a specific tri-standard terminal (3GPP LTE, IEEE802.16e and IEEE802.11g). However, instances and sizes of LFSR change for each operation to execute. As a consequence, the definition of a single type of operator and the scheduling of these different instances are the curbs in the deployment of one generic LFSR. To overcome this issue, we present in this article a special architecture of LFSR, able to execute one or several LFSR of different sizes at the same time. Applied in the context of the Common Operator Technique presented in [1], the Structure allows us to create a reconfigurable design, which avoids the scheduling issue though optimizing the Hardware complexity up to 50%.