Abstract

A new function split option for the next generation fronthaul interface (NGFI) is demonstrated based on all-digital RF transmitter using bandpass delta-sigma modulation. Different from other low layer split (LLS) options, such as option 6 (MAC-PHY), 7 (high-low PHY), and 8 (CPRI), the proposed option 9 implements RF functions in the digital domain, and splits within the RF layer, with high-RF layer centralized in the distributed unit (DU) and low-RF layer distributed in remote radio units (RRUs). A proof-of-concept all-digital RF transmitter based on real-time delta-sigma modulation is implemented using a Xilinx Virtex-7 FPGA. A 5-GSa/s delta-sigma modulator is demonstrated to encode LTE/5G signals with bandwidth up to 252 MHz and modulation format up to 1024-QAM to a 5-Gb/s OOK signal, which is transmitted over 30-km single-mode fiber from DU to RRU. To relax the FPGA speed requirement, a 32-pipeline architecture is designed. Two-carrier aggregation of 5G and 14-carrier aggregation of LTE signals are demonstrated with error vector magnitude (EVM) performance satisfying the 3GPP specifications. Compared with option 8 (CPRI), although the proposed option 9 split occurs at a lower level, it offers improved spectral efficiency and reduced NGFI data rate than CPRI. Moreover, other LLS options, such as 6, 7, and 8, all require a complete RF layer implemented in the analog domain at remote cell sites; whereas option 9 realizes high-RF layer in the digital domain at DU, and eliminates the need of analog RF devices, such as DAC, local oscillator and mixer at RRU, which not only makes low-cost, energy-efficient, and small-footprint cell sites possible for the wide deployment of small cells, but also paves the road toward software defined radio (SDR) and virtualization of DU and RRU for improved compatibility and reconfigurability among multiple radio access technologies (multi-RATs). Given its centralized architecture and deterministic latency, option 9 is suitable for radio coordination applications, and has potential in low-frequency narrowband scenarios with cost, power, and/or size sensitive cell sites, such as massive machine type communication (mMTC) and narrowband internet of things (NB-IoT).

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2018 (2)

C.-L. I, H. Li, J. Korhonen, J. Huang, and L. Han, “RAN revolution with NGFI (xhaul) for 5G,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 541–550, 2018.

J. Wang, Z. Jia, L. A. Campos, L. Cheng, C. Knittle, and G. K. Chang, “Delta-sigma digitization and optical coherent transmission of DOCSIS 3.1 signals in hybrid fiber coax networks,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 568–579, 2018.

2017 (3)

R. F. Cordeiro, A. Prata, A. S. R. Oliveira, J. M. N. Vieira, and N. B. De Carvalho, “Agile all-digital RF transceiver implemented in FPGA,” IEEE Trans. Microw. Theory Techn., vol. 65, no. 11, pp. 4229–4240, 2017.

J. Wanget al., “Digital mobile fronthaul based on delta-sigma modulation for 32 LTE carrier aggregation and FBMC signals,” IEEE/OSA J. Opt. Commun. Netw., vol. 9, no. 2, pp. A233–A244, 2017.

M. Xu, F. Lu, J. Wang, L. Cheng, D. Guidotti, and G. K. Chang, “Key technologies for next-generation digital RoF mobile fronthaul with statistical data compression and multiband modulation,” IEEE J. Lightw. Technol., vol. 35, no. 17, pp. 3671–3679, 2017.

2016 (4)

J. Wanget al., “Nonlinear inter-band subcarrier intermodulations for multi-RAT OFDM wireless services in 5G heterogeneous mobile fronthaul networks,” IEEE J. Lightw. Technol., vol. 34, no. 17, pp. 4089–4103, 2016.

C.-L. I, S. Han, Z. Xu, S. Wang, Q. Sun, and Y. Chen, “New paradigm of 5G wireless internet,” IEEE J. Sel. Areas Commun., vol. 34, no. 3, pp. 474–482, 2016.

M. Agiwal, A. Roy, and N. Saxena, “Next generation 5G wireless networks: A comprehensive survey,” IEEE Commun. Surveys. Tuts., vol. 18, no. 3, pp. 1617–1655, 2016.

X. Liu, H. Zeng, N. Chand, and F. Effenberger, “Efficient mobile fronthaul via DSP-based channel aggregation,” IEEE J. Lightw. Technol., vol. 34, no. 6, pp. 1556–1564, 2016.

2015 (7)

T. Pfeiffer, “Next generation mobile fronthaul and midhaul architectures,” IEEE/OSA J. Opt. Commun. Netw., vol. 7, no. 11, pp. B38–B45, 2015.

A. Checkoet al., “Cloud RAN for mobile networks - A technology overview,” IEEE Commun. Surveys. Tuts., vol. 17, no. 1, pp. 405–426, 2015.

A. Pizzinat, P. Chanclou, F. Saliou, and T. Diallo, “Things you should know about fronthaul,” IEEE J. Lightw. Technol., vol. 33, no. 5, pp. 1077–1083, 2015.

A. Gupta and R. K. Jha, “A survey of 5G network: Architecture and emerging technologies,” IEEE Access, vol. 3, pp. 1206–1232, 2015.

L. Bettini, T. Christen, T. Burger, and Q. Huang, “A reconfigurable DT ΔΣ modulator for multi-standard 2G/3G/4G wireless receivers,” IEEE J. Emerg. Sel. Topics Circuits Syst., vol. 5, no. 4, pp. 525–536, 2015.

M. Englundet al., “A programmable 0.7–2.7 GHz direct ΔΣ receiver in 40 nm CMOS,” IEEE J. Solid-State Circuits, vol. 50, no. 3, pp. 644–655, 2015.

S. Chung, R. Ma, S. Shinjo, H. Nakamizo, K. Parsons, and K. H. Teo, “Concurrent multiband digital outphasing transmitter architecture using multidimensional power coding,” IEEE Trans. Microw. Theory Techn., vol. 63, no. 2, pp. 598–613, 2015.

2014 (5)

S. Hatami, M. Helaoui, F. M. Ghannouchi, and M. Pedram, “Single-bit pseudoparallel processing low-oversampling delta-sigma modulator suitable for SDR wireless transmitters,” IEEE Trans. Very Large Scale Integr. Syst., vol. 22, no. 4, pp. 922–931, 2014.

C. Wu, E. Alon, and B. Nikolić, “A wideband 400 MHz-to-4 GHz direct RF-to-digital multimode ΔΣ receiver,” IEEE J. Solid-State Circuits, vol. 49, no. 7, pp. 1639–1652, 2014.

J. Wang, C. Liu, M. Zhu, A. Yi, L. Cheng, and G. K. Chang, “Investigation of data-dependent channel cross-modulation in multiband radio-over-fiber systems,” IEEE J. Lightw. Technol., vol. 32, no. 10, pp. 1861–1871, 2014.

C.-L. I, C. Rowell, S. Han, Z. Xu, G. Li, and Z. Pan, “Toward green and soft: A 5G perspective,” IEEE Commun. Mag., vol. 52, no. 2, pp. 66–73, 2014.

S.H. Park, O. Simeone, O. Sahin, and S. Shamai, “Fronthaul compression for cloud radio access networks: Signal processing advances inspired by network information theory,” IEEE Signal Process. Mag., vol. 31, no. 6, pp. 69–79, 2014.

2013 (2)

B. Guo, W. Cao, A. Tao, and D. Samardzija, “LTE/LTE-A signal compression on the CPRI interface,” Bell Labs Tech. J., vol. 18, no. 2, pp. 117–133, 2013.

N. V. Silva, A. S. R. Oliveira, and N. B. Carvalho, “Design and optimization of flexible and coding efficient all-digital RF transmitters,” IEEE Trans. Microw. Theory Techn., vol. 61, no. 1, pp. 625–632, 2013.

2012 (1)

H. Shibataet al., “A DC-to-1 GHz tunable RF ΔΣ ADC achieving DR = 74 dB and BW = 150 MHz at f0 = 450 MHz using 550 mW,” IEEE J. Solid-State Circuits, vol. 47, no. 12, pp. 2888–2897, 2012.

