Mobile Communications
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Transcript Mobile Communications
Mobile Communications
Chapter 7: Wireless LANs
Characteristics
IEEE 802.11
PHY
MAC
Roaming
.11a, b, g, h, i …
HIPERLAN (Não é dado)
Bluetooth / IEEE 802.15.x
IEEE 802.16/.20/.21/.22
RFID
Comparison
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.1
Mobile Communication Technology according to IEEE
Local wireless networks
WLAN 802.11
WiFi
802.11a
802.11b
802.11h
802.11i/e/…/w
802.11g
ZigBee
802.15.4
Personal wireless nw.
WPAN 802.15
802.15.1
802.15.2
802.15.4a/b
802.15.5
802.15.3
802.15.3a/b
Bluetooth
Wireless distribution networks
WMAN 802.16 (Broadband Wireless Access)
WiMAX
+ Mobility
802.20 (Mobile Broadband Wireless Access)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.2
Characteristics of wireless LANs
Advantages
very flexible within the reception area
Ad-hoc networks without previous planning possible
(almost) no wiring difficulties (e.g. historic buildings, firewalls)
more robust against disasters like, e.g., earthquakes, fire - or users pulling
a plug...
Disadvantages
typically very low bandwidth compared to wired networks
(1-10 Mbit/s) due to shared medium
many proprietary solutions, especially for higher bit-rates, standards take
their time (e.g. IEEE 802.11)
products have to follow many national restrictions if working wireless, it
takes a vary long time to establish global solutions like, e.g., IMT-2000
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.3
Design goals for wireless LANs
global, seamless operation
low power for battery use
no special permissions or licenses needed to use the LAN
robust transmission technology
simplified spontaneous cooperation at meetings
easy to use for everyone, simple management
protection of investment in wired networks
security (no one should be able to read my data), privacy (no one should
be able to collect user profiles), safety (low radiation)
transparency concerning applications and higher layer protocols, but also
location awareness if necessary
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.4
Comparison: infrared vs. radio transmission
Infrared
uses IR diodes, diffuse light,
multiple reflections (walls,
furniture etc.)
Radio
Advantages
Advantages
experience from wireless WAN
and mobile phones can be used
coverage of larger areas
possible (radio can penetrate
walls, furniture etc.)
simple, cheap, available in
many mobile devices
no licenses needed
simple shielding possible
Disadvantages
Disadvantages
very limited license free
frequency bands
shielding more difficult,
interference with other electrical
devices
interference by sunlight, heat
sources etc.
many things shield or absorb IR
light
low bandwidth
Example
typically using the license free
ISM band at 2.4 GHz
Example
IrDA (Infrared Data Association)
interface available everywhere
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
Many different products
MC SS05
7.5
Comparison: infrastructure vs. ad-hoc networks
infrastructure
network
AP
AP
wired network
AP: Access Point
AP
ad-hoc network
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.6
802.11 - Architecture of an infrastructure network
Station (STA)
802.11 LAN
STA1
802.x LAN
Basic Service Set (BSS)
BSS1
Portal
Access
Point
Access
Point
ESS
group of stations using the same
radio frequency
Access Point
Distribution System
station integrated into the wireless
LAN and the distribution system
Portal
BSS2
bridge to other (wired) networks
Distribution System
STA2
terminal with access mechanisms
to the wireless medium and radio
contact to the access point
802.11 LAN
STA3
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
interconnection network to form
one logical network (EES:
Extended Service Set) based
on several BSS
MC SS05
7.7
802.11 - Architecture of an ad-hoc network
Direct communication within a limited
range
802.11 LAN
Station (STA):
terminal with access mechanisms to
the wireless medium
Independent Basic Service Set
(IBSS):
group of stations using the same
radio frequency
STA1
STA3
IBSS1
STA2
IBSS2
STA5
STA4
802.11 LAN
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.8
IEEE standard 802.11
fixed
terminal
mobile terminal
infrastructure
network
access point
application
application
TCP
TCP
IP
IP
LLC
LLC
LLC
802.11 MAC
802.11 MAC
802.3 MAC
802.3 MAC
802.11 PHY
802.11 PHY
802.3 PHY
802.3 PHY
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.9
802.11 - Layers and functions
MAC
PLCP Physical Layer Convergence Protocol
MAC Management
access mechanisms, fragmentation,
encryption
clear channel assessment signal
(carrier sense)
PMD Physical Medium Dependent
synchronization, roaming, MIB,
power management
modulation, coding
PHY Management
channel selection, MIB
Station Management
LLC
MAC
MAC Management
PLCP
PHY Management
PMD
coordination of all management
functions
Station Management
PHY
DLC
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.10
802.11 - Physical layer (classical)
3 versions: 2 radio (typ. 2.4 GHz), 1 IR
data rates 1 or 2 Mbit/s
FHSS (Frequency Hopping Spread Spectrum)
spreading, despreading, signal strength, typ. 1 Mbit/s
min. 2.5 frequency hops/s (USA), two-level GFSK modulation
DSSS (Direct Sequence Spread Spectrum)
DBPSK modulation for 1 Mbit/s (Differential Binary Phase Shift Keying),
DQPSK for 2 Mbit/s (Differential Quadrature PSK)
preamble and header of a frame is always transmitted with 1 Mbit/s, rest
of transmission 1 or 2 Mbit/s
chip sequence (11 symbols) : +1, -1, +1, +1, -1, +1, +1, +1, -1, -1, -1
(Barker code)
max. radiated power 1 W (USA), 100 mW (EU), min. 1mW
Infrared
850-950 nm, diffuse light, typ. 10 m range
carrier detection, energy detection, synchronization
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.11
FHSS PHY packet format (Não)
Synchronization
synch with 010101... pattern
SFD (Start Frame Delimiter)
0000110010111101 start pattern
PLW (PLCP_PDU Length Word)
length of payload incl. 32 bit CRC of payload, PLW < 4096
PSF (PLCP Signaling Field)
data of payload (1 or 2 Mbit/s)
HEC (Header Error Check)
CRC with x16+x12+x5+1
80
synchronization
16
12
4
16
variable
SFD
PLW
PSF
HEC
payload
PLCP preamble
bits
PLCP header
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.12
DSSS PHY packet format
Synchronization
synch., gain setting, energy detection, frequency offset compensation
SFD (Start Frame Delimiter)
1111001110100000
Signal
data rate of the payload (0A: 1 Mbit/s DBPSK; 14: 2 Mbit/s DQPSK)
Service
Length
future use, 00: 802.11 compliant
length of the payload
HEC (Header Error Check)
protection of signal, service and length, x16+x12+x5+1
128
synchronization
16
SFD
PLCP preamble
8
8
16
16
signal service length HEC
variable
bits
payload
PLCP header
128 +16 + 8 + 8 + 16 + 16 = 192 bit a 1 Mbps -> 192 us (em 802.11b a partir de “signal“ pode ser a 2 Mbps)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.13
