Chapter 1: Product description Wireless operationPage 1-16Wireless operationThis section describes how the 450 Platform Family wireless link is operated, including modulationmodes, power control and security.Time division duplexingThe system uses Time Division Duplexing (TDD) – one channel alternately transmits and receives ratherthan using one channel for transmitting and a second channel for receiving. To accomplish TDD, theAP/BHM must provide sync to its SM/BHS. Furthermore, collocated APs/BHMs must be synced together– an unsynchronized AP/BHM that transmits during the receive cycle of a collocated AP/BHM can preventa second AP/BHM from being able to decode the signals from its APs/BHSs. In addition, across ageographical area, APs/BHMs that can “hear” each other benefit from using a common sync to furtherreduce self-interference within the network.Modules use TDD on a common frequency to divide frames for uplink (orange) and downlink (green)usage, as shown in the figure below.For more information on synchronization configuration options, see GPS synchronization on page 2-45.Figure 2 TDD frame divisionTime
