EP0958668A2 - Procede et dispositif correspondant permettant une repetition de signal - Google Patents

Procede et dispositif correspondant permettant une repetition de signal

Info

Publication number
EP0958668A2
EP0958668A2 EP97913594A EP97913594A EP0958668A2 EP 0958668 A2 EP0958668 A2 EP 0958668A2 EP 97913594 A EP97913594 A EP 97913594A EP 97913594 A EP97913594 A EP 97913594A EP 0958668 A2 EP0958668 A2 EP 0958668A2
Authority
EP
European Patent Office
Prior art keywords
linearity
signal
electrical
optical
linear
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.)
Withdrawn
Application number
EP97913594A
Other languages
German (de)
English (en)
Inventor
Lars Thylen
Eilert Berglind
Peter ÖHLEN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Telefonaktiebolaget LM Ericsson AB
Original Assignee
Telefonaktiebolaget LM Ericsson AB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Telefonaktiebolaget LM Ericsson AB filed Critical Telefonaktiebolaget LM Ericsson AB
Publication of EP0958668A2 publication Critical patent/EP0958668A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • 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
    • H04B10/29—Repeaters

Definitions

  • the present invention relates to a device and a method for telecommunications, especially for signal processing in optical or electro-optical networks.
  • optical networks In the field of telecommunications today there exist optical as well as electrical networks and combinations thereof.
  • the purely optical networks have large transmission capacities for point to point transfers but with more complex network configurations the electrical networks can be superior in certain respects.
  • the reason for this is that the complex networks require repeated operations, such as distribution of light, filtering, switching etc., and general operations where losses and thereby noise generating amplification are involved.
  • a completely optical network is analogue which makes it difficult for it to cope with repeated operations such as distributing light, filtering, switching etc., and general operations where losses and thereby noise generating amplification are involved.
  • bit error probability One factor which contributes to deciding a network's transmission capacity is the bit error probability.
  • Dispersion means that different wavelengths propagate at different speeds through the fibres, and a pulse which is sent through the fibres therefore spreads out which gives rise to intersymbol interference.
  • Intersymbol interference means that adjacent pulses go into each other and thereby give an increased risk for incorrect detecting of the pulses.
  • EOP eye opening penalty
  • B is the eye's vertical opening, i.e. the distance from the zero-level to the one- level, for the ideal case where only the network's attenuation irifluences the signals
  • A is the same distance for the case where the signal is also influenced by dispersion and the like. If the eye opening is reduced then the margin for permitted noise is reduced and thereby the margin for error decisions less. Consequently, the lower the EOP, the better performance the net has.
  • a communication network has a high transparency with respect to e.g. bit rate. This means that the communication functions for a large number of different bit rates, i.e. that the network's architecture does not place too narrow requirement for given bit rates.
  • noise can comprise a time jitter of the signal flanks (jitter) and signal level noise (amplitude noise).
  • a further object of the invention is to solve the above problems concerning scalability, transparency, noise and dispersion at bit rates up to and over 10 Gb/sec.
  • the invention achieves the above objects through using as repeaters simple analogue bit rate transparent OEO-circuits (opto-electric-optic) comprising an inverter, and through introducing an intentional non-linearity in preferably the electronics.
  • a method comprising that a signal which is to be repeated, is inverted and/or given a non-linearity, and also a device comprising inverters and/or non-linearity units.
  • bit error rate (below called BER) accumulates much more slowly through the nonlinear pulse forming if the amplitude noise is the predominant bit error source. This is the case for instance if the system band width is significantly greater than the maximum allowable bit rate, since increased band width reduces the jitter.
  • the intersymbol interference also accumulates more slowly through non-linear pulse foraiing. This reduction of intersymbol interference increases, i.e. the performance of the network is improved further, through mverting of the signals as performed according to the invention. These effects lower the bit error probability for the transfer on the communication network. Furthermore, no clocking of the signals is required. This implies further advantages as the solution becomes cheaper to implement without clock. Furthermore the implementation is easier without a clock with higher bit rates in the transfer, and the network's transparency with respect to bit rate becomes higher.
  • Figure 1 shows a device according to a first embodiment of the invention.
  • Figure 2 shows an example of a non-linearity function in a non-linearity unit according to the invention.
  • Figure 3 shows noise accumulation expressed in BER (Bit Error Rate) as a function of the non-linearity if the amplitude noise is the predominant.
  • Figure 4 shows a device accordmg to a second embodiment of the invention.
  • Figure 5 shows intersymbol interference expressed in eye-opening-penalty
  • FIG. 6 shows a device according to a third embodiment of the invention.
  • Fig. 1 shows a device 1 according to a first embodiment of the invention.
  • the device 1 comprises an optical input 2 connected to an input 3 on an opto-electrical converter 4.
  • An output 5 on the opto-electrical converter 4 is connected to an input 6 on a filter 7.
  • An output 8 on the filter 7 is connected to an input 9 on a non-linearity unit 10.
  • An output 11 on the non-linearity unit 10 is connected to an input 12 on an amplifier 13.
  • An output 14 on the amplifier 13 is connected to an input 15 on an electro-optical converter 16.
  • An output 17 on the electro-optical converter 16 is connected to an output 18 on the device 1.
  • the non-linearity unit 10 is placed between the filter 7 and the amplifier 13, but other embodiments are conceivable where the non-linearity 10 is placed in some other position along the chain in the device 1, in a manner well known in the technical field.
  • Other embodiments can also be conceived where the constituent units are comprised in each other in different combinations in a manner well known to the skilled person.
  • the amplifier 13 and filter 7 can be comprised in the same unit.
  • the amplification can also be divided up into several amplifiers, and the amplifier 13 or amplifiers can comprise automatic regulation of e.g. their amplification factor.
  • the different units can also be cascade-connected in different order in a manner also well known to the skilled person.
  • the non-linearity lies in the electrical domain.
  • the electro-optical converter 16 can comprise the functions of the non-linearity unit 10.
  • a further possibility is to move all of the functions of the invention to the optical domain.
  • the opto-electrical converter 4 and the electro-optical converter 16 in this case are removed and the other constituent parts are optical.
  • the device 1 can be used as a repeater in an optical communication network.
  • the input 2 and output 18 of the device 1 are connected to an optical fibre connection (not shown) along which the signal needs to be repeated because of the length of the connection.
  • the optical signal received on the input 2 are converted to an electrical signal by the opto-electrical converter 4.
  • the electrical signal is filtered by the filter 7.
  • the filter 7 can be a pure low-pass filter but also other types of filters well known witfiin the technical field can be used. It is also possible to vary the relative position between components constituent in the device in a manner well known to the skilled person.
  • the output signal from the output 8 of the filter 7 is fed to the non-linearity 10, where the signal is given an intentional non-linearity.
  • the non-linearity unit 10 has a transfer function f (x) which gives an output signal which is a non-linear response to its input signal, which response can be, but does not need to be, non-binary.
  • the signal is then amplified by the amplifier 13 and converted to an optical signal again by the electro- optical converter 16.
  • the so obtained optical signal is retransmitted via the output 18 of the device 1 to the optical fibre connection (not shown).
  • Fig. 2 shows the function in the non-linearity unit 10.
  • x corresponds here to the signal in on the input 9 of the non-linearity 10
  • f (x) corresponds to the signal on the output 11.
  • a straight line in the diagram with a constant slope should correspond to the completely linear case, while a pure step function would illustrate the completely nonlinear case.
  • the figure shows an example of a partially non-linear case.
  • a non-linearity factor ⁇ can be defined out of this according to:
  • Fig. 3 shows BER (Bit Error Rate) caused by amplitude noise accumulation for a link with approximately ten repeaters, as a function of the non-linearity which is applied to the signal through the non-linearity unit 10.
  • the non-linearity which is applied to the signal according to the invention gives a reducing effect on the bit error probability through noise suppression if the amplitude noise is the predominant source of bit error.
  • the bit rate transparency of the network is consequently not limited either.
  • bit error probability for the transmission on the communication network is lowered so that no clocking of the signals is required. This implies further advantages as the solution will be cheaper to implement without clocks. Furthermore, the implementation is more simple without clocks at higher bit rates in the transmission, and the transparency of the network with respect to bit rate becomes higher.
  • Fig. 4 shows a device 41 according to a second embodiment of the invention.
  • the device 41 comprises the same parts as the device 1, according to the first embodiment of the invention, connected in a similar way but with the difference that it also comprises an inverter 21.
  • the inverter 21 is according to this embodiment connected between the filter 7 and the non-linearity unit 10, but other positions are also conceivable, in a manner well known to the skilled person.
  • An input 20 on the inverter 21 is connected here to the output 8 of the filter 7, and an output 22 on the inverter 21 is connected to the input 9 of the non-linearity unit 10.
  • variations can also be conceived, as mentioned in connection with the first embodiment.
  • the function of the device 41 is similar to that of the device 1. In addition to the earlier mentioned noise suppression's favourable effect on the bit error probability, this is now further reduced through the inversion also suppressing the effect of the disperson of the fibre. This reduces in turn the intersymbol interference and thereby thus lowers the bit error probability further.
  • Fig. 5 shows the intersymbol interference expressed in eye-opening-penalty (below called EOP) in dB, as a function of the fibre connection's length in kilometres, for different non-linearities of the invention according to the second embodiment.
  • EOP eye-opening-penalty
  • the best result is obtained at complete non-linearity but this can, as mentioned earlier, be difficult to achieve at high bit rates (over 10 Gb/sec).
  • Fig. 6 shows a device 61 according to a third embodiment of the invention.
  • the device 61 comprises the same parts as the device 41 according to the second embodiment of the invention, combined in the similar way but with the difference that the non-linearity unit 10 is removed, and the output 22 of the inverter 21 is directly connected to the input 12 of the amplifier 13.
  • variations can also be conceived, as mentioned in connection with the first embodiment.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optical Communication System (AREA)

