Channel encoding and decoding method and apparatus

• US 6,735,188 B1
• Filed: 09/28/1999
• Issued: 05/11/2004
• Est. Priority Date: 08/27/1999
• Status: Expired due to Fees

• Current Assignee: Tachyon, Inc. (Tachyon Networks Incorporated)
• Original Assignee: Tachyon, Inc. (Tachyon Networks Incorporated)
• Inventors: Becker, Donald W., Leigh, William E. L.
• Primary Examiner(s): HSU, ALPUS
• Application Number:
  US09/407,644
• Time in Patent Office: 1,687 Days
• Field of Search: 370/329, 370/335, 370/341, 370/342, 370/350, 370/441, 370/445, 370/447, 370/461, 370/462, 370/503, 375/130, 375/140, 375/141, 375/142, 375/145, 375/146, 375/147, 375/149, 375/150, 375/279, 375/280, 375/308, 375/340, 375/343, 375/356, 455/450, 455/451, 455/452, 455/507, 455/509, 455/511, 455/515, 455/517, 455/522
• US Class Current: 370/342
• CPC Class Codes: G06F 11/0757 by exceeding a time limit, i.e. time-out, e.g. watchdogs
• CPC Class Codes: G06F 11/1441 Resetting or repowering
• CPC Class Codes: H03J 7/065 the counter or frequency divider being used in a phase locked loop
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/18582 Arrangements for data linking, i.e. for data framing, for error recovery, for multiple access
• CPC Class Codes: H04L 27/22 Demodulator circuits; Receiver circuits
• CPC Class Codes: H04L 7/0029 interpolation of received data signal
• CPC Class Codes: H04L 7/04 Speed or phase control by synchronisation signals H04L7/0075 takes precedence
• CPC Class Codes: H04N 21/235 Processing of additional data, e.g. scrambling of additional data or processing content descriptors
• CPC Class Codes: H04N 21/23614 Multiplexing of additional data and video streams arrangements for simultaneous broadcast of plural pieces of information H04H20/28
• CPC Class Codes: H04N 21/2385 Channel allocation H04N21/266 takes precedence; Bandwidth allocation H04N21/24 takes precedence ; allocation of channels according to the instantaneous demands of the users in time-division multiplex systems H04J3/1682; admission control, resource allocation in open networks H04L12/5692; arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896; negotiating bandwidth in wireless networks H04W28/16
• CPC Class Codes: H04N 21/4348 Demultiplexing of additional data and video streams
• CPC Class Codes: H04N 21/435 Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream
• CPC Class Codes: H04N 21/4381 Recovering the multiplex stream from a specific network, e.g. recovering MPEG packets from ATM cells transmission of MPEG streams over ATM H04L12/5601
• CPC Class Codes: H04N 21/6143 involving transmission via a satellite
• CPC Class Codes: H04N 21/64322 IP
• CPC Class Codes: H04W 56/0085 detecting a given structure in the signal

Abstract

A method and apparatus related to a communication system in which a plurality of remote units encode data bursts using a predetermined codeword set and transmit the encoded data bursts to a hub station over a multiple-access channel. When the hub station receives a data burst from one of the remote units, the hub station demodulates the received data burst and correlates the received data burst with each codeword within the predetermined codeword set to determine which codeword has the maximum correlation. The hub station uses the correlation to derive a timing synchronization signal and/or a carrier frequency adjustment signal to be sent back to the remote unit. The signals provide information to the remote unit to synchronize its timing or adjust its carrier frequency for transmitting subsequent data bursts. The hub station may also use the correlation to estimate a signal-to-noise ratio.

Claims

1. In a communication system in which a plurality of remote units transmit data to a hub station, a method of communicating comprising:

receiving a data burst from a remote unit, the data burst being encoded using a predetermined codeword set;

sampling the data burst received by the hub station at a plurality of different timing offsets;

correlating the data burst received by the hub station with the codeword set to find a codeword with maximum correlation;

correlating the codeword having the maximum correlation with one or more of the plurality of different timing offset samples;

deriving a timing synchronization signal, the timing synchronization signal providing information to the remote unit to synchronize its timing for transmitting subsequent data bursts; and

sending the timing synchronization signal to the remote unit.

2. The method of claim 1, further comprising:

encoding a data burst at a remote unit using a predetermined codeword set; and

transmitting the encoded data burst from the remote unit to the hub station over a multiple-access channel.

3. The method of claim 1, further comprising sending the timing synchronization signal back to the remote unit after a plurality of data bursts from the remote unit have been received and processed by the hub station, the timing synchronization signal being based on a plurality of correlations of the data bursts with the codeword set.

4. The method of claim 1, further comprising deriving a carrier frequency adjustment signal to be sent back to the remote unit, the carrier frequency adjustment signal providing information to the remote unit to adjust a carrier frequency for transmitting subsequent data bursts.

5. The method of claim 4, further comprising rotating a carrier phase of the data burst to create three separate frequency sample sequences comprising:

a slow frequency sample sequence;

a fast frequency sample sequence; and

an on-frequency sample sequence.

6. The method of claim 4, further comprising sending the carrier frequency adjustment signal back to the remote unit after a plurality of data bursts from the remote unit have been received and processed by the hub station, the carrier frequency adjustment signal being based on a plurality of correlations of the data bursts with the codeword set.

7. The method of claim 1, wherein the plurality of different timing offsets comprises an early offset resample, an on-time sample and a late offset sample.

8. The method of claim 1, wherein the data burst is encoded using a predetermined, non-coherent QPSK codeword set.

9. The method of claim 8, wherein the QPSK codeword set comprises 64 9-symbol codewords in which each codeword has equal noise immunity.

10. The method of claim 8, further comprising demodulating the encoded data burst using noncoherent demodulation.

11. The method of claim 1, wherein the data burst does not have a preamble.

12. In a communication system in which a plurality of remote units transmit data to a hub station, a method of communicating comprising:

receiving a data burst from a remote unit, the data burst encoded using a predetermined codeword set;

sampling the data burst received by the hub station at a plurality of different timing offsets;

correlating the data burst received by the hub station with the codeword set to find a codeword with maximum correlation;

correlating the codeword having the maximum correlation with the plurality of different timing offset samples;

deriving a carrier frequency adjustment signal, the carrier frequency adjustment signal providing information to the remote unit to adjust a carrier frequency for transmitting subsequent data bursts; and

sending the carrier frequency adjustment signal to the remote unit.

13. In a system in which multiple remote units compete for limited communication resources to access a hub station, a hub station comprising:

a receiver adapted to receive a data burst from a remote unit;

a matched filter adapted to sample the received data burst at a plurality of different timing offsets;

a microprocessor adapted to correlate the received data burst with a plurality of codewords from a codeword set to find a codeword with maximum correlation; and

a timing synchronization circuit adapted to send a signal back to the remote unit, the signal providing information to the remote unit to synchronize its timing for transmitting subsequent data bursts.

14. The hub station of claim 13, further comprising a carrier frequency adjustment circuit adapted to correlate the codeword having the maximum correlation found by the microprocessor with a plurality of different carrier frequency offset samples, the carrier frequency adjustment circuit being adapted to send a carrier frequency adjustment signal to the remote unit, the carrier frequency adjustment signal providing information to the remote unit to adjust a carrier frequency for transmitting subsequent data bursts.