Transcript IEEE 802.15.3 - UF CISE

CIS 6930: Review on
Network Technology
Jonathan C.L. Liu, Ph.D.
Department of Computer, Information
Science and Engineering (CISE),
University of Florida
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Network Hardware
Local Area Networks
Metropolitan Area Networks
Wide Area Networks
Wireless Networks
Home Networks
Inter-networks
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Local Area Networks
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Metropolitan Area Networks
A metropolitan area network based on
cable TV.
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Wide Area Networks
A stream of packets from sender to
receiver.
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Wireless Networks
(a) Bluetooth configuration
(b) Wireless LAN
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Network Software
Protocol Hierarchies
Design Issues for the Layers
Connection-Oriented and
Connectionless Services
Service Primitives
The Relationship of Services to
Protocols
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Connection-Oriented and
Connectionless Services
Six different types of service.
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Service Primitives
Packets sent in a simple clientserver interaction on a
connection-oriented network.
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Fiber Optic Networks
A fiber optic ring with active repeaters.
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The Electromagnetic Spectrum
The electromagnetic spectrum and its
uses for communication.
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Global Star
(a) Relaying in space.
(b) Relaying on the
ground.
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Structure of the Telephone System
A typical circuit route for a mediumdistance call.
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Time Division Multiplexing
The T1 carrier (1.544 Mbps).
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Time Division Multiplexing (3)
Multiplexing T1 streams into higher
carriers.
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Packet Switching
A comparison of circuit switched and packetswitched networks.
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Functions of the Data Link Layer
• Provide service interface to the
network layer
• Dealing with transmission errors
• Regulating data flow
•
Slow receivers not swamped by fast
senders
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Elementary Data Link Protocols
• An Unrestricted Simplex Protocol
• A Simplex Stop-and-Wait Protocol
• A Simplex Protocol for a Noisy
Channel
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Unrestricted
Simplex
Protocol
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Simplex
Stop-andWait
Protocol
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For a Noisy Channel
A positive
acknowledgement
with retransmission
protocol.
Continued 
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For a Noisy Channel (2)
A positive acknowledgement with retransmission protocol.
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Sliding Window Protocols
• A One-Bit Sliding Window
Protocol
• A Protocol Using Go Back N
• A Protocol Using Selective
Repeat
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Dynamic Channel Allocation
Station Model.
Single Channel Assumption.
Collision Assumption.
(a) Continuous Time.
(b) Slotted Time.
(a) Carrier Sense.
(b) No Carrier Sense.
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Pure ALOHA
In pure ALOHA, frames are transmitted at
completely arbitrary times.
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Pure ALOHA (2)
Vulnerable period for the shaded frame.
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Pure ALOHA (3)
Throughput versus offered traffic for
ALOHA systems.
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Performance Comparison
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CSMA with Collision Detection
CSMA/CD can be in one of three
states: contention, transmission, or
idle.
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Ethernet Cabling
The most common kinds of Ethernet
cabling.
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Ethernet MAC Sublayer Protocol
Collision detection can take as long as 2 .
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Ethernet Performance
Efficiency of Ethernet at 10 Mbps with
512-bit slot times.
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Switched Ethernet
A simple example of switched Ethernet.
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Fast Ethernet
The original fast Ethernet cabling.
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Some Wireless Networks
54 Mbps
5-11 Mbps
802.11{a,g}
802.11b
.11 p-to-p link
1 Mbps
802.15
3G
UMTS/WCDMA, CDMA2000
384 Kbps
2G
IS-95 CDMA, GSM
56 Kbps
Indoor
Outdoor
Mid range
outdoor
Long range
outdoor
10 – 30m
50 – 200m
200m – 4km
5km – 20km
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Wireless Link Characteristics
Differences from a wired link ….
decreased signal strength: radio signal
attenuates as it propagates through matter
(path loss)
interference from other sources: standardized
wireless network frequencies (e.g., 2.4 GHz)
shared by other devices (e.g., phone); devices
(motors) interfere as well
multipath propagation: radio signal reflects off
objects ground, arriving at destination with
slightly different times
…. make communication across (even a point
to point) wireless link much more “difficult”
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IEEE 802.11 Wireless LAN
802.11b
2.4-5 GHz unlicensed
radio spectrum
up to 11 Mbps
direct sequence
spread spectrum
(DSSS) in physical
layer
• all hosts use same
chipping code
widely deployed,
using base stations
802.11a
5-6 GHz range
up to 54 Mbps
802.11g
2.4-5 GHz range
up to 54 Mbps
All use CSMA/CA for
multiple access
All have base-station
and ad-hoc network
versions
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Hidden-Node Problem
(a) The hidden station
problem.
(b) The exposed station
problem.
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IEEE 802.11: multiple access
avoid collisions: 2+ nodes transmitting at same
time
802.11: CSMA - sense before transmitting
don’t collide with ongoing transmission by other node
802.11: no collision detection!
difficult to receive (sense collisions) when
transmitting due to weak received signals (fading)
can’t sense all collisions in any case: hidden nodes,
and/or fading
goal: avoid collisions: CSMA/C(ollision)A(voidance)
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Timing of the protocol
The use of virtual channel sensing using
CSMA/CA.
