CN108512788B - PCM module based on noise shaping for digital mobile forward link - Google Patents
PCM module based on noise shaping for digital mobile forward link Download PDFInfo
- Publication number
- CN108512788B CN108512788B CN201810274285.6A CN201810274285A CN108512788B CN 108512788 B CN108512788 B CN 108512788B CN 201810274285 A CN201810274285 A CN 201810274285A CN 108512788 B CN108512788 B CN 108512788B
- Authority
- CN
- China
- Prior art keywords
- signal
- quantizer
- fir filter
- noise
- digital mobile
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03828—Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties
- H04L25/03834—Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties using pulse shaping
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/516—Details of coding or modulation
- H04B10/524—Pulse modulation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B14/00—Transmission systems not characterised by the medium used for transmission
- H04B14/02—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation
- H04B14/04—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation using pulse code modulation
- H04B14/046—Systems or methods for reducing noise or bandwidth
Abstract
The invention discloses a PCM module based on noise shaping and used for a digital mobile forward link, and relates to the field of optical and wireless converged access networks. The PCM module includes a quantizer and a FIR filter with a feedback loop, the quantizer and FIR filter forming a noise shaping based PCM module that is capable of changing the frequency domain distribution of quantization noise generated by the baseband OFDM signal as it passes through the quantizer, reducing the quantization noise power on data modulated subcarriers and increasing the power on non-data modulated subcarriers. The invention can effectively reduce the error vector magnitude of the demodulated data caused by quantization noise, realize high spectral efficiency and high-quality transmission, and effectively solve the problem of contradiction between the spectral efficiency (quantization bit number) and the transmission quality of signal transmission between the BBU and the RRH in the digital mobile fronthaul.
Description
Technical Field
The invention relates to the field of optical and wireless converged access networks, in particular to a Pulse Code Modulation (PCM) module based on noise shaping and used for a digital mobile forward link.
Background
A Centralized Radio access network (C-RAN) is a green Radio access network architecture (Clean system) based on Centralized Processing (Centralized Processing), cooperative Radio (Collaborative Radio) and Real-time Cloud computing architecture (Real-time Cloud Infrastructure). The essential of the method is that the number of base station rooms is reduced, energy consumption is reduced, a cooperation and virtualization technology is adopted, resource sharing and dynamic scheduling are realized, and spectrum efficiency is improved, so that operation with low cost, high bandwidth and flexibility is achieved.
In the C-RAN, a portion connected by a fiber link between a Base Band Unit (BBU) and a Remote Radio Head (RRH) is called mobile fronthaul. In the existing mobile forward transmission, a Digital-over-fiber Radio technology (D-RoF) based On Common Public Radio Interface (CPRI) Digital signals is adopted, an LTE (Long Term Evolution) signal at the BBU end is quantized into a binary OOK (On-Off Keying) signal through two paths of I/Q15 bits, and then transmitted through an optical fiber through Intensity Modulation/Direct Detection (IM/DD, Intensity Modulation/Direct Detection). The spectrum efficiency is reduced, the bandwidth requirement on the optical fiber channel is increased, and the requirements on optical devices and bandwidth are higher and higher along with the increase of the rate of the BBU end wireless signals. On one hand, increasing the number of quantization bits can reduce quantization noise, thereby ensuring high quality transmission, but as more bits are required, the spectral efficiency is reduced; on the other hand, reducing the number of quantization bits can improve spectral efficiency, but can increase quantization noise, resulting in impaired transmission quality. How to solve the contradiction is an important problem to be solved urgently in the next generation digital mobile forward link.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a PCM module based on noise shaping for a digital mobile forward link, which can effectively reduce the Error Vector Magnitude (EVM) of demodulation data caused by quantization noise and realize high-frequency spectrum efficiency and high-quality transmission.
