Download 第6章作业应用

第6章 接入网应用
6.1 IP分组多媒体通信
6.2 行业应用
2017/5/8
Dr. Zhanqi XU, access to him at :
web.xidian.edu.cn/zqxu, Xidian University
1
MultiMedia Communication
Based on Packet Network
Architecture, Protocols, Progress
 Overview
 Protocols (H.323 & SIP)
 IP Telephone Architecture
2017/5/8
Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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Overview
Features
Multimedia Communication (MMC) means
more than one set of forms comprising
still/moving images, graphic, text, and sound
are reproduced on an intelligent terminal
Implementation of MMC
–Transmission media
• Wireless ( Radio, Microwave, Satellite, optical, …)
• Wired ( Twisted Pair, Cable, Optic Fiber,…)
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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–Switching
• Circuit-switched ( traditional CS, fast CS,…)
• Packet-switched (ATM,MPLS , Ethernet, FR ,
Token ring, Token bus), X.25,…)
–Media processing
• Sampling ( 8Khz, 16Khz, …)
• Coding( G.711 A/-law for voice, …)
• Compressing / Decompressing ( G723.1, G729A,
for voice; H.261/H.263, JPEG (Joint Photographic
Experts Group) , MPEG-4 (Motion Picture Experts
Group) for Video
• Storing , editing,…
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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MMC network architecture
PSTN
Computer
Net
V5/ No.7, No.1
Integrated
Access
PSTN
Telephone
CATV
Fiber/ Cable
Modem
Cable
xDSL CO.
Copper/Optical
PSTN Tel
Cable Modem
IP Tel
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LAN
IP Tel
LAN
Cable Tel
LAN
Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 Applications
Areas
Education
Examples
Distance teaching/learning interactively, examination on-network,…
VoD (video on demand), Live
Entertainment
picture, on-line game/Chat, …
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Electronic
Commerce
Trading, shopping, stock exchange,
banking, …
Public Info.
News, magazine, forum, E-mail,…
Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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Protocols
Generally speaking,MMC includes almost all
techniques in info. processing, transmission,
and switching, the limited-space makes our
discussion to packet-based network.
H.323
• Specified by ITU in 1996 ( V2, 1998)
• Describes the protocols stacks of terminal equipments,
and services for multimedia communication over LAN
and IP networks
• These networks don’t provide guaranteed QoS (Quality
of Services).
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 H.323 Architecture
Control and management
Application
Video Coding
Terminal
H.245
H.225.0
(Sig. Ch.)
H.225.0
(RAS)
RTCP
TCP
Audio Coding
RTP
UDP
IP
NIC ( Network Interface Controller)
PBX
Gateway
IP
Backbone
Client
Gatekeeper
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 Main Components in H.323
– Terminal: media processing and call control
• PC, Video/TV, Telephone, Fax, ….
• H.323-compliant ( multimedia-PC,Telephone,…)
• Other terminals:
– H.320 terminal on N_ISDN
– H.310/H.321 terminal on B_ISDN using ATM
– H.324 terminal on PSTN
– Gateway: translation of call signaling, media
format, multiplexing , etc.
– Gatekeeper网闸: providing administration of
access, bandwidth, address translation, etc.
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 H.323 Protocols Stack
Items
Protocols or Function
Audio Coding
G.711, G.722, G.723.1, G.726, G.728, G.729
Video Coding
H.261, H.263
RTP(Real-Time
Trans. Prot.
)
Processing related to sequencing, sync., payload
type, source identification,…
RTCP
Additional info. to session participants: QoS
feedback, identification, session control,…
RAS (H.225.0)
RAS: Registration, Admission, Status
Conveying the registration, admissions, bandwidth,
status, …
Sign. Ch. (H.225.0)
setup or release of call connection based on Q.931
Ch. CTRL (H.245)
Capability Negotiation, coding, conference req.,…
UDP
Efficient but unreliable transport of packets
TCP
Conn.-oriented , reliable transport of packets
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 H.323 Protocols Stack－video coding/decoding
H.261: compression/decompression of digital video, specified by ITU
in 1990 , P*64kbps, mainly in ISDN, (from M777 p52)
H.263, defined by ITU, compression of the moving picture
component of audio-visual service at low bit rates.
JPEG treats its picture independently( intraframe coding)
while H.261 tries to predict the current picture from the previous one
(interframe coding)
MPEG-Motion Picture Experts Group, belongs a family of ISO/IEC
(International Electrical Committee )
MPEG-1 uses the same format as H.261, but allows a greater choice
of image size
MPEG-2 developed by ISO/IEC, ITU , up to 100Mbps for Video,
supports HDTV
MPEG-4 video coding method for low bit rates
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 H.323 Protocols Stack-RTP/RTCP comments
RTP comments:
Sequencing: sequence nu. for detecting lost packets
Sync. : timestamps to compensate the different delay jitter, needed
by player-out buffers.
Payload: identified the encoding of media, to change the encoding
of media dynamically due to the bandwidth availability.
Source identification: identifier for the originator of the frame in
multicast session.
RTCP comments:
In RTP session, the participants periodically send RTCP packets to
obtain QoS info, etc.
QoS feedback: no. of lost packets, round-trip time, jitter, etc.
Session CTRL: leaving a session by sending BYE packet
Identification: info. such as e-mail, name, phone
Intermedia Sync.: synchronizing the video and audio for receiver
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to2017/5/8
play
Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
 SIP#
Developed by IETF MMUSIC (Multi-Party Multimedia
Session Control) work group, evolved from HTTP
–SIP features
• Open, simple, and lightweight protocol
• Text –based protocol (text: 文本、明文)
• Internet heritage – easier to integrate with
telephony/Video and Internet functions
• Already implemented on most soft-switches and
gateways
• Advanced extensibility
• Transport independent-TCP or UDP (reliability for
both)
–SIP Architecture (next page)
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 SIP Architecture
Control and management
Application
Terminal
SIP
Video/Audio coding
RTCP
TCP
RTP
Request
UDP
Response
IP
NIC
2
Redirect
Server
5
3
4
6
7
Location
Service
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1
Agent Server
SIP Proxy
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SIP Client 1
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10
8
SIP Client 2
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
SIP Proxy
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 SIP Components
 Clients
– End systems
– Send SIP requests
– Usually contain SIP
user agent server
 Redirect Server
– “Network” server; redirects
users to try other server
(user agent may act as a
redirect server)
 User Agent Server
– Listens for call
requests
– Prompts user or
executes program to
determine response
 Proxy Server
– “Network Server” Proxies
request to another server
(user agent also may do this)
– Can “fork” request to
multiple servers, creating a
search tree
注解：agent接近用户，proxy一般远离用户；（仅对SIP）前者翻译为
“用户代理”，后者译为“网络代理”；what is your better idea about
Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
2017/5/8translations?
their
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 SIP message example
(the below message is from RFC2543)
INVITE sip:[email protected] SIP/2.0
Via: SIP/2.0/UDP 169.130.12.5
From: <sip:[email protected]>
To: T. A. Watson <sip:[email protected]>
Call-ID: [email protected]
Content-Length: 885
Encryption: PGP version=2.6.2, encoding=ascii
NOTE: "MIME security with pretty good privacy (PGP)", RFC 2015,
October 1996.
SIP has only a limited number of methods:
1) Invite, 2) ACK, 3)Options, 4) Bye, 5)Cancel, 6)Register
Cancel: unusually cancel a connection which is going on
Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
2017/5/8
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 H.323 vs. SIP
Items
H.323
SIP
Messages
Binary-based
Text-based
Develop & Update
Complicated
Easy
Elements &
Interactions
Hundreds,
Complicated
37 headers,
Simple
Setup of a task
V.1(call,ctrl,media) 3
Single round-trip
round-trip, V.2 faststart
Extensibility
ITU developed only
Any registered
State
State or stateless
Mobility support
Limited
Easier
Market
Becoming less
Growing extensively
( Codecs)
Scalability
(large
number of call processing)
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 IP Telephone
General
– Definition
In contrast to traditional telephone in CS network, it
means real-time services, such as voice, video, etc,
transferred in best-effort PS network.
– Brief history
Time
Events
Players
March,1995
First commercial IP
phone for PC’s
Vocaltec
1996
PC-to-phone,Phone-to-phone
Free world Dialup,MIT,…
1997~1998
Part commercial application
Vocaltec, Net2phone,…
1999~
High density (4~8 T1/E1),
large capacity (>100T1)
Audiocodes, analogic,
NMS,…
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 IP Phone Network
Gatekeeper
Gateway
IP backbone
network
Gatekeeper
Gateway
PSTN
FAX
PSTN
Telephone
Fax
Gateway
Hong Kong
Fax
Telephone
Gatekeeper
New York
PSTN
Shanghai
Telephone
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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– Call Procedure
• Pick the hook up (Off-hooks), dial special service
number,
ex 17900 for China Telecom
• Voice response: Please input account & password
• When it is OK, voice response: input the called
number,ex 86-21-56781234# for Shanghai
• Voice response: the time allowed XXX, please wait
• Local Gateway performs PSTN-IP translation , send
necessary info. to remote gateway by using H.323 or
SIP
• Remote gateway is ringing to the called user,
performs the negotiation of parameters, such as
coding, RTP/RTCP sessions,etc.
• If user answered, the info. is sent to original gateway
• Voice transmission begins
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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– Voice Processing
•PCM(64Kb/s)compression 8Kb/s(G.729a),…
•Encapsulation ( packetized ):
IP Header
20 Bytes
UDP header RTP Header
8 Bytes
Payload
12 Bytes
•Transmission and switching in packet network,
ex. Ethernet, FR, ATM,…
• Disassemble : extracted voice payload from
the IP Packet
• Voice payload  decompression (echo
canceling, gain control,..)reproduced Voice
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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– Coding Comparison
Coding
G.711
G.728
G.729a
G.723.1
NetCoder
2017/5/8
Rate(Kbps)
Complexity
(MIPS)
64
N/A
Very good
N/A
16
Very high
(40)
Good
8 or 16 ms
8
Moderate
(10)
Fair
10ms(2X5)
ModerateHigh (14/20)
Good/Fair
30ms
(4X7.5)
Low (7.5)
Very good
(-)
20ms
6.4/5.3
9.6/8.0/7.2
Quality
Frame
Size
Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 Advantages & Disadvantages
– Death of distance, distance becomes less
significant
– Very low price,even free (More calls with less
bandwidth)
In china, domestic toll 1 Yuan/min, IP 0.3 Yuan/min
– Provide integrated voice, data, image by one
terminal
– Web-based multimedia services,…
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 Advantages & Disadvantages
– Limited and finite in capacity, area
– Significant drawbacks (gap, influent, click noise,..)
in network congestion, or in large-delayed
route,…
Comments: These were really true when this
presentation was written in 2000
Quality vs. Latency
Excellent
0
2017/5/8
>450
Good
150
Poor
300
unacceptable
450
One-way in ms
Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 Latest Advanced Products (around 2000)
Company
Model
Analogic
TP-400
AG4000
Max. nu.
4
of T1/E1
4
1,2,4
Bus
Interface
cPCI
cPCI
Extended
Interface
H.110
H.110
DSP
TMS320C549
AudioCode TMS320AC48105
C549
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TAP-810
Audiocode
Natural MicroSystem
Dialogic
D/300PCI-E1
D/300SC-2E1
2
cPCI or PCI PCI or SC
H.110
H.100
Motorla
5630X
Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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Company
On-Board
Ethernet
Analogic
10/100M
Channels of
120/96
compression
Solaris,
UNIX,Win NT
OS
SDK
TAP-8XX
Advantages
DSP
(advanced)
Disadvantages
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Hard in
R&D
Audiocode
Natural MicroSystem
Dialogic
100Base-T
no
no
120/96 (plus
60/48 (plus
120/96
daughter board)daughter board)
Win NT
Win NT,
Solaris
-
Fusion
Win NT
Solaris,UNIX
-
DSP,RTP/
Easy to R&D Wide
RTCP onLocal service service
board
Hard in
Daughter
Low density
R&D
board
Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 Research & Development
– Hardware: Higher density, integrated more functions
into one board or chassis , e.g., a DSP daughter
board is inserted to main board, now it is not used
any more.
– In software
•Support more OS, extend to Solaris , Unix,…
•Support more signaling , for example, SS7,…
•Support new protocols being developed, ex. Vovida.com
provides open MGCP
•Some software is embedded into board, NMS put its
RTP/RTCP on board
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 Research & Development
– In China, the gateway with capacity up to 160 E1
has been developed
– Application-oriented, web-based( 800,…), call
transfer,…
– New application, IP-based-PBX, call centre,
telephone banking,…
Question:
Could you describe the similarities and
dissimilarities/differences of call-free services in
the modes between the traditional telephone and
Internet web-based ?
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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Products
 In
China

China had chosen H.323 as the standard used
domestically (comments: this was true around
2000)

There are a lot of players to announce to provide
SIP solution, e.g., capital telecom company.
It is reasonable to say that the largest telecom
companies provide the SIP solutions in two years,
such as Zhongxing, Huawei . (this was really true
when the PPT was written in 1999)
Today, there are more and more manufacturers
involved in SIP products, which represents the
future of IP-based multimedia communication.


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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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Products
 International (when time was in 2000)

There are a lots of H.323-based products used
widely, including telephone (hardware/
software), Gateways, Gatekeepers, MCUs
(Multi-points Control Unit), etc. The players
include Audiocodes, Cisco, Clarent( 冠远),
Dialogic, Nortel networks, Lucent, …
 There
are a few hundreds players to provide
solutions of SIP, e.g., Audiocodes, Nortel
networks, Lucent,…
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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 The future
 The
SIP will become more and more important, but it takes a
long way to coexist with H.323 and to replace (?) absolutely
 The
researching topics include:
 H.323 interworking with SIP

H.323 and SIP applications in wired and wireless networks
(3G - 3rd generation, WLAN,…)
H.323/SIP interworking with Softswitch system (H.248, we
discuss it in next section)
IP
Multimedia Subsystem (IMS #)- a new networking
architecture, widely used and dominates the session control
protocol in mobile networks (3G,4G) and mixed Fixed/mobile
networks
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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Appendix
Quality of Voice is measured via Mean Opinion Score(MOS，5~1) #, 5 Is
the best and 1 is the worst
G.726 ADPCM 8K~32K (Adaptive Differential PCM)
G.728 LD-CELP (Low Delay of Code Excited Linear Predictive)
G.729# CS-ACELP (Constant-Structure, Algebraic CELP)
G.723.1 6.4K MP-MLQ ( Multi Pulse, Maximum –Likelihood
Quantization) 5.3K ACELP
We must note that ITU compression algorithms are not the best.
According to Audiocodes.com, its NetCoder quality at 9.6 Kbps is
indistinguishable from G.711 PCM.
PCI#– Peripheral Component Interconnection
cPCI#— compact PCI , SC-widely used computer bus in the past
H.100/H.110 is the CT ( Computer Telephony) Bus implementation on the
PCI/cPCI form.
H.100: 4096 bi-directional time slots
H.110: 32 data streams at 8.192Mb/s.
OS: Operation System
2017/5/8
SDK#: Software Development Kit
Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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6.1 IP分组多媒体通信
6.2 行业应用
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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接入网广泛地应用于生活、工作和国民经济的众多部门，
本节简述在家居网、行业的应用。
一、 家居网定义与组成
家庭网络，是指在家庭范围内（可扩展至邻居或小区
）将个人计算机（PC）、家电、安全和照明系统等相
互连接，组成一个家庭内部的网络，并与广域网相连接
，在家庭内部以及家庭与公网之间提供多种服务的一种
新的组网和应用技术。
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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通信类
互连
互通
消费电
子类
IT类
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 家庭网络由以下部分组成：
（1）外部网络：
运营商提供的物理网络接口和服务，如广电网、PSTN
、因特网、其它网络等；
（2）家庭主网关：
实现家庭内部网络与外部网络连接的“桥接器”，实
现与所附接设备、内部多个子网关的数据传送与控制；
（3）子网关：
实现各子网内部与家庭主网关连接的“桥接器”，实
现与所附接设备的数据传送与控制；
（4）终端：
实现不同功能的信息传送、控制等功能。
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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二、 家居网的主要网络技术
 HomePlug
 MoCA
 HomePNA
 无线网络
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Dr. Zhanqi XU, National Key Lab on ISN, Xidian University
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HomePlug概述
 HomePlug PowerLine Alliance 家庭插座电力
线联盟
 HomePlug技术使用家庭中的电源线作为家庭网
络基础设施，通过覆盖于整个家庭的电源线，进
行家庭内部音频、视频、数据业务的传输
 用户只需简单地将HomePlug适配器插入一个标
准的电源插座 ，然后将通信终端与该适配器相
连，即可通过电源线建立网络
HomePlug网络结构
HomePlug技术指标
 物理拓扑结构为共享总线型，逻辑拓扑结构为全
互联结构
 单信道带宽为28.2MHz,占用频带1.8-30MHz
 物理层最大速率200Mbps，MAC层最大速率
100Mbps
 双工方式为TDD，多址方式为TDMA和CSMA/CA
 支持组播,支持VLAN
 提供基于优先级和基于流的QoS保证
 单个局端支持最大终端数为253个
HomePlug协议栈
 两个面：control，data
MoCA
 Multimedia over Coax Alliance，同轴电缆多媒
体联盟 ，成立于2004.1
 MoCA技术采用目前有线电视CATV使用的同轴
电缆，因此无需另行布线、施工，就可在家庭
内部构建高速的家庭网络
 2006.3.28，MoCA MAC/PHY v1.0发布
2007年底，MoCA 1.1标准通过
MoCA网络结构
MoCA技术指标
 MoCA网络的频率范围在850MHz-1525MHz，每个
信道带宽为50MHz，每个MoCA网络最多可支持16
个MoCA节点之间的通信
 MoCA标准的物理层使用TDD方式 ，MoCA MAC
层协议是建立在全协调的TDMA信道上
 MoCA网络中最大的PHY层速率为270Mbps，，最
大的MAC层速率为175Mbps，最大的数据包长度
为1518字节，最大的网路时延为5ms，平均网络时
延为3.5ms
MoCA协议栈
 PHY层进行物理层组帧，信道预均衡，
调制技术，功率控制等
Upper Layers (Core Networks )
 MAC层进行控制帧和数据帧的传输，控
制帧包括节点接纳，链路维护，带宽请
求，MAP帧等相关帧；数据帧主要指上
层数据流
Convergence Layers
802.3
MPEG2 TS
MAC Layer
Physical Layer
DSS TS
 汇聚层主要功能是将上层数据进行封装,
使得上层数据与MAC层进行适配,同时
还包括优先级映射等（TS：transport
System：定义若干多媒体流的“封装
encapsulation”协议）
HomePNA概述
 HomePNA（Home Phone Line Networking Alliance，家庭电
话线网络联盟）
 HomePNA技术利用现有电话线和家庭内部同轴电缆传输宽
带数据信号，无需重新布线，满足用户宽带上网的要求
 HomePNA 1.0, HomePNA 2.0
 2005年5月，ITU推出了数据传输率达128Mbps的HomePNA
3.0规范,该标准数据率可以扩展到240Mbps，最大连接设备
数目增至50个
 2007年3月,ITU宣布 HomePNA 3.1规范,HomePNA 3.1标准允
许服务提供商通过家庭内部电话线和电缆以最高320Mbps的
速度提供高速的三重业务整合（triple-play）等互联网服务
HomePNA网络结构
HomePNA协议栈
HomePNA协议栈
HomePNA帧格式
Ethern
et type
无线网络
 IEEE 802.11b/g/n
 外网（家庭网关）
3G/4G 上网卡，以太
网，EPON，ADSL
等
 专用无线网络：无线
电话子母机，对讲机
 Zigbee网络：Zigbee
协议包括高层应用规
范(profile)、汇聚层
、网络层、数据链路
层和物理层，其中数
据链路层和物理层标
准由IEEE802.15.4负
责制定，网络层和传
送层由Zigbee联盟制
定。
已学过的相关技术
 HFC
 EoC（多达10种变形）
三、 新一代家居网技术

由于目前家庭内部组网的技术很多，为了能够
更好的进行信息的互联互通和兼容性的考虑，
HomeGrid论坛成员希望制定统一的互联方案，
以此来替代诸如MoCA，HomePNA，HomePlug
等所作的工作，使用该标准的芯片能以超过
1Gbps的速率在同轴电缆，电话线和电力线上传
输数据。
国际电联G.hn标准
 由ITU提出的G.hn（home networking）是关于家
庭电话线，电源线和同轴电缆的一套协议规范；
 G.hn支持数据传输，高清电视，语音服务，共享
服务等所有家庭多媒体业务；
 G.hn标准基于OFDM技术，提供严格的QoS支持
以进行可靠的视频传输，并避免与线路中已有服
务造成干扰。
G.hn标准特征
 多介质：电力线，电话线，同轴电缆；
 性能：高达1G的信息速率；
 突发性：视频，音频以及数据服务的QoS保证
 安全：AES128加密；
 共存：对非G.hn的兼容；
 管理：遵从TR-69的管理协议；
 网状网：支持区域扩展和自动中继；
 低功耗：满足smart grid和European CoC要求
G.hn网络拓扑
G.hn协议栈
 G.hn协议栈包括物理层和数据链
路层
 G.hn的数据链路层分为3个子层
– APC(应用协议汇聚子层)
– LLC(逻辑链路控制子层)
– MAC(媒质接入控制子层)
 G.hn的物理层分为3个子层
– PCS(物理编码子层)
– PMA(物理媒质连接子层)
– PMD(物理媒质相关子层)