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United States Patent | 6,782,037 |
Krishnamoorthy , et al. | August 24, 2004 |
In a wireless communication system, the constellation mapping scheme employed may be changed on a per-time-slot basis, i.e., from time slot to time slot, so that the constellation used to encode the symbols of each time slot may be different for each time slot within a single frame and may be different for a particular time slot in different consecutive frames. In other words, several constellation mapping schemes are available, with each providing the ability to transmit a different number of bits per symbol, and the particular constellation mapping scheme employed for any time slot need be selected for that time slot only. The ability to use any particular constellation mapping scheme is dependent on the current channel quality. The particular constellation mapping used for the user data of the time slot may be indicated in the preamble of the time slot. To this end, each time slot may have its own preamble that is mapped with a constellation mapping scheme which is a) known a priori, b) may be the same for all time slots, and c) may be different from the constellation mapping scheme used to encode user data in the time slot. A receiver can determine the constellation mapping used for each time slot from solely from the preamble of the time slot.
Inventors: | Krishnamoorthy; Rajeev (Middletown, NJ); Li; Xiaodong (Piscataway, NJ); Narayanaswamy; Shankar (Sunnyvale, CA); Rupp; Markus (Lincroft, NJ); Viswanathan; Harish (Matawan, NJ) |
Assignee: | Lucent Technologies Inc. (Murray Hill, NJ) |
Appl. No.: | 361317 |
Filed: | July 27, 1999 |
Current U.S. Class: | 375/138 |
Intern'l Class: | H04B 001/69 |
Field of Search: | 375/138,139,130,150 370/342,335,350,468,437 |
5289476 | Feb., 1994 | Johnson et al. | 371/37. |
5930243 | Jul., 1999 | Parish et al. | 370/334. |
6028901 | Feb., 2000 | Huynh et al. | 375/229. |
6400928 | Jun., 2002 | Khullar et al. | 455/67. |
6452913 | Sep., 2002 | Proctor, Jr. | 370/335. |
6473506 | Oct., 2002 | Hook et al. | 379/279. |
6490270 | Dec., 2002 | Krishnamoorthy et al. | 370/347. |
European Search Report No. 00306079.5-2216, Nov. 28, 2000--European Patent Office--The Hague. Otsuki, S. et al., "Performance of Modulation-Level-Controlled Adaptive Modulation Systems", Electronics and Communications in Japan, Part 1, vol. 79, No. 7, pp. 81-93; 1996. Hamaguchi, K. et al., "Implementation and Performance of Qam-Level-Controlled Adaptive Modulation For Land Mobile Communications", Electronics Letters, vol. 33, No. 18; Aug. 28, 1997. |
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