In order to achieve the above purposes, the technical scheme adopted by the invention is as follows: there is provided a PCM module based on noise shaping for a digital mobile fronthaul link, the PCM module comprising: a quantizer and a FIR filter with a feedback loop, the quantizer and the FIR filter forming a noise-shaping based PCM block capable of changing a frequency domain distribution of quantization noise generated by the baseband OFDM signal while passing through the quantizer, reducing quantization noise power on the data-modulated subcarriers and increasing power on the non-data-modulated subcarriers.
On the basis of the above technical solution, the PCM module based on noise shaping includes: a quantizer, a FIR filter and two adders; the signal e n that enters the quantizer for the first time]After being processed by a quantizer, a quantized signal e is obtainedq[n]N is the serial number of the input signal; an adder subtracts the signals before and after quantization to obtain a signalq[n](q[n]＝eq[n]-e[n]) Then, the signal q [ n ]]Sending the signal to an FIR filter; filtering by FIR filter to obtain signal qf[n](ii) a Another adder adds the signal qf[n]And a baseband OFDM signal s [ n ]]And adding to obtain the signal input to the quantizer at the next moment.
On the basis of the above technical scheme, the signal qf[n]The following requirements are met:
qf[n]＝a1q[n-1]+a2q[n-2]+…+aMq[n-M]；
wherein M is the order of the filter and is a positive integer which is more than or equal to 1 and less than n; a isi(i ═ 1,2, …, M) is a preset FIR filter coefficient.
On the basis of the technical scheme, the preset FIR filter coefficient meets the following preset rules: so that the signal qf[n]The spectrum of (a) is reduced on the data modulated subcarriers and the power is increased on the non-data modulated subcarriers.
On the basis of the above technical solution, the FIR filter includes: m delayers, M multipliers and M-1 adders form an FIR filter of M orders, wherein M is a positive integer which is more than or equal to 1 and less than n; the output of each delayer is used as the input of the next-order delayer and the same-order multiplier, the output of the first-order multiplier is used as the input of the first-order adder, the outputs of the other multipliers are fed back to the previous-order adder as the input of the previous-order adder, and the output of each adder is also used as the input of the next-order adder.
On the basis of the technical scheme, the digital mobile forward link comprises a centralized BBU pool serving as a sending end and an RRH serving as a receiving end, and the centralized BBU pool and the RRH are connected through an intensity modulation/direct detection optical fiber link; the centralized BBU pool comprises a baseband processing module, a PCM module and a framing module which are connected in sequence; the RRH comprises a frame decoding module, a PCM decoding module, a DAC, a radio frequency front end and an antenna which are connected in sequence.
On the basis of the technical scheme, the intensity modulation/direct detection optical fiber link is an OOK/PAM-4 optical fiber link.
The invention has the beneficial effects that:
the invention adds a feedback loop and a designed finite-length single-bit impulse response filter in a quantizer part, thereby forming a PCM module based on noise shaping. The PCM module based on noise shaping changes the frequency domain distribution of quantization noise generated when a baseband OFDM signal passes through the PCM module, reduces the power of the quantization noise on a data modulation subcarrier, and increases the power on a non-data modulation subcarrier, so that the demodulation data EVM caused by the quantization noise can be effectively reduced under the condition that the quantization bit number is certain, namely the total power of the quantization noise is certain, and the problem of contradiction between the signal transmission spectrum efficiency (quantization bit number) and the transmission quality between BBU and RRH in digital mobile fronthaul is effectively solved.
Drawings
Fig. 1 is a schematic structural diagram of a digital mobile forward link for use in the present invention;
FIG. 2 is a schematic diagram of a PCM module based on noise shaping according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an FIR filter according to an embodiment of the present invention;
FIG. 4 is a quantization noise power distribution diagram;
fig. 5 is a diagram of EVM versus demodulated data in a simulation example.
Detailed Description
The invention is described in further detail below with reference to the figures and the embodiments.
