Achieving good coexistence in the 2.4 GHz ISM band

摘要

As the worldwide open 2.4 GHz ISM band becomes ever more crowded, good coexistence becomes vital to the successful deployment of an RF solution. Poor coexistence leads to packet loss which translates to increased latency and power consumption due to retransmissions. The two most important factors to achieve good coexistence are selectivity and frequency hopping/agility algorithm. In addition to explaining the importance of coexistence, this presentation shows the effects of selectivity in practice through real world examples and discusses software implementations of frequency agility. The worldwide availability of the 2.4 GHz ISM band has ensured its popularity with manufacturers of a wide variety of devices. Not only the number of devices deployed grows rapidly, but the number of radio technologies and protocols that share band is also on the rise. It is of course important that all these devices play nice and operate within the limits of regulations, but even if this is the case there is ample opportunity for radio interference between the devices in the band. Interference will cause packets to be lost, power consumption to increase and network performance to be reduced. The key to coexisting well with other devices in this band is robustness with respect to interference. Good selectivity with a frequency agility scheme suited for the application is the way to ensure this.