CLAP: Chip-Level Augmentation of IEEE 802.15.4 PHY for Error-Intolerant WSN Communication

Communication reliability is the ultimate priority in safety-critical wireless sensor network (WSN) communication. Surprisingly enough, the enormous potential of error control on direct sequence spread spectrum (DSSS) chips in IEEE 802.15.4 has been completely overlooked by the WSN community, possibly due to incorrect presumptions, such as the concerns about computational overhead. Current error-correction schemes in WSN counteract the error process once the errors have already propagated to bit- and packet-level. Motivated by the notion that errors should be confronted at the earliest stage, this work presents CLAP, a novel method that tremendously improves the error correction in WSN by fortifying the IEEE 802.15.4 Physical layer (PHY) with straightforward manipulations of DSSS chips. CLAP is implemented on a software-defined radio platform, and evaluated on real error traces from heavily WLAN-interfered IEEE 802.15.4 transmissions at 3 different environments. CLAP boosts the number of corrected packets by 1.78-6.88 times on severely interfered links, compared to two other state-of-the-art schemes. The overhead in terms of computational complexity is about 10% of execution time of the OQPSK demodulator in the legacy IEEE 802.15.4 receiver chain.