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EP-3599792-B1 - DISTRIBUTED ANTENNA SYSTEM FOR WIRELESS NETWORK SYSTEMS

EP3599792B1EP 3599792 B1EP3599792 B1EP 3599792B1EP-3599792-B1

Inventors

  • CLEARY, DENNIS, M.
  • HANSON, VAN
  • EISENWINTER, STEFAN
  • SCHMALISCH, MATHIAS
  • KUMMETZ, THOMAS
  • MCALLISTER, DONALD, R.
  • PAGANO, CARMINE
  • YAN, HONGJU

Dates

Publication Date
20260506
Application Date
20100324

Claims (13)

  1. A distributed antenna system, DAS, comprising: a master unit (42) configured for communicatively coupling to at least one base station (24); and at least one remote unit (44) comprising a local antenna (62) locatable remotely to the master unit (42) and configured to be communicatively coupled to the master unit (42), wherein the master unit (42) includes: a first wideband analog-to-digital converter (84) configured to generate a first wideband digitized signal from a first analog signal received over a first downlink RF band of an RF spectrum from the at least one base station (24) by digitizing the entire first downlink RF band, the first downlink RF band including a first plurality of channels, and a second wideband analog-to-digital converter (84) configured to generate a second wideband digitized signal from a second analog signal received over a second downlink RF band of the RF spectrum received from the at least one base station (24) by digitizing the entire second downlink RF band, the second downlink RF band including a second plurality of channels, wherein the second downlink RF band is distinct from the first downlink RF band, wherein the first wideband digitized signal has a first data rate, wherein the second wideband digitized signal has a second data rate; a first resampler (86) configured to generate a first resampled digital signal from the first wideband digitized signal, wherein the first resampled digital signal (i) has a third data rate synchronized to an optical network bit rate, and (ii) corresponds to a first downlink signal in the first downlink RF band of the RF spectrum received from the at least one base station (24); a second resampler (86) configured to generate a second resampled digital signal from the second wideband digitized signal, wherein the second resampled digital signal (i) has a fourth data rate that is synchronized to the optical network bit rate, and (ii) corresponds to a second downlink signal in the second downlink RF band of the RF spectrum received from the at least one base station (24); and a formatter (106) configured to block the first resampled digital signal and the second resampled digital signal into time division multiplexed frames for transport that is transmitted in a downstream direction to the at least one remote unit (44), wherein the at least one remote unit (44) is configured to communicate, via the local antenna (62), at least one signal to at least one subscriber unit (30) derived from the time division multiplexed frames, in which the at least one signal includes data that corresponds to the first resampled digital signal and the second resampled digital signal.
  2. The DAS of claim 1, wherein the first resampler (86) is configured to provide the first resampled digital signal by digitally down-converting the first wideband digitized signal, wherein the second resampler (86) is configured to provide the second resampled digital signal by digitally down-converting the second wideband digitized signal.
  3. The DAS of claim 1, wherein the formatter (106) is configured to serialize the time division multiplexed frames to form serial data for transport on a communication medium.
  4. The DAS of claim 3, wherein the formatter (106) is configured to reduce redundant digital information in the serial data by applying data compression to the serial data.
  5. The DAS of claim 1, wherein the master unit (42) further comprises an Ethernet switch (78) and the formatter (106) is configured to block an Ethernet signal with the first resampled digital signal and the second resampled digital signal into the time division multiplexed frames for transport.
  6. The DAS of claim 1, further comprising a controller (52) configured to automatically control filter configurations in the first resampler (86) and the second resampler (86) based on detected active channels in the RF spectrum.
  7. The DAS of claim 1, further comprising: a third resampler (92) included in the master unit (42) configured to generate a first reverse path digitized signal from a first reverse path digital signal received from the at least one remote unit (44), the first reverse path digitized signal including first information corresponding to the first downlink RF band of the RF spectrum; and a fourth resampler (92) included in the master unit (42) configured to generate a second reverse path digitized signal from a second reverse path digital signal received from the at least one remote unit (44), the second reverse path digitized signal including second information corresponding to the second downlink RF band of the RF spectrum, wherein the RF spectrum is configured to generate the first reverse path digital signal and the second reverse path digital signal from at least one reverse path transport frame received from a communication medium.
