DISTRIBUTED ANTENNA SYSTEM FOR MIMO TECHNOLOGIES

摘要

The invention is directed to a method and system for supporting MIMO technologies which can require the transport of multiple spatial streams on a traditional Distributed Antenna System (DAS). According to the invention, at one end of the DAS, each spatial stream is shifted in frequency to a pre-assigned band (such as a band at a frequency lower than the native frequency) that does not overlap the band assigned to other spatial streams (or the band of any other services being carried by the DAS). Each of the spatial streams can be combined and transmitted as a combined signal over a common coaxial cable. At the other “end” of the DAS, the different streams are shifted back to their original (overlapping) frequencies but retain their individual “identities” by being radiated through physically separate antenna elements.

主权项

1. A distributed antenna system for distributing MIMO signals for at least one MIMO service in a distributed antenna system (DAS), comprising:
a radio interface unit configured to:
receive a plurality of downlink RF spatial MIMO streams in a native downlink frequency band for at least one MIMO service from at least one base station;frequency shift at least one of the plurality of downlink RF spatial MIMO streams from the native downlink frequency band to at least one non-native, non-overlapping downlink RF spatial MIMO stream; andcombine each of the plurality of downlink RF spatial MIMO streams into a combined downlink RF MIMO signal onto an electrical downlink; a base unit configured to:
receive the combined downlink RF MIMO signal over the electrical downlink; andconvert the combined downlink RF MIMO signal into a combined downlink optical MIMO signal; andseparate the combined downlink optical MIMO signal into a plurality of combined downlink optical MIMO signals; a plurality of downlink media converter components each configured to:
receive a combined downlink optical MIMO signal among the plurality of combined downlink optical MIMO signals; andconvert the received combined downlink optical MIMO signal into a combined downlink RF MIMO signal among a plurality of combined downlink RF MIMO signals; and a plurality of antenna units, each antenna unit among the plurality of antenna units configured to:
separate a combined downlink RF MIMO signal among the plurality of combined downlink RF MIMO signals into separated downlink RF spatial MIMO streams;frequency shift the at least one non-native, non-overlapping downlink RF spatial MIMO stream from at least one of the separated downlink RF spatial MIMO streams to the native downlink frequency band;transmit a first downlink RF MIMO spatial stream among the separated downlink RF spatial MIMO streams in the native downlink frequency band to a first downlink MIMO antenna to be transmitted wirelessly; andtransmit a second downlink RF MIMO spatial stream among the separated downlink RF spatial MIMO streams in the native downlink frequency band to a second downlink MIMO antenna to be transmitted wirelessly; each antenna unit among the plurality of antenna units is further configured to:
receive a first uplink RF spatial MIMO stream for at least a MIMO service over a first uplink MIMO antenna;receive a second uplink RF spatial MIMO stream for at least a MIMO service over a second uplink MIMO antenna;frequency shift at least one of the first uplink RF spatial MIMO stream and the second uplink RF spatial MIMO stream from a native uplink frequency band to at least one non-native, non-overlapping uplink RF spatial MIMO stream; andcombine the first uplink RF spatial MIMO stream and the second uplink RF spatial MIMO stream into a combined uplink RF MIMO stream; and a plurality of uplink media converter components, each uplink media converter among the plurality of uplink media converter components configured to:
receive a combined uplink RF MIMO stream among a plurality of combined uplink RF MIMO streams from an antenna unit among the plurality of antenna units over a respective optical fiber link; andconvert the combined uplink RF MIMO stream into a combined uplink optical MIMO signal among a plurality of combined uplink optical MIMO signals; and the base unit further configured to:
combine the plurality of combined uplink optical MIMO signals into a combined uplink optical MIMO signal;convert the combined uplink optical MIMO signal into a combined downlink RF MIMO signal; anddistribute the combined uplink RF MIMO signal over an electrical uplink to the radio interface unit; and the radio interface unit further configured to:
receive the combined uplink RF MIMO signal over the electrical uplink;separate the combined uplink RF MIMO signal from the base unit into a plurality of combined first uplink RF spatial MIMO streams and a plurality of combined second uplink RF spatial MIMO streams; andfrequency shift the at least one non-native, non-overlapping uplink RF spatial MIMO stream among the plurality of combined first uplink RF spatial MIMO streams and the plurality of combined second uplink RF spatial MIMO streams into the native uplink frequency band; the electrical downlink is comprised of a single downlink coaxial cable; and the electrical uplink is comprised of a single uplink coaxial cable.