A method for enabling self-coexistence of devices in a flexible wireless system employing a flexible MAC protocol designed to support both a centralized and a distributed mode and to enable a smooth transition from one operation mode to another, the flexible wireless system includes first and second wireless networks sharing a frequency band, the method comprising: a device belonging to the first network discovering a second device operable in the second wireless network that overlaps with the first wireless network, wherein the first network and the second network can operate in the distributed or the centralized mode such that three different configuration modes exist in the flexible wireless system, distributed-distributed, centralized-distributed, and centralized-centralized; reporting the discovered second device to a first device operable in the first wireless network; determining if an adjustment is needed between a first beacon period of the first device and a second beacon period of the second device, wherein each device is categorized into a move group or a stay group, wherein devices in the move group need to adjust their beacon period and devices in the stay group do not make adjustments, wherein the categorization is based on the configuration mode of the flexible wireless network, wherein if the configuration mode of the flexible wireless system is distributed-distributed, the stay group is defined to include devices having a largest number of reserved slots, a largest beacon period length, or a largest superframe number, wherein if the configuration mode of the flexible wireless system is centralized-centralized, the stay group is defined to include a master device with a largest number of slave devices with active reservations or a master device with a largest number of reserved slots, and wherein if such master device is not found, including in the stay group devices with a largest overall number of reserved slots, a largest beacon period length, or a largest superframe number, wherein if the configuration mode of the flexible wireless system is centralized-distributed the stay group is defined to include at least one slave device operating in a centralized mode with active reservation, and wherein if such slave device is not found, including in the stay group devices with a largest overall number of reserved slots, a largest beacon period length, or a largest superframe number, wherein devices that are not included in the stay group are added to the move group; and adjusting a first beacon period start time (BPST) of the first device to synchronize with a second BPST of the second device if the first device is categorized in the move group such that an adjustment is needed. a device belonging to the first network discovering a second device operable in the second wireless network that overlaps with the first wireless network, wherein the first network and the second network can operate in the distributed or the centralized mode such that three different configuration modes exist in the flexible wireless system, distributed-distributed, centralized-distributed, and centralized-centralized; reporting the discovered second device to a first device operable in the first wireless network; determining if an adjustment is needed between a first beacon period of the first device and a second beacon period of the second device, wherein each device is categorized into a move group or a stay group, wherein devices in the move group need to adjust their beacon period and devices in the stay group do not make adjustments, wherein the categorization is based on the configuration mode of the flexible wireless network, wherein if the configuration mode of the flexible wireless system is distributed-distributed, the stay group is defined to include devices having a largest number of reserved slots, a largest beacon period length, or a largest superframe number, wherein if the configuration mode of the flexible wireless system is centralized-centralized, the stay group is defined to include a master device with a largest number of slave devices with active reservations or a master device with a largest number of reserved slots, and wherein if such master device is not found, including in the stay group devices with a largest overall number of reserved slots, a largest beacon period length, or a largest superframe number, wherein if the configuration mode of the flexible wireless system is centralized-distributed the stay group is defined to include at least one slave device operating in a centralized mode with active reservation, and wherein if such slave device is not found, including in the stay group devices with a largest overall number of reserved slots, a largest beacon period length, or a largest superframe number, wherein devices that are not included in the stay group are added to the move group; and adjusting a first beacon period start time (BPST) of the first device to synchronize with a second BPST of the second device if the first device is categorized in the move group such that an adjustment is needed.