Aiming at the problem that in the prior art, the frequency spectrum efficiency is reduced because quantization noise is reduced by increasing the quantization bit number; or the spectrum efficiency is improved by reducing the quantization bit number, which leads to the contradiction that the transmission quality is damaged. The PCM module based on noise shaping for the digital mobile forward link can effectively reduce the error vector magnitude of demodulation data caused by quantization noise, realize high-frequency spectrum efficiency and high-quality transmission and effectively solve the related contradiction problem in the prior art.
The invention provides a PCM module based on noise shaping for a digital mobile forward link. The digital mobile fronthaul link may be as shown in fig. 1, and includes a centralized BBU pool as a sending end and an RRH as a receiving end, where the centralized BBU pool and the RRH are connected by an intensity modulation/direct detection (IM/DD) optical fiber link. For example, as shown in fig. 1, the fiber link connection can be directly calibrated at low cost by OOK/PAM-4(On-Off Keying/Pulse Amplitude Modulation-4, binary On-Off Keying/4-level Pulse Amplitude Modulation). Specifically, the centralized BBU pool comprises a baseband processing module (BBU), a PCM module and a framing module which are connected in sequence; the RRH includes a frame decoding module, a PCM decoding module, a DAC (Digital to Analog Converter), a radio frequency front end and an antenna, which are connected in sequence. After baseband OFDM (Orthogonal Frequency Division Multiplexing) signals in the centralized BBU pool are processed by a baseband processing module (BBU), baseband OFDM complex continuous signals are generated, and a real part (I path) and an imaginary part (Q path) of the baseband OFDM complex continuous signals respectively pass through a PCM module to generate discrete digital signals; and after framing by the framing module, the signal is transmitted to the RRH through the intensity modulation/direct detection optical fiber link. A frame decoding module in the RRH performs frame decoding operation on the signals to obtain baseband discrete signals, then PCM decoding is performed to obtain baseband OFDM continuous signals, and a real part (I path) and an imaginary part (Q path) of the baseband OFDM continuous signals respectively enter a radio frequency front end after being changed into analog signals through a DAC and then are sent to corresponding antennas to be sent.
In the invention, a feedback loop and a designed FIR (Finite impulse response) filter are added in a quantizer part in a PCM module of an original digital mobile forward interface, thereby forming a PCM module based on noise shaping. The PCM module based on noise shaping can change the frequency domain distribution of quantization noise generated by baseband OFDM signals through the PCM module, reduce the power of the quantization noise on data modulation subcarriers, and increase the power on non-data modulation subcarriers, so that the demodulation data EVM caused by the quantization noise can be effectively reduced under the condition that the number of quantization bits is certain, namely the total power of the quantization noise is certain. In other words, under the same EVM performance requirement, the required quantization bit number can be reduced, thereby improving the spectrum efficiency.
In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail with reference to the accompanying drawings and specific embodiments.
The embodiment of the invention provides a PCM module based on noise shaping for a digital mobile forward link, which comprises: a quantizer and a FIR filter with a feedback loop, said quantizer and FIR filter forming a noise shaping based PCM block that is able to change the frequency domain distribution of the quantization noise generated by the baseband OFDM signal when passing through (i.e. when passing through the quantizer of the noise shaping based PCM block), reducing the quantization noise power on the data modulated subcarriers and increasing the power on the non-data modulated subcarriers.
Further, in an alternative embodiment, as shown in fig. 2, the specific structure of the PCM module based on noise shaping includes: one quantizer, one FIR filter and two adders. The signal e n that enters the quantizer for the first time](n is the serial number of the input signal), and a quantized signal e is obtained after the processing of the quantizerq[n](ii) a An adder subtracts the signals before and after quantization to obtain a signal q [ n ]](q[n]＝eq[n]-e[n]) Then, the signal q [ n ]]Sending the signal to an FIR filter; filtering by FIR filter to obtain signal qf[n](ii) a Another adder adds the signal qf[n]And a baseband OFDM signal s [ n ]]And adding to obtain the signal input to the quantizer at the next moment.