  8. The DAS of claim 7, wherein the third resampler (92) is configured to generate the first reverse path digitized signal by digitally up-converting the first reverse path digital signal, wherein the fourth resampler (92) is configured to generate the second reverse path digitized signal by digitally up-converting the second reverse path digital signal.
  9. The DAS of claim 8, further comprising: a digital-to-analog converter (94) configured to generate an analog RF signal from the first reverse path digitized signal; and an up-converter (96) configured to up-convert the analog RF signal to a frequency in the first downlink RF band of the RF spectrum.
  10. The DAS of claim 1, wherein the at least one remote unit (44) includes a wideband digital-to-analog converter (154), a fifth resampler (152), and a second formatter (132), wherein: the second formatter (132) being configured to recover the first resampled digital signal and the second resampled digital signal from the time division multiplexed frames, the fifth resampler (152) being configured to generate the first wideband digitized signal of the first downlink RF band of the RF spectrum from the first resampled digital signal and the second wideband digitized signal of the second downlink RF band of the RF spectrum from the second resampled digital signal, wherein the first wideband digitized signal of the first downlink RF band of the RF spectrum and the second wideband digitized signal of the second downlink RF band of the RF spectrum generated by the fifth resampler (152) have different data rates than the first resampled digital signal and the second resampled digital signal, and the wideband digital-to-analog converter (154) is configured to generate RF signals from the first wideband digitized signal and the second wideband digitized signal.
  11. The DAS of claim 10, wherein the first resampler (86) is configured to generate the first resampled digital signal from a first digitized version of the first downlink RF band and to generate the second resampled digital signal from a second digitized version of the second downlink RF band.
  12. A method comprising: generating, at a master unit (42) of a distributed antenna system, DAS, a first wideband digitized version of a first analog signal received over a first downlink RF band of an RF spectrum from at least one base station (24) communicatively coupled to the master unit (42) by digitizing the entire first downlink RF band, the first downlink RF band including a first plurality of channels, the first wideband digitized version having a first data rate; generating, at the master unit (42), a first resampled digital signal from the first wideband digitized version of the first downlink RF band of the RF spectrum from the at least one base station (24) communicatively coupled to the master unit (42), the first resampled digital signal having a third data rate that is synchronized to an optical network bit rate; generating, at the master unit (42), a second wideband digitized version of a second analog signal received over a second downlink RF band of the RF spectrum received from the at least one base station (24) communicatively coupled to the master unit (42), the second downlink RF band distinct from the first downlink RF band and including a second plurality of channels, the second wideband digitized version having a second data rate; generating, at the master unit (42), a second resampled digital signal from the second wideband digitized version of the second downlink RF band of the RF spectrum from the at least one base station (24) communicatively coupled to the master unit (42), the second resampled digital signal having a fourth data rate that is synchronized to the optical network bit rate; blocking the first resampled digital signal and the second resampled digital signal into time division multiplexed frames for transport; transmitting the time division multiplexed frames with the first resampled digital signal and the second resampled digital signal in a downstream direction to at least one remote unit (44) of the DAS located remotely from the master unit (42); and wirelessly communicating at least one signal derived from the time division multiplexed frames and including data that corresponds to the first resampled digital signal and the second resampled digital signal to at least one subscriber unit (30) from the at least one remote unit (44).
  13. The method of claim 12, wherein generating the first resampled digital signal includes down converting the first wideband digitized version of the first downlink RF band of the RF spectrum, wherein generating the second resampled digital signal includes down converting the second wideband digitized version of the second downlink RF band of the RF spectrum.