2011 (2)

M. M. Ebrahimi, M. Helaoui, and F. Ghannouchi, “Time-interleaved delta-sigma modulator for wideband digital GHz transmitter design and SDR applications,” Progr. Electromagn. Res. B, vol. 34, pp. 263–281, 2011.

China Mobile, “C-RAN the road towards green RAN (version 2.5),” White Paper, chapter 2-3, pp. 5–12, 2011.

2010 (1)

F. M. Ghannouchi, S. Hatami, P. Aflaki, M. Helaoui, and R. Negra, “Accurate power efficiency estimation of GHz wireless delta-sigma transmitters for different classes of switching mode power amplifiers,” IEEE Trans. Microw. Theory Techn., vol. 58, no. 11, pp. 2812–2819, 2010.

2009 (1)

A. Frappe, A. Flament, B. Stefanelli, A. Kaiser, and A. Cathelin, “An all-digital RF signal generator using high-speed ΔΣ modulators,” IEEE J. Solid-State Circuits, vol. 44, no. 10, pp. 2722–2732, 2009.

2008 (1)

M. Helaoui, S. Hatami, R. Negra, and F. M. Ghannouchi, “A novel architecture of delta-sigma modulator enabling all-digital multiband multistandard RF transmitters design,” IEEE Trans. Circuits Syst. II, Exp. Briefs, vol. 55, no. 11, pp. 1129–1133, 2008.

2007 (1)

A. Jerng and C. G. Sodini, “A wideband ΔΣ digital-RF modulator for high data rate transmitters,” IEEE J. Solid-State Circuits, vol. 42, no. 8, pp. 1710–1722, 2007.

2004 (1)

S. Yan and E. Sanchez-Sinencio, “A continuous-time sigma-delta modulator with 88-dB dynamic range and 1.1-MHz signal bandwidth,” IEEE J. Solid-State Circuits, vol. 39, no. 1, pp. 75–86, 2004.

2003 (1)

M. R. Miller and C. S. Petrie, “A multibit sigma-delta ADC for multimode receivers,” IEEE J. Solid-State Circuits, vol. 38, no. 3, pp. 475–482, 2003.

2002 (1)

I. Galton, “Delta-sigma data conversion in wireless transceivers,” IEEE Trans. Microw. Theory Techn., vol. 50, no. 1, pp. 302–315, 2002.

Aflaki, P.

F. M. Ghannouchi, S. Hatami, P. Aflaki, M. Helaoui, and R. Negra, “Accurate power efficiency estimation of GHz wireless delta-sigma transmitters for different classes of switching mode power amplifiers,” IEEE Trans. Microw. Theory Techn., vol. 58, no. 11, pp. 2812–2819, 2010.

Agiwal, M.

M. Agiwal, A. Roy, and N. Saxena, “Next generation 5G wireless networks: A comprehensive survey,” IEEE Commun. Surveys. Tuts., vol. 18, no. 3, pp. 1617–1655, 2016.

Alon, E.

C. Wu, E. Alon, and B. Nikolić, “A wideband 400 MHz-to-4 GHz direct RF-to-digital multimode ΔΣ receiver,” IEEE J. Solid-State Circuits, vol. 49, no. 7, pp. 1639–1652, 2014.

Bettini, L.

L. Bettini, T. Christen, T. Burger, and Q. Huang, “A reconfigurable DT ΔΣ modulator for multi-standard 2G/3G/4G wireless receivers,” IEEE J. Emerg. Sel. Topics Circuits Syst., vol. 5, no. 4, pp. 525–536, 2015.

Boulemnakher, M.

A. Pozsgay, T. Zounes, R. Hossain, M. Boulemnakher, V. Knopik, and S. Grange, “A fully digital 65nm CMOS transmitter for the 2.4-to-2.7 GHz WiFi/WiMAX bands using 5.4 GHz ΔΣ RF DACs,” in Proc. IEEE Int. Solid-State Circuits Conf., 2008, pp. 360–361.

Burger, T.

L. Bettini, T. Christen, T. Burger, and Q. Huang, “A reconfigurable DT ΔΣ modulator for multi-standard 2G/3G/4G wireless receivers,” IEEE J. Emerg. Sel. Topics Circuits Syst., vol. 5, no. 4, pp. 525–536, 2015.

Campos, L. A.

J. Wang, Z. Jia, L. A. Campos, L. Cheng, C. Knittle, and G. K. Chang, “Delta-sigma digitization and optical coherent transmission of DOCSIS 3.1 signals in hybrid fiber coax networks,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 568–579, 2018.

J. Wang, Z. Jia, L. A. Campos, C. Knittle, and G. Chang, “Optical coherent transmission of 20x192-MHz DOCSIS 3.1 channels with 16384QAM based on delta-sigma digitization,” in Proc. Opt. Fiber Commun. Conf., 2017, Paper Th1K.1.

M. Xu, Z. Jia, J. Wang, L. A. Campos, and G. Chang, “A novel data-compression technology for digital mobile fronthaul with Lloyd algorithm and differential coding,” in Proc. Opt. Fiber Commun. Conf., 2018, Paper Tu2K.2.

Cao, W.

B. Guo, W. Cao, A. Tao, and D. Samardzija, “LTE/LTE-A signal compression on the CPRI interface,” Bell Labs Tech. J., vol. 18, no. 2, pp. 117–133, 2013.

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A. Frappe, A. Flament, B. Stefanelli, A. Kaiser, and A. Cathelin, “An all-digital RF signal generator using high-speed ΔΣ modulators,” IEEE J. Solid-State Circuits, vol. 44, no. 10, pp. 2722–2732, 2009.

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A. Pizzinat, P. Chanclou, F. Saliou, and T. Diallo, “Things you should know about fronthaul,” IEEE J. Lightw. Technol., vol. 33, no. 5, pp. 1077–1083, 2015.

Chand, N.

X. Liu, H. Zeng, N. Chand, and F. Effenberger, “Efficient mobile fronthaul via DSP-based channel aggregation,” IEEE J. Lightw. Technol., vol. 34, no. 6, pp. 1556–1564, 2016.

X. Liu, F. Effenberger, N. Chand, L. Zhou, and H. Lin, “Demonstration of bandwidth-efficient mobile fronthaul enabling seamless aggregation of 36 E-UTRA-like wireless signals in a single 1.1-GHz wavelength channel,” in Proc. Opt. Fiber Commun. Conf., 2015, Paper M2J.2.

M. Xu, X. Liu, N. Chand, F. Effenberger, and G. K. Chang, “Fast statistical estimation in highly compressed digital RoF systems for efficient 5G wireless signal delivery,” in Proc. Opt. Fiber Commun. Conf., 2017, Paper M3E.7.

Chang, G.

M. Xu, Z. Jia, J. Wang, L. A. Campos, and G. Chang, “A novel data-compression technology for digital mobile fronthaul with Lloyd algorithm and differential coding,” in Proc. Opt. Fiber Commun. Conf., 2018, Paper Tu2K.2.

J. Wang, Z. Jia, L. A. Campos, C. Knittle, and G. Chang, “Optical coherent transmission of 20x192-MHz DOCSIS 3.1 channels with 16384QAM based on delta-sigma digitization,” in Proc. Opt. Fiber Commun. Conf., 2017, Paper Th1K.1.

Chang, G. K.

J. Wang, Z. Jia, L. A. Campos, L. Cheng, C. Knittle, and G. K. Chang, “Delta-sigma digitization and optical coherent transmission of DOCSIS 3.1 signals in hybrid fiber coax networks,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 568–579, 2018.

M. Xu, F. Lu, J. Wang, L. Cheng, D. Guidotti, and G. K. Chang, “Key technologies for next-generation digital RoF mobile fronthaul with statistical data compression and multiband modulation,” IEEE J. Lightw. Technol., vol. 35, no. 17, pp. 3671–3679, 2017.

