Blockage mitigation techniques for information transmission

• US 7,298,696 B1
• Filed: 10/14/2004
• Issued: 11/20/2007
• Est. Priority Date: 10/14/2004
• Status: Expired due to Fees

• Current Assignee: William W. Wu
• Original Assignee: William W. Wu
• Inventors: Wu, William W.
• Primary Examiner(s): Pham; Chi
• Assistant Examiner(s): Chou; Albert T.
• Application Number:
  US10/963,527
• Time in Patent Office: 1,132 Days
• Field of Search: 370/216, 370/229, 370/311, 455/45, 455/67.3, 714/48, 714/790, 714/490, 714/748, 714/789, 375/224
• US Class Current: 370/229
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/02 by diversity reception
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/1803 Stop-and-wait protocols
• CPC Class Codes: H04L 1/20 using signal quality detector

Abstract

Transmission channel monitoring, detection, classification, and adaptation provide solutions to severe information blockage problems during transmission. Channel monitoring is achieved through two types of detection and re-transmission strategies. Channel detection is accomplished by means of counting the number of negative acknowledgements, which classifies the channel degradation level and determines which alternatives to be adapted in order to combat specific blockage phenomenon. Blockage level is first translated into and related to transmission link parameters in terms of total carrier power to noise ratios, from which the methods of bit rate reduction, modem density increasing, and higher encoding rate are brought forth. A blockage identifier and the optimal smearing technique are used. Frequency-diversity and space-diversity, a method for combating complete blockage and an adaptive programmable channel equalization technique independent of channel characteristics are described. A cascading technique is taught to improve significantly false- and miss-detection probabilities. Performance measures are established in terms of system efficiency and error probability for blockage mitigation with unequal terminal capabilities.

Claims

1. A blockage mitigation method for information transmission systems comprising:

detecting channels,

wherein the detecting channels comprises continuous counting of negative acknowledgements received at a transmitter during error detection and retransmission from a receiver;

partitioning or segmenting the counting,

wherein the partition or segmentation of the counting is arbitrary;

monitoring the channels,

wherein the monitoring channels comprises channel classification and identification,

adapting blockage mitigation for the channels;

wherein the adapting the blockage mitigation channels comprises selecting and switching the blockage mitigation; and

constructing and deriving the blockage mitigation,

wherein the construction and the derivation of the blockage mitigation measure, compare and evaluate systems performance criteria in terms of error probabilities and efficiencies for the systems comparison and evaluation, wherein the selecting and switching the blockage mitigation comprise measuring channel degradations due to blockage, wherein the measuring is performed in terms of total carrier power to noise density ratio.

2. The method of claim 1, wherein the selecting and switching the blockage mitigation further comprises compensating for channel degradation by reducing transmission bit rate dB by dB.

3. The method of claim 2, wherein the measuring is performed in terms of total carrier power to noise density ratios in a transmission link, regardless of system bandwidth, type of modems, or error codecs used.

4. The method of claim 3, further comprising maintaining a consistent level of communication quality through a constant required ratio of transmitting signal energy per bit to noise density.

5. The method of claim 4, wherein total carrier power is the parallel sum of transmitting and receiving antenna power.

6. The method of claim 1, wherein the selecting and switching the blockage mitigation further comprise measuring channel degradation due to blockage compensating by increasing or switching to higher bit per symbol densities of all modems in the transmission link in terms of total carrier power to noise ratio.

7. The method of claim 6, further comprising maintaining consistent system bandwidth, error encoding rate, message bit rate, and level of communication quality.

8. The method of claim 1, wherein the selecting and switching strategies comprise measuring, in terms of total carrier power to noise ratio, the amount of decrease in carrier power due to blockage compensating by increasing or switching to higher rates error correcting codecs in a transmission link.

9. The method of claim 8, further comprising maintaining original modems, message bit rates, system bandwidth, and level of communication quality.

10. The method of claim 1, wherein the selecting and switching strategies comprise one or more of the following steps:

measuring channel degradations due to blockage compensating by reducing transmission bit rate dB by dB,

measuring channel degradation due to blockage compensating by increasing or switching to higher bit per symbol density modems in the transmission link, and

measuring, in terms of total carrier power to noise ratio, the amount of decrease in carrier power due to blockage compensating by increasing or switching to higher rates error correcting codecs in a transmission link.

17. The method of claim 1, wherein if transmission blockage is complete, utilizing a stop-and-wait method by counting excessive number of negative acknowledgements, and resuming transmission with a next positive acknowledgement declared by the detection and re-transmission scheme.

11. A blockage mitigation method for information transmission systems comprising:

detecting channels,

wherein the detecting channels comprises continuous counting of negative acknowledgements received at a transmitter during error detection and retransmission from a receiver;

partitioning or segmenting the counting,

wherein the partition or segmentation of the counting is arbitrary;

monitoring the channels,

wherein the monitoring channels comprises channel classification and identification,

adapting blockage mitigation for the channels;

wherein the adapting the blockage mitigation channels comprises selecting and switching the blockage mitigation; and

constructing and deriving the blockage mitigation,

wherein the construction and the derivation of the blockage mitigation measure, compare and evaluate systems performance criteria in terms of error probabilities and efficiencies for the systems comparison and evaluation,

further comprising;

identifying blockage through two non-identical modems,

providing an adaptive cancellator, wherein the adaptive cancellator comprises;

a correlator for multiplication, sampling, and filtering,

a transversal filter, and

a differential adaptor, wherein the differential adaptor comprises a level

detector and a low pass filter,

providing an arithmetic unit.

