01 Intro To Broadband Access Technologies - Splau.v2
01 Intro To Broadband Access Technologies - Splau.v2
01 Intro To Broadband Access Technologies - Splau.v2
INTRODUCTION TO BROADBAND
ACCESS TECHNOLOGIES
What is Broadband?
• In telecommunications, broadband is wide bandwidth data
transmission which transports multiple signals and traffic types.
The medium can be coaxial cable, optical fiber, radio or
twisted pair.
• In the context of Internet access, broadband is used to mean
any high-speed Internet access that is always on and faster
than dial-up access over traditional analog or ISDN PSTN
services.
– Dial-up uses the facilities of the public switched telephone network
(PSTN) to establish a connection to an Internet service provider (ISP)
by dialing a telephone number on a conventional telephone line
(56 kbit/s download using the V.90 or V.92 protocol and 20 kbit/s in
extremely noisy environments)
Some typical dial-up modem (V.34 or V.92)
Communication Infrastructure Overview
Communication Infrastructure Overview
• Access Network
– Last mile access
– Twisted pair, coaxial cable, lease lines (fiber)
– Few km to 20km
– Mbps (personal) to Gbps (business)
• Metropolitan Area Network
– Small coverage region fiber network
– 2.5Gbps to 10Gbps
• Wide Area Network
– Inter-city, inter-country, inter-continent
– Wavelength division fiber connection
– Tens of Gbps
– Few thousands to tens thousands km submarine cabling
Service Convergence
• Traffic:
– Voice (PSTN – Public Switched Telephone Network),
• Circuit switching not suitable for bursty traffic
– Video (hybrid fiber coax) and
• Usually one way communication
– Data (Internet)
• Packet switching difficult to meet stringent delay requirement
Downstream
upstream
9
First-Last-Mile Bottleneck
• APON, BPON, EPON and GPON are optical access technologies for FTTx (Fiber to the x)
Where x stands for home, curb, neighborhood, office, business, premise, etc
Type of broadband / access technologies
• Digital Subscriber Line (DSL)
• Broadband over Power Lines (BPL) / Power Line
Communication (PLC)
• Hybrid Fiber Coax (HFC)
• Passive Optical Network (PON)
• Point-to-point Ethernet Optical Network
• Point-to-point Optical Wireless Links
• Wireless Broadband Access
• Local Multipoint Distribution Services (LMDS)
• Multichannel Multipoint Distribution Services (MMDS)
Digital Subscriber Line (DSL) Overview
DSL Overview
• Uses existing telephone line (twisted pair) to provide broadband services
• Uses the upper limit of 3.4KHz to carry data, which can be extended to tens of MHz
• Take advantage of unused bandwidth of copper via multiple-frequency channels.
• Allow simultaneous use of telephone and broadband access on the same twisted
pair
• DSLAM (DSL Access Multiplexer) is used at central office and DSL modem is used at
user premises for data modulation and demodulation
• ADSL (asymmetric ratio of 2:1 or 3:1), distance up to 5.5km, ADSL1: 8Mbps/900kbps,
ADSL2: 15Mbps/3.8Mbps
• VDSL (Very-high-bit-rate DSL - high rate but shorter range), VDSL1: 1.5km,
50Mbps/30Mbps, VDSL2: 0.5km, 100Mbps, 1km, 50Mbps
• Symmetric connection: HDSL (High-bit-rate DSL - 1.5Mbps, 4km) and SHDSL
(Symmetric high-speed DSL - 6.7Mbps, 5.5km)
ADSL Frequency Bands
Broadband over Power Lines (BPL) / Power
Line Communication (PLC)
Broadband over Power Lines (BPL) / PLC
• Runs across AC power lines (50/60Hz) at higher
frequency (~5MHz)
• Cheaper to provide data services over existing
infrastructure (i.e., rural areas)
• Uses medium voltage power distribution lines (10kV
and below) to reach households
• Repeaters required for long distance
communication and couplers (by pass device) to
allow data to by pass transformers
• BPL modem (plug into power socket) is used as
transceiver for data over power lines
• Data rates from hundreds of kbps to few Mbps (or
even Gbps using Orthogonal Frequency-division
Multiplexing (OFDM))
• Smart grid applications have been and continue to
be today a successful and promising area
Broadband over Power Lines (BPL) / PLC
• Challenges:
– Transformers along the transmission lines,
they do not pass RF signals
– Massive interference and noise over the
power lines (i.e., power motors)
– Unshielded and untwisted wires create large
antenna emitting RF signal interfering other
RF communication
– Shared medium with limited bandwidth
– Security concern for private communication
– smaller capacity compared to DSL and Transformer
cable, and the availability of other (and
often cheaper) means to provide
broadband access to consumers
Broadband over Power Line at Home
Hybrid Fiber Coax (HFC) Overview
Hybrid Fiber Coax (HFC) Overview
• Designed for TV signal distribution
– One way, point to multipoint broadcasting
• No electronic amplifier required along the trunk
• Fiber (trunk) + coaxial cable (distribution)
• 500 to 2000 subscribers
• Share medium tree topology, medium access control (MAC)
required at upstream transmission only, downstream uses
broadcasting mode
– The most popular protocol for providing voice and data access is Data
Over Cable Service Interface Specification (DOCSIS)
• Coaxial support 1GHz bandwidth for higher data rate, 40Mbps
(downstream) and 10Mbps (upstream)
• Downside – shared bandwidth by all cable modems connected
Passive Optical Network (PON) Overview
or splitter
PON Overview
• Based on low cost photonic components and passive optical network architecture
• No active component between central office and user premises
• Based on ratio 1:N (1 single mode feeder fiber to N passive optical power splitters
and distribution fibers)
• Distance limited to 20km
• Users supported from 2 to 128 depending on power budget (typical 16, 32, 64 users)
• Multiple users access based on time-division multiplexing (TDM) wavelength-division
multiplexing (WDM), code-division multiplexing (CDM)
– WDM – each ONU needs a unique wavelength, very hard to administer if subscribers are
allowed to buy their own ONU.
– CDM – can be implemented with entirely passive components at the transmitter and
receiver.
• Others ATM based PON (APON, 622Mbps) and higher bit rate PONs (BPON, 1.2Gbps
and GPON, 2.5Gbps)
Point-to-point Ethernet Optical Network
Point-to-point Ethernet Optical Network
• “speed” of is actually determined by the smaller of the access rates of the wireless portion
and the backhaul portion
• Two types of technologies that are most popular for providing broadband access today are:
– The IEEE802.11-based Wireless LAN (WLAN) standard, popularly known as WiFi
– The third, fourth, and fifth generations of cellular technology
Long range wireless access at Bario,
Sarawak
Relay points
The team
Local Multipoint Distribution Services (LMDS)
Local Multipoint Distribution Services (LMDS)
• Last mile point-to-point wireless access technology by
IEEE802.16.1 working group
• Frequency bands: 1.3GHz, 28-31GHz, 24-43.5GHz
(depends on region)
• Data rates: 34-38Mbps
• Distance: 3-5km
• Multiple cells structure to provide larger coverage
• Base station with multiple transceivers mounted on roof
top (tall buildings) to create a cell for access
• Point-to-point link to each subscriber
Multichannel Multipoint Distribution Services (MMDS)
Multichannel Multipoint Distribution Services (MMDS)