Digital baseband transport in telecommunications distribution systems
A telecommunications system is provided that includes a unit for communicating channelized digital baseband signals with remotely located units. The channelized digital baseband signals include call information for wireless communication. The unit includes a channelizer section and a transport section. The channelizer section can extract, per channel, the channelized digital baseband signals using channel filters and digital down-converters. The transport section can format the channelized digital baseband signals for transport together using a transport schedule unit for packetizing and packet scheduling the channelized digital baseband signals. A signal processing subsystem can control a gain of uplink digital baseband signals, independently, that are received from the remotely located units prior to summing the uplink digital baseband signals.
1. A telecommunications system, comprising:
a head end unit configured for communicating, with remotely located units, channelized digital baseband signals that include call information for wireless communication, the head end unit including:
channelizer circuitry configured for extracting, per channel, the channelized digital baseband signals using channel filters and digital down-converters; and
transport circuitry configured for formatting the channelized digital baseband signals for transport together using a transport schedule unit configured for packetizing and packet scheduling the channelized digital baseband signals, wherein the transport circuitry includes:
transport channel processors configured for performing decimation, filtering, and signal gain changes on the channelized digital baseband signals; and
a transport device including the transport schedule unit and a baseband signal extractor, the baseband signal extractor being configured for extracting received channelized digital baseband signals from a transport physical interface device.
2. The telecommunications system of claim 1 , wherein the channelizer circuitry includes signal processing circuitry configured for controlling a gain of each of a plurality of uplink digital baseband signals received from the remotely located units independently prior to summing the plurality of uplink digital baseband signals.
3. The telecommunications system of claim 2 , wherein the signal processing circuitry includes:
a summer;
variable gain blocks, each of the variable gain blocks being associated with a signal envelope peak detector of a plurality of signal envelope peak detectors,
wherein the signal envelope peak detector is configured for determining a signal magnitude of an uplink digital baseband signal from a remotely located unit, determining a peak average based on the signal magnitude, and determining a scale factor based on the peak average,
wherein a variable gain block associated with the signal envelope peak detector is configured for scaling the uplink digital baseband signal using the scale factor.
4. The telecommunications system of claim 1 , wherein the channelizer circuitry is configured for digitally up-converting received digital baseband signals, per channel, to produce received digital signals, and for summing the received digital signals to produce summed digital signals to be converted to analog signals.
5. The telecommunications system of claim 4 , wherein the channelizer circuitry includes, per channel:
a channel filter;
an interpolator; and
a mixer associated with a numerically controlled oscillator.
6. The telecommunications system of claim 1 , wherein the transport device includes:
framing circuitry that includes:
a framer configured for interleaving samples from different digital baseband data streams into frames; and
a de-framer configured for extracting digital baseband data streams from frames;
an Ethernet transceiver that includes:
a first bit stream converter configured for converting framed digital baseband data streams to a different bit rate;
an Ethernet framer configured for mapping the framed digital baseband data streams into Ethernet frames;
an Ethernet de-framer configured for extracting digital baseband data stream frames from received Ethernet frames; and
a second bit stream converter configured for converting the digital baseband data stream frames to a different data bit rate; and
a high-speed transceiver configured for communicating signals with the transport physical interface device.
7. The telecommunications system of claim 1 , wherein the transport circuitry includes a media access controller communicatively coupled to a transport physical interface device, the media access controller being configured for allowing a multiple access scheme on a digital transport communication medium between the head end unit and the remotely located units for asynchronous transport.
8. A distributed antenna system comprising:
at least two remote units configured for wirelessly transmitting signals in a coverage area;
a head end unit configured for communicating, with the at least two remote units, channelized digital baseband signals that include call information for wireless communication;
channelizer circuitry configured for extracting, per channel, the channelized digital baseband signals using channel filters and digital down-converters; and
transport circuitry configured for formatting the channelized digital baseband signals for transport together using a transport schedule unit configured for packetizing and packet scheduling the channelized digital baseband signals, wherein the transport circuitry includes:
transport channel processors configured for performing decimation, filtering, and signal gain changes on the channelized digital baseband signals; and
a transport device including the transport schedule unit and a baseband signal extractor, the baseband signal extractor being configured for extracting received channelized digital baseband signals from a transport physical interface device.
9. The distributed antenna system of claim 8 , wherein the channelizer circuitry and the transport circuitry are in the head end unit.
10. The distributed antenna system of claim 8 , wherein the channelizer circuitry and the transport circuitry are in at least one of the at least two remote units.
11. The distributed antenna system of claim 8 , further comprising signal processing circuitry configured for controlling a gain of each of a plurality of uplink digital baseband signals received from the at least two remote units independently prior to summing the plurality of uplink digital baseband signals.
12. The distributed antenna system of claim 11 , further comprising an extension unit between the head end unit and the at least two remote units, wherein the signal processing circuitry is in the extension unit.
13. The distributed antenna system of claim 11 , wherein the signal processing circuitry includes:
a summer;
variable gain blocks, each of the variable gain blocks being associated with a signal envelope peak detector of a plurality of signal envelope peak detectors,
wherein the signal envelope peak detector is configured for determining a signal magnitude of an uplink digital baseband signal from a remote unit, determining a peak average based on the signal magnitude, and determining a scale factor based on the peak average,
wherein a variable gain block associated with the signal envelope peak detector is configured for scaling the uplink digital baseband signal using the scale factor.
14. The distributed antenna system of claim 8 , wherein the channelizer circuitry is configured for digitally up-converting received digital baseband signals, per channel, to produce received digital signals, and for summing the received digital signals to produce summed digital signals to be converted to analog signals.
15. The distributed antenna system of claim 8 , wherein the transport device includes:
framing circuitry that includes:
a framer configured for interleaving samples from different digital baseband data streams into frames; and
a de-framer configured for extracting digital baseband data streams from frames;
an Ethernet transceiver that includes:
a first bit stream converter configured for converting framed digital baseband data streams to a different bit rate;
an Ethernet framer configured for mapping the framed digital baseband data streams into Ethernet frames;
an Ethernet de-framer configured for extracting digital baseband data stream frames from received Ethernet frames; and
a second bit stream converter configured for converting the digital baseband data stream frames to a different data bit rate; and
a high-speed transceiver configured for communicating signals with the transport physical interface device.
16. The distributed antenna system of claim 8 , wherein the transport circuitry includes a media access controller communicatively coupled to a transport physical interface device, the media access controller being configured for allowing a multiple access scheme on a digital transport communication medium between the head end unit and the at least two remote units for asynchronous transport.
17. A telecommunications system, comprising:
a head end unit configured for communicating, with remotely located units, channelized digital baseband signals that include call information for wireless communication, the head end unit including:
transport circuitry configured for formatting the channelized digital baseband signals for transport together using a transport schedule unit configured for packetizing and packet scheduling the channelized digital baseband signals; and
signal processing circuitry configured for controlling a gain of each of a plurality of uplink digital baseband signals received from the remotely located units independently prior to summing the plurality of uplink digital baseband signals, wherein the signal processing circuitry includes:
a variable gain block associated with a signal envelope peak detector and configured for scaling summed uplink digital baseband signals;
a shifter device configured for shifting the summed uplink digital baseband signals; and
a saturate device configured for clipping the summed uplink digital baseband signals at a level selected by the shifter device.
18. The telecommunications system of claim 17 , wherein the transport circuitry includes:
transport channel processors configured for performing decimation, filtering, and signal gain changes on the channelized digital baseband signals; and
a transport device including the transport schedule unit and a baseband signal extractor, the baseband signal extractor being configured for extracting received channelized digital baseband signals from a transport physical interface device.