 ranging and hand- over. Non-contention based random access is used for periodic ranging. The physical ranging channel for non-synchronized mobile stations consists of a Ranging Cyclic Prefix (RCP) and a Ranging Preamble (RP). The value of the ranging cyclic prefix must be greater than the sum of the maximum channel delay spread and the round trip delay corresponding to the maximum cell size. The duration of the ranging preamble must be greater than RCP. To support large cell sizes, the ranging channel for non-synchronized mobile stations may be extended to multiple concatenated subframes (as shown in Figure 10-16). The physical ranging channel for non-synchronized mobile stations consists of a Ranging Preamble (RP) of length TRP whose value depends on the ranging channel sub-carrier spacing A fRP (which is a fraction of the OFDMA system sub-carrier spacing of given in Table 9-2) and a Ranging Cyclic Prefix (RCP) of length TRCP in time-domain. The ranging channel occupies a number of contiguous sub-carriers corresponding to one sub-band. Power control can be applied to the ranging channel to ensure robust signal transmission. The parameters of the initial ranging channel for the two supported formats are provided in Table 10-20, assuming a six symbol OFDM subframe. The OFDMA parameters Tg, Tu, and of are given in Table 9-2. The maximum coverage of ranging channels of the legacy and new systems are compared in Table 10-20 where it is shown that the legacy ranging channel may not meet the rigorous system requirements of IEEE 802.16m [3]. 10.3 Uplink control channels Copy Samples Non-Synchronized Initial Ranging Format 0 RangingCP Uplink Subframe Copy Samples Non-Synchronized Initial Ranging Format 1 RangingCP Uplink Subframe Synchronized Ranging 3 OFDM Symbols = 1 Basic Unit 3 OFDM Symbols = 1 Repeated Basic Unit 6 OFDM Symbols = 1 Uplink Subframe Copy Samples Copy Samples Legacy Non- Synchronized Initial Ranging Initial and Periodic Samples Samples Samples Samples Ranging Channels in FDM-based UL-PUSC Initial Rang