802.11 - MAC layer I - DFWMAC
Traffic services
Asynchronous Data Service (mandatory)
exchange of data packets based on “best-effort”
support of broadcast and multicast
Time-Bounded Service (optional)
implemented using PCF (Point Coordination Function)
Access methods
DFWMAC-DCF CSMA/CA (mandatory)
collision avoidance via randomized „back-off“ mechanism
minimum distance between consecutive packets
ACK packet for acknowledgements (not for broadcasts)
DFWMAC-DCF w/ RTS/CTS (optional)
Distributed Foundation Wireless MAC
avoids hidden terminal problem
DFWMAC- PCF (optional)
access point polls terminals according to a list
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.14
802.11 - MAC layer II
Priorities
defined through different inter frame spaces
no guaranteed, hard priorities
SIFS (Short Inter Frame Spacing)
PIFS (PCF IFS)
highest priority, for ACK, CTS, polling response
medium priority, for time-bounded service using PCF
DIFS (DCF, Distributed Coordination Function IFS)
lowest priority, for asynchronous data service
Tslot = 9; SIFS = 16; PIFS = 25; DIFS = 34 us
DIFS
DIFS
medium busy
PIFS
SIFS
contention
next frame
t
direct access if
medium is free DIFS
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.15
802.11 - CSMA/CA access method I
DIFS
contention window (CW)
(randomized back-off
mechanism)
DIFS
medium busy
direct access if
medium is free DIFS
next frame
t
slot time
station ready to send starts sensing the medium (Carrier Sense
based on CCA, Clear Channel Assessment)
if the medium is free for the duration of an Inter-Frame Space (IFS),
the station can start sending (IFS depends on service type)
if the medium is busy, the station has to wait for a free IFS, then the
station must additionally wait a random back-off time (collision
avoidance, multiple of slot-time) CW = 7, 15, 31, 63, 127
if another station occupies the medium during the back-off time of
the station, the back-off timer stops (fairness)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.16
802.11 - Binary Exponential Backoff
Stations choose their backoff time randomly from contention
Window
Ideal contention window size is trade-off between acceptable load
and experienced delay
Initial contention window size (CWmin) is 7 slots (backoff time between
0 and 7)
After collision (no ack), contention window is “doubled” until CWmax
= 255 is reached: 7 -> 15 -> 31 -> 63 -> 127 -> 255
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.17
802.11 - competing stations - simple version (no RTS/CTS)
DIFS
DIFS
station1
station2
DIFS
boe
bor
boe
busy
DIFS
boe bor
boe
busy
boe busy
boe bor
boe
boe
busy
station3
station4
boe bor
station5
busy
bor
t
busy
medium not idle (frame, ack etc.)
boe elapsed backoff time
packet arrival at MAC
bor residual backoff time
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.18
802.11 - CSMA/CA access method II
Sending unicast packets
station has to wait for DIFS before sending data
receivers acknowledge at once (after waiting for SIFS) if the packet was
received correctly (CRC)
automatic retransmission of data packets in case of transmission errors
DIFS
sender
data
SIFS
receiver
ACK
DIFS
other
stations
waiting time
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
data
t
contention
MC SS05
7.19
802.11 – DFWMAC (Distributed Foundation Wireless MAC)
Sending unicast packets
station can send RTS with reservation parameter after waiting for DIFS
(reservation determines amount of time the data packet needs the medium)
acknowledgement via CTS after SIFS by receiver (if ready to receive)
sender can now send data at once, acknowledgement via ACK
other stations store medium reservations distributed via RTS and CTS
DIFS
sender
RTS
data
SIFS
receiver
other
stations
CTS SIFS
SIFS
NAV (RTS)
NAV (CTS)
defer access
ACK
DIFS
data
t
contention
NAV – Network Allocation Vector
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.20
Timing diagram of collision and successful transmission.
(a) RTS/CTS collision, (b) RTS/CTS successful transmission,
(c) Basic frame collision (d) Basic frame successful transmission
( note: in (a) and (c), crossed block represents collision).
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.21
Fragmentation
DIFS
sender
RTS
frag1
SIFS
receiver
CTS SIFS
frag2
SIFS
ACK1 SIFS
SIFS
ACK2
NAV (RTS)
NAV (CTS)
other
stations
DIFS
NAV (frag1)
NAV (ACK1)
contention
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.22
data
t
DFWMAC-PCF
t0 t1
medium busy PIFS
point
coordinator
wireless
stations
stations‘
NAV
SuperFrame
SIFS
D1
SIFS
D2
SIFS
SIFS
U1
U2
NAV
contention free period
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.23
DFWMAC-PCF II (cont.)
t2
point
coordinator
wireless
stations
stations‘
NAV
D3
PIFS
SIFS
D4
t3
t4
CFend
SIFS
U4
NAV
contention free period
contention
period
t
CFend - contention free period end
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.24
802.11 - Frame format
Types
control frames, management frames, data frames
Sequence numbers
important against duplicated frames due to lost ACKs
Addresses
receiver, transmitter (physical), BSS identifier, sender (logical)
Miscellaneous
sending time, checksum, frame control, data
bytes
2
2
6
6
6
2
6
Frame Duration/ Address Address Address Sequence Address
Control
ID
1
2
3
Control
4
bits
2
2
4
1
1
1
1
1
1
1
0-2312
4
Data
CRC
1
Protocol
To From More
Power More
Type Subtype
Retry
WEP Order
version
DS DS Frag
Mgmt Data
MAC header + trailer = 34 octets
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.25
MAC address format
scenario
ad-hoc network
infrastructure
network, from AP
infrastructure
network, to AP
infrastructure
network, within DS
to DS from
DS
0
0
0
1
address 1 address 2 address 3 address 4
DA
DA
SA
BSSID
BSSID
SA
-
1
0
BSSID
SA
DA
-
1
1
RA
TA
DA
SA
DS: Distribution System
AP: Access Point
DA: Destination Address
SA: Source Address
BSSID: Basic Service Set Identifier
RA: Receiver Address (AP)
TA: Transmitter Address (AP)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.26
Endereços MAC 802.11
00 – adhoc
DA, SA, BSSID
01 – wired to wireless
DA, BSSID, SA
10 – wireless to wired
(BSSID)
SA
DA
BSSID
DA
SA
DA,SA
BSSID
SA
DA
BSSID, SA, DA
11 – via wireless (bridge)
RA, TA, DA, SA
DA,SA
RA
TA
SA
DA
DA,SA
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
DA,SA
MC SS05
7.27
Special Frames: ACK, RTS, CTS
Acknowledgement
bytes
ACK
2
2
6
Frame
Receiver
Duration
Control
Address
4
CRC
Request To Send
bytes
RTS
2
2
6
6
Frame
Receiver Transmitter
Duration
Control
Address Address
Clear To Send
bytes
CTS
2
2
6
Frame
Receiver
Duration
Control
Address
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
4
CRC
7.28
4
CRC
802.11 - MAC management
Synchronization
try to find a WLAN, try to stay within a WLAN
timer etc.
