AU2019100030A4

AU2019100030A4 - A high-reliability communication system that utilizes all-optical coding in optical networks-on-chip (ONoCs)

Info

Publication number: AU2019100030A4
Application number: AU2019100030A
Authority: AU
Inventors: Lixia Fu; Ye SU; Yiyuan Xie
Original assignee: Southwest University
Current assignee: Southwest University
Priority date: 2019-01-10
Filing date: 2019-01-10
Publication date: 2019-02-14
Anticipated expiration: 2027-01-10

Abstract

Abstract A high-reliability communication system that utilizes all-optical coding in optical networks-on-chip (ONoCs). The system mainly includes three parts: an all-optical encoder, error detection and correction module (EDC), and retransmission mechanism (RT). A micro-resonators (MRs)-based all-optical linear block codes encoder is designed as the core component of implementing the communication system, and its function is to encode the data sequence before transmission. When the encoded information are transmitted to the receiver, the EDC module at receiving end can detect and correct the uncorrectable data according to certain rules. Moreover, for bit errors that are outside the error correction range, the RT module is activated in communication system, which serves to close the communication pair that produces the maximum crosstalk noise for the current communication and retransmit the uncorrectable data group. Compared with the traditional ONoCs, the ONoCs applying the invention can reduce the bit error rate (BER) of the optical signal, thereby effectively optimizing the information transmission quality. Retransmission module aser Part------ig.r1 -- network----r1 -- -------- LC -pia -2 -so -JDtetrs Transmitter Receiver Fig. 1 0 100 200 300 400 500 cT(ptm) (a) .l 0.001 0 100 200 300 400 500 cT( tm) (b) 0 100 200 300 400 500 cT(ptm) (c) Fig. 2

Description

A HIGH-RELIABILITY COMMUNICATION SYSTEM THAT UTILIZES ALL-OPTICAL

LINEAR BLOCK CODES ENCODER

TECHNICAL FIELD

The invention relates to the field of optical networks-on-chip and nano-scale optical logic devices.

BACKGROUND

With the increasing of chips integration, multi-processors system-on-chip (MPSoC) gradually replaces single-core chip structures, since it has a capacity to solve the bottleneck of single-core chip design, such as interconnect delay and power consumption limit. How to select efficient interconnection among processing cores to make full use of computing resources is an important factor in determining the performance of MPSoC. While, network-on-chip (NoCs) is a new idea to solve the issue of MPSoC interconnection. It transplants computer network technology into chip design, which can solves a series of problems brought by traditional bus architecture. NoCs include electrical interconnects and optical interconnects. Traditional electrical interconnects are limited in bandwidth, high power consumption, and large delays, which impede the sustained development of MPSoC. However, the optical networkson-chip (ONoCs) that replace electrical connections with optical connections is expected to break this barrier and solve the issues faced by electrical interconnections. Moreover, ONoCs can extend bandwidth by using WDM. Multiple optical signals transmitted in parallel effectively improve the communication bandwidth, reduce the delay and the power consumption. However, WDM-based ONoCs suffer from the effects of insertion loss and internal noise. These factors may lead to the misjudgement of the transmitted information by the receiver, thus affecting the communication performance and reducing the reliability of the communication system.

Fortunately, coding technology is well suited to solve these problems, because it has error correction and error detection functions. Coding technology is the main technical means to achieve reliable transmission, so it has become an indispensable part of the digital communication system. Currently, coding technology is widely used in satellite communications and mobile communications. In these fields, a large number of studies have shown that the use of this technology can obviously improve the reliability of communication systems and enhance communication quality. Therefore, the introduction of coding technology into ONoCs has become an inevitable trend.

SUMMARY OF THE INVENTION

The present invention proposes a reliable communication system based on an all-optical linear block codes encoder composed of micro-resonators (MRs). The encoder is used to encode the information transmitted in the WDM-based ONoCs in order to verify the correctness of the received data at the receiver. Using the error correction and error detection characteristics of linear block codes, some error bits can be detected and

2019100030 10 Jan 2019 corrected by the error detection and correction (EDC) module set at the receiver. Moreover, the present invention set a retransmission (RT) mechanism for the information beyond the correction range, which performs noise reduction and retransmission processing for the data group that cannot be corrected. The invention can remarkably decrease the bit error rate (BER), thereby improving the reliability of ONoCs.