Further, in an alternative embodiment, as shown in fig. 3, the specific structure of the FIR filter includes: m time delay units (Z)-1) M multipliers and (M-1) adders, forming an FIR filter of M orders, wherein M is a positive integer greater than or equal to 1 and less than n; the output of each delayer is used as the input of the next-order delayer and the same-order multiplier, the output of the first-order multiplier is used as the input of the first-order adder, the outputs of the rest multipliers (namely the rest multipliers except the first-order multiplier) are fed back to the last-order adder as the input of the last-order adder, and the output of each adder is also used as the input of the next-order adder.
FIR filter based on the above structure, signal q obtained after processingf[n]The following requirements are met:
qf[n]＝a1q[n-1]+a2q[n-2]+…+aMq[n-M]；
wherein M is the order of the filter and is a positive integer greater than or equal to 1 and less than n, ai(i-1, 2, …, M) are designed filter coefficients that satisfy certain design rules such that the signal q is a signal qf[n]The spectrum of (a) decreases on the data-modulated subcarriers and the power increases on the non-data-modulated subcarriers, as shown in figure 4.
The embodiment of the invention adds a feedback loop and a designed finite-length single-bit impulse response filter in a quantizer part, thereby forming a PCM module based on noise shaping. The PCM module based on noise shaping changes the frequency domain distribution of quantization noise generated when a baseband OFDM signal passes through the PCM module, reduces the power of the quantization noise on a data modulation subcarrier, and increases the power on a non-data modulation subcarrier, so that the demodulation data EVM caused by the quantization noise can be effectively reduced under the condition that the quantization bit number is certain, namely the total power of the quantization noise is certain, and the problem of contradiction between the signal transmission spectrum efficiency (quantization bit number) and the transmission quality between BBU and RRH in digital mobile fronthaul is effectively solved.
In order to further verify the technical effects achieved by the present invention, the following describes in detail the technical effects of the PCM module based on noise shaping for digital mobile fronthaul link according to the present invention with reference to the accompanying drawings and simulation examples.
In the simulation example, the EVM performance of the demodulated signal is shown in fig. 4 by taking a quantized bit number of 5, 64QAM-OFDM signal as an example. It can be seen that the demodulation signal EVM of the PCM (NS-PCM) scheme based on noise shaping proposed by the present invention is significantly improved compared to the existing PCM scheme.
The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention.
Those not described in detail in this specification are within the skill of the art.
Claims (6)
1. A PCM module for digital mobile fronthaul link based on noise shaping, the PCM module comprising: a quantizer and a FIR filter having a feedback loop, the quantizer and FIR filter forming a noise shaping based PCM block capable of changing the frequency domain distribution of quantization noise generated by the baseband OFDM signal when passing through the quantizer, reducing the quantization noise power on data modulated subcarriers and increasing the power on non-data modulated subcarriers;
the FIR filter includes: m delayers, M multipliers and M-1 adders form an FIR filter of M orders, wherein M is a positive integer which is more than or equal to 1 and less than n;
the output of each delayer is used as the input of the next-order delayer and the same-order multiplier, the output of the first-order multiplier is used as the input of the first-order adder, the outputs of the other multipliers are fed back to the previous-order adder as the input of the previous-order adder, and the output of each adder is also used as the input of the next-order adder.
2. The noise-shaping based PCM module for a digital mobile forward link of claim 1, wherein said noise-shaping based PCM module comprises: a quantizer, a FIR filter and two adders;
the signal e n that enters the quantizer for the first time]After being processed by a quantizer, a quantized signal e is obtainedq[n]N is the serial number of the input signal; an adder subtracts the signals before and after quantization to obtain a signal q [ n ]](q[n]＝eq[n]-e[n]) Then, the signal q [ n ]]Sending the signal to an FIR filter; filtering by FIR filter to obtain signal qf[n](ii) a Another adder adds the signal qf[n]And a baseband OFDM signal s [ n ]]And adding to obtain the signal input to the quantizer at the next moment.