J. Wang, C. Liu, M. Zhu, A. Yi, L. Cheng, and G. K. Chang, “Investigation of data-dependent channel cross-modulation in multiband radio-over-fiber systems,” IEEE J. Lightw. Technol., vol. 32, no. 10, pp. 1861–1871, 2014.

M. Xu, X. Liu, N. Chand, F. Effenberger, and G. K. Chang, “Fast statistical estimation in highly compressed digital RoF systems for efficient 5G wireless signal delivery,” in Proc. Opt. Fiber Commun. Conf., 2017, Paper M3E.7.

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Cheng, L.

J. Wang, Z. Jia, L. A. Campos, L. Cheng, C. Knittle, and G. K. Chang, “Delta-sigma digitization and optical coherent transmission of DOCSIS 3.1 signals in hybrid fiber coax networks,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 568–579, 2018.

M. Xu, F. Lu, J. Wang, L. Cheng, D. Guidotti, and G. K. Chang, “Key technologies for next-generation digital RoF mobile fronthaul with statistical data compression and multiband modulation,” IEEE J. Lightw. Technol., vol. 35, no. 17, pp. 3671–3679, 2017.

J. Wang, C. Liu, M. Zhu, A. Yi, L. Cheng, and G. K. Chang, “Investigation of data-dependent channel cross-modulation in multiband radio-over-fiber systems,” IEEE J. Lightw. Technol., vol. 32, no. 10, pp. 1861–1871, 2014.

Christen, T.

L. Bettini, T. Christen, T. Burger, and Q. Huang, “A reconfigurable DT ΔΣ modulator for multi-standard 2G/3G/4G wireless receivers,” IEEE J. Emerg. Sel. Topics Circuits Syst., vol. 5, no. 4, pp. 525–536, 2015.

Chung, S.

S. Chung, R. Ma, S. Shinjo, H. Nakamizo, K. Parsons, and K. H. Teo, “Concurrent multiband digital outphasing transmitter architecture using multidimensional power coding,” IEEE Trans. Microw. Theory Techn., vol. 63, no. 2, pp. 598–613, 2015.

S. Chung, R. Ma, K. H. Teo, and K. Parsons, “Outphasing multi-level RF-PWM signals for inter-band carrier aggregation in digital transmitters,” in Proc. IEEE Radio Wireless Symp., 2015, pp. 212–214.

S. Chung, R. Ma, S. Shinjo, and K. H. Teo, “Inter-band carrier aggregation digital transmitter architecture with concurrent multi-band delta-sigma modulation using out-of-band noise cancellation,” in Proc. IEEE MTT-S Int. Microw. Symp., 2015.

S. Chung, R. Ma, S. Shinjo, K. Yamanaka, and K. H. Teo, “A concurrent triple-band digital transmitter using feedforward noise cancellation for delta-sigma modulation,” in Proc. 12th Eur. Microw. Integr. Circuits Conf., 2017, pp. 400–403.

Cordeiro, R. F.

R. F. Cordeiro, A. Prata, A. S. R. Oliveira, J. M. N. Vieira, and N. B. De Carvalho, “Agile all-digital RF transceiver implemented in FPGA,” IEEE Trans. Microw. Theory Techn., vol. 65, no. 11, pp. 4229–4240, 2017.

R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and N. V. Silva, “Gigasample time-interleaved delta-sigma modulator for FPGA-based all-digital transmitters,” in Proc. 17th Euromicro Conf. Digit. Syst. Design, 2014, pp. 222–227.

R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and T. O. e Silva, “Wideband all-digital transmitter based on multicore DSM,” in Proc. IEEE MTT-S Int. Microw. Symp., 2016.

D. C. Dinis, R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and T. O. Silva, “Improving the performance of all-digital transmitter based on parallel delta-sigma modulators through propagation of state registers,” in Proc. IEEE 60th Int. Midwest Symp. Circuits Syst., 2017, pp. 1133–1137.

De Carvalho, N. B.

R. F. Cordeiro, A. Prata, A. S. R. Oliveira, J. M. N. Vieira, and N. B. De Carvalho, “Agile all-digital RF transceiver implemented in FPGA,” IEEE Trans. Microw. Theory Techn., vol. 65, no. 11, pp. 4229–4240, 2017.

Diallo, T.

A. Pizzinat, P. Chanclou, F. Saliou, and T. Diallo, “Things you should know about fronthaul,” IEEE J. Lightw. Technol., vol. 33, no. 5, pp. 1077–1083, 2015.

Dinis, D. C.

D. C. Dinis, R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and T. O. Silva, “Improving the performance of all-digital transmitter based on parallel delta-sigma modulators through propagation of state registers,” in Proc. IEEE 60th Int. Midwest Symp. Circuits Syst., 2017, pp. 1133–1137.

e Silva, T. O.

R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and T. O. e Silva, “Wideband all-digital transmitter based on multicore DSM,” in Proc. IEEE MTT-S Int. Microw. Symp., 2016.

Ebrahimi, M. M.

M. M. Ebrahimi, M. Helaoui, and F. Ghannouchi, “Time-interleaved delta-sigma modulator for wideband digital GHz transmitter design and SDR applications,” Progr. Electromagn. Res. B, vol. 34, pp. 263–281, 2011.

Effenberger, F.

X. Liu, H. Zeng, N. Chand, and F. Effenberger, “Efficient mobile fronthaul via DSP-based channel aggregation,” IEEE J. Lightw. Technol., vol. 34, no. 6, pp. 1556–1564, 2016.

X. Liu, F. Effenberger, N. Chand, L. Zhou, and H. Lin, “Demonstration of bandwidth-efficient mobile fronthaul enabling seamless aggregation of 36 E-UTRA-like wireless signals in a single 1.1-GHz wavelength channel,” in Proc. Opt. Fiber Commun. Conf., 2015, Paper M2J.2.

M. Xu, X. Liu, N. Chand, F. Effenberger, and G. K. Chang, “Fast statistical estimation in highly compressed digital RoF systems for efficient 5G wireless signal delivery,” in Proc. Opt. Fiber Commun. Conf., 2017, Paper M3E.7.

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A. Frappe, A. Flament, B. Stefanelli, A. Kaiser, and A. Cathelin, “An all-digital RF signal generator using high-speed ΔΣ modulators,” IEEE J. Solid-State Circuits, vol. 44, no. 10, pp. 2722–2732, 2009.

Frappe, A.

A. Frappe, A. Flament, B. Stefanelli, A. Kaiser, and A. Cathelin, “An all-digital RF signal generator using high-speed ΔΣ modulators,” IEEE J. Solid-State Circuits, vol. 44, no. 10, pp. 2722–2732, 2009.

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Ghannouchi, F.

M. M. Ebrahimi, M. Helaoui, and F. Ghannouchi, “Time-interleaved delta-sigma modulator for wideband digital GHz transmitter design and SDR applications,” Progr. Electromagn. Res. B, vol. 34, pp. 263–281, 2011.

Ghannouchi, F. M.

S. Hatami, M. Helaoui, F. M. Ghannouchi, and M. Pedram, “Single-bit pseudoparallel processing low-oversampling delta-sigma modulator suitable for SDR wireless transmitters,” IEEE Trans. Very Large Scale Integr. Syst., vol. 22, no. 4, pp. 922–931, 2014.

F. M. Ghannouchi, S. Hatami, P. Aflaki, M. Helaoui, and R. Negra, “Accurate power efficiency estimation of GHz wireless delta-sigma transmitters for different classes of switching mode power amplifiers,” IEEE Trans. Microw. Theory Techn., vol. 58, no. 11, pp. 2812–2819, 2010.

M. Helaoui, S. Hatami, R. Negra, and F. M. Ghannouchi, “A novel architecture of delta-sigma modulator enabling all-digital multiband multistandard RF transmitters design,” IEEE Trans. Circuits Syst. II, Exp. Briefs, vol. 55, no. 11, pp. 1129–1133, 2008.

Grange, S.