SPECIFIC IMPLEMENTATION METHODS

In order to better understand the present invention, the implementation of the present invention is further described in detail below with reference to the accompanying drawings:

The present invention introduce a high-reliability communication system in ONoCs, as shown in the Fig. 1. The implementation of this reliable system mainly relies on the all-optical encoder, error detection and correction module (EDC), and retransmission mechanism (RT).

Linear block codes encoder is essential as a prerequisite for implementing the present invention. According to the characteristics of the linear block codes, it can be known that if the check matrix is fixed, the check bits can be obtained according to the information symbols. Therefore, the key to the realization of the encoder is to solve the difficulty of how to automatically generate check bits, based on the known information bits. In the present invention, (7,4) linear block codes are used, one of its check matrices is

1110100

1101010 .10 110 0 1.

The codeword and information group are represented as C [c₆ c₅ c₄ c₃ c₂ c₄ c₀] and M = [m₃ m₂ m₄ m₀] respectively, where c₆, c₅, c₄ , and c₃ are equal m₃ m₂ m₄ m₀. The check bits can be expressed as:

c₂ = m₃ +m₂ +m₁ c₄ = m₃ + m₂ + m₀ (1) c₀ = m₃ + m₄ + m₀

Furthermore, MRs have two states: resonant state (ON) and non-resonant state (OFF), and can switch between the two states by changing its resonant wavelength. Combining the characteristics of linear block codes and MRs, the designed encoder is shown in the part 1 of Fig. 1.

In the encoder, the control voltage is applied to the MRs according to the information bits mi in the form of logic “0” and “1” to switch the ON or OFF states, and the continuous wave (CW) is injected from a port. When the output port has an optical signal output, it means that the corresponding check bit of the port is “1”, otherwise, the corresponding check bit is “0”. The MRs of different colors in the figure represent that they have different resonance wavelengths..

As shown in Fig. 1, the transmitted information is m₃, m₂, m₄, m₀, and the transmitter modulates informations by activating the corresponding MRs through the metal interconnection structure between the two layers that shown by the dotted line. Simultaneously, the MRs in the linear block codes encoder are also activated according

2019100030 10 Jan 2019 to the logic data to generate check bits. The check bits and the information bits then enter the WDM multiplexer, which multiplexes all wavelengths into a single optical waveguide and transmits them in the ONoCs. When the signal is transmitted to the receiving end, the photodetector converts the optical signal into an electrical signal. Next, it is handed over to the error detection and correction module (EDC) module of the present invention.

The EDC can detect whether the received information R has transmission errors and correct a part of the errors. Above all, the receiver calculates the syndrome S according to R and the linear block codes check matrix. The relevant formula is:

S^T = HR^T (2)

When S = 0, it is judged that the^ is correct, and when S ψ 0, the received sequence is concluded to be incorrect. At the same time, EDC can correct errors according to the comparison of error location and syndrome shown in Table 1. Then, after removing the check bits, the error-free or corrected data is sent to the IP core. If the EDC determines that the R is in error and the errors cannot be corrected, then a signal will be output to the RT module, which can close the communication pair that produces the maximum crosstalk noise for the current communication and retransmit the uncorrectable data group.

Table 1 Relationship between the location of bit error and the syndrome

yndrome (S_OS1S₂)	Location of bit error
	^co
	Cl
too	c₂
011	c₃
101	c₄
110	c₅
111	^co
000	^c0

Next, we verify the superiority of the invention by simulation.

Firstly, the feasibility of the proposed encoder is verified. We use the RSoft simulation environment to construct a MRs-based linear block codes encoder structure that adjusts the MRs state according to 0, 1 of information. Suppose the information bits M - [111 0], according to the Eq. (1), the check bits can expressed as : (c₂ = 1 + 1 + 1

0-1 = 1 + 1 + 0 .c₀ = 1 + 1 + 0 and the theoretically codeword is C — [111 0 1 0 0]. Injecting CW into the drawn structure and detecting the c₂, c_1? and c₀ ports with the monitor, the results obtained are shown in Fig. 2. It can been see that the power detected by these three ports are approximately 0.7, 0.002, and 0.002, respectively, so the check bits generated are 1, 0,

2019100030 10 Jan 2019 and 0. The results are in good agreement with the theoretical calculation, which verifies the feasibility of the proposed encoder.