3. The PCM module for digital mobile fronthaul link based on noise shaping as claimed in claim 2 wherein said signal qf[n]The following requirements are met:
qf[n]＝a1q[n-1]+a2q[n-2]+…+aMq[n-M]；
wherein M is the order of the filter and is a positive integer which is more than or equal to 1 and less than n; a isi(i ═ 1,2, …, M) is a preset FIR filter coefficient.
4. The noise-shaping based PCM module for a digital mobile fronthaul link of claim 3 wherein said preset FIR filter coefficients satisfy the following preset rules: so that the signal qf[n]The spectrum of (a) is reduced on the data modulated subcarriers and the power is increased on the non-data modulated subcarriers.
5. A PCM module for digital mobile forward link based noise shaping according to any of claims 1 to 4, wherein: the digital mobile fronthaul link comprises a centralized BBU pool serving as a sending end and an RRH serving as a receiving end, and the centralized BBU pool and the RRH are connected through an intensity modulation/direct detection optical fiber link;
the centralized BBU pool comprises a baseband processing module, a PCM module and a framing module which are connected in sequence; the RRH comprises a frame decoding module, a PCM decoding module, a DAC, a radio frequency front end and an antenna which are connected in sequence.
6. The noise-shaping based PCM module for a digital mobile forward link of claim 5, wherein: the intensity modulation/direct detection optical fiber link is an OOK/PAM-4 optical fiber link.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810274285.6A CN108512788B (en) | 2018-03-29 | 2018-03-29 | PCM module based on noise shaping for digital mobile forward link |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810274285.6A CN108512788B (en) | 2018-03-29 | 2018-03-29 | PCM module based on noise shaping for digital mobile forward link |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108512788A CN108512788A (en) | 2018-09-07 |
| CN108512788B true CN108512788B (en) | 2020-12-08 |
Family
ID=63379501
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810274285.6A Active CN108512788B (en) | 2018-03-29 | 2018-03-29 | PCM module based on noise shaping for digital mobile forward link |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108512788B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109495415B (en) * | 2018-10-12 | 2021-05-14 | 武汉邮电科学研究院有限公司 | Digital mobile forward transmission method and link based on digital cosine transform and segmented quantization |
| CN113938200B (en) * | 2021-09-07 | 2023-03-28 | 华中科技大学 | Digital mobile forward transmission method and device based on Delta-Sigma modulation |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1588806A (en) * | 2004-09-03 | 2005-03-02 | 浙江大学 | Quantizing noise shaping modulator and quantizing noise shaping method |
| CN2742680Y (en) * | 2004-09-03 | 2005-11-23 | 浙江大学 | Quantized noise shaping modulator |
| CN101282322A (en) * | 2008-03-05 | 2008-10-08 | 中科院嘉兴中心微系统所分中心 | Built-in digital filter apparatus for physical layer of wireless intermediate-range sensing network |
| CN106788476A (en) * | 2016-12-12 | 2017-05-31 | 武汉邮电科学研究院 | Based on the Walsh yards of mobile forward pass device and method of channel aggregation |
| CN107735967A (en) * | 2015-06-18 | 2018-02-23 | 华为技术有限公司 | The cascade waveform modulated with embedded control signal for high-performance mobile forward pass |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9806816B2 (en) * | 2014-10-10 | 2017-10-31 | Futurewei Technologies, Inc. | Re-modulation crosstalk and intensity noise cancellation in wavelength-division multiplexing (WDM) passive optical networks (PONs) |
-
2018
- 2018-03-29 CN CN201810274285.6A patent/CN108512788B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1588806A (en) * | 2004-09-03 | 2005-03-02 | 浙江大学 | Quantizing noise shaping modulator and quantizing noise shaping method |
