1. A method for terrestrial broadcast of digital data to stationary receivers, comprising:
encoding and modulating digital data using coded orthogonal frequency division multiplexing (COFDM) to produce a data stream; and
communicating said data stream to a stationary receiver via a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%.
2. A method in accordance with claim 1, wherein:
said 50% coherence bandwidth is less than 250 kHz; and
said allocated channel bandwidth is less than 500 kHz.
3. A method in accordance with clam 1, wherein:
said data stream has a data rate of no more than about 1 Mbps.
4. A method in accordance with claim 1, wherein:
said COFDM comprises an 80 tone COFDM scheme.
5. A method in accordance with claim 1, wherein:
said COFDM comprises a COFDM scheme having 4 kHz tone spacing.
6. A method in accordance with claim 1, wherein:
said COFDM comprises a COFDM scheme with an approximately 50 microsecond cyclic prefix guard interval.
7. A method in accordance with claim 1, wherein:
said COFDM scheme comprises a COFDM scheme having a continuous in-frequency pseudo-random pilot symbol for channel estimation and timing.
8. A method in accordance with claim 1, further comprising:
forward error correction coding of said digital data using one of variable rate convolutional coding, low-density parity-check (LDPC) coding, Turbo coding, or concatenated coding of said digital data.
9. A method in accordance with claim 8, wherein:
said forward error correction coding of said digital data comprises rate \xbd convolutional coding with a constraint length of K=6.
10. A method in accordance with claim 8, wherein:
said forward error correction coding of said digital data comprises rate \xbe punctured convolutional coding with a constraint length of K=6.
11. A method in accordance with claim 8, further comprising:
block interleaving of said convolutional coded digital data.
12. A method in accordance with claim 11, wherein:
said block interleaving has interleaving parameters (B, M) of B=10 and M=32.
13. A method in accordance with claim 12, further comprising:
modulating said digital data for communication to said stationary receiver using quadrature amplitude modulation (QAM).
14. A method in accordance with claim 13, wherein:
said QAM comprises rate \xbd coded 16-QAM; and
a data rate of said data stream is approximately 487 kbps.
15. A method in accordance with claim 13, wherein:
said QAM comprises rate \xbe coded 16-QAM; and
a data rate of said data stream is approximately 740 kbps.
16. A method in accordance with claim 13, further comprising:
Gray coded mapping of interleaved output bits to QAM symbols.
17. A method in accordance with claim 11, wherein:
said block interleaving has interleaving parameters (B, M) of B=15 and M=32.
18. A method in accordance with claim 17, further comprising:
modulating said digital data for communication to said stationary receiver using quadrature amplitude modulation (QAM).
19. A method in accordance with claim 18, wherein:
said QAM comprises rate \xbe coded 64-QAM; and
a data rate of said data stream is approximately 1.12 Mbps.
20. A method in accordance with claim 18, wherein:
said QAM comprises rate \xbd coded 64-QAM; and
a data rate of said data stream is approximately 740 kbps.
21. A method in accordance with claim 8, further comprising:
modulating said digital data for communication to said stationary receiver using Quadrature Phase Shift Keying (QPSK) modulation.
22. A method in accordance with claim 1, further comprising:
receiving satellite transmissions containing said digital data at one or more satellite downlink locations;
demodulating and decoding said received digital data prior to said encoding and modulating which produces said data stream for transmission to said stationary receiver via said terrestrial wireless link.
23. A method in accordance with claim 1, further comprising:
receiving said data stream at said stationary receiver;
demodulating and decoding said data stream to recover said digital data for use at said stationary receiver.
24. Apparatus for terrestrial broadcast of digital data to stationary receivers, comprising:
an encodermodulator for encoding and modulating digital data using coded orthogonal frequency division multiplexing (COFDM) to produce a data stream; and
a transmitter for communicating said data stream to a stationary receiver via a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%.
25. A system for terrestrial broadcast of digital data to stationary receivers, comprising:
an encodermodulator for encoding and modulating digital data using coded orthogonal frequency division multiplexing (COFDM) to produce a data stream;
a transmitter for transmitting said data stream;
a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%; and
a stationary receiver for receiving said data stream from said transmitter via said terrestrial wireless link.
26. A stationary receiver for receiving a data stream via a terrestrial wireless link, said receiver comprising:
a tuner for receiving a data stream via a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%, said data stream produced by encoding and modulating digital data using coded orthogonal frequency division multiplexing (COFDM);
a demodulator for demodulating said data stream to produce a demodulated data stream; and
a decoder for decoding said demodulated data stream to recover said digital data.
27. A method for receiving a data stream via a terrestrial wireless link, said method comprising:
receiving a data stream via a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%, said data stream produced by encoding and modulating digital data using coded orthogonal frequency division multiplexing (COFDM);
demodulatng said data stream to produce a demodulated data stream;
decoding said demodulated data stream to recover said digital data.
28. A data stream for carrying digital data via a terrestrial wireless link, said data stream comprising:
digital data that is encoded and modulated using coded orthogonal frequency division multiplexing (COFDM) to produce said data stream which is adapted for communication to a stationary receiver via a terrestrial wireless link having a ratio of (i) 50% coherence bandwidth to (ii) allocated channel bandwidth of not greater than 50%.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. In a network environment where messages relating to faults that occur in the network over time are stored as rows in a database having a finite amount of memory allocated for storing the messages, a fault message purge procedure, comprising:
expunging a predetermined number of the rows in the database at the end of a current period;
determining the predetermined number prior to beginning the step of expunging by:
determining a rate at which the messages are being stored in the database for the current period, a size of the rows in the database, the finite amount of memory allocated for storing the messages in the database, a period at which the computer code is executed, and a period of time for which information relating to the faults is to be retained in the database;
applying a purge script that specifies that the predetermined number of the rows to be expunged is 45,000 where the rate at which the messages are stored in the database is 15 per second, the size of the rows in the database is 1.5 kilobytes, the finite amount of memory allocated for storing the messages in the databases is 5 gigabytes, the period at which the computer code is executed is once per hour, and the period of time for which information relating to the faults is to be retained is 10 days, the purge script further specifying that when the rate at which the messages are stored in the database increases to 50 per second for the current period, then the predetermined number is increased to 1,500,000; and
counting each message saved and expunged from the memory during a time period, wherein the count of saved and expunged messages are utilized for performance analysis.
2. The procedure of claim 1 comprising maintaining a log file of all the messages saved to and expunged from the database.
3. The procedure of claim 1 comprising monitoring the expunging of the messages from the database to ensure that the expunging of the messages from the database functions properly.
4. The procedure of claim 3 further comprising re-executing the step of expunging if the expunging of the messages from the database does not function properly.
5. The procedure of claim 1 wherein the network comprises a telecommunications network.
6. The procedure of claim 5 wherein the memory contains an executable computer code for performing the expunging and further comprises a fault database.