Enhanced Spectral Keying for Wireless Ultra Wideband Communications
Methods provide for the amount of information encoded by spectral keying into a UWB symbol having a plurality of modulation symbol times, to be increased by operating two or more frequency band carriers simultaneously during at least one of a plurality of modulation symbol times. In one aspect of the present invention, once a frequency resource, such as a carrier, has been used during a given modulation symbol time, those frequency resources are not used again within that UWB symbol. A method of transmitting symbols, includes providing ( 302 ) data to be transmitted, determining ( 304 ), which frequency carriers, if any, of a set of n frequency carriers, are to be turned on during each of n modulation symbol times, and turning on ( 306 ) each of the determined frequency carriers during each of the modulation symbol times, and wherein each frequency carrier is turned on only once during the transmission of the symbol.
1 . A method of generating information symbols, comprising: (a) turning on, for an i th predetermined length of time, during an i th time period, x i frequency carriers, where 0≦x i ≦n, and 1≦i≦n; (b) determining whether n−Σx i =0; and (c) if the determination of (b) is negative, repeating (a) through (b); wherein x i represents an integer number of frequency carriers, and n represents a total number of available frequency carriers.
2 . The method of claim 1 , further comprising: (d) if the determination of (b) is affirmative, waiting for a period of time.
3 . The method of claim 2 , further comprising: subsequent to waiting for the period of time, repeating (a) through (c).
4 . The method of claim 3 , wherein the period of time is a predetermined guard band that is disposed between information symbols.
5 . The method of claim 4 , wherein the information symbols occupy a frequency bandwidth greater than 500 MHz.
6 . A method of transmitting symbols, each symbol having n modulation symbol times, with a transmitter having a set of n frequency carriers, comprising: providing data to be transmitted; and determining based at least in part on the provided data, which frequency carriers, if any, of the set of n frequency carriers, are to be turned on during each of the n modulation symbol times, each modulation symbol time being of a predetermined amount of time; and turning on each of the frequency carriers as determined in (b) during each of the modulation symbol times; wherein each frequency carrier must be turned on for a period of time not greater than the modulation symbol time; and wherein each frequency carrier is turned on only once during the transmission of the symbol.
7 . The method of claim 6 , wherein at least one modulation symbol time has no frequency carriers turned on.
8 . The method of claim 7 , wherein at least one modulation symbol time has at least two frequency carriers turned on.
9 . The method of claim 8 , wherein a BPSK modulation is used.
10 . The method of claim 6 , wherein if n frequency carriers are turned on in one modulation symbol time, then no frequency carriers are turned on in the other n−1 modulation symbol times.
11 . The method of claim 6 , wherein the transmitted symbols occupy a frequency bandwidth greater than 500 MHz.
12 . The method of claim 6 , wherein the transmitted symbols occupy a frequency bandwidth greater than 2 GHz.
13 . The method of claim 11 , wherein the n frequency carriers transmit signals in n contiguous frequency bands, and n is an integer.
14 . The method of claim 11 , wherein the n frequency carriers transmit signals in n non-contiguous frequency bands, and n is an integer.
15 . A method of transmitting ultra wideband symbols, comprising: (a) turning on, for an i th predetermined length of time, during an i th time period, x i frequency carriers, where 0≦x i ≦n, and 1≦i≦m; (b) determining whether m time periods have expired; and (c) if the determination of (b) is negative, repeating (a) through (b); wherein x 1 represents an integer number of frequency carriers, n represents a total number of available frequency carriers, and m represents a total number of time periods contained within each of the ultra wideband symbols.