| CN2742680Y (en) * | 2004-09-03 | 2005-11-23 | 浙江大学 | Quantized noise shaping modulator |
| CN101282322A (en) * | 2008-03-05 | 2008-10-08 | 中科院嘉兴中心微系统所分中心 | Built-in digital filter apparatus for physical layer of wireless intermediate-range sensing network |
| CN107735967A (en) * | 2015-06-18 | 2018-02-23 | 华为技术有限公司 | The cascade waveform modulated with embedded control signal for high-performance mobile forward pass |
| CN106788476A (en) * | 2016-12-12 | 2017-05-31 | 武汉邮电科学研究院 | Based on the Walsh yards of mobile forward pass device and method of channel aggregation |
Non-Patent Citations (3)
| Title |
|---|
| "Least squares Theory and Design of Optimal Niose Shaping Filters";Werner Verhelst等;《AES 22nd International Conference on Virtual ,Synthetic and Entertainment Audio》;20021231;图2，第1-2页 * |
| "Quntization Niose shaping for LTE Fronthaul Downlink";Mahamda,Alaa等;《LUP Student papers》;20170306;第ii页，第21-26页 * |
| "移动前传光网络新型方案";邓宁等;《邮电设计技术》;20151211;全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108512788A (en) | 2018-09-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US10880006B2 (en) | Systems and methods for multiband delta sigma digitization | |
| CN107534487B (en) | The numerical method and device of Multilevel modulation formatted analog signal and control word | |
| US8989088B2 (en) | OFDM signal processing in a base transceiver system | |
| US9059778B2 (en) | Frequency domain compression in a base transceiver system | |
| RU2667071C1 (en) | Cascade modulation of the waveform with the in line control signal for the high-productive peripheral transit of mobile communication | |
| Kim et al. | Experimental demonstration of CPRI data compression based on partial bit sampling for mobile front-haul link in C-RAN | |
| Guo et al. | CPRI compression transport for LTE and LTE-A signal in C-RAN | |
| Zhang et al. | Toward terabit digital radio over fiber systems: Architecture and key technologies | |
| US11025461B2 (en) | Systems and methods for delta-sigma digitization | |
| CN113938200B (en) | Digital mobile forward transmission method and device based on Delta-Sigma modulation | |
| CN107017927B (en) | Base station DAC precision configuration method in large-scale MIMO system | |
| CN108512788B (en) | PCM module based on noise shaping for digital mobile forward link | |
| US9398489B1 (en) | Method and apparatus for context based data compression in a communication system | |
| RU2501168C2 (en) | Wireless transmitter, mobile station and method for wireless transmission of data units | |
| Hinrichs et al. | Analog vs. next-generation digital fronthaul: How to minimize optical bandwidth utilization | |
| CN109495415B (en) | Digital mobile forward transmission method and link based on digital cosine transform and segmented quantization | |
| Zhu et al. | FPGA-based adaptive space–time compression towards 5G MIMO fronthaul | |
| CN113132008B (en) | Efficient mobile forward-transmission-oriented method and device for aggregating and separating flexible bandwidth channels | |
| Habel et al. | 5 Gbit/s real-time processing using π/4-shift DQPSK for bidirectional radio-over-fibre system | |
| CN109792426B (en) | Method for adapting null cyclic prefix to frequency domain null single carrier communication system | |
| JP2013016978A (en) | Optical communication system and optical communication method | |
| CN106160989B (en) | Method and device for capacity enhancement in passive optical network | |
| CN116996075B (en) | Layered multi-level noise shaping Delta-sigma modulation method | |
| CN111049634B (en) | Low-delay carrier aggregation method and device for 5G mobile forward transmission | |
| Osorio et al. | Dual-mode distance-adaptive transceiver architecture for 5G optical fiber fronthaul |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |