Ofdm/ofdma frame structure for communication systems

Abstract

An OFDM/OFDMA frame structure technology for communication systems is disclosed. The OFDM/OFDMA frame structure technology comprises a variable length sub-frame structure with efficiently sized cyclic prefixes and efficient transition gap durations operable to effectively utilize OFDM/OFDMA bandwidth. Furthermore, the frame structure provides compatibility with multiple wireless communication systems. An uplink frame structure and a downlink frame structure are provided.

What is claimed is: 
     
         1 . A communication system comprising:
 a plurality of base stations supporting variable cyclic prefix durations, and   a processor module for providing a flexible radio frame structure utilizing the variable size cyclic prefix durations and capable of choosing the variable size cyclic prefix durations based on compatibility with characteristics of a base station of the plurality of base stations, wherein the flexible radio frame structure is used by at least one base station of the plurality of base stations for transmitting data wirelessly to a mobile station and wherein the characteristics of the base station include cell coverage area.   
     
     
         2 . The communication system of  claim 1 , wherein the variable cyclic prefix durations are chosen based also on a fixed subcarrier spacing. 
     
     
         3 . The communication system of  claim 2 , wherein the fixed subcarrier spacing comprises 12.5 KHz. 
     
     
         4 . The communication system of  claim 3 , wherein the variable cyclic prefix durations, plus a timing window, comprise one of the group consisting of: about 3.125 μs, 10 μs, and 16.875 μs for a n×1.25 MHz bandwidth series. 
     
     
         5 . The communication system of  claim 3 , wherein the variable cyclic prefix durations, plus a timing window, comprise one of the group consisting of: about 3.281 μs, 10 μs, and 16.178 μs for a n×3.5 MHz bandwidth series. 
     
     
         6 . The communication system of  claim 3 , wherein the variable cyclic prefix durations, plus a timing window, comprise one of the group consisting of: about 2.5 μs, 9.375 μs, and 16.875 μs for a n×1.25 MHz and a n×3.25 MHz bandwidths series. 
     
     
         7 . The communication system of  claim 3 , wherein the variable cyclic prefix durations comprise one of the group consisting of: about 2.5 μs, 10 μs, 15 μs, and 20 μs for a 5 MHz bandwidth series. 
     
     
         8 . The communication system of  claim 2 , wherein the fixed subcarrier spacing comprises about 10.9375 KHz. 
     
     
         9 . The communication system of  claim 8 , wherein the variable cyclic prefix durations comprise one of the group consisting of: about 2.857 μs, 11.428 μs, 17.142 μs, and 22.857 μs for a 5 MHz bandwidth series. 
     
     
         10 . The communication system of  claim 2 , wherein the fixed subcarrier spacing comprises about 25 KHz. 
     
     
         11 . The communication system of  claim 10 , wherein the variable cyclic prefix durations comprise one of the group consisting of: about 2.5 μs, 10 μs, 15 μs, and 20 for a 5 KHz bandwidth series. 
     
     
         12 . The communication system of  claim 1 , wherein a first cyclic prefix duration for a first base station differs from a second cyclic prefix duration for a second base station. 
     
     
         13 . The communication system of  claim 1 , wherein the flexible radio frame structure comprises a 10 ms radio frame. 
     
     
         14 . The communication system of  claim 1 , wherein the flexible radio frame structure comprises sub-frames which comprise sub-frame duration options based on the variable cyclic prefix durations. 
     
     
         15 . The communication system of  claim 14 , wherein the sub-frame duration options comprise one of the group consisting of: about 0.5 ms, 0.675 ms, 1 ms, 1.25 ms, 1.5 ms, 2 ms, and 2.5 ms. 
     
     
         16 . The communication system of  claim 14 , wherein the sub-frame duration options allow a system to reduce interference with systems based on a plurality of industry standards. 
     
     
         17 . The communication system of  claim 16 , wherein the industry standards comprise one of the group consisting of: Third Generation Partnership Project Long Term Evolution (3GPP LTE), Third Generation Partnership Project 2 Ultra Mobile Broadband (3 Gpp2 UMB), Time Division-Synchronous Code Division Multiple Access (TD-SCDMA), and Wireless Interoperability for Microwave Access (WiMAX). 
     
     
         18 . The communication system of  claim 14 , wherein the sub-frames comprise a plurality of sub-frame sizes. 
     
     
         19 . The communication system of  claim 18 , wherein the variable cyclic prefix durations are selected for each of the sub-frame sizes. 
     
     
         20 . The communication system of  claim 14 , wherein the processor module is further operable to calculate a plurality of timing gaps associated with at least one of the sub-frames, wherein the timing gaps are calculated based in part on the variable cyclic prefix durations. 
     
     
         21 . The communication system of  claim 20 , wherein the timing gaps comprise one of the group consisting of: a transmission timing gap for an uplink TTG(UL), a transmission timing gap for a downlink uplink TTG(DL), and a transmit-receive timing gap (RTG).