CN108880691B

CN108880691B - Method, apparatus and computer readable medium for demodulating a signal

Info

Publication number: CN108880691B
Application number: CN201710330758.5A
Authority: CN
Inventors: 冯翰林
Original assignee: Nokia Shanghai Bell Co Ltd
Current assignee: Nokia Shanghai Bell Co Ltd
Priority date: 2017-05-11
Filing date: 2017-05-11
Publication date: 2020-07-31
Anticipated expiration: 2037-05-11
Also published as: CN108880691A; WO2018206807A1

Abstract

Embodiments of the present disclosure relate to methods, apparatuses, and computer-readable media for demodulating signals. For example, the methods of embodiments of the present disclosure may enable demodulation of signals. In the demodulation process, the least significant bit signal is demodulated by being associated with the most significant bit signal obtained by the demodulation.

Description

Method, apparatus and computer readable medium for demodulating a signal

Technical Field

Embodiments of the present disclosure relate generally to communication technology and, more particularly, relate to a method, apparatus, and computer-readable medium for demodulating signals in optical fiber communication.

Background

In recent years, a 4-level pulse amplitude modulation (PAM-4) signal format has been the subject of intense research in next-generation passive optical networks (NG-PONs) and short-distance optical fiber transmission systems. Compared to non-return-to-zero (NRZ) formats, PAM-4 techniques can improve channel spectral efficiency, which further improves transmission capacity. Furthermore, due to the high spectral efficiency, the dispersion tolerance of PAM-4 signals is superior to NRZ and duobinary signals. At the same time, the transmitter and/or receiver of PAM-4 has a simple structure by using strong modulation (IM) and Direct Detection (DD). However, there are still some problems to be solved in PAM-4.

Disclosure of Invention

In general, embodiments of the present disclosure relate to device-to-device communication methods and corresponding network devices and terminal devices.

In a first aspect, embodiments of the present disclosure provide a method of demodulating a signal. The method comprises the following steps: dividing a modulated signal generated based on a first signal and a second signal into a first part and a second part; demodulating the first portion to generate a third signal, the third signal including information of the first signal; demodulating the second portion in association with the third signal generates a fourth signal, the fourth signal including information of the second signal.

In a second aspect, embodiments of the present disclosure provide a communication device. A communication device at least one processor; and a memory coupled with the at least one processor, the memory having instructions stored therein that, when executed by the at least one processor, cause the communication device to perform acts comprising: dividing a modulated signal generated based on a first signal and a second signal into a first part and a second part; demodulating the first portion to generate a third signal, the third signal including information of the first signal; demodulating the second portion in association with the third signal generates a fourth signal, the fourth signal including information of the second signal.

In a third aspect, embodiments of the present disclosure provide a computer-readable medium. The computer readable medium has stored thereon instructions that, when executed by a processor of a machine, cause the machine to perform: dividing a modulated signal generated based on a first signal and a second signal into a first part and a second part; demodulating the first portion to generate a third signal, the third signal including information of the first signal; demodulating the second portion in association with the third signal generates a fourth signal, the fourth signal including information of the second signal.

It should be understood that the statements herein reciting aspects are not intended to limit the critical or essential features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description.

Drawings

The above and other features, advantages and aspects of various embodiments of the present disclosure will become more apparent by referring to the following detailed description when taken in conjunction with the accompanying drawings, in which:

fig. 1 illustrates an example communication system in which embodiments of the present disclosure may be implemented;

fig. 2 shows an example of a prior art technique for demodulating a PAM-4 signal;

FIG. 3 shows a schematic diagram of certain signal processing according to an embodiment of the present disclosure;

FIG. 4 illustrates a flow diagram of a demodulation method in accordance with certain embodiments of the present disclosure;

FIG. 5 illustrates a block diagram of an apparatus in accordance with certain embodiments of the present disclosure;

FIG. 6 illustrates a block diagram of an apparatus according to certain embodiments of the present disclosure;

FIG. 7 illustrates a simulation diagram in accordance with certain embodiments of the present disclosure; and

fig. 8 shows a graph of results according to certain embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numbers refer to the same or similar elements.

Detailed Description

Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While certain embodiments of the present disclosure are shown in the drawings, it is to be understood that the present disclosure may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but rather are provided for a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the disclosure are for illustration purposes only and are not intended to limit the scope of the disclosure.

The term "communication device" as used herein refers to a base station or other entity or node having a particular function in a communication network. A "base station" (BS) may represent a node B (NodeB or NB), an evolved node B (eNodeB or eNB), a Remote Radio Unit (RRU), a Radio Head (RH), a Remote Radio Head (RRH), a relay, or a low power node such as a pico base station, a femto base station, or the like. In the context of the present disclosure, the terms "communication device" and "base station" may be used interchangeably for purposes of discussion convenience, and may primarily be referred to as an eNB as an example of a network device.

The term "terminal equipment" or "user equipment" (UE) as used herein refers to any terminal equipment capable of wireless communication with a base station or with each other. As an example, the terminal device may include a Mobile Terminal (MT), a Subscriber Station (SS), a Portable Subscriber Station (PSS), a Mobile Station (MS), or an Access Terminal (AT), and the above-described devices in a vehicle. In the context of the present disclosure, the terms "terminal device" and "user equipment" may be used interchangeably for purposes of discussion convenience.

The terms "include" and variations thereof as used herein are inclusive and open-ended, i.e., "including but not limited to. The term "based on" is "based, at least in part, on". The term "certain embodiments" means "at least certain embodiments"; the term "another embodiment" means "at least one additional embodiment". Relevant definitions for other terms will be given in the following description.

As described above, the PAM-4 technique has been a popular problem in the field of optical fiber communication. In order to apply PAM-4 signals in NG-PONs and further reduce costs, there are still some issues that need to be solved. For example, existing demodulation schemes for PAM-4 signals can be divided into two categories. One type is to use three threshold decision circuits to demodulate the PAM-4 signal. By such a scheme, the PAM-4 signal can be directly transformed to different levels. However, if the PAM-4 signal has a very high baud rate, it would be very difficult and costly to implement an analog circuit for this circuit. Another solution is based on analog-to-digital converters (ADCs). By using an ADC, the received PAM-4 signal may be sampled and converted to different levels using either on-line or off-line digital signal processing techniques. However, the cost of a high performance ADC is prohibitive. For the above reasons, there is a need for a cost-effective, high performance demodulation scheme for PAM-4, which can be applied on a large scale in NG-PON and short-range fiber transmission.

To address these and other potential problems, at least in part, embodiments of the present disclosure provide a demodulation method. According to the embodiments of the present disclosure, a simplified cost-effective PAM-4 demodulation method may be achieved. The PAM-4 demodulation may be determined based on a single threshold.

Embodiments of the present disclosure have at least the advantage over the prior art that the PAM-4 signal can be demodulated by using only one decision threshold, ordinary digital binary CDRs and passive device elements can be used to demodulate PAM-4 signals without using complex multi-level threshold slicers, which reduces cost.

Fig. 1 illustrates an example communication network 100 in which embodiments of the present disclosure may be implemented. Communication network 100 may include a transmitting device 102, an optical fiber 104, and a receiving device 106. It should be understood that although not shown, other devices such as repeaters, fiber connectors, passive devices such as couplers, etc. may also be included in the communication system 100. It should be understood that the number of transmitters, receivers, and optical fibers shown in FIG. 1 is for illustration purposes only and is not intended to be limiting. Network 100 may include any suitable number of transmitting devices, receiving devices, and optical fibers.

Communications in network 100 may be implemented in accordance with any suitable communication protocol, including, but not limited to, first-generation (1G), second-generation (2G), third-generation (3G), fourth-generation (4G), and fifth-generation (5G) cellular communication protocols, wireless local area network communication protocols such as Institute of Electrical and Electronics Engineers (IEEE)802.11, and/or any other protocol now known or later developed. Moreover, the communication may be via any suitable wireless communication technique and/or fiber optic communication, including, but not limited to, Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple Input Multiple Output (MIMO), orthogonal frequency division multiple access (OFDM), and/or any other technique now known or later developed.

Fig. 2 shows an example 200 of a prior art method for demodulating a PAM-4 signal, as shown, a PAM-4 signal 202 is received by a receiver 106, the signal 202 is divided 230 into two groups (a first user group and a second user group), the signal 204 of the first user group generates 250 a Most Significant Bit (MSB) signal 208 via clock data recovery, the signal 206 of the second user group generates 270 a least significant bit (L SB) signal 210, a decision via two voltage thresholds and then an addition operation is required in the process of generating the signal 210 by the signal 206.

Fig. 3 illustrates a schematic diagram of signal processing 300 according to some embodiments of the present disclosure. The signal processing shown in fig. 3 may be implemented at the receiving device 106. It should be understood that the schematic diagram of the process 300 shown in fig. 3 is merely exemplary and not limiting. As shown in fig. 3, signal 302 is a modulated signal. For example, signal 302 may be a modulated signal in a PAM-4 format. Although not shown, signal 302 is formed based on two signal (referred to as a "first signal" and a second signal) modulations. Although not shown, in some embodiments, signal 302 may be detected by a light detector (PD) (not shown). For example only, the amplitude of the first signal may be "2, -2, -2", the amplitude of the second signal may be "-1, -1, -1", and the amplitude of signal 302 may be "1, -3, -3, 1, 3, -3".

The modulated signal 302 is divided 330 into a first portion 304 and a second portion 306. In certain embodiments, the first portion 304 and the second portion 306 have a predetermined power ratio. For example, the predetermined power ratio may be 1 in some embodiments. I.e. the first part and the second part have the same power.

The first portion 304 is demodulated 340 to generate a third signal 308. The third signal 308 comprises information of the first signal. For example, the third signal 308 may have the same signal sequence as the first signal, but a different amplitude. During demodulation 340, the first portion 304 may be demodulated using only one threshold (e.g., a zero threshold).

In certain embodiments, the clock data recovers the first portion 304 to generate the third signal 308 based on a predetermined threshold. For example, Clock Data Recovery (CDR) may be used for clock data recovery first portion 304 to generate third signal 308. In some embodiments, the amplitude of the first portion 304 may be amplified during demodulation.

In some embodiments, the third signal 308 is divided 350 into a third portion 310 and a fourth portion 312, the third portion 310 and the fourth portion 312 having the same power. For example only, while the amplitude of the first signal may be "2, -2, -2", the amplitudes of the third portion 310 and the fourth portion 312 may be "2, -2, -2". In some embodiments, an optical splitter may be used to split third signal 308 into third portion 310 and fourth portion 312.

The second portion 306 is demodulated in association with the third signal 308 to generate a fourth signal 316. The fourth signal 316 includes information of the second signal. In some embodiments, the second portion 306 is enlarged 360. In some embodiments, the amplified second portion 314 is differentially processed 370 with any of the third portion 310 and the fourth portion 312 to generate a fourth signal 316. In certain embodiments, the amplified second portion 314 has a predetermined power ratio to the third portion 310 and the fourth portion 312. For example, the power ratio may be 1.5. It should be understood that the above power ratios are exemplary only. Those skilled in the art can set and adjust to obtain the desired power ratio. By way of example only, the amplified second portion 314 and fourth portion 312 are shown in fig. 3 as being differentially processed 370.

For example only, the amplitude of the amplified second portion 314 may be "1, -3, -3, 1, 3, -3", the amplitude of the fourth portion 312 may be "2, -2, -2", and the amplitude of the fourth signal 316 generated by the differencing process may be "-1, -1, -1".

In certain embodiments. A passive Balun (Balun) converter (not shown) may be used to generate the fourth signal 316. A balun converter is used as the subtractor. Specifically, the amplified second portion 314 is sent to the positive input port of the balun and the fourth portion 312 is sent to the negative input port of the balun. The output port of the balun outputs a fourth signal 316. It should be understood that other components may be used to perform the differential processing. For example, the differential operation may be performed using a normal differential output PD. In such a case, the amplification of the first portion 304 and the second portion 306 may be adjusted for subsequent differential operations.

Fig. 4 is a flow chart of a method 400 according to certain embodiments of the present disclosure. The method 400 shown in fig. 4 may be implemented at the receiver 106 in fig. 1.

At 402, a modulated signal 302 generated based on a first signal and a second signal is split into a first portion 304 and a second portion 306. In certain embodiments, the first portion 304 and the second portion 306 have a predetermined power ratio. For example, the predetermined power ratio may be 1 in some embodiments. I.e. the first part and the second part have the same power.

At 404, the first portion 304 is demodulated to generate a third signal 308. The third signal 308 comprises information of the first signal. For example, the third signal 308 may have the same signal sequence as the first signal, but a different amplitude. During demodulation 340, the first portion 304 may be demodulated using only one threshold (e.g., a zero threshold).

In certain embodiments, the clock data recovers the first portion 304 to generate the third signal 308 based on a predetermined threshold. For example, Clock Data Recovery (CDR) may be used for clock data recovery first portion 304 to generate third signal 308. In some embodiments, the amplitude of the first portion 304 may be amplified during demodulation. In some embodiments, the third signal 308 is divided 350 into a third portion 310 and a fourth portion 312, the third portion 310 and the fourth portion 312 having the same power. In some embodiments, an optical splitter may be used to split third signal 308 into third portion 310 and fourth portion 312.

At 406, the second portion 306 is demodulated in association with the third signal 308 to generate a fourth signal 316. The fourth signal includes information of the second signal. In some embodiments, the second portion 306 is amplified, and the amplified second portion 314 is differentially processed from any of the third portion 310 and the fourth portion 312 to generate a fourth signal 316. In certain embodiments, the amplified second portion 314 has a predetermined power ratio to the third portion 310 and the fourth portion 312. For example, the power ratio may be 1.5. It should be understood that the above power ratios are exemplary only. Those skilled in the art can set and adjust to obtain the desired power ratio. By way of example only, the following may be mentioned,

fig. 5 is a block diagram of a device 500 that may implement embodiments in accordance with the present disclosure. As shown in fig. 5, the device 500 includes one or more processors 510, one or more memories 520 coupled to the processors 510, one or more transmitters and/or receivers 540 coupled to the processors 510

The processor 510 may be of any suitable type suitable to the local technical environment, and the processor 510 may include, by way of non-limiting example, one or more general purpose computers, special purpose computers, microprocessors, digital signal processors, and processors based on a multi-core processor architecture. The device 500 may have multiple processors, such as application specific integrated circuit chips, that are synchronized in time with the main processor.

The memory 520 may be of any suitable type suitable to the local technical environment and may be implemented using any suitable data storage technology, including but not limited to non-transitory computer-readable media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems.

Memory 520 stores at least a portion of instructions 530. The transmitter/receiver 540 may be adapted for bi-directional communication. The transmitter/receiver 540 has at least one antenna for communication and the transmitter/receiver 540 may support fiber optic communication, but in practice there may be several access nodes referred to by the present disclosure. The communication interface may represent any necessary interface for communicating with other network elements.

The instructions 530 are assumed to comprise program instructions that, when executed by the associated processor 510, cause the device 500 to operate in accordance with the embodiments described in this disclosure with reference to fig. 3 and 4. That is, embodiments of the present disclosure may be implemented by the processor 510 of the device 500, by computer software execution, or by hardware, or by a combination of software and hardware.

Fig. 6 illustrates a block diagram of an apparatus 600 according to some embodiments of the present disclosure. It is to be appreciated that the apparatus 600 may be implemented at the receiving device 106 shown in fig. 1. As shown in fig. 6, the apparatus 600 may include: a first separation unit 610 configured to separate a modulation signal generated based on a first signal and a second signal into a first part and a second part; a first demodulation unit 630 configured to demodulate the first portion to generate a third signal, the third signal including information of the first signal; a second demodulation unit configured to demodulate the second portion in association with the third signal to generate a fourth signal, the fourth signal including information of the second signal.

In certain embodiments, the first separation unit 610 is further configured to: the modulated signal is divided into a first portion and a second portion such that the first portion and the second portion have a predetermined power ratio.

In some embodiments, the first demodulation unit 630 is further configured to: based on a predetermined threshold, the clock data recovers the first portion to generate a third signal. In certain embodiments, the first demodulation unit 630 is further configured to amplify the clock data recovered first portion based on a predetermined first amplification parameter to generate a third signal.

In some embodiments, the apparatus 600 further comprises a second splitting unit configured to split the third signal into a third part and a fourth part, such that the third part and the fourth part have the same power. In some embodiments, the second demodulation unit 650 is further configured to amplify the second portion and differentially process the amplified second portion and one of the third portion and the fourth portion to generate a fourth signal. In some embodiments, the second demodulation unit 650 is further configured to amplify the second portion such that the amplified second portion has a predetermined power ratio to the third portion and the fourth portion.

It should be understood that each unit recited in the apparatus 600 corresponds to each action in the process 300 and the method 400 described with reference to fig. 3-4, respectively. Therefore, the operations and features described above in connection with fig. 3 to 4 are also applicable to the apparatus 600 and the units included therein, and have the same effects, and detailed description is omitted here.

In addition or as an alternative, some or all of the units in apparatus 600 may be implemented at least in part by one or more hardware logic components.

The elements shown in fig. 6 may be implemented partially or wholly as hardware modules, software modules, firmware modules, or any combination thereof. In particular, in certain embodiments, the processes, methods, or procedures described above may be implemented by hardware in a network device. For example, the network device may utilize its transmitter, receiver, transceiver, and/or processor or controller to implement the process 300 shown in fig. 3 and the method 400 shown in fig. 4.

Fig. 7 shows a simulation diagram of demodulating a PAM-4 signal and fig. 8 shows a graph of the results according to some embodiments of the present disclosure. As can be seen from the results shown in fig. 7 and 8, embodiments of the present disclosure can effectively demodulate a PAM-4 signal.

In general, the various example embodiments of this disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Certain aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While aspects of embodiments of the disclosure have been illustrated or described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

By way of example, embodiments of the disclosure may be described in the context of machine-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or divided between program modules as described. Machine-executable instructions for program modules may be executed within local or distributed devices. In a distributed facility, program modules may be located in both local and remote memory storage media.

Computer program code for implementing the methods of the present disclosure may be written in one or more programming languages. These computer program codes may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the computer or other programmable data processing apparatus, cause the functions/acts specified in the flowchart and/or block diagram block or blocks to be performed. The program code may execute entirely on the computer, partly on the computer, as a stand-alone software package, partly on the computer and partly on a remote computer or entirely on the remote computer or server.

In the context of this disclosure, a machine-readable medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More detailed examples of a machine-readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical storage device, a magnetic storage device, or any suitable combination thereof.

Additionally, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking or parallel processing may be beneficial. Likewise, while the above discussion contains certain specific implementation details, this should not be construed as limiting the scope of any invention or claims, but rather as describing particular embodiments that may be directed to particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A method for demodulating a signal for 4-level pulse amplitude modulation, comprising:

dividing a modulated signal generated based on a first signal and a second signal into a first part and a second part;

demodulating the first portion to generate a third signal, the third signal comprising information of the first signal;

demodulating the second portion in association with the third signal to generate a fourth signal, the fourth signal comprising information of the second signal,

wherein generating the fourth signal comprises:

dividing the third signal into a third portion and a fourth portion such that the third portion and the fourth portion have the same power;

amplifying the second portion; and

and performing differential processing on the amplified second part and one of the third part and the fourth part to generate a fourth signal.

2. The method of claim 1, wherein splitting the modulated signal into a first portion and a second portion comprises:

dividing the modulated signal into the first portion and the second portion such that the first portion and the second portion have a predetermined power ratio.

3. The method of claim 1, wherein demodulating the first portion to generate a third signal comprises:

clock data recovers the first portion to generate a third signal based on a predetermined threshold.

4. The method of claim 3, wherein demodulating the first portion to generate a third signal comprises:

amplifying the first portion recovered by the clock data to generate the third signal based on a predetermined first amplification parameter.

5. The method of claim 1, wherein amplifying the second portion comprises:

amplifying the second portion such that the amplified second portion has a predetermined power ratio to the third portion and the fourth portion.

6. A communication device for 4-level pulse amplitude modulation, comprising:

at least one processor; and

a memory coupled with the at least one processor having instructions stored therein that, when executed by the at least one processor, cause the communication device to perform acts comprising:

wherein generating the fourth signal comprises:

amplifying the second portion; and

7. The communication device of claim 6, the acts further comprising:

8. The communication device of claim 6, the acts further comprising:

9. The communication device of claim 8, the acts further comprising:

10. The communication device of claim 6, the acts further comprising:

11. A computer-readable medium having instructions stored thereon, which when executed by at least one processing unit of a machine, cause the machine to be configured to perform a method for demodulating a signal for 4-level pulse amplitude modulation, the method comprising:

wherein generating the fourth signal comprises:

amplifying the second portion; and

and carrying out differential processing on the amplified second part and any one of the third part and the fourth part to generate a fourth signal.

12. The medium of claim 11, wherein the method further comprises:

13. The medium of claim 11, wherein the method further comprises:

14. The medium of claim 13, wherein the method comprises:

15. The medium of claim 11, wherein the method further comprises: