an approximation. When two or more adjacent Wi-Fi networks are operat- ing concurrently, they will utilize different 22 MHz Methods for improving Bluetooth sections of the 2.4 GHz band-three nonoverlapping and Wi-Fi coexistence Wi-Fi channels are possible. In this case, Bluetooth may not be able to avoid collisions while using a minimum of By dynamically modifying one or more system operating 15 hop frequencies. In addition, if there are several parameters according to detected interference levels, Bluetooth piconets in the same area, collisions among coexistence between Bluetooth and Wi-Fi can be im- themselves will be much more frequent than when the proved. Some of these methods are discussed below. full 79 channel hopping sequences are used. CHAPTER 5.2 Short-range wireless applications and technologies Packet fragmentation The two interference-avoiding methods described above are applicable primarily for action by the Bluetooth network. One method that the Wi-Fi network can employ to improve throughput is packet fragmentation. By fragmenting data packets and sending more, but shorter transmission frames, each transmission will have a lower probability of collision with a Bluetooth packet. Although reducing frame size increases the percentage of overhead bits in the transmission, when interference is Figure 5.2-27 UWB monopulse. heavy the overall effect may be higher throughput than if fragmentation was not used. Increasing bit rate for Differing from conventional radio communication a constant packet length will also result in a shorter systems, which use up conversion and down conversion transmitted frame and less exposure to interference. to pass information signals between baseband and band- The methods mentioned above for reducing in- pass frequency channels where wireless propagation terference presume no coordination between the two occurs, UWB signal generation and detection use base- different types of collocated wireless networks. How- band techniques. An example of a UWB "carrier" is ever, devices 