Systems and methods for delta-sigma digitization
A baseband processing unit includes a baseband processor configured to receive a plurality of component carriers of a radio access technology wireless service, and a delta-sigma digitization interface configured to digitize at least one carrier signal of the plurality of component carriers into a digitized bit stream, for transport over a transport medium, by (i) oversampling the at least one carrier signal, (ii) quantizing the oversampled carrier signal into the digitized bit stream using two or fewer quantization bits.
1. A baseband processing unit (BBU), comprising:
a baseband processor configured to receive a plurality of component carriers of a radio access technology wireless service; and
a delta-sigma digitization interface comprising a delta-sigma analog-to-digital converter (ADC) configured to digitize at least one carrier signal of the plurality of component carriers into a digitized bit stream, for transport over a transport medium, by (i) oversampling the at least one carrier signal, (ii) quantizing the oversampled carrier signal into the digitized bit stream, wherein an input of the delta-sigma ADC includes at least one recursion loop from an output of the delta-sigma ADC.
2. The BBU of claim 1 , wherein the delta-sigma ADC comprises a one-bit quantizer.
3. The BBU of claim 2 , wherein the delta-sigma ADC further comprises a second-order impulse filter including at least two feedback loops.
4. The BBU of claim 2 , wherein the plurality of component carriers comprises 32 long term evolution carriers.
5. The BBU of claim 1 , wherein the delta-sigma ADC comprises a two-bit quantizer.
6. The BBU of claim 5 , wherein the delta-sigma ADC further comprises a second-order filter including at least two feedback loops.
7. The BBU of claim 5 , wherein the delta-sigma ADC further comprises a fourth-order filter including at least four feedback loops.
8. The BBU of claim 7 , wherein the fourth-order filter includes a plurality of feedforward coefficients and a plurality of feedback coefficients.
9. The BBU of claim 8 , wherein the plurality of feedforward coefficients and the plurality of feedback coefficients are tunable.
10. The BBU of claim 5 , wherein the plurality of component carriers comprises 32 long term evolution carriers.
11. The BBU of claim 5 , wherein the plurality of component carriers comprises 37 long term evolution carriers.
12. The BBU of claim 5 , wherein a first portion of the plurality of component carriers has a different modulation format than a second portion of the plurality of component carriers.
13. The BBU of claim 1 , wherein the delta-sigma ADC is further configured to quantizing the oversampled carrier signal into the digitized bit stream using two or fewer quantization bits.
14. The BBU of claim 5 , wherein the delta-sigma ADC further comprises an infinite impulse response filter.