2003年CRC出版社光纤通信网络手册：经典永存

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"这是一本关于光纤通信网络的手册，出自CRC出版社，由Richard C. Dorf编辑的《电气工程手册系列》之一。尽管出版于2003年，但其内容对于理解光通信网络的基础和应用依然具有很高的价值。该书与其他专业手册并列，如无线网络、生物医学工程、电路与滤波器等，显示了其在工程领域的权威性。" 光纤通信网络是现代通信技术中的核心部分，它利用光的传输特性来实现高速、大容量的数据传输。手册可能涵盖了以下几个关键知识点： 1. **光纤基础**：介绍光纤的构造，包括芯线、包层、涂覆层等部分，以及单模和多模光纤的区别，它们在不同应用场景中的选择依据。 2. **光信号传输**：讲解光的产生（激光器和LED）、光的调制方式（幅度、频率、相位调制），以及光信号在光纤中的传播原理，包括衰减、色散和非线性效应等。 3. **光电子器件**：讨论光发射机、光接收机、光放大器等关键器件的工作原理和性能指标，以及如何优化它们以提高系统的整体性能。 4. **光纤连接与耦合**：介绍光纤接头类型、耦合技术，以及如何进行光纤熔接和机械连接，确保信号传输的可靠性。 5. **光网络架构**：探讨不同类型的光网络，如SDH（同步数字体系）、SONET（同步光网络）、WDM（波分复用）、DWDM（密集波分复用）和OTN（光传送网）等，以及它们在网络中的应用。 6. **光纤通信系统的工程设计**：讲述系统规划、容量计算、故障检测和故障排除方法，以及网络性能监控和优化。 7. **光通信的最新发展**：虽然手册出版于2003年，但它可能会涉及当时的一些前沿技术，如光纤到户(FTTH)、光纤到节点(FTTN)和全光网络等，这些技术至今仍对通信网络有深远影响。 8. **标准与规范**：可能会提及当时的国际和行业标准，如ITU-T和IEEE的相关规定，虽然随着时间推移，部分标准可能已更新，但了解历史标准有助于理解技术演进。 9. **系统集成与测试**：涵盖系统集成过程中的挑战和解决方案，以及如何进行性能测试和维护。这本手册对于学习和理解光纤通信网络的理论与实践具有重要参考价值，无论是初学者还是专业人士，都能从中受益。尽管出版时间较早，但基本概念和技术原理仍然有效，对于理解现代光通信网络的运作机制有着不可忽视的作用。

Chapter one: Overview of optical communication networks 3

ﬁber’s potential bandwidth is nearly three orders of magnitude higher than

electronic data rates of a few tens of gigabits per second (Gbps), we need to

tap into this huge optic-electronic bandwidth mismatch. Because the maxi-

mum rate at which an end user — which can be a workstation or a gateway

that interfaces with lower-speed sub-networks — can access the network is

limited by electronic speed, concurrency among multiple user transmissions

should be introduced to exploit the ﬁber’s huge bandwidth.

WDM is a favorite multiplexing technology in optical communication

networks because it supports a cost-effective method to provide concur-

rency among multiple transmissions in the wavelength domain. Several

communication channels, each carried by a different wavelength, are mul-

tiplexed into a single ﬁber strand at one end and demultiplexed at the

other end, thereby enabling multiple simultaneous transmissions. Each

communication channel (wavelength) can operate at any electronic pro-

cessing speed (e.g., OC-192 or OC-768).* For example, a ﬁber strand that

supports 160 communication channels (i.e., 160 wavelengths, each operat-

ing at 40 Gbps) would yield an aggregate capacity of 6.4 Tbps.

Today’s telecom network can be considered to consist of three sub-net-

works: access (spanning about 1 to 10 km), metropolitan (covering about 10

to 100 km), and long haul (extending to 100s or 1000s of km) (see Figure

1.2); and ﬁber is being extensively deployed in all three sub-networks. Typ-

ically, the network topology for access can be a star, a bus, or a ring; for

metro a ring; and for long haul a mesh. Each of these sub-networks has a

different set of functions to perform; hence, each has a different set of chal-

lenges, technological requirements, and research problems. For example, for

the long-haul network, carriers are more concerned with capacity, protection,

Figure 1.1

Past and projected future growth of data and voice trafﬁc.

* OC-n stands for an “optical channel” with data rate of n x 51.84 Mbps approximately.

Relative Load

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

Data

Voice

1333_FrameBook.book Page 3 Tuesday, February 25, 2003 11:33 AM

4 The handbook of optical communication networks

and restoration, while for the metro or access network, carriers are more

concerned with service provisioning/monitoring, ﬂexibility, etc.

The focus of this chapter is to present technological advances, promising

architectures, and exciting research issues in designing and operating

next-generation optical WDM networks that are scalable and ﬂexible. The

next section provides a brief discussion on the important building blocks of

optical WDM networks. This is followed by an overview of access, metro-

politan, and long-haul networks separately. Special attention has been paid

to the long-haul network because there is a tremendous need to develop

new intelligent algorithms and approaches to efﬁciently design and operate

these wide-area-optical-mesh networks built on new emerging technologies.

We present several research topics including routing and wavelength assign-

ment (RWA), fault management, multicasting, trafﬁc grooming, optical

packet switching, and various connection-management problems.

1.2 Enabling WDM technologies

An important factor to consider in the design of a WDM network is the

number of wavelengths to use. The maximum number of wavelengths is

limited by optical device technology and is affected primarily by the total

available bandwidth or spectral range of the components (including the

ﬁber) and the spacing between channels. Conventional ﬁbers have a low

attenuation region between 1335 and 1625 nm with a “water-peak window”

at 1385 nm. New “all-wave” ﬁbers do not have this water peak and hence

can use a larger spectrum (see Figure 1.3). Channel spacing itself is affected

by several factors such as the channel bit rates, optical power budget, non-

linearities in the ﬁber, and the resolution of transmitters and receivers. In

dense

wavelength-division multiplexing (DWDM), a large number of wave-

lengths (>160) is packed densely into the ﬁber with small channel spacing.

An alternative WDM technology with a smaller number of wavelengths (<

Figure 1.2

Telecom network overview.

Long Haul

- 100s–1000s km

- Mesh

Metro (Interoffice)

- 10s of km

- Rings

Access

- A Few km

- Hubbed Rings, PONs

Users

1333_FrameBook.book Page 4 Tuesday, February 25, 2003 11:33 AM

6 The handbook of optical communication networks

The EDFAs with gain spectrum of 30 to 40 nm each (typically in the 1530

to 1560 nm range; see Figure 1.4) can be interconnected to broaden their gain

bandwidth. This “ampliﬁer circuit” is referred to as an ultrawide-band

EDFA, which can fully exploit the expanded low-attenuation region of the

new “all-wave ﬁber” (see Figure 1.4).

OADMs — also referred to as wavelength add-drop multiplexers

(WADMs) — are employed to take in (add) and take out (drop) individual

wavelengths from an optical ﬁber completely in the optical domain (i.e.,

without any conversion of the optical signal into electronic domain).

OADMs, which can add and drop a speciﬁc predeﬁned channel (or a group

of channels), are said to be ﬁxed-tuned (or static) and the technology for

manufacturing them is mature. Reconﬁgurable OADMs (ROADMs), with

add-drop wavelengths that can be controlled by an external stimulus (e.g.,

by software) are said to be tunable (or dynamic). ROADMs are more pow-

erful because they can adapt to the ﬂuctuating trafﬁc demand but the tech-

nology for building ROADMs is still in nascent stage.

When the network topology is a mesh, where nodes are interconnected

by ﬁbers to form an arbitrary graph, an additional ﬁber interconnection

device is needed to route the signals from an input port to the desired output

port. These devices are called optical crossconnects (OXCs). They can either

transparent

(to bit rates and signal formats) in which signals are switched

all-optically

or be

opaque

in which incoming signals are converted from

optical to electronic domain and switched electronically. A possible architec-

ture for a transparent OXC is presented in Figure 1.5, where all signals on

a particular wavelength (e.g.,

) arriving on M input ﬁbers are switched

separately by a wavelength-speciﬁc MxM switch. As more and more wave-

lengths are packed into a ﬁber, the size of the OXCs is expected to increase.

Among several technologies (e.g., bubble, liquid crystal, thermo-optic, holo-

graphic, electro-optic, LiNbO

, etc.) used for building all-optical OXCs,

MEMS (micro-electro-mechanical-systems) based OXCs are becoming pop-

ular because of their compact design, low power consumption, and promise

Figure 1.5

An optical crossconnect (OXC) of size NM x NM (N is the number of

wavelengths; M is the number of incoming/outgoing ﬁbers).

1333_FrameBook.book Page 6 Tuesday, February 25, 2003 11:33 AM

Chapter one: Overview of optical communication networks 7

for high port count.

For details on emerging MEMS-based OXC architec-

tures, please refer to Reference 5.

1.3 Access networks

The access network connects the subscribers (home or business) to the service

providers; in other words, it serves as the “last mile” (as well as the “ﬁrst

mile”) of the information ﬂow. To meet the growing trafﬁc demand, service

providers expend most of their effort on increasing the bandwidth on their

backbone network. But little has changed in the access network. It is now

the general opinion that the last mile has become a bottleneck in today’s

network infrastructure.

Optical technology is a promising candidate for

solving the bandwidth problem in access networks because it can provide

at least 10 to 100 times more bandwidth over a larger coverage area. The

next wave in access network deployment will bring the ﬁber to the building

(FTTB) or to the home (FTTH), enabling Gbps speeds at costs comparable

to other technologies such as digital subscriber line (DSL) and hybrid ﬁber

coax (HFC).

Three optical technologies are promising candidates for the next-gener-

ation access networks: point-to-point topologies, passive optical networks,

and free-space optics.

1.3.1 Point-to-point topologies

Point-to-point dedicated ﬁber links can connect each subscriber to the tele-

com central ofﬁce (CO), as illustrated in Figure 1.6a. This architecture is

simple but expensive due to the extensive ﬁber deployment. An alternative

approach is to use an active star topology, where a curb switch is placed

close to the subscribers to multiplex/de-multiplex signals between the sub-

scribers and the CO. This alternative in Figure 1.6b is more cost effective in

terms of deployed ﬁber. A disadvantage of this approach is that the curb

switch is an active component that requires electrical power as well as

backup power at the curb-unit location.

1.3.2 Passive optical networks

Passive optical networks (PONs) replace the curb switch with a passive

optical component such as an optical splitter (Figure 1.6c). This is one of the

several possible topologies suitable for PONs including tree-and-branch,

ring, and bus. PON minimizes the amount of ﬁber deployed, total number

of optical transceivers in the system, and electrical power consumption.

Currently, two PON technologies are being investigated: ATM PONs

(APON) and Ethernet PONs (EPON). APON uses ATM as its layer-2 proto-

col; thus, it can provide quality-of-service features. EPON carries all data

encapsulated in Ethernet frames, and can provide a relatively inexpensive

solution compared to APON. EPON is gaining popularity and is being

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2003年CRC出版社光纤通信网络手册：经典永存

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