Power management
sleep-mode without missing a message
periodic sleep, frame buffering, traffic measurements
Association/Reassociation
integration into a LAN
roaming, i.e. change networks by changing access points
scanning, i.e. active search for a network
MIB - Management Information Base
managing, read, write (SNMP)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.29
Synchronization using a Beacon (infrastructure)
beacon interval
access
point
medium
B
B
busy
busy
B
busy
B
busy
t
value of the timestamp
B
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
beacon frame (BSSID, Timestamp)
MC SS05
7.30
Synchronization using a Beacon (ad-hoc)
beacon interval
station1
B1
B1
B2
station2
medium
busy
busy
B2
busy
busy
t
value of the timestamp
B
beacon frame
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
random delay
7.31
Power management
Idea: switch the transceiver off if not needed
States of a station: sleep and awake
Timing Synchronization Function (TSF)
stations wake up at the same time
Infrastructure
Traffic Indication Map (TIM)
list of unicast receivers transmitted by AP
Delivery Traffic Indication Map (DTIM)
list of broadcast/multicast receivers transmitted by AP
Ad-hoc
Ad-hoc Traffic Indication Map (ATIM)
announcement of receivers by stations buffering frames
more complicated - no central AP
collision of ATIMs possible (scalability?)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.32
Power saving with wake-up patterns (infrastructure)
TIM interval
access
point
DTIM interval
D B
T
busy
medium
busy
T
d
D B
busy
busy
p
station
d
t
T
TIM
D
B
broadcast/multicast
DTIM
awake
p PS poll
d data transmission
to/from the station
PS – Power Saving
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.33
Power saving with wake-up patterns (ad-hoc)
ATIM
window
station1
beacon interval
B1
station2
A
B2
B2
D
a
B1
d
t
B
beacon frame
awake
random delay
a acknowledge ATIM
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
A transmit ATIM
D transmit data
d acknowledge data
MC SS05
7.34
Scanning
Scanning involves the active search for a BSS. IEEE 802.11 differentiates
between passive and active scanning.
Passive scanning - listening into the medium to find other networks, i.e.,
receiving the beacon of another network issued by access point.
Active scanning - sending a probe on each channel and waiting for a
response. Beacon and probe responses contain the information
necessary to join the new BSS.
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.35
Active Scanning
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.36
802.11 - Roaming
No or bad connection? Then perform:
Scanning
scan the environment, i.e., listen into the medium for beacon signals or
send probes into the medium and wait for an answer
Reassociation Request
station sends a request to one or several AP(s)
Reassociation Response
success: AP has answered, station can now participate
failure: continue scanning
AP accepts Reassociation Request
signal the new station to the distribution system
the distribution system updates its data base (i.e., location information)
typically, the distribution system now informs the old AP so it can release
resources
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.37
Roaming:
Active Scanning / Authentication/ Reassociation
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.38
Handoff with IAPP (Inter Access Point Protocol), IEEE 802.11f
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.39
WLAN: IEEE 802.11b
Data rate
Connection set-up time
1, 2, 5.5, 11 Mbit/s, depending on
SNR
User data rate max. approx. 6
Mbit/s
Transmission range
300m outdoor, 30m indoor
Max. data rate ~10m indoor
Frequency
Quality of Service
Limited (no automated key
distribution, sym. Encryption)
Special Advantages/Disadvantages
Free 2.4 GHz ISM-band
Limited, WEP insecure, SSID
Availability
Typ. Best effort, no guarantees
(unless polling is used, limited
support in products)
Manageability
Security
Connectionless/always on
Many products, many vendors
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
Advantage: many installed systems,
lot of experience, available
worldwide, free ISM-band, many
vendors, integrated in laptops,
simple system
Disadvantage: heavy interference
on ISM-band, no service
guarantees, slow relative speed
only
MC SS05
7.40
IEEE 802.11b – PHY frame formats
Long PLCP PPDU format
128
16
synchronization
SFD
8
8
16
16
signal service length HEC
PLCP preamble
bits
variable
payload
PLCP header
192 µs at 1 Mbit/s DBPSK
1, 2, 5.5 or 11 Mbit/s
Short PLCP PPDU format (optional)
56
short synch.
16
SFD
8
8
16
16
signal service length HEC
PLCP preamble
(1 Mbit/s, DBPSK)
bits
variable
payload
PLCP header
(2 Mbit/s, DQPSK)
96 µs
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
2, 5.5 or 11 Mbit/s
MC SS05
7.41
Channel selection (non-overlapping)
Europe (ETSI)
channel 1
2400
2412
channel 7
channel 13
2442
2472
22 MHz
2483.5
[MHz]
US (FCC) / Canada (IC)
channel 1
2400
2412
channel 6
channel 11
2437
2462
22 MHz
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
2483.5
[MHz]
7.42
WLAN: IEEE 802.11a
Data rate
Connection set-up time
6, 9, 12, 18, 24, 36, 48, 54 Mbit/s,
depending on SNR
User throughput (1500 byte packets): 5.3
(6), 18 (24), 24 (36), 32 (54)
6, 12, 24 Mbit/s mandatory
Transmission range
Quality of Service
E.g., 54 Mbit/s up to 5 m, 48 up to 12 m,
36 up to 25 m, 24 up to 30m, 18 up to 40
m, 12 up to 60 m
Free 5.15-5.25, 5.25-5.35, 5.725-5.825
GHz ISM-band
Security
Limited (no automated key distribution,
sym. Encryption)
Special Advantages/Disadvantages
Frequency
Typ. best effort, no guarantees (same as
all 802.11 products)
Manageability
100m outdoor, 10m indoor
Connectionless/always on
Limited, WEP insecure, SSID
Advantage: fits into 802.x standards, free
ISM-band, available, simple system,
uses less crowded 5 GHz band
Disadvantage: stronger shading due to
higher frequency, no QoS
Availability
Some products, some vendors
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.43
IEEE 802.11a – PHY frame format
4
1
12
1
rate reserved length parity
6
16
tail service
variable
6
variable
payload
tail
pad
bits
PLCP header
PLCP preamble
12
signal
data
1
6 Mbit/s
variable
symbols
6, 9, 12, 18, 24, 36, 48, 54 Mbit/s
250 Ksymbol/s -> Tsymbol = 4 ms -> PLCP+signal = 13x4 = 52 ms
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.44
Operating channels for 802.11a / US U-NII
36
5150
40
44
48
52
56
60
64
5180 5200 5220 5240 5260 5280 5300 5320
channel
5350 [MHz]
16.6 MHz
149
153
157
161
channel
center frequency =
5000 + 5*channel number [MHz]
5725 5745 5765 5785 5805 5825 [MHz]
16.6 MHz
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.45
OFDM in IEEE 802.11a (and HiperLAN2)
OFDM with 52 used subcarriers (64 in total)
48 data + 4 pilot
(plus 12 virtual subcarriers)
312.5 kHz spacing
312.5 kHz
pilot
-26 -21
-7 -1 1
7
21 26
channel center frequency
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
subcarrier
number
7.46
WLAN: IEEE 802.11 – developments (03/2005)
802.11c: Bridge Support
Definition of MAC procedures to support bridges as extension to 802.1D
802.11d: Regulatory Domain Update
Support of additional regulations related to channel selection, hopping sequences
802.11e: MAC Enhancements – QoS
Enhance the current 802.11 MAC to expand support for applications with Quality of
Service requirements, and in the capabilities and efficiency of the protocol
Definition of a data flow (“connection”) with parameters like rate, burst, period…
Additional energy saving mechanisms and more efficient retransmission
802.11f: Inter-Access Point Protocol
Establish an Inter-Access Point Protocol for data exchange via the distribution
system
802.11g: Data Rates > 20 Mbit/s at 2.4 GHz; 54 Mbit/s, OFDM
Successful successor of 802.11b, performance loss during mixed operation with 11b
802.11h: Spectrum Managed 802.11a
Extension for operation of 802.11a in Europe by mechanisms like channel
measurement for dynamic channel selection (DFS, Dynamic Frequency Selection)
and power control (TPC, Transmit Power Control)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.47
WLAN: IEEE 802.11– developments (03/2005)
802.11i: Enhanced Security Mechanisms
Enhance the current 802.11 MAC to provide improvements in security.