A. Pozsgay, T. Zounes, R. Hossain, M. Boulemnakher, V. Knopik, and S. Grange, “A fully digital 65nm CMOS transmitter for the 2.4-to-2.7 GHz WiFi/WiMAX bands using 5.4 GHz ΔΣ RF DACs,” in Proc. IEEE Int. Solid-State Circuits Conf., 2008, pp. 360–361.

Guidotti, D.

M. Xu, F. Lu, J. Wang, L. Cheng, D. Guidotti, and G. K. Chang, “Key technologies for next-generation digital RoF mobile fronthaul with statistical data compression and multiband modulation,” IEEE J. Lightw. Technol., vol. 35, no. 17, pp. 3671–3679, 2017.

Guo, B.

B. Guo, W. Cao, A. Tao, and D. Samardzija, “LTE/LTE-A signal compression on the CPRI interface,” Bell Labs Tech. J., vol. 18, no. 2, pp. 117–133, 2013.

Gupta, A.

A. Gupta and R. K. Jha, “A survey of 5G network: Architecture and emerging technologies,” IEEE Access, vol. 3, pp. 1206–1232, 2015.

Halonen, K.

J. Sommarek, J. Vankka, J. Ketola, J. Lindeberg, and K. Halonen, “A digital modulator with bandpass delta-sigma modulator,” in Proc. 30th Eur. Solid-State Circuits Conf., 2004, pp. 159–162.

Han, L.

C.-L. I, H. Li, J. Korhonen, J. Huang, and L. Han, “RAN revolution with NGFI (xhaul) for 5G,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 541–550, 2018.

Han, S.

C.-L. I, S. Han, Z. Xu, S. Wang, Q. Sun, and Y. Chen, “New paradigm of 5G wireless internet,” IEEE J. Sel. Areas Commun., vol. 34, no. 3, pp. 474–482, 2016.

C.-L. I, C. Rowell, S. Han, Z. Xu, G. Li, and Z. Pan, “Toward green and soft: A 5G perspective,” IEEE Commun. Mag., vol. 52, no. 2, pp. 66–73, 2014.

Hatami, S.

S. Hatami, M. Helaoui, F. M. Ghannouchi, and M. Pedram, “Single-bit pseudoparallel processing low-oversampling delta-sigma modulator suitable for SDR wireless transmitters,” IEEE Trans. Very Large Scale Integr. Syst., vol. 22, no. 4, pp. 922–931, 2014.

F. M. Ghannouchi, S. Hatami, P. Aflaki, M. Helaoui, and R. Negra, “Accurate power efficiency estimation of GHz wireless delta-sigma transmitters for different classes of switching mode power amplifiers,” IEEE Trans. Microw. Theory Techn., vol. 58, no. 11, pp. 2812–2819, 2010.

M. Helaoui, S. Hatami, R. Negra, and F. M. Ghannouchi, “A novel architecture of delta-sigma modulator enabling all-digital multiband multistandard RF transmitters design,” IEEE Trans. Circuits Syst. II, Exp. Briefs, vol. 55, no. 11, pp. 1129–1133, 2008.

Hayakawa, M.

M. Tanio, S. Hori, M. Hayakawa, N. Tawa, K. Motoi, and K. Kunihiro, “A linear and efficient 1-bit digital transmitter with envelope delta-sigma modulation for 700 MHz LTE,” in Proc. IEEE MTT-S Int. Microw. Symp., 2014.

Helaoui, M.

S. Hatami, M. Helaoui, F. M. Ghannouchi, and M. Pedram, “Single-bit pseudoparallel processing low-oversampling delta-sigma modulator suitable for SDR wireless transmitters,” IEEE Trans. Very Large Scale Integr. Syst., vol. 22, no. 4, pp. 922–931, 2014.

M. M. Ebrahimi, M. Helaoui, and F. Ghannouchi, “Time-interleaved delta-sigma modulator for wideband digital GHz transmitter design and SDR applications,” Progr. Electromagn. Res. B, vol. 34, pp. 263–281, 2011.

F. M. Ghannouchi, S. Hatami, P. Aflaki, M. Helaoui, and R. Negra, “Accurate power efficiency estimation of GHz wireless delta-sigma transmitters for different classes of switching mode power amplifiers,” IEEE Trans. Microw. Theory Techn., vol. 58, no. 11, pp. 2812–2819, 2010.

M. Helaoui, S. Hatami, R. Negra, and F. M. Ghannouchi, “A novel architecture of delta-sigma modulator enabling all-digital multiband multistandard RF transmitters design,” IEEE Trans. Circuits Syst. II, Exp. Briefs, vol. 55, no. 11, pp. 1129–1133, 2008.

Hori, S.

M. Tanio, S. Hori, M. Hayakawa, N. Tawa, K. Motoi, and K. Kunihiro, “A linear and efficient 1-bit digital transmitter with envelope delta-sigma modulation for 700 MHz LTE,” in Proc. IEEE MTT-S Int. Microw. Symp., 2014.

M. Tanio, S. Hori, N. Tawa, T. Yamase, and K. Kunihiro, “An FPGA-based all-digital transmitter with 28-GHz time-interleaved delta-sigma modulation,” in Proc. IEEE MTT-S Int. Microw. Symp., 2016.

M. Tanio, S. Hori, N. Tawa, and K. Kunihiro, “An FPGA-based all-digital transmitter with 9.6-GHz 2nd order time-interleaved delta-sigma modulation for 500-MHz bandwidth,” in Proc. IEEE MTT-S Int. Microw. Symp., 2017, pp. 149–152.

Hossain, R.

A. Pozsgay, T. Zounes, R. Hossain, M. Boulemnakher, V. Knopik, and S. Grange, “A fully digital 65nm CMOS transmitter for the 2.4-to-2.7 GHz WiFi/WiMAX bands using 5.4 GHz ΔΣ RF DACs,” in Proc. IEEE Int. Solid-State Circuits Conf., 2008, pp. 360–361.

Huang, J.

C.-L. I, H. Li, J. Korhonen, J. Huang, and L. Han, “RAN revolution with NGFI (xhaul) for 5G,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 541–550, 2018.

C.-L. I and J. Huang, “RAN revolution with NGFI (xHaul) for 5G,” in Proc. Opt. Fiber Commun. Conf., 2017, Paper W1C.7.

Huang, Q.

L. Bettini, T. Christen, T. Burger, and Q. Huang, “A reconfigurable DT ΔΣ modulator for multi-standard 2G/3G/4G wireless receivers,” IEEE J. Emerg. Sel. Topics Circuits Syst., vol. 5, no. 4, pp. 525–536, 2015.

I, C.-L.

C.-L. I, H. Li, J. Korhonen, J. Huang, and L. Han, “RAN revolution with NGFI (xhaul) for 5G,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 541–550, 2018.

C.-L. I, S. Han, Z. Xu, S. Wang, Q. Sun, and Y. Chen, “New paradigm of 5G wireless internet,” IEEE J. Sel. Areas Commun., vol. 34, no. 3, pp. 474–482, 2016.

C.-L. I, C. Rowell, S. Han, Z. Xu, G. Li, and Z. Pan, “Toward green and soft: A 5G perspective,” IEEE Commun. Mag., vol. 52, no. 2, pp. 66–73, 2014.

C.-L. I and J. Huang, “RAN revolution with NGFI (xHaul) for 5G,” in Proc. Opt. Fiber Commun. Conf., 2017, Paper W1C.7.

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A. Jerng and C. G. Sodini, “A wideband ΔΣ digital-RF modulator for high data rate transmitters,” IEEE J. Solid-State Circuits, vol. 42, no. 8, pp. 1710–1722, 2007.

Jha, R. K.

A. Gupta and R. K. Jha, “A survey of 5G network: Architecture and emerging technologies,” IEEE Access, vol. 3, pp. 1206–1232, 2015.

Jia, Z.

J. Wang, Z. Jia, L. A. Campos, L. Cheng, C. Knittle, and G. K. Chang, “Delta-sigma digitization and optical coherent transmission of DOCSIS 3.1 signals in hybrid fiber coax networks,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 568–579, 2018.