Then, a numerical simulation of mesh-based ONoCs with seven optical wavelengths is taken based on the MATLAB environment to compare the performance of the ONoCs Leveraging the reliable system proposed and traditional ONoCs. The simulation is based on the worst case in the ONoCs, which means that the accumulated crosstalk power and the power loss are the largest in the case, and it is found with the SNR of the optical signal of the target node approaching zero as a criterion.

BER is an indicator for measuring the accuracy of informaton transmission within a specified time period and is an important parameter for evaluating the reliability of a communication system. Therefore, we demonstrate the superiority of the present invention by comparing the BER of both the traditional mesh-based ONoCs and the ONoCs with the present invention. Fig.3 shows the worst-case BER in the two ONoCs. The X-axis and Y-axis respectively correspond to the sizes M and N in the ONoCs, and the Z-axis corresponds to the BER. It can be seen that in both ONoCs, the BER grows with the increase of the network scale, and gradually tends to a relatively stable value. However, it can be clearly seen that the ONoCs using the present invention show superior BER than traditional mesh-based ONoCs.

It is apparent that the above-described simulation examples of the present invention are merely examples for clearly demonstrating the superiority of the present invention, and are not intended to limit the application of the present invention. For applications in ONoCs, the invention can also be applied to various network topologies based on the above description. There is no need and no way to exhaust all of the implementations. Any modifications made within the spirit and scope of the present invention, equivalents, modifications, and the like in accordance with the present invention are intended to be included within the scope of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a diagram of the reliable communication scheme in ONoCs.

Fig. 2 is the energy detected by the output ports, (a) c₂ (b) (c) c₀.

Fig. 3 is the BER comparison in Μ x N mesh-based ONoCs with WDM using the present invention and traditional mesh-based ONoCs with WDM.

2019100030 10 Jan 2019

EDITORIAL NOTE

There is one page in the claims only .

2019100030 10 Jan 2019

Claims

The claims defining the invention are as follows:

1. A high-reliability communication system that utilizes all-optical coding in optical networks-on-chip (ONoCs). The system utilizes the error detection and error correction feature of the linear block codes to reduce the bit error rate (BER) of the communication system, and combines the retransmission (RT) mechanism designed in the system to improve the reliability of ONoCs communication. The implementation of the present invention mainly relies on the all-optical encoder, error detection and correction module (EDC), and retransmission mechanism (RT).
2. An all-optical encoder (subject to claim 1).

An encoder structure is designed by utilizing the characteristic that the micro-rings (MRs) resonance wavelengths are variable. Its main part consists of three XOR gates with the same structure to generate check bits. In the encoder, a continuous wave (CW) is injected from a port, while the control voltage is applied to the MRs in the form of logic “0” and “1” on the basis of the information bits to change MRs resonant state and non-resonant state. The corresponding logical number of MRs are determined by the information bits according to the linear block code check matrix. When the output port has optical signals output, it indicates that the corresponding check bit is “1”, otherwise, the corresponding check bit is “0”. Finally, the check bits combine the information bits to form a integral codeword.
3. Error detection and correction module (EDC) (subject to claim 1).

When the transmitted optical signal arrives at the destination, it is converted into electrical signal by photoelectric detector. After receiving the electrical signals R (r₆r₅r₄r₃r₂r₁r₀), the receiver calculates the syndrome S according to the R and the linear block code check matrix. When S = 0, it is judged that theZis correct, and when S A 0, the ~R is concluded to be incorrect. Simultaneously, EDC can correct errors according to the comparison of error location and syndrome.
4. Retransmission (RT) mechanism (subject to claim 1).

A mechanism that can resend current data. If the EDC module determines that the received information R is in error and the errors cannot be corrected, then a signal is outputted from the EDC module. When the signal arrives at the RT module, which can close the communication pair that produces the maximum crosstalk noise for the current communication and retransmit the uncorrectable data group.