Description

FIELD OF THE INVENTION The present invention is directed to wireless transceiver systems for use in wireless communication systems, and specifically is directed to a distributed antenna system for the wireless transceiver system. BACKGROUND OF THE INVENTION Contemporary cellular phone systems and broadband wireless metropolitan networks 20, as shown in FIG. 1, are generally divided into a number of cells 22 distributed in a pattern to preclude co-channel interferences and provide coverage of mobile and fixed subscriber units operating within the service area of the system. Each cell 22 includes a base station 24 that employs radio frequency (RF) transceiver equipment, antennas 26, and wire line 28 communication equipment. Mobile/fixed subscriber units 30 within the geographic area of the cell site use RF transceiver equipment to communicate with RF transceivers within the base station 24. The base station 24 relays voice and data traffic to/from the subscriber mobile units or devices (e.g. a phone) 30 and to/from a Mobile Telephone Switching Office 32 or Access Service Gateway which in turn are connected to a central network such as the public switched telephone network (PSTN) 34 or packet switched networks such as the Internet, for example. To improve the capacity of a base station 24 to handle more mobile users 30, cells 22 may be divided into sectors 38 or are further subdivided into smaller cells with the base station 24 being replaced with lower cost, reduced capability micro or pico cells 36. In some configurations, distributed antenna systems (DAS) may be employed to optimize the RF distribution in larger cells in order to increase capacity at an even lower cost than with pico and/or micro cells 36. These approaches permit the reuse of a limited number of expensive RF channels without incurring the costs of one or more complete base stations 24. Further, these techniques may also be used to extend coverage to areas within the cell site where RF propagation may be limited by obstruction, such as in buildings and tunnels, or to areas where the amount of traffic (revenue) does not justify the investment required for a complete base station 24. Distributed antenna systems allow the RF coverage to be adapted to the specific environment in a homogeneous way to assist in reducing the amount of introduced interference. In addition, the amount of extra traffic is kept low as only existing cells are distributed and no hand-off between cells is required. In order to reduce the costs associated with the development of their communication systems, multiple service providers often locate their base stations 24 at the same geographical point. The providers can then share such items as antennas, antenna towers, primary power drops, land costs, and regulatory costs. These service providers may employ multiple RF bands, multiple channels within the same RF band and multiple air interface standards (e.g. CDMA, UMTS, TDMA, and WiMax). The cost for each service provider to extend coverage to increase capacity by deploying their own micro/pico cells and/or distributed antennas may be quite high. Further in some areas where RF propagation is poor, such as sporting venues or shopping malls, the owners of such facilities may not permit the installation of such equipment by multiple service providers for aesthetic reasons or because of space limitations. Therefore, there is a need in the art for a system that maybe used by multiple service providers to extend coverage and increase capacity. US patent no. 6.785,558 B1 discloses a method for transporting wireless communication signals between a base station hotel and remote cell sites with separately digitized RF carrier signals. SUMMARY OF THE INVENTION The invention is as specified in the claims. Embodiments of the present invention provide a distributed antenna system ("DAS") that can be used by multiple wireless service providers to increase the capacity and the coverage area of multiple communication systems without the need for each provider to incur the cost of deploying one or more micro/pico cells or DAS. To that end, embodiments of the invention are capable of simultaneously distributing signals between collocated base stations, operated by multiple service providers, and remote or fixed subscriber units. The signals may encompass multiple RF bands, multiple channels within those bands, and multiple air interface standards. Embodiments of the invention may provide to wireless service providers a solution that, when compared to micro cells or pico cells, allows them to cover certain environments at a lower cost with similar or even improved signal quality. Some embodiments of the distributed antenna system include a system controller and a master unit communicating with at least one of a plurality of base stations. Remote units communicate over a high data rate media with the master unit and/or another upstream or downstream Remote unit. In some embodiments, the remote