J. Wang, Z. Jia, L. A. Campos, C. Knittle, and G. Chang, “Optical coherent transmission of 20x192-MHz DOCSIS 3.1 channels with 16384QAM based on delta-sigma digitization,” in Proc. Opt. Fiber Commun. Conf., 2017, Paper Th1K.1.

M. Xu, Z. Jia, J. Wang, L. A. Campos, and G. Chang, “A novel data-compression technology for digital mobile fronthaul with Lloyd algorithm and differential coding,” in Proc. Opt. Fiber Commun. Conf., 2018, Paper Tu2K.2.

Kaiser, A.

A. Frappe, A. Flament, B. Stefanelli, A. Kaiser, and A. Cathelin, “An all-digital RF signal generator using high-speed ΔΣ modulators,” IEEE J. Solid-State Circuits, vol. 44, no. 10, pp. 2722–2732, 2009.

Kameda, S.

T. Maehata, K. Totani, S. Kameda, and N. Suematsu, “Concurrent dual-band 1-bit digital transmitter using band-pass delta-sigma modulator,” in Proc. Eur. Microw. Conf., 2013, pp. 1523–1526.

Ketola, J.

J. Sommarek, J. Vankka, J. Ketola, J. Lindeberg, and K. Halonen, “A digital modulator with bandpass delta-sigma modulator,” in Proc. 30th Eur. Solid-State Circuits Conf., 2004, pp. 159–162.

Knittle, C.

J. Wang, Z. Jia, L. A. Campos, L. Cheng, C. Knittle, and G. K. Chang, “Delta-sigma digitization and optical coherent transmission of DOCSIS 3.1 signals in hybrid fiber coax networks,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 568–579, 2018.

J. Wang, Z. Jia, L. A. Campos, C. Knittle, and G. Chang, “Optical coherent transmission of 20x192-MHz DOCSIS 3.1 channels with 16384QAM based on delta-sigma digitization,” in Proc. Opt. Fiber Commun. Conf., 2017, Paper Th1K.1.

Knopik, V.

A. Pozsgay, T. Zounes, R. Hossain, M. Boulemnakher, V. Knopik, and S. Grange, “A fully digital 65nm CMOS transmitter for the 2.4-to-2.7 GHz WiFi/WiMAX bands using 5.4 GHz ΔΣ RF DACs,” in Proc. IEEE Int. Solid-State Circuits Conf., 2008, pp. 360–361.

Korhonen, J.

C.-L. I, H. Li, J. Korhonen, J. Huang, and L. Han, “RAN revolution with NGFI (xhaul) for 5G,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 541–550, 2018.

Kunihiro, K.

M. Tanio, S. Hori, N. Tawa, and K. Kunihiro, “An FPGA-based all-digital transmitter with 9.6-GHz 2nd order time-interleaved delta-sigma modulation for 500-MHz bandwidth,” in Proc. IEEE MTT-S Int. Microw. Symp., 2017, pp. 149–152.

M. Tanio, S. Hori, N. Tawa, T. Yamase, and K. Kunihiro, “An FPGA-based all-digital transmitter with 28-GHz time-interleaved delta-sigma modulation,” in Proc. IEEE MTT-S Int. Microw. Symp., 2016.

M. Tanio, S. Hori, M. Hayakawa, N. Tawa, K. Motoi, and K. Kunihiro, “A linear and efficient 1-bit digital transmitter with envelope delta-sigma modulation for 700 MHz LTE,” in Proc. IEEE MTT-S Int. Microw. Symp., 2014.

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N. Shibata, T. Tashiro, S. Kuwano, N. Yuki, J. Terada, and A. Otaka, “Mobile front-haul employing ethernet-based TDM-PON system for small cells,” in Proc. Opt. Fiber Commun. Conf., 2015, Paper M2J.1.

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P. Seddighrad, A. Ravi, M. Sajadieh, H. Lakdawala, and K. Soumyanath, “A 3.6 GHz, 16 mW ΣΔ DAC for a 802.11n / 802.16e transmitter with 30 dB digital power control in 90 nm CMOS,” in Proc. 34th Eur. Solid-State Circuits Conf., 2008, pp. 202–205.

Li, G.

C.-L. I, C. Rowell, S. Han, Z. Xu, G. Li, and Z. Pan, “Toward green and soft: A 5G perspective,” IEEE Commun. Mag., vol. 52, no. 2, pp. 66–73, 2014.

Li, H.

C.-L. I, H. Li, J. Korhonen, J. Huang, and L. Han, “RAN revolution with NGFI (xhaul) for 5G,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 541–550, 2018.

Lin, H.

X. Liu, F. Effenberger, N. Chand, L. Zhou, and H. Lin, “Demonstration of bandwidth-efficient mobile fronthaul enabling seamless aggregation of 36 E-UTRA-like wireless signals in a single 1.1-GHz wavelength channel,” in Proc. Opt. Fiber Commun. Conf., 2015, Paper M2J.2.

Lindeberg, J.

J. Sommarek, J. Vankka, J. Ketola, J. Lindeberg, and K. Halonen, “A digital modulator with bandpass delta-sigma modulator,” in Proc. 30th Eur. Solid-State Circuits Conf., 2004, pp. 159–162.

Liu, C.

J. Wang, C. Liu, M. Zhu, A. Yi, L. Cheng, and G. K. Chang, “Investigation of data-dependent channel cross-modulation in multiband radio-over-fiber systems,” IEEE J. Lightw. Technol., vol. 32, no. 10, pp. 1861–1871, 2014.

Liu, X.

X. Liu, H. Zeng, N. Chand, and F. Effenberger, “Efficient mobile fronthaul via DSP-based channel aggregation,” IEEE J. Lightw. Technol., vol. 34, no. 6, pp. 1556–1564, 2016.

X. Liu, F. Effenberger, N. Chand, L. Zhou, and H. Lin, “Demonstration of bandwidth-efficient mobile fronthaul enabling seamless aggregation of 36 E-UTRA-like wireless signals in a single 1.1-GHz wavelength channel,” in Proc. Opt. Fiber Commun. Conf., 2015, Paper M2J.2.

M. Xu, X. Liu, N. Chand, F. Effenberger, and G. K. Chang, “Fast statistical estimation in highly compressed digital RoF systems for efficient 5G wireless signal delivery,” in Proc. Opt. Fiber Commun. Conf., 2017, Paper M3E.7.

Lu, F.

M. Xu, F. Lu, J. Wang, L. Cheng, D. Guidotti, and G. K. Chang, “Key technologies for next-generation digital RoF mobile fronthaul with statistical data compression and multiband modulation,” IEEE J. Lightw. Technol., vol. 35, no. 17, pp. 3671–3679, 2017.

Ma, R.

S. Chung, R. Ma, S. Shinjo, H. Nakamizo, K. Parsons, and K. H. Teo, “Concurrent multiband digital outphasing transmitter architecture using multidimensional power coding,” IEEE Trans. Microw. Theory Techn., vol. 63, no. 2, pp. 598–613, 2015.

S. Chung, R. Ma, K. H. Teo, and K. Parsons, “Outphasing multi-level RF-PWM signals for inter-band carrier aggregation in digital transmitters,” in Proc. IEEE Radio Wireless Symp., 2015, pp. 212–214.

S. Chung, R. Ma, S. Shinjo, and K. H. Teo, “Inter-band carrier aggregation digital transmitter architecture with concurrent multi-band delta-sigma modulation using out-of-band noise cancellation,” in Proc. IEEE MTT-S Int. Microw. Symp., 2015.

S. Chung, R. Ma, S. Shinjo, K. Yamanaka, and K. H. Teo, “A concurrent triple-band digital transmitter using feedforward noise cancellation for delta-sigma modulation,” in Proc. 12th Eur. Microw. Integr. Circuits Conf., 2017, pp. 400–403.

Maehata, T.

T. Maehata, K. Totani, S. Kameda, and N. Suematsu, “Concurrent dual-band 1-bit digital transmitter using band-pass delta-sigma modulator,” in Proc. Eur. Microw. Conf., 2013, pp. 1523–1526.

