Transport data reduction for DAS systems
A distributed antenna system having improved data transmission features incorporates endpoints of the system, which are coupled together by serial data link. At the endpoints, processing may occur utilizing processing circuitry to determine similarities between multiple signal streams. If the streams are similar, the data sent over the serial digital link is reduced by only sending one of the representative signals. In an alternative embodiment of the invention, the difference between the signals might be sent as well. Alternatively, all signals might be sent, but may be compressed with compression circuitry before the signals are transmitted over the serial link. At the endpoint of the system, the signals are reconstructed for further processing and transmission.
1. An endpoint element of a distributed antenna system having multiple endpoints coupled together by serial data links, comprising:
processing circuitry configured for processing a plurality of digital signals at one endpoint for conditioning the signals;
circuitry configured for evaluating similarities between at least first and second signals of the digital signals and forming a similarity value indicative of similarities between the first and second signals;
threshold circuitry configured for comparing the similarity value to a threshold value;
signal transmission circuitry coupled with the threshold circuitry and configured for only transmitting the first digital signal as a representative signal for both the first and second digital signals to another endpoint over the serial data link if the similarity value compares favorably to the threshold value.
2. The endpoint element of claim 1 wherein the circuitry configured for evaluating similarities between at least first and second signals includes correlation circuitry configured for correlating the first and second signals of the digital signals and forming a correlation value indicative of similarities between the first and second signals.
3. The endpoint element of claim 1 wherein signal transmission circuitry is configured for transmitting the first and second digital signals to another endpoint over a serial data link if the similarity value does not compare favorably to the threshold value.
4. The endpoint element of claim 1 wherein the circuitry configured for evaluating similarities between at least first and second signals includes circuitry configured for reviewing an error signal associated with the processing of the digital signals and forming a difference value indicative of similarities between the first and second signals.
5. The endpoint element of claim 1 further comprising memory circuitry for storing other digital data, the transmission circuitry configured for sending the other digital data from the memory circuitry in the place of the second digital signals when the correlation value is above the threshold.
6. The endpoint element of claim 1 wherein the processing circuitry is configured for processing first and second digital signals that are one of MIMO signals or diversity signals.
7. The endpoint element of claim 1 wherein the threshold circuitry is further configured for generating flag information that is indicative that the similarity value compares favorably to the threshold value, the signal transmission circuitry further configured for transmitting the flag information when the correlation value is above the threshold.
8. The endpoint element of claim 1 wherein the processing circuitry is configured for transmitting, over the serial data link, processing information regarding the processing of the plurality of digital signals.
9. The endpoint element of claim 1 wherein the processing circuitry is configured for adaptively filtering the signals using an adaptive filter that uses a minimization of error algorithm.