TKIP enhances the insecure WEP, but remains compatible to older WEP systems
AES provides a secure encryption method and is based on new hardware
802.11j: Extensions for operations in Japan
Changes of 802.11a for operation at 5GHz in Japan using only half the channel
width at larger range
802.11k: Methods for channel measurements
Devices and access points should be able to estimate channel quality in order to be
able to choose a better access point of channel
802.11m: Updates of the 802.11 standards
802.11n: Higher data rates above 100Mbit/s
Changes of PHY and MAC with the goal of 100Mbit/s at MAC SAP
MIMO antennas (Multiple Input Multiple Output), up to 600Mbit/s are currently
feasible
However, still a large overhead due to protocol headers and inefficient mechanisms
802.11p: Inter car communications
Communication between cars/road side and cars/cars
Planned for relative speeds of min. 200km/h and ranges over 1000m
Usage of 5.850-5.925GHz band in North America
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.48
WLAN: IEEE 802.11– future developments (03/2005)
802.11r: Faster Handover between BSS
Secure, fast handover of a station from one AP to another within an ESS
Current mechanisms (even newer standards like 802.11i) plus incompatible devices from
different vendors are massive problems for the use of, e.g., VoIP in WLANs
Handover should be feasible within 50ms in order to support multimedia applications efficiently
802.11s: Mesh Networking
Design of a self-configuring Wireless Distribution System (WDS) based on 802.11
Support of point-to-point and broadcast communication across several hops
802.11t: Performance evaluation of 802.11 networks
Standardization of performance measurement schemes
802.11u: Interworking with additional external networks
802.11v: Network management
Extensions of current management functions, channel measurements
Definition of a unified interface
802.11w: Securing of network control
Classical standards like 802.11, but also 802.11i protect only data frames, not the control frames.
Thus, this standard should extend 802.11i in a way that, e.g., no control frames can be forged.
Note: Not all “standards” will end in products, many ideas get stuck at working group level
Info: www.ieee802.org/11/, 802wirelessworld.com, standards.ieee.org/getieee802/
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.49
ETSI – HIPERLAN (historical) (não é dado)
ETSI standard
European standard, cf. GSM, DECT, ...
Enhancement of local Networks and interworking with fixed networks
integration of time-sensitive services from the early beginning
HIPERLAN family
one standard cannot satisfy all requirements
range, bandwidth, QoS support
commercial constraints
HIPERLAN 1 standardized since 1996 – no products!
higher layers
medium access
control layer
channel access
control layer
physical layer
HIPERLAN layers
logical link
control layer
medium access
control layer
network layer
data link layer
physical layer
OSI layers
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
physical layer
IEEE 802.x layers
MC SS05
7.50
Overview: original HIPERLAN protocol family
Application
Frequency
Topology
Antenna
Range
QoS
Mobility
Interface
Data rate
Power
conservation
HIPERLAN 1
wireless LAN
HIPERLAN 2
access to ATM
fixed networks
HIPERLAN 3
wireless local
loop
HIPERLAN 4
point-to-point
wireless ATM
connections
17.2-17.3GHz
point-to-point
5.1-5.3GHz
decentralized adcellular,
point-tohoc/infrastructure
centralized
multipoint
omni-directional
directional
50 m
50-100 m
5000 m
150 m
statistical
ATM traffic classes (VBR, CBR, ABR, UBR)
<10m/s
stationary
conventional LAN
ATM networks
23.5 Mbit/s
>20 Mbit/s
yes
155 Mbit/s
not necessary
HIPERLAN 1 never reached product status,
the other standards have been renamed/modfied !
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.51
HIPERLAN 1 - Characteristics
Data transmission
point-to-point, point-to-multipoint, connectionless
23.5 Mbit/s, 1 W power, 2383 byte max. packet size
Services
asynchronous and time-bounded services with hierarchical priorities
compatible with ISO MAC
Topology
infrastructure or ad-hoc networks
transmission range can be larger then coverage of a single node
(„forwarding“ integrated in mobile terminals)
Further mechanisms
power saving, encryption, checksums
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.52
HIPERLAN 1 - Physical layer
Scope
modulation, demodulation, bit and frame synchronization
forward error correction mechanisms
measurements of signal strength
channel sensing
Channels
3 mandatory and 2 optional channels (with their carrier frequencies)
mandatory
channel 0: 5.1764680 GHz
channel 1: 5.1999974 GHz
channel 2: 5.2235268 GHz
optional
channel 3: 5.2470562 GHz
channel 4: 5.2705856 GHz
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.53
HIPERLAN 1 - Physical layer frames
Maintaining a high data-rate (23.5 Mbit/s) is power consuming problematic for mobile terminals
packet header with low bit-rate comprising receiver information
only receiver(s) address by a packet continue receiving
Frame structure
LBR (Low Bit-Rate) header with 1.4 Mbit/s
450 bit synchronization
minimum 1, maximum 47 frames with 496 bit each
for higher velocities of the mobile terminal (> 1.4 m/s) the maximum
number of frames has to be reduced
HBR
LBR
synchronization
data0
data1
...
