Method and system for improving uplink performance

Abstract

Distributed antenna systems and more particularly to methods and systems for improving uplink communications are disclosed. In one embodiment, Aggregation Point Noise Blocking provides for blocking or filtering of the noise contributed by one or more of the branches coupled to an aggregation point that are not carrying the signal from a particular terminal. Signal activity from a given terminal on a particular branch can be identified and that information can be used to selectively block or filter the signal noise contributed by the other branches to an aggregation point. The selective blocking or filtering can also include an attenuation function to attenuate the signal and provide dynamic range smoothing.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This is a continuation of U.S. patent application Ser. No. 12 / 033,226, filed Feb. 19, 2008, which claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application No. 60 / 890,587, filed Feb. 19, 2007, both of which applications are hereby incorporated by reference in their entireties.[0002]This application is related to U.S. application Ser. No. 12 / 033,252, filed on Feb. 19, 2008, entitled “METHOD AND SYSTEM FOR IMPROVING UPLINK PERFORMANCE”, which is hereby incorporated by reference in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH[0003]Not ApplicableREFERENCE TO MICROFICHE APPENDIX[0004]Not ApplicableBACKGROUND[0005]1. Technical Field of the Invention[0006]The present invention is directed to improvements for distributed antenna systems and more particularly to methods and systems for improving uplink communications.[0007]2. Description of the Prior Art[0008]Distributed Antenna Systems (DAS) are used to ...

AI Technical Summary

Benefits of technology

[0027]One way is to increase the spacing between the antennas, and thus decrease the number of antennas required to cover a given area. The increase in Path Losses, can be offset by the decrease in uplink NF to maintain the Link Budget and reduce the cost of the DAS.

[0028]The second way is to increase the total area that can be covered by a DAS system connected to a single receiver / transmitter. This follows from the fact that adding another branch to the DAS (to extend the coverage area) increases the NF of the DAS. However, if the NF of each branch is improved, the cumulative NF decreases and more branches can be added. Theoretically, any improvement of 3 dB in the NF of a single branch would allow for a doubling of the coverage area.

[0029]The benefits of increasing the coverage area of a DAS include: 1) For networking technologies that support sectorization (such as cellular networks), the ability to extend the coverage area associated with a single sector means that potentially less base-station equipment is required to cover a given area; 2) Some networking technologies, such as certain types of medical telemetry, do not support sectorization, meaning in essence that the whole coverage area must be connected to a single receiver / transmitter. In this case, the ability to increase the coverage area associated with a single receiver directly impacts the total coverage area in which this wireless service can be made available.

[0031]A method that would allow a DAS to “smooth” out the differences between strong and weak uplink signals would help in overcoming the dynamic range limitations of the receiver and thus would allow for increasing the antenna spacing and the associated positive financial impact. Thus, improving the Uplink Performance of a DAS, and more particularly, its Dynamic Range behavior can provide tangible economical and functional benefits to a DAS.

[0032]In accordance with the invention, the SNR at an aggregation point can be improved by blocking or filtering the noise attributed to one or more of the branches that do not carry the signal. This can be accomplished by detecting whether there is signal activity from a particular terminal on any branch connected to an aggregation point and selectively blocking or filtering the input noise to be aggregated from one or more of the other branches connected to the aggregation point.

[0033]In accordance with the invention, the SNR of the uplink path can be improved by regenerating the signal at one or more points along the uplink path. This can be accomplished by using an Uplink Regeneration Block (URB) which can demodulate the signal and then re-modulate the signal at a very high SNR. While URBs can be located anywhere in the uplink signal path, there is a cost / performance tradeoff that can be used as a guide for determining the location and how many URBs are used. To reduce costs, the URBs can be located upstream of aggregation points in order to reduce the number of URB's used (lower cost) and improve the SNR of the aggregated signal, but to improve performance, the URBs should be located as far downstream as possible before the SNR has been deteriorated by the aggregation points (however many more URBs may be required).

Problems solved by technology

In another way, the level of the signal remains constant or is increased, but the noise level increases even more.

As a result, aggregating multiple uplink paths increases the noise level and therefore reduces the SNR of the uplink signal.

In some cases, the environment may exhibit a higher level of noise in the specific frequency range in which the signal of interest operates.

However, there is a cost penalty associated with doing this.

An amplifier however, introduces a minimal noise level which is typically higher than the Thermal noise level and increases commensurate with the gain of the amplifier, and thereby will always decrease the SNR of the signal.

The signal level does not change, while the noise level increases, and therefore the SNR is impaired.

Since there is no way to limit the strongest signal, the only available way is to ensure the weakest signal is not too weak As explained above, this can be accomplished by decreasing the distance between the antennas, with the associated negative financial impact.

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