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M. R. Miller and C. S. Petrie, “A multibit sigma-delta ADC for multimode receivers,” IEEE J. Solid-State Circuits, vol. 38, no. 3, pp. 475–482, 2003.

Motoi, K.

M. Tanio, S. Hori, M. Hayakawa, N. Tawa, K. Motoi, and K. Kunihiro, “A linear and efficient 1-bit digital transmitter with envelope delta-sigma modulation for 700 MHz LTE,” in Proc. IEEE MTT-S Int. Microw. Symp., 2014.

Nakamizo, H.

S. Chung, R. Ma, S. Shinjo, H. Nakamizo, K. Parsons, and K. H. Teo, “Concurrent multiband digital outphasing transmitter architecture using multidimensional power coding,” IEEE Trans. Microw. Theory Techn., vol. 63, no. 2, pp. 598–613, 2015.

Negra, R.

F. M. Ghannouchi, S. Hatami, P. Aflaki, M. Helaoui, and R. Negra, “Accurate power efficiency estimation of GHz wireless delta-sigma transmitters for different classes of switching mode power amplifiers,” IEEE Trans. Microw. Theory Techn., vol. 58, no. 11, pp. 2812–2819, 2010.

M. Helaoui, S. Hatami, R. Negra, and F. M. Ghannouchi, “A novel architecture of delta-sigma modulator enabling all-digital multiband multistandard RF transmitters design,” IEEE Trans. Circuits Syst. II, Exp. Briefs, vol. 55, no. 11, pp. 1129–1133, 2008.

Nikolic, B.

C. Wu, E. Alon, and B. Nikolić, “A wideband 400 MHz-to-4 GHz direct RF-to-digital multimode ΔΣ receiver,” IEEE J. Solid-State Circuits, vol. 49, no. 7, pp. 1639–1652, 2014.

Oliveira, A. S. R.

R. F. Cordeiro, A. Prata, A. S. R. Oliveira, J. M. N. Vieira, and N. B. De Carvalho, “Agile all-digital RF transceiver implemented in FPGA,” IEEE Trans. Microw. Theory Techn., vol. 65, no. 11, pp. 4229–4240, 2017.

N. V. Silva, A. S. R. Oliveira, and N. B. Carvalho, “Design and optimization of flexible and coding efficient all-digital RF transmitters,” IEEE Trans. Microw. Theory Techn., vol. 61, no. 1, pp. 625–632, 2013.

N. V. Silva, A. S. R. Oliveira, and N. B. Carvalho, “Evaluation of pulse modulators for all-digital agile transmitters,” in Proc. IEEE MTT-S Int. Microw. Symp., 2012.

R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and T. O. e Silva, “Wideband all-digital transmitter based on multicore DSM,” in Proc. IEEE MTT-S Int. Microw. Symp., 2016.

D. C. Dinis, R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and T. O. Silva, “Improving the performance of all-digital transmitter based on parallel delta-sigma modulators through propagation of state registers,” in Proc. IEEE 60th Int. Midwest Symp. Circuits Syst., 2017, pp. 1133–1137.

R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and N. V. Silva, “Gigasample time-interleaved delta-sigma modulator for FPGA-based all-digital transmitters,” in Proc. 17th Euromicro Conf. Digit. Syst. Design, 2014, pp. 222–227.

Otaka, A.

N. Shibata, T. Tashiro, S. Kuwano, N. Yuki, J. Terada, and A. Otaka, “Mobile front-haul employing ethernet-based TDM-PON system for small cells,” in Proc. Opt. Fiber Commun. Conf., 2015, Paper M2J.1.

Pan, Z.

C.-L. I, C. Rowell, S. Han, Z. Xu, G. Li, and Z. Pan, “Toward green and soft: A 5G perspective,” IEEE Commun. Mag., vol. 52, no. 2, pp. 66–73, 2014.

Park, S.H.

S.H. Park, O. Simeone, O. Sahin, and S. Shamai, “Fronthaul compression for cloud radio access networks: Signal processing advances inspired by network information theory,” IEEE Signal Process. Mag., vol. 31, no. 6, pp. 69–79, 2014.

Parsons, K.

S. Chung, R. Ma, S. Shinjo, H. Nakamizo, K. Parsons, and K. H. Teo, “Concurrent multiband digital outphasing transmitter architecture using multidimensional power coding,” IEEE Trans. Microw. Theory Techn., vol. 63, no. 2, pp. 598–613, 2015.

S. Chung, R. Ma, K. H. Teo, and K. Parsons, “Outphasing multi-level RF-PWM signals for inter-band carrier aggregation in digital transmitters,” in Proc. IEEE Radio Wireless Symp., 2015, pp. 212–214.

Pedram, M.

S. Hatami, M. Helaoui, F. M. Ghannouchi, and M. Pedram, “Single-bit pseudoparallel processing low-oversampling delta-sigma modulator suitable for SDR wireless transmitters,” IEEE Trans. Very Large Scale Integr. Syst., vol. 22, no. 4, pp. 922–931, 2014.

Petrie, C. S.

M. R. Miller and C. S. Petrie, “A multibit sigma-delta ADC for multimode receivers,” IEEE J. Solid-State Circuits, vol. 38, no. 3, pp. 475–482, 2003.

Pfeiffer, T.

T. Pfeiffer, “Next generation mobile fronthaul and midhaul architectures,” IEEE/OSA J. Opt. Commun. Netw., vol. 7, no. 11, pp. B38–B45, 2015.

T. Pfeiffer, “Next generation mobile fronthaul architectures,” in Proc. Opt. Fiber Commun. Conf., 2015, Paper M2J.7.

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A. Pizzinat, P. Chanclou, F. Saliou, and T. Diallo, “Things you should know about fronthaul,” IEEE J. Lightw. Technol., vol. 33, no. 5, pp. 1077–1083, 2015.

Pozsgay, A.

A. Pozsgay, T. Zounes, R. Hossain, M. Boulemnakher, V. Knopik, and S. Grange, “A fully digital 65nm CMOS transmitter for the 2.4-to-2.7 GHz WiFi/WiMAX bands using 5.4 GHz ΔΣ RF DACs,” in Proc. IEEE Int. Solid-State Circuits Conf., 2008, pp. 360–361.

Prata, A.

R. F. Cordeiro, A. Prata, A. S. R. Oliveira, J. M. N. Vieira, and N. B. De Carvalho, “Agile all-digital RF transceiver implemented in FPGA,” IEEE Trans. Microw. Theory Techn., vol. 65, no. 11, pp. 4229–4240, 2017.

Ravi, A.

P. Seddighrad, A. Ravi, M. Sajadieh, H. Lakdawala, and K. Soumyanath, “A 3.6 GHz, 16 mW ΣΔ DAC for a 802.11n / 802.16e transmitter with 30 dB digital power control in 90 nm CMOS,” in Proc. 34th Eur. Solid-State Circuits Conf., 2008, pp. 202–205.

Rowell, C.

C.-L. I, C. Rowell, S. Han, Z. Xu, G. Li, and Z. Pan, “Toward green and soft: A 5G perspective,” IEEE Commun. Mag., vol. 52, no. 2, pp. 66–73, 2014.

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M. Agiwal, A. Roy, and N. Saxena, “Next generation 5G wireless networks: A comprehensive survey,” IEEE Commun. Surveys. Tuts., vol. 18, no. 3, pp. 1617–1655, 2016.

Sahin, O.

S.H. Park, O. Simeone, O. Sahin, and S. Shamai, “Fronthaul compression for cloud radio access networks: Signal processing advances inspired by network information theory,” IEEE Signal Process. Mag., vol. 31, no. 6, pp. 69–79, 2014.

Sajadieh, M.

P. Seddighrad, A. Ravi, M. Sajadieh, H. Lakdawala, and K. Soumyanath, “A 3.6 GHz, 16 mW ΣΔ DAC for a 802.11n / 802.16e transmitter with 30 dB digital power control in 90 nm CMOS,” in Proc. 34th Eur. Solid-State Circuits Conf., 2008, pp. 202–205.

Saliou, F.

A. Pizzinat, P. Chanclou, F. Saliou, and T. Diallo, “Things you should know about fronthaul,” IEEE J. Lightw. Technol., vol. 33, no. 5, pp. 1077–1083, 2015.

Samardzija, D.

B. Guo, W. Cao, A. Tao, and D. Samardzija, “LTE/LTE-A signal compression on the CPRI interface,” Bell Labs Tech. J., vol. 18, no. 2, pp. 117–133, 2013.

Sanchez-Sinencio, E.

S. Yan and E. Sanchez-Sinencio, “A continuous-time sigma-delta modulator with 88-dB dynamic range and 1.1-MHz signal bandwidth,” IEEE J. Solid-State Circuits, vol. 39, no. 1, pp. 75–86, 2004.

Saxena, N.

M. Agiwal, A. Roy, and N. Saxena, “Next generation 5G wireless networks: A comprehensive survey,” IEEE Commun. Surveys. Tuts., vol. 18, no. 3, pp. 1617–1655, 2016.

Seddighrad, P.

P. Seddighrad, A. Ravi, M. Sajadieh, H. Lakdawala, and K. Soumyanath, “A 3.6 GHz, 16 mW ΣΔ DAC for a 802.11n / 802.16e transmitter with 30 dB digital power control in 90 nm CMOS,” in Proc. 34th Eur. Solid-State Circuits Conf., 2008, pp. 202–205.

Shamai, S.

S.H. Park, O. Simeone, O. Sahin, and S. Shamai, “Fronthaul compression for cloud radio access networks: Signal processing advances inspired by network information theory,” IEEE Signal Process. Mag., vol. 31, no. 6, pp. 69–79, 2014.

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Shibata, N.

N. Shibata, T. Tashiro, S. Kuwano, N. Yuki, J. Terada, and A. Otaka, “Mobile front-haul employing ethernet-based TDM-PON system for small cells,” in Proc. Opt. Fiber Commun. Conf., 2015, Paper M2J.1.

Shinjo, S.

S. Chung, R. Ma, S. Shinjo, H. Nakamizo, K. Parsons, and K. H. Teo, “Concurrent multiband digital outphasing transmitter architecture using multidimensional power coding,” IEEE Trans. Microw. Theory Techn., vol. 63, no. 2, pp. 598–613, 2015.

S. Chung, R. Ma, S. Shinjo, and K. H. Teo, “Inter-band carrier aggregation digital transmitter architecture with concurrent multi-band delta-sigma modulation using out-of-band noise cancellation,” in Proc. IEEE MTT-S Int. Microw. Symp., 2015.

S. Chung, R. Ma, S. Shinjo, K. Yamanaka, and K. H. Teo, “A concurrent triple-band digital transmitter using feedforward noise cancellation for delta-sigma modulation,” in Proc. 12th Eur. Microw. Integr. Circuits Conf., 2017, pp. 400–403.

Silva, N. V.

N. V. Silva, A. S. R. Oliveira, and N. B. Carvalho, “Design and optimization of flexible and coding efficient all-digital RF transmitters,” IEEE Trans. Microw. Theory Techn., vol. 61, no. 1, pp. 625–632, 2013.

N. V. Silva, A. S. R. Oliveira, and N. B. Carvalho, “Evaluation of pulse modulators for all-digital agile transmitters,” in Proc. IEEE MTT-S Int. Microw. Symp., 2012.

R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and N. V. Silva, “Gigasample time-interleaved delta-sigma modulator for FPGA-based all-digital transmitters,” in Proc. 17th Euromicro Conf. Digit. Syst. Design, 2014, pp. 222–227.

Silva, T. O.

D. C. Dinis, R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and T. O. Silva, “Improving the performance of all-digital transmitter based on parallel delta-sigma modulators through propagation of state registers,” in Proc. IEEE 60th Int. Midwest Symp. Circuits Syst., 2017, pp. 1133–1137.

Simeone, O.

S.H. Park, O. Simeone, O. Sahin, and S. Shamai, “Fronthaul compression for cloud radio access networks: Signal processing advances inspired by network information theory,” IEEE Signal Process. Mag., vol. 31, no. 6, pp. 69–79, 2014.

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Soumyanath, K.

P. Seddighrad, A. Ravi, M. Sajadieh, H. Lakdawala, and K. Soumyanath, “A 3.6 GHz, 16 mW ΣΔ DAC for a 802.11n / 802.16e transmitter with 30 dB digital power control in 90 nm CMOS,” in Proc. 34th Eur. Solid-State Circuits Conf., 2008, pp. 202–205.

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Suematsu, N.

T. Maehata, K. Totani, S. Kameda, and N. Suematsu, “Concurrent dual-band 1-bit digital transmitter using band-pass delta-sigma modulator,” in Proc. Eur. Microw. Conf., 2013, pp. 1523–1526.

Sun, Q.

C.-L. I, S. Han, Z. Xu, S. Wang, Q. Sun, and Y. Chen, “New paradigm of 5G wireless internet,” IEEE J. Sel. Areas Commun., vol. 34, no. 3, pp. 474–482, 2016.

Tanio, M.

M. Tanio, S. Hori, M. Hayakawa, N. Tawa, K. Motoi, and K. Kunihiro, “A linear and efficient 1-bit digital transmitter with envelope delta-sigma modulation for 700 MHz LTE,” in Proc. IEEE MTT-S Int. Microw. Symp., 2014.

M. Tanio, S. Hori, N. Tawa, T. Yamase, and K. Kunihiro, “An FPGA-based all-digital transmitter with 28-GHz time-interleaved delta-sigma modulation,” in Proc. IEEE MTT-S Int. Microw. Symp., 2016.

M. Tanio, S. Hori, N. Tawa, and K. Kunihiro, “An FPGA-based all-digital transmitter with 9.6-GHz 2nd order time-interleaved delta-sigma modulation for 500-MHz bandwidth,” in Proc. IEEE MTT-S Int. Microw. Symp., 2017, pp. 149–152.

Tao, A.

B. Guo, W. Cao, A. Tao, and D. Samardzija, “LTE/LTE-A signal compression on the CPRI interface,” Bell Labs Tech. J., vol. 18, no. 2, pp. 117–133, 2013.

Tashiro, T.

N. Shibata, T. Tashiro, S. Kuwano, N. Yuki, J. Terada, and A. Otaka, “Mobile front-haul employing ethernet-based TDM-PON system for small cells,” in Proc. Opt. Fiber Commun. Conf., 2015, Paper M2J.1.

Tawa, N.

M. Tanio, S. Hori, N. Tawa, T. Yamase, and K. Kunihiro, “An FPGA-based all-digital transmitter with 28-GHz time-interleaved delta-sigma modulation,” in Proc. IEEE MTT-S Int. Microw. Symp., 2016.

M. Tanio, S. Hori, N. Tawa, and K. Kunihiro, “An FPGA-based all-digital transmitter with 9.6-GHz 2nd order time-interleaved delta-sigma modulation for 500-MHz bandwidth,” in Proc. IEEE MTT-S Int. Microw. Symp., 2017, pp. 149–152.

M. Tanio, S. Hori, M. Hayakawa, N. Tawa, K. Motoi, and K. Kunihiro, “A linear and efficient 1-bit digital transmitter with envelope delta-sigma modulation for 700 MHz LTE,” in Proc. IEEE MTT-S Int. Microw. Symp., 2014.

Teo, K. H.

S. Chung, R. Ma, S. Shinjo, H. Nakamizo, K. Parsons, and K. H. Teo, “Concurrent multiband digital outphasing transmitter architecture using multidimensional power coding,” IEEE Trans. Microw. Theory Techn., vol. 63, no. 2, pp. 598–613, 2015.

S. Chung, R. Ma, S. Shinjo, K. Yamanaka, and K. H. Teo, “A concurrent triple-band digital transmitter using feedforward noise cancellation for delta-sigma modulation,” in Proc. 12th Eur. Microw. Integr. Circuits Conf., 2017, pp. 400–403.