Abstract

L'invention a trait à un procédé ainsi qu'au dispositif correspondant permettant, avec une faible probabilité d'erreur sur les bits, de répéter des signaux dans un réseau électro-optique. Ce procédé consiste à recevoir un signal optique et à le convertir en signal électrique, à inverser le signal électrique et/ou lui appliquer une non-linéarité, à convertir ledit signal électrique en signal optique et enfin à transmettre ce signal optique.
EP97913594A 1996-11-18 1997-11-07 Procede et dispositif correspondant permettant une repetition de signal Withdrawn EP0958668A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9604214 1996-11-18
SE9604214A SE9604214L (sv) 1996-11-18 1996-11-18 Förfarande och anordning inom telekommunikation
PCT/SE1997/001869 WO1998023064A2 (fr) 1996-11-18 1997-11-07 Procede et dispositif correspondant permettant une repetition de signal

Publications (1)

Publication Number Publication Date
EP0958668A2 true EP0958668A2 (fr) 1999-11-24

Family

ID=20404645

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97913594A Withdrawn EP0958668A2 (fr) 1996-11-18 1997-11-07 Procede et dispositif correspondant permettant une repetition de signal

Country Status (9)

Country Link
EP (1) EP0958668A2 (fr)
JP (1) JP2001505734A (fr)
KR (1) KR100367814B1 (fr)
CN (1) CN1244981A (fr)
AU (1) AU5073998A (fr)
CA (1) CA2272242A1 (fr)
SE (1) SE9604214L (fr)
TW (1) TW372380B (fr)
WO (1) WO1998023064A2 (fr)

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6416135A (en) * 1987-07-10 1989-01-19 Nippon Telegraph & Telephone Optical relay transmission system
US5161044A (en) * 1989-07-11 1992-11-03 Harmonic Lightwaves, Inc. Optical transmitters linearized by means of parametric feedback
US4935377A (en) * 1989-08-01 1990-06-19 Watkins Johnson Company Method of fabricating microwave FET having gate with submicron length
JPH03119839A (ja) * 1989-10-02 1991-05-22 Furukawa Electric Co Ltd:The アナログ光中継器
JPH0738648B2 (ja) * 1989-10-06 1995-04-26 富士通株式会社 光信号中継伝送制御方式
US5040865A (en) * 1990-04-20 1991-08-20 Hughes Aircraft Company Frequency multiplying electro-optic modulator configuration and method
JP2771071B2 (ja) * 1992-04-23 1998-07-02 日立造船株式会社 中継局を経由する伝送方法
US5327279A (en) * 1992-07-17 1994-07-05 United Technologies Corporation Apparatus for linearization of optic modulators using a feed-forward predistortion circuit

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9823064A2 *

Also Published As

Publication number Publication date
KR20000053309A (ko) 2000-08-25
WO1998023064A3 (fr) 1998-08-06
TW372380B (en) 1999-10-21
AU5073998A (en) 1998-06-10
SE9604214D0 (sv) 1996-11-18
WO1998023064A2 (fr) 1998-05-28
SE9604214L (sv) 1998-05-19
KR100367814B1 (ko) 2003-01-14
JP2001505734A (ja) 2001-04-24
CN1244981A (zh) 2000-02-16
CA2272242A1 (fr) 1998-05-28

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