datam-1
Modulation
GMSK for high bit-rate, FSK for LBR header
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.54
HIPERLAN 1 - CAC sublayer
Channel Access Control (CAC)
assure that terminal does not access forbidden channels
priority scheme, access with EY-NPMA
Priorities
5 priority levels for QoS support
QoS is mapped onto a priority level with the help of the packet
lifetime (set by an application)
if packet lifetime = 0 it makes no sense to forward the packet to the
receiver any longer
standard start value 500ms, maximum 16000ms
if a terminal cannot send the packet due to its current priority, waiting
time is permanently subtracted from lifetime
based on packet lifetime, waiting time in a sender and number of hops to
the receiver, the packet is assigned to one out of five priorities
the priority of waiting packets, therefore, rises automatically
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.55
HIPERLAN 1 - EY-NPMA I
EY-NPMA (Elimination Yield Non-preemptive Priority Multiple Access)
3 phases: priority resolution, contention resolution, transmission
finding the highest priority
transmission
prioritization
contention
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
user data
yield listening
elimination survival
verification
elimination burst
priority assertion
priority detection
synchronization
every priority corresponds to a time-slot to send in the first phase, the
higher the priority the earlier the time-slot to send
higher priorities can not be preempted
if an earlier time-slot for a higher priority remains empty, stations with the
next lower priority might send
after this first phase the highest current priority has been determined
IPS
IPA
IES IESV IYS
transmission
MC SS05
t
7.56
HIPERLAN 1 - EY-NPMA II
Several terminals can now have the same priority and wish to send
contention phase
Elimination Burst: all remaining terminals send a burst to eliminate
contenders (11111010100010011100000110010110, high bit- rate)
Elimination Survival Verification: contenders now sense the channel, if the
channel is free they can continue, otherwise they have been eliminated
Yield Listening: contenders again listen in slots with a nonzero probability,
if the terminal senses its slot idle it is free to transmit at the end of the
contention phase
the important part is now to set the parameters for burst duration and
channel sensing (slot-based, exponentially distributed)
data transmission
the winner can now send its data (however, a small chance of collision
remains)
if the channel was idle for a longer time (min. for a duration of 1700 bit) a
terminal can send at once without using EY-NPMA
synchronization using the last data transmission
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.57
HIPERLAN 1 - DT-HCPDU/AK-HCPDU
LBR
LBR
0 1 2 3 4 5 6 7
1 0 1 0 1 0 1 0
0 1 HI
HDA
bit
bit
HBR
HID
DA
SA
UD
PAD
CS
Data HCPDU
bit
Acknowledgement HCPDU
HDA
HDACS
BLIR = n
BLIRCS 1
0 1 2 3 4 5 6 7
TI
BLI = n
PLI = m
0 1 2 3 4 5 6 7
1 0 1 0 1 0 1 0
0 1 HI
AID
AID
AIDCS
byte
1
2
3-6
7 - 12
13 - 18
19 - (52n-m-4)
(52n-m-3) - (52n-4)
(52n-3) - 52n
HI: HBR-part Indicator
HDA: Hashed Destination HCSAP Address
HDACS: HDA CheckSum
BLIR: Block Length Indicator
BLIRCS: BLIR CheckSum
TI: Type Indicator
BLI: Block Length Indicator
HID: HIPERLAN IDentifier
DA: Destination Address
SA: Source Address
UD: User Data (1-2422 byte)
PAD: PADding
CS: CheckSum
AID: Acknowledgement IDentifier
AIDS: AID CheckSum
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.58
HIPERLAN 1 - MAC layer
Compatible to ISO MAC
Supports time-bounded services via a priority scheme
Packet forwarding
support of directed (point-to-point) forwarding and broadcast forwarding (if
no path information is available)
support of QoS while forwarding
Encryption mechanisms
mechanisms integrated, but without key management
Power conservation mechanisms
mobile terminals can agree upon awake patterns (e.g., periodic wake-ups
to receive data)
additionally, some nodes in the networks must be able to buffer data for
sleeping terminals and to forward them at the right time (so called stores)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.59
HIPERLAN 1 - DT-HMPDU
bit
0 1 2 3 4 5 6 7
LI = n
TI = 1
RL
byte
1-2
3
4-5
PSN
DA
SA
ADA
ASA
ML
ML
6-7
8 - 13
14 - 19
20 - 25
26 - 31
32
33
UP
KID
IV
IV
UD
SC
Data HMPDU
34
35 - 37
38 - (n-2)
(n-1) - n
n= 40–2422
LI: Length Indicator
TI: Type Indicator
RL: Residual Lifetime
PSN: Sequence Number
DA: Destination Address
SA: Source Address
ADA: Alias Destination Address
ASA: Alias Source Address
UP: User Priority
ML: MSDU Lifetime
KID: Key Identifier
IV: Initialization Vector
UD: User Data, 1–2383 byte
SC: Sanity Check (for the
unencrypted PDU)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.60
Information bases
Route Information Base (RIB) - how to reach a destination
[destination, next hop, distance]
Neighbor Information Base (NIB) - status of direct neighbors
[neighbor, status]
Hello Information Base (HIB) - status of destination (via next hop)
[destination, status, next hop]
Alias Information Base (AIB) - address of nodes outside the net
[original MSAP address, alias MSAP address]
Source Multipoint Relay Information Base (SMRIB) - current MP status
[local multipoint forwarder, multipoint relay set]
Topology Information Base (TIB) - current HIPERLAN topology
[destination, forwarder, sequence]
Duplicate Detection Information Base (DDIB) - remove duplicates
[source, sequence]
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.61
Ad-hoc networks using HIPERLAN 1
1
RIB
NIB
HIB
AIB
SMRIB
TIB
DDIB
RIB
NIB
HIB
AIB
DDIB
2
Forwarder
4
Information Bases (IB):
RIB: Route
NIB: Neighbor
HIB: Hello
AIB: Alias
SMRIB: Source Multipoint Relay
TIB: Topology
DDIB: Duplicate Detection
3
Forwarder
RIB
NIB
HIB
AIB
DDIB
5
RIB
NIB
HIB
AIB
DDIB
RIB
NIB
HIB
AIB
SMRIB
TIB
DDIB
neighborhood
(i.e., within radio range)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
RIB
NIB
HIB
AIB
SMRIB
TIB
DDIB
MC SS05
6
Forwarder
7.62
Some history: Why wireless ATM?
seamless connection to wired ATM, a integrated services highperformance network supporting different types a traffic streams
ATM networks scale well: private and corporate LANs, WAN
B-ISDN uses ATM as backbone infrastructure and integrates several
different services in one universal system
mobile phones and mobile communications have an ever increasing
importance in everyday life
current wireless LANs do not offer adequate support for multimedia
data streams
merging mobile communication and ATM leads to wireless ATM from a
telecommunication provider point of view
goal: seamless integration of mobility into B-ISDN
Problem: very high complexity of the system – never reached products
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.63
ATM - basic principle
favored by the telecommunication industry for advanced high-performance
networks, e.g., B-ISDN, as transport mechanism
statistical (asynchronous, on demand) TDM (ATDM, STDM)
cell header determines the connection the user data belongs to
mixing of different cell-rates is possible
different bit-rates, constant or variable, feasible
interesting for data sources with varying bit-rate:
e.g., guaranteed minimum bit-rate
additionally bursty traffic if allowed by the network
ATM cell:
5
48
[byte]
cell header
user data
connection identifier, checksum etc.
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.64
Cell-based transmission
asynchronous, cell-based transmission as basis for ATM
continuous cell-stream
additional cells necessary for operation and maintenance of the network
(OAM cells; Operation and Maintenance)
OAM cells can be inserted after fixed intervals to create a logical frame
structure
if a station has no data to send it automatically inserts idle cells that can be
discarded at every intermediate system without further notice
if no synchronous frame is available for the transport of cells (e.g., SDH or
Sonet) cell boundaries have to be detected separately (e.g., via the
checksum in the cell header)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.65
B-ISDN protocol reference model
3 dimensional reference model
three vertical planes (columns)
user plane
control plane
management plane
three hierarchical layers
Out-of-Band-Signaling: user data is
transmitted separately from control
information
control
user
plane
plane
higher
higher
layers
layers
layer management
physical layer
ATM layer
ATM adaptation layer
ATM adaptation layer
ATM layer
layers
physical layer
planes
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.66
plane management
management plane
ATM layers
Physical layer, consisting of two sub-layers
physical medium dependent sub-layer
coding
bit timing
transmission
transmission convergence sub-layer
HEC (Header Error Correction) sequence generation and verification
transmission frame adaptation, generation, and recovery
cell delineation, cell rate decoupling
ATM layer
cell multiplexing/demultiplexing
VPI/VCI translation
cell header generation and verification
GFC (Generic Flow Control)
ATM adaptation layer (AAL)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.67
ATM adaptation layer (AAL)
Provides different service classes on top of ATM based on:
bit rate:
constant bit rate: e.g. traditional telephone line
variable bit rate: e.g. data communication, compressed video
time constraints between sender and receiver:
with time constraints: e.g. real-time applications, interactive voice and video
without time constraints: e.g. mail, file transfer
mode of connection:
connection oriented or connectionless
AAL consists of two sub-layers:
Convergence Sublayer (CS): service dependent adaptation
Common Part Convergence Sublayer (CPCS)
Service Specific Convergence Sublayer (SSCS)
Segmentation and Reassembly Sublayer (SAR)
sub-layers can be empty
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.68
ATM and AAL connections
end-system A
AAL
ATM
end-system B
service dependent
AAL connections
service independent
ATM connections
AAL
ATM
physical
layer
ATM layer:
physical
layer
ATM network
service independent transport of ATM cells
multiplex and demultiplex functionality
application
AAL layer: support of different services
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.69
ATM Forum Wireless ATM Working Group
ATM Forum founded the Wireless ATM Working Group June 1996
Task: development of specifications to enable the use of ATM
technology also for wireless networks with a large coverage of
current network scenarios (private and public, local and global)
compatibility to existing ATM Forum standards important
it should be possible to easily upgrade existing ATM networks with
mobility functions and radio access
two sub-groups of work items
Radio Access Layer (RAL) Protocols
radio access layer
wireless media access control
wireless data link control
radio resource control
handover issues
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
Mobile ATM Protocol Extensions
handover signaling
location management
mobile routing
traffic and QoS Control
network management
MC SS05
7.70
WATM services
Office environment
multimedia conferencing, online multimedia database access
Universities, schools, training centers
distance learning, teaching
Industry
database connection, surveillance, real-time factory management
Hospitals
reliable, high-bandwidth network, medical images, remote monitoring
Home
high-bandwidth interconnect of devices (TV, CD, PC, ...)
Networked vehicles
trucks, aircraft etc. interconnect, platooning, intelligent roads
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.71
WATM components
WMT (Wireless Mobile ATM Terminal)
RAS (Radio Access System)
EMAS-E (End-user Mobility-supporting ATM Switch - Edge)
EMAS-N (End-user Mobility-supporting ATM Switch - Network)
M-NNI (Network-to-Network Interface with Mobility support)
LS (Location Server)
AUS (Authentication Server)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.72
Reference model
EMAS-N
WMT
RAS
EMAS-E
M-NNI
WMT
RAS
EMAS-N
LS
AUS
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.73
User plane protocol layers
fixed network segment
radio segment
MATM
terminal
WATM
terminal
adapter
RAS
EMAS
-E
EMAS
-N
fixed
end
system
ATMSwitch
user process
user
process
AAL
AAL
ATM
ATMCL
ATMCL
RAL
RAL
ATM
ATM
ATM
ATM
ATM
PHY
PHY PHY
PHY PHY
PHY PHY
PHY
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.74
Control plane protocol layers
fixed network segment
radio segment
MATM
terminal
WATM
terminal
adapter
EMAS
-E
EMAS
-N
ATMSwitch
fixed
end
system
SIG,
M-UNI
SIG,
M-UNI,
M-PNNI
SIG,
M-PNNI
SIG,
PNNI,
UNI
SIG,
UNI
SAAL
SAAL
SAAL
SAAL
SAAL
ATM
ATM
ATM
ATM
PHY PHY
PHY
RAS
M-ATM
ATMCL
ATMCL
RAL
RAL
ATM
PHY
PHY PHY PHY PHY
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.75
Reference model with further access scenarios I
1: wireless ad-hoc ATM network
2: wireless mobile ATM terminals
3: mobile ATM terminals
4: mobile ATM switches
5: fixed ATM terminals
6: fixed wireless ATM terminals
WMT: wireless mobile terminal
WT: wireless terminal
MT: mobile terminal
T: terminal
AP: access point
EMAS: end-user mobility supporting ATM switch (-E: edge, -N: network)
NMAS: network mobility supporting ATM switch
MS: mobile ATM switch
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.76
Reference model with further access scenarios II
WMT
1
RAS
2
WMT
EMAS
-E
RAS
ACT
WMT
EMAS
-N
EMAS
-E
MT
5
T
6
RAS
3
WT
NMAS
MS
RAS
RAS
T
4
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.77
BRAN – Broadband Radio Access Networks
Motivation
deregulation, privatization, new companies, new services
How to reach the customer?
alternatives: xDSL, cable, satellite, radio
Radio access
flexible (supports traffic mix, multiplexing for higher efficiency, can be
asymmetrical)
quick installation
economic (incremental growth possible)
Market
private customers (Internet access, tele-xy...)
small and medium sized business (Internet, MM conferencing, VPN)
Scope of standardization
access networks, indoor/campus mobility, 25-155 Mbit/s, 50 m-5 km
coordination with ATM Forum, IETF, ETSI, IEEE, ....
