Channel mapping for an aggregated touchless wireless fronthaul
A method implemented by a wireless fronthaul unit, the method comprises aggregating a plurality of first wireless channel signals to produce a first aggregated signal via digital frequency-domain mapping (FDM), wherein the first wireless channel signals are positioned in the first aggregated signal in non-overlapping first frequency bands, each non-overlapping first frequency band having a first bandwidth and a center frequency, wherein each respective center frequency is an odd integer multiple of a lowest center frequency, converting the first aggregated signal into a first modulated signal, and transmitting the first modulated signal to a wireless fronthaul link.
1. A method implemented by a wireless fronthaul unit, the method comprising:
aggregating a plurality of first wireless channel signals to produce a first aggregated signal via digital frequency-domain mapping (FDM), wherein the first wireless channel signals are positioned in the first aggregated signal in non-overlapping first frequency bands, each non-overlapping first frequency band having a first bandwidth and a center frequency, wherein each respective center frequency is an odd-integer multiple of a lowest center frequency;
converting the first aggregated signal into a first modulated signal; and
transmitting the first modulated signal to a wireless fronthaul link.
2. The method of claim 1 , wherein the first bandwidth is a sampling rate (SR) of a wireless signal with a largest bandwidth.
3. The method of claim 2 , wherein the SR is a multiple of 30.72 megahertz (MHz).
4. The method of claim 1 , further comprising undersampling the first aggregated signal.
5. The method of claim 4 , further comprising sampling, by a digital-to-analog converter (DAC), the first aggregated signal at a sampling rate that is (N max +2) times the first bandwidth, where N max is a channel index of a highest center frequency odd channel.
6. The method of claim 1 , wherein the odd-integer multiple of the center frequency of a lowest first frequency band has a value of 1.
7. The method of claim 4 , further comprising receiving, by a deaggregation unit, the first aggregated signal, wherein the wireless fronthaul unit comprises the deaggregation unit.
8. The method of claim 7 , further comprising deaggregating, by the deaggregation unit, the first aggregated signal into a plurality of baseband signals.
9. The method of claim 1 , further comprising generating the first frequency bands by:
upsampling a set of second frequency bands; and
filtering the set of second frequency bands to remove each of the second frequency bands having a center frequency that is an even integer multiple of the lowest center frequency.
10. The method of claim 1 , wherein the wireless fronthaul unit is a baseband unit (BBU), wherein the first wireless channel signals comprise wireless downlink (DL) channel signals, and wherein the method further comprises generating the first wireless channel signals in a baseband (BB).
11. The method of claim 1 , wherein the first modulated signal comprises one of an optical signal, a cable signal, or a free-space microwave signal.
12. The method of claim 1 , further comprising generating the first modulated signal with a directly-modulated laser (DML).
13. The method of claim 12 , wherein the first modulated signal incurs clipping of a signal amplitude in the DML.
14. The method of claim 13 , wherein the clipping is asymmetric.
15. A wireless fronthaul unit comprising:
an optical frontend configured to receive wireless uplink signals; and
a channel aggregation unit coupled to the optical frontend and configured to aggregate the wireless uplink signals via digital frequency-domain mapping (FDM) to produce an aggregated signal,
wherein the wireless uplink signals are positioned in the aggregated signal in frequency bands,
wherein each frequency band has a first bandwidth and a center frequency, and
wherein each center frequency is an odd integer multiple of a lowest center frequency.
16. The wireless fronthaul unit of claim 15 , wherein the first bandwidth is a sampling rate (SR) of a wireless signal with a largest bandwidth.
17. The wireless fronthaul unit of claim 15 , wherein the channel aggregation unit is further configured to undersample the aggregated signal.
18. The wireless fronthaul unit of claim 17 , further comprising a digital-to-analog converter (DAC) configured to sample the aggregated signal at a rate that is (N max +2) times the first bandwidth, where N max is a channel index of a highest-frequency odd channel.
19. The wireless fronthaul unit of claim 15 , wherein the wireless fronthaul unit further comprises a deaggregation unit.