S. Chung, R. Ma, S. Shinjo, and K. H. Teo, “Inter-band carrier aggregation digital transmitter architecture with concurrent multi-band delta-sigma modulation using out-of-band noise cancellation,” in Proc. IEEE MTT-S Int. Microw. Symp., 2015.

S. Chung, R. Ma, K. H. Teo, and K. Parsons, “Outphasing multi-level RF-PWM signals for inter-band carrier aggregation in digital transmitters,” in Proc. IEEE Radio Wireless Symp., 2015, pp. 212–214.

Terada, J.

N. Shibata, T. Tashiro, S. Kuwano, N. Yuki, J. Terada, and A. Otaka, “Mobile front-haul employing ethernet-based TDM-PON system for small cells,” in Proc. Opt. Fiber Commun. Conf., 2015, Paper M2J.1.

Totani, K.

T. Maehata, K. Totani, S. Kameda, and N. Suematsu, “Concurrent dual-band 1-bit digital transmitter using band-pass delta-sigma modulator,” in Proc. Eur. Microw. Conf., 2013, pp. 1523–1526.

Vankka, J.

J. Sommarek, J. Vankka, J. Ketola, J. Lindeberg, and K. Halonen, “A digital modulator with bandpass delta-sigma modulator,” in Proc. 30th Eur. Solid-State Circuits Conf., 2004, pp. 159–162.

Vieira, J.

D. C. Dinis, R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and T. O. Silva, “Improving the performance of all-digital transmitter based on parallel delta-sigma modulators through propagation of state registers,” in Proc. IEEE 60th Int. Midwest Symp. Circuits Syst., 2017, pp. 1133–1137.

R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and T. O. e Silva, “Wideband all-digital transmitter based on multicore DSM,” in Proc. IEEE MTT-S Int. Microw. Symp., 2016.

R. F. Cordeiro, A. S. R. Oliveira, J. Vieira, and N. V. Silva, “Gigasample time-interleaved delta-sigma modulator for FPGA-based all-digital transmitters,” in Proc. 17th Euromicro Conf. Digit. Syst. Design, 2014, pp. 222–227.

Vieira, J. M. N.

R. F. Cordeiro, A. Prata, A. S. R. Oliveira, J. M. N. Vieira, and N. B. De Carvalho, “Agile all-digital RF transceiver implemented in FPGA,” IEEE Trans. Microw. Theory Techn., vol. 65, no. 11, pp. 4229–4240, 2017.

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J. Wang, Z. Jia, L. A. Campos, L. Cheng, C. Knittle, and G. K. Chang, “Delta-sigma digitization and optical coherent transmission of DOCSIS 3.1 signals in hybrid fiber coax networks,” IEEE J. Lightw. Technol., vol. 36, no. 2, pp. 568–579, 2018.

J. Wanget al., “Digital mobile fronthaul based on delta-sigma modulation for 32 LTE carrier aggregation and FBMC signals,” IEEE/OSA J. Opt. Commun. Netw., vol. 9, no. 2, pp. A233–A244, 2017.

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M. Xu, Z. Jia, J. Wang, L. A. Campos, and G. Chang, “A novel data-compression technology for digital mobile fronthaul with Lloyd algorithm and differential coding,” in Proc. Opt. Fiber Commun. Conf., 2018, Paper Tu2K.2.

J. Wang, Z. Jia, L. A. Campos, C. Knittle, and G. Chang, “Optical coherent transmission of 20x192-MHz DOCSIS 3.1 channels with 16384QAM based on delta-sigma digitization,” in Proc. Opt. Fiber Commun. Conf., 2017, Paper Th1K.1.

J. Wanget al., “Delta-sigma modulation for digital mobile fronthaul enabling carrier aggregation of 32 4G-LTE / 30 5G-FBMC signals in a single-λ 10-Gb/s IM-DD channel,” in Proc. Opt. Fiber Commun. Conf., 2016, Paper W1H.2.

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C.-L. I, S. Han, Z. Xu, S. Wang, Q. Sun, and Y. Chen, “New paradigm of 5G wireless internet,” IEEE J. Sel. Areas Commun., vol. 34, no. 3, pp. 474–482, 2016.

Wu, C.

C. Wu, E. Alon, and B. Nikolić, “A wideband 400 MHz-to-4 GHz direct RF-to-digital multimode ΔΣ receiver,” IEEE J. Solid-State Circuits, vol. 49, no. 7, pp. 1639–1652, 2014.

Xu, M.

M. Xu, F. Lu, J. Wang, L. Cheng, D. Guidotti, and G. K. Chang, “Key technologies for next-generation digital RoF mobile fronthaul with statistical data compression and multiband modulation,” IEEE J. Lightw. Technol., vol. 35, no. 17, pp. 3671–3679, 2017.

M. Xu, Z. Jia, J. Wang, L. A. Campos, and G. Chang, “A novel data-compression technology for digital mobile fronthaul with Lloyd algorithm and differential coding,” in Proc. Opt. Fiber Commun. Conf., 2018, Paper Tu2K.2.

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S. Chung, R. Ma, S. Shinjo, K. Yamanaka, and K. H. Teo, “A concurrent triple-band digital transmitter using feedforward noise cancellation for delta-sigma modulation,” in Proc. 12th Eur. Microw. Integr. Circuits Conf., 2017, pp. 400–403.

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M. Tanio, S. Hori, N. Tawa, T. Yamase, and K. Kunihiro, “An FPGA-based all-digital transmitter with 28-GHz time-interleaved delta-sigma modulation,” in Proc. IEEE MTT-S Int. Microw. Symp., 2016.

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S. Yan and E. Sanchez-Sinencio, “A continuous-time sigma-delta modulator with 88-dB dynamic range and 1.1-MHz signal bandwidth,” IEEE J. Solid-State Circuits, vol. 39, no. 1, pp. 75–86, 2004.

Yi, A.

J. Wang, C. Liu, M. Zhu, A. Yi, L. Cheng, and G. K. Chang, “Investigation of data-dependent channel cross-modulation in multiband radio-over-fiber systems,” IEEE J. Lightw. Technol., vol. 32, no. 10, pp. 1861–1871, 2014.

Yuki, N.

N. Shibata, T. Tashiro, S. Kuwano, N. Yuki, J. Terada, and A. Otaka, “Mobile front-haul employing ethernet-based TDM-PON system for small cells,” in Proc. Opt. Fiber Commun. Conf., 2015, Paper M2J.1.

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J. Wang, C. Liu, M. Zhu, A. Yi, L. Cheng, and G. K. Chang, “Investigation of data-dependent channel cross-modulation in multiband radio-over-fiber systems,” IEEE J. Lightw. Technol., vol. 32, no. 10, pp. 1861–1871, 2014.

Zounes, T.

A. Pozsgay, T. Zounes, R. Hossain, M. Boulemnakher, V. Knopik, and S. Grange, “A fully digital 65nm CMOS transmitter for the 2.4-to-2.7 GHz WiFi/WiMAX bands using 5.4 GHz ΔΣ RF DACs,” in Proc. IEEE Int. Solid-State Circuits Conf., 2008, pp. 360–361.

3GPP TR 38.801: (1)

3GPP TR 38.801: “Study on new radio access technology: Radio access architecture and interfaces,” V14.0.0, 2017–03 (Release 14).

3GPP TS 36.104: (1)

3GPP TS 36.104: “Evolved Universal Terrestrial Radio Access (E-UTRA): Base Station (BS) radio transmission and reception,” V15.2.0, 2018–03 (Release 15).

3GPP TS 36.141: (1)

3GPP TS 36.141: “Base Station (BS) Conformance Testing,” V15.3.0, 2018–06 (Release 15).

3GPP TS 38.401: (1)

3GPP TS 38.401: “NG-RAN: Architecture description,” V15.1.0, 2018–03 (Release 15).

Bell Labs Tech. J. (1)

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