Multiband orthogonal frequency-division multiplexing (MB-OFDM) systems employ frequencyhopping technology to achieve the capabilities of multiple access and frequency diversity. However, they also complicate packet detector (PD) and time-frequency code synchronization, in terms of the requirement for fast synchronization for the frequency hopping, the extremely low receiver sensitivity, and the high hardware complexity. In this paper, we firstly systematically analyze the differences between MB-OFDM and conventional OFDM systems, and then propose a band tracking PD (BT-PD) that can cope with a worse-case multipath channel SNR of –8.4 dB with a packet detection error rate of less than 10–5 .