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.78
Broadband network types
Common characteristics
ATM QoS (CBR, VBR, UBR, ABR)
HIPERLAN/2
short range (< 200 m), indoor/campus, 25 Mbit/s user data rate
access to telecommunication systems, multimedia applications, mobility
(<10 m/s)
HIPERACCESS
wider range (< 5 km), outdoor, 25 Mbit/s user data rate
fixed radio links to customers (“last mile”), alternative to xDSL or cable
modem, quick installation
Several (proprietary) products exist with 155 Mbit/s plus QoS
HIPERLINK – currently no activities
intermediate link, 155 Mbit/s
connection of HIPERLAN access points or connection between
HIPERACCESS nodes
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.79
BRAN and legacy networks
Independence
BRAN as access network independent from the fixed network
Interworking of TCP/IP and ATM under study
Layered model
Network Convergence Sub-layer as superset of all requirements for IP and
ATM
Coordination
core network
ATM
core network
IP
network convergence sublayer
BRAN data link control
BRAN PHY-1
BRAN PHY-2
IETF (TCP/IP)
ATM forum (ATM)
ETSI (UMTS)
CEPT, ITU-R, ...
(radio frequencies)
...
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.80
HiperLAN2 (historical)
Official name: BRAN HIPERLAN Type 2
H/2, HIPERLAN/2 also used
High data rates for users
More efficient than 802.11a
Connection oriented
QoS support
Dynamic frequency selection
Security support
Strong encryption/authentication
Mobility support
Network and application independent
convergence layers for Ethernet, IEEE 1394, ATM, 3G
Power save modes
Plug and Play
No products – but several mechanisms have been
Adopted by other standards (e.g. 802.11a)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.81
HiperLAN2 architecture and handover scenarios
AP
MT1
1
APT
APC
MT2
3
MT3
APT
APC
2
MT4
AP
Core
Network
(Ethernet,
Firewire,
ATM,
UMTS)
APT
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.82
Centralized vs. direct mode
AP
AP/CC
control
control
control
data
MT1
MT2
MT1
data
Centralized
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MT2
MT1
data
control
Direct
MC SS05
7.83
MT2 +CC
HiperLAN2 protocol stack
Higher layers
DLC control
SAP
Radio link control sublayer
Radio
resource
control
DLC user
SAP
Convergence layer
DLC
conn.
control
Assoc.
control
Data link control basic data
transport function
Error
control
Radio link control
Scope of
HiperLAN2
standards
Medium access control
Physical layer
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.84
Physical layer reference configuration
PDU train from DLC
(PSDU)
mapping
scrambling
FEC coding
interleaving
OFDM
PHY bursts
(PPDU)
radio
transmitter
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.85
Operating channels of HiperLAN2 in Europe
36
5150
40
44
48
52
56
60
64
channel
5180 5200 5220 5240 5260 5280 5300 5320
5350 [MHz]
16.6 MHz
100
5470
140
channel
5500 5520 5540 5560 5580 5600 5620 5640 5660 5680 5700
5725
[MHz]
16.6 MHz
104
108
112
116
120
124
128
132
136
center frequency =
5000 + 5*channel number [MHz]
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.86
Basic structure of HiperLAN2 MAC frames
2 ms
2 ms
MAC frame
2 ms
MAC frame
broadcast phase
MAC frame
downlink phase
variable
2 ms
MAC frame
random
access phase
uplink phase
variable
...
TDD,
500 OFDM
symbols
per frame
variable
2
406
24
LCH PDU type
payload
CRC
2
10
396
24
LCH PDU type
sequence
number
payload
CRC
bit
LCH transfer syntax
bit
UDCH transfer syntax
(long PDU)
54 byte
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.87
Valid configurations of HiperLAN2 MAC frames
2 ms
2 ms
MAC frame
MAC frame
broadcast
2 ms
MAC frame
downlink
2 ms
MAC frame
uplink
random
access
BCH
FCH
ACH
DL phase DiL phase UL phase
RCHs
BCH
FCH
ACH
DiL phase UL phase
RCHs
BCH
FCH
ACH
UL phase
RCHs
BCH
FCH
ACH
UL phase
RCHs
BCH
FCH
ACH
DL phase DiL phase
RCHs
BCH
FCH
ACH
DiL phase
RCHs
BCH
FCH
ACH
BCH
FCH
ACH
DL phase
DL phase
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
...
Valid
combinations
of MAC frames
for a single
sector AP
RCHs
RCHs
MC SS05
7.88
Mapping of logical and transport channels
BCCH
FCCH
RFCH
LCCH
RBCH
DCCH
UDCH
UBCH
UMCH
downlink
BCH
FCH
ACH
UDCH
DCCH
LCCH
LCH
SCH
RCH
SCH
ASCH
UDCH
LCH
UBCH
uplink
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
UMCH
DCCH RBCH
LCH
SCH
direct link
MC SS05
7.89
LCCH
Bluetooth
Idea
Universal radio interface for ad-hoc wireless connectivity
Interconnecting computer and peripherals, handheld devices, PDAs, cell
phones – replacement of IrDA
Embedded in other devices, goal: 5€/device (2005: 40€/USB bluetooth)
Short range (10 m), low power consumption, license-free 2.45 GHz ISM
Voice and data transmission, approx. 1 Mbit/s gross data rate
One of the first modules (Ericsson).
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.90
Bluetooth
History
1994: Ericsson (Mattison/Haartsen), “MC-link” project
Renaming of the project: Bluetooth according to Harald “Blåtand” Gormsen
[son of Gorm], King of Denmark in the 10th century
(was:
)
1998: foundation of Bluetooth SIG, www.bluetooth.org
1999: erection of a rune stone at Ercisson/Lund ;-)
2001: first consumer products for mass market, spec. version 1.1 released
2005: 5 million chips/week
Special Interest Group
Original founding members: Ericsson, Intel, IBM, Nokia, Toshiba
Added promoters: 3Com, Agere (was: Lucent), Microsoft, Motorola
> 2500 members
Common specification and certification of products
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.91
History and hi-tech…
1999:
Ericsson mobile
communications AB
reste denna sten till
minne av Harald
Blåtand, som fick ge
sitt namn åt en ny
teknologi för trådlös,
mobil kommunikation.
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.92
…and the real rune stone
Located in Jelling, Denmark,
erected by King Harald “Blåtand”
in memory of his parents.
The stone has three sides – one side
showing a picture of Christ.
Inscription:
"Harald king executes these sepulchral
monuments after Gorm, his father and
Thyra, his mother. The Harald who won the
whole of Denmark and Norway and turned
the Danes to Christianity."
Btw: Blåtand means “of dark complexion”
(not having a blue tooth…)
This could be the “original” colors
of the stone.
