Framing technique for a multi-rate CDMA communication system

摘要

A method and means of modifying the multi-rate high speed data CDMA system by increasing the physical layer data rate to n times the basic IS-95 rate, while not increasing the frame size proportionally to avoid the use of larger frames, and varying the data rate by changing the number of frames, N, transmitted during each period of T see, using the relationship R = N x F/T, where R bps is the physical layer data rate, F bits is the physical layer frame size, and T see is the frame period and the interleave depth. Using this approach, the data rate can be varied between F/T bps and N x F/T bps using the same set of allowed frame sizes. Further, a major frame of data is formed using a fixed number of minor frames in combination, which minor frames are full rate and simple fractions of a full rate, i.e., 1/2 rate, 1/4 rate, and 1/8 rate. A basic data rate is established which is the data rate that will use a single full rate frame. The sizes of the minor frames needed to generate a major frame are determined by dividing the desired data rate by the basic data rate to form a ratio, the integer portion of which ratio indicates the number of full rate frames and the fractional portion of which determines the size of the single fractional rate frame to use. The full rate frames are concatenated with the single fractional rate frame to produce the final frame structure that is transmitted.