We investigate the performance of simple cognitive personal area networks (CPANs) with cooperative sensing. Nodes are equipped with small buffers of capacity K each, and each node is allowed to transmit a batch of up to mu packets in one transmission cycle. Upon transmission, each node must support the operation of the CPAN by performing sensing duty in the amount obtained by multiplying the number of packets sent in a batch by a variable penalty coefficient. We model this system and show the relationship between values of design parameters and piconet performance. We also show that performance and bandwidth utilization can be improved by a simple technique of dynamically adjusting the duration of the superframe to cater to instantaneous traffic volume. Copyright (C) 2011 John Wiley & Sons, Ltd.