Large set construction of user uplink ranging codes for M2M applications

Machine-to-machine (M2M) communications are to exchange information between a subscriber station and a server in the core network through a base station or between subscriber stations which may be realized without any human interaction or intervention. There are some requirements when designing M2M communication systems such resource allocation for large number of M2M devices or users. In this paper the authors propose a design way for the large set of user uplink codes in M2M communications. The zero-correlation-zone (ZCZ) sequences and Gold sequence have been applied as spreading sequences in this code division multiplexing access (CDMA)-like system according to different correlation characteristics. This system supports number of simultaneous users up to 256 and the total synchronization time is about 200 ms under reasonable chip rate 2.5 Mcps. Compared with previous systems for ranging process, it only requires 33% cycles of IEEE 802.16e and 16.7% cycles of IEEE 802.16m. Besides, the logic design and FPGA emulation based on low complexity are presented and the estimated about 11k total gate counts.