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Avoiding collisions (more)
idea:
allow sender to “reserve” channel rather than random
access of data frames: avoid collisions of long data frames
sender first transmits small request-to-send (RTS) packets to BS
using CSMA
RTS may still collide with each other (but they’re short)
BS broadcasts clear-to-send (CTS) in response to RTS
RTS heard by all nodes
sender transmits data frame
other stations defer transmissions
Avoid data frame collisions completely
using small reservation packets!
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Collision Avoidance: RTS-CTS exchange
A
AP
B
reservation collision
DATA (A)
defer
time
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802.11: Channels, association
802.11b: 2.4GHz-2.485GHz spectrum divided into
11 channels at different frequencies
AP admin chooses frequency for AP
interference possible: channel can be same as
that chosen by neighboring AP!
host: must associate with an AP
scans channels, listening for beacon frames
containing AP’s name and MAC address
selects AP to associate with
may perform authentication
will typically run DHCP to get IP address in
AP’s subnet
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Broadband Wireless
• The
• The
• The
• The
802.16
802.16
802.16
802.16
Protocol Stack
Physical Layer
MAC Sublayer Protocol
Frame Structure
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The 802.16 Protocol Stack
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The 802.16 Physical Layer
The 802.16 transmission environment.
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The 802.16 Physical Layer (2)
Frames and time slots for time division
duplexing.
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802.16 MAC Sublayer Protocol
Service Classes
• Constant bit rate service
• Real-time variable bit rate service
• Non-real-time variable bit rate
service
• Best efforts service
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802.16 Frame Structure
(a) A generic frame. (b) A bandwidth
request frame.
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Bluetooth
• Bluetooth Architecture
• Bluetooth Applications
• The Bluetooth Protocol Stack
• The Bluetooth Radio Layer
• The Bluetooth Baseband Layer
• The Bluetooth L2CAP Layer
• The Bluetooth Frame Structure
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802.15: personal area network
less than 10 m diameter
replacement for cables
(mouse, keyboard,
headphones)
ad hoc: no infrastructure
master/slaves:
slaves request permission to
send (to master)
master grants requests
802.15: evolved from
Bluetooth specification
2.4-2.5 GHz radio band
up to 721 kbps
P
S
P
radius of
coverage
M
S
P
S
P
M Master device
S Slave device
P Parked device (inactive)
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The Bluetooth Protocol Stack
The 802.15 version of the Bluetooth
protocol architecture.
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The Bluetooth Frame Structure
A typical Bluetooth data frame.
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IEEE 802.15.3 - Overview
High data rate WPAN
Potential future standard
Motivation: The need for higher
bandwidths currently supported with
802.15.1
100 Mpbs within 10 meter
400 Mpbs within 5 meter
Data, High quality TV, Home cinema
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IEEE 802.15.3 - Overview
Dynamic topology
Mobile devices often join and leave the
piconet
Short connection times
High spatial capacity
Multiple Power Management modes
Secure Network
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IEEE 802.15.3 - Overview
Based on piconets
Data Devices (DEV) establish peer-topeer communication
Includes also a Piconet Coordinator
(PNC)
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IEEE 802.15.3 - Topology
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IEEE 802.15.3 - Superframe
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IEEE 802.15.3 - Beacon
Beacon
Control information
Allocates GTS
Synchronization
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IEEE 802.15.3 - CAP
CAP
Allows contention via CSMA/CA
Command exchange between DEV and
PNC
File transfers from DEV without request
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IEEE 802.15.3 - CFP
CFP
Time slot allocation specified in the beacon
Reserved bandwidth for DEV
MTS: Command, GTS: Data
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IEEE 802.15.3 - GTS
GTS reservation
DEV sends a Channel Time Request (CTR)
to PNC
• Isochronous data: number and duration of
slot(s)
• Asynchronous data: Total amount of data
PNC allocates GTSs to DEV via CTA
DEV is responsible of utilizing allocated
GTSs
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IEEE 802.15.3 - GTS
Two types of GTSs
Dynamic GTS
• Location within a superframe may change
• PNC can optimize channel utilization
Pseudostatic GTS
• Only for isochronous data
• Fixed location within a superframe
• May be changed, but only after a series of
notitications to the DEV
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IEEE 802.15.3
Starting a piconet
DEV scans the for the best channel and
sends out beacons -> the DEV becomes
PNC
If no channels available: Establishes a child
or neighbor piconet instead
• Requests a private GTS from parent PNC
• All communication takes place within assigned
GTS
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IEEE 802.15.3 - QoS
QoS
IEEE 802.15.3 supports both synchronous
and asynchronous data
CAP offers only best-effort
The PNC will allocate resources in the CFP
• Through admission control
• Synchronous data: Based on number of time
slots per superframe, duration of slot, priority
and GTS type
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IEEE 802.15.3 - QoS
• Asynchronous data: Based on total data and
priority
After performing admission control, GTSs
may be allocated
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