12. The method of claim 11, further comprising providing a frequency-diversity improvement method for minimizing aliasing effect to minimizing blockage comprising systematic application of existing and/or new combinatorial set parameters.

13. The method of claim 11, further comprising providing a space-diversity improvement method for elimination of sidelobes for compacting antenna locations comprising the automatic and systematic applications of existing and/or new combinatorial sets.

14. The method of claim 11, further comprising providing a time smearing method comprising:

non-binary sequence generation,

implementation comprising frequency dividers, time delay units, and an assembler at

a receiver, and

automatic and systematic applications of existing and/or new combinatorial sets.

15. The method of claim 14, further comprising set generation.

16. The method of claim 11, further comprising adaptive programmable channel equalization wider known or unknown transmission channel conditions, comprising sampling, sequence adaptation, inverse matching, and channel equalization.

18. The method of claim 11, further comprising utilizing both continuous and stop-and-wait methods, wherein the continuous and stop-and-wait methods further comprise using a single error correcting encoder, a replica of the encoder, and a single or a bank of modulo-2 adders.

19. The method of claim 18, wherein the continuous and stop-and-wait methods further comprise using a (31, 21, 5) code derivation, encoder design configuration, test vector generation, and wherein both block codes and convolutional codes are applicable for the detection and re-transmission process.

20. The method of claim 11, further comprising utilizing a cascading approach under blockage or low signal-to-noise ratio transmission channel conditions for bit, symbol, and frame acquisition and synchronization for creating significantly lower false- and miss-detection probabilities.

21. A communication blockage mitigation method comprising:

acquiring bit, carrier and frame signals,

detecting sequences in the frame signals,

calculating sequence lengths n, channel bit error rate p, tolerable error t_E and number

of frame cascading times,

detecting channel signal transmission characteristics,

detecting signal transmission blockages,

classifying the signal transmission blockages as short term, mid term, long term or complete, and

providing blockage mitigation alternatives which differ according to the classification of short, mid and long term or complete transmission blockage,

adapting to the blockages by switching between mitigation alternatives according to the classifying.

22. The method of claim 21, further comprising detecting errors in the signals at a receiving terminal, when no error is detected transmitting positive acknowledgment from a receiving terminal, and otherwise sending negative acknowledgments.

23. The method of claim 22, wherein for blockages of less than Ω

, sending negative acknowledgment, classifying the blockages as short term, and wherein the mitigation technique further comprises reducing transmission rate, increasing modem density or increasing encoding rate.

24. The method of claim 22, wherein for blockages of more than Ω

, but less than Φ

, sending negative acknowledgment, classifying the blockages as mid term, and wherein the mitigation technique further comprises using two modems and an adaptive cancellator, identifying channel blockages and optimizing time smearing with unique sequence generation and characteristics.

25. The method of claim 22, wherein for blockages of more than Φ

, but less than x, sending negative acknowledgment, classifying the blockages as long term, and wherein the mitigation technique further comprises minimizing sidelobes by precisely locating antennas, minimizing aliasing by assigning frequencies or adaptively equalizing programmable channels.

26. The method of claim 22, wherein for blockages greater than x, stopping transmitting until positive acknowledgment is received from the receiver, then resuming transmission.

27. A method of measuring information transmission characteristics comprising establishing methods of performance measure criteria for utilization of comparison and evaluation applicable to an error detection system in information transmission systems where transmitter and receiver capabilities are different, such as to and from base stations and handheld units and to and from base stations and communication statellites, wherein the establishing further comprises calculating values of detection probabilities of sequence length, and channel bit error rate, and number of tolerable errors in the transmission system acquiring signals from the transmission systems in bit, carrier and frame or sequence levels classifying transmission system blockages according to automatic repeat requests in the acquired signals, or positive and negative act as short, mid or long term blockages or complete blockages according to the calculated values.

28. The method of claim 27, wherein for blockages of less than Ω

, sending negative acknowledgment, classifying the blockages as short term, and wherein the mitigation technique further comprises reducing transmission rate, increasing modem density or increasing encoding rate, wherein for blockages of more than Ω

, but less than Φ

, sending negative acknowledgment, classifying the blockages as mid term, and wherein the mitigation technique further comprises using two modems and an adaptive cancellator, identifying channel blockages and optimizing time smearing with unique sequence generation and characteristics, wherein for blockages of more than Φ

, but less than x, sending negative acknowledgment, classifying the blockages as long term, and wherein the mitigation technique further comprises minimizing sidelobes by precisely locating antennas, minimizing aliasing by assigning frequencies or adaptively equalizing programmable channels, and wherein for blockages greater than x, stopping transmitting until positive acknowledgment is received from the receiver, then resuming transmission.