Inscription:
“auk tani karthi kristna” (and
made the Danes Christians)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.93
Characteristics
2.4 GHz ISM band, 79 (23) RF channels, 1 MHz carrier spacing
Channel 0: 2402 MHz … channel 78: 2480 MHz
G-FSK modulation, 1-100 mW transmit power
FHSS and TDD
Frequency hopping with 1600 hops/s
Hopping sequence in a pseudo random fashion, determined by a master
Time division duplex for send/receive separation
Voice link – SCO (Synchronous Connection Oriented)
FEC (forward error correction), no retransmission, 64 kbit/s duplex, pointto-point, circuit switched
Data link – ACL (Asynchronous ConnectionLess)
Asynchronous, fast acknowledge, point-to-multipoint, up to 433.9 kbit/s
symmetric or 723.2/57.6 kbit/s asymmetric, packet switched
Topology
Overlapping piconets (stars) forming a scatternet
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.94
Piconet
Collection of devices connected in an ad hoc
fashion
P
One unit acts as master and the others as slaves
for the lifetime of the piconet
S
S
M
Master determines hopping pattern, slaves have
to synchronize
SB
S
P
Each piconet has a unique hopping pattern
Participation in a piconet = synchronization to
hopping sequence
P
M=Master
S=Slave
SB
P=Parked
SB=Standby
Each piconet has one master and up to 7
simultaneous slaves (> 200 could be parked)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.95
Forming a piconet
All devices in a piconet hop together
Master gives slaves its clock and device ID
Hopping pattern: determined by device ID (48 bit, unique worldwide)
Phase in hopping pattern determined by clock
Addressing
Active Member Address (AMA, 3 bit)
Parked Member Address (PMA, 8 bit)
SB
SB
SB
SB
SB
SB
SB
S
SB
SB
SB
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
P
S
M
P
S
P
SB
7.96
Scatternet
Linking of multiple co-located piconets through the sharing of common
master or slave devices
Devices can be slave in one piconet and master of another
Communication between piconets
Devices jumping back and forth between the piconets
P
S
S
S
P
P
M
Piconets
(each with a
capacity of
720 kbit/s)
M
SB
M=Master
S=Slave
P=Parked
SB=Standby
S
P
SB
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
SB
S
MC SS05
7.97
Bluetooth protocol stack
audio apps.
NW apps.
vCal/vCard
TCP/UDP
OBEX
telephony apps.
AT modem
commands
IP
mgmnt. apps.
TCS BIN
SDP
BNEP PPP
Control
RFCOMM (serial line interface)
Audio
Logical Link Control and Adaptation Protocol (L2CAP)
Link Manager
Baseband
Radio
AT: attention sequence
OBEX: object exchange
TCS BIN: telephony control protocol specification – binary
BNEP: Bluetooth network encapsulation protocol
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
SDP: service discovery protocol
RFCOMM: radio frequency comm.
MC SS05
7.98
Host
Controller
Interface
Frequency selection during data transmission
625 µs
fk
M
fk+1
fk+2
fk+3
fk+4
fk+5
fk+6
S
M
S
M
S
M
t
fk
fk+3
fk+4
fk+5
fk+6
M
S
M
S
M
t
fk
fk+1
M
S
fk+6
M
t
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.99
Baseband
Piconet/channel definition
Low-level packet definition
Access code
Channel, device access, e.g., derived from master address (48-bit)
Packet header
1/3-FEC, active member address (broadcast + 7 slaves), link type, alternating
bit ARQ/SEQ, checksum
68(72)
54
0-2745
access code packet header
4
preamble
64
sync.
(4)
3
(trailer) AM address
bits
payload
4
1
1
1
8
type
flow
ARQN
SEQN
HEC
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.100
bits
SCO payload types
payload (30)
HV1
audio (10)
HV2
audio (20)
HV3
DV
FEC (20)
FEC (10)
audio (30)
audio (10)
header (1)
payload (0-9)
2/3 FEC
CRC (2)
(bytes)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.101
ACL Payload types
payload (0-343)
header (1/2)
DM1 header (1)
DH1 header (1)
DM3
header (2)
DH3
header (2)
DM5
header (2)
DH5
header (2)
AUX1 header (1)
payload (0-339)
payload (0-17)
2/3 FEC
payload (0-27)
payload (0-121)
CRC (2)
CRC (2)
(bytes)
CRC (2)
2/3 FEC
CRC (2)
payload (0-183)
CRC (2)
payload (0-224)
2/3 FEC
payload (0-339)
CRC (2)
CRC (2)
payload (0-29)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.102
Baseband data rates
ACL
1 slot
3 slot
5 slot
SCO
Type
Payload User
Header Payload
[byte]
[byte]
FEC
CRC
Symmetric Asymmetric
max. Rate max. Rate [kbit/s]
[kbit/s]
Forward
Reverse
DM1
1
0-17
2/3
yes
108.8
108.8
108.8
DH1
1
0-27
no
yes
172.8
172.8
172.8
DM3
2
0-121
2/3
yes
258.1
387.2
54.4
DH3
2
0-183
no
yes
390.4
585.6
86.4
DM5
2
0-224
2/3
yes
286.7
477.8
36.3
DH5
2
0-339
no
yes
433.9
723.2
57.6
AUX1
1
0-29
no
no
185.6
185.6
185.6
HV1
na
10
1/3
no
64.0
HV2
na
20
2/3
no
64.0
HV3
na
30
no
no
64.0
DV
1D
10+(0-9) D 2/3 D yes D
64.0+57.6 D
Data Medium/High rate, High-quality Voice, Data and Voice
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.103
Baseband link types
Polling-based TDD packet transmission
625µs slots, master polls slaves
SCO (Synchronous Connection Oriented) – Voice
Periodic single slot packet assignment, 64 kbit/s full-duplex, point-to-point
ACL (Asynchronous ConnectionLess) – Data
MASTER
SLAVE 1
SLAVE 2
Variable packet size (1,3,5 slots), asymmetric bandwidth, point-to-multipoint
SCO
f0
ACL
f4
SCO
f6
f1
ACL
f8
f7
SCO
f12
f9
ACL
f14
f13
ACL
f20
f19
f17
f5
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
SCO
f18
MC SS05
f21
7.104
Robustness
Slow frequency hopping with hopping patterns determined by a master
Protection from interference on certain frequencies
Separation from other piconets (FH-CDMA)
Retransmission
Error in payload
(not header!)
ACL only, very fast
Forward Error Correction
MASTER
SLAVE 1
NAK
SCO and ACL
A
C
B
C
D
F
ACK
H
E
SLAVE 2
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
G
MC SS05
G
7.105
Baseband states of a Bluetooth device
unconnected
standby
detach
inquiry
transmit
AMA
park
PMA
page
connected
AMA
hold
AMA
Standby: do nothing
Inquire: search for other devices
Page: connect to a specific device
Connected: participate in a piconet
sniff
AMA
connecting
active
low power
Park: release AMA, get PMA
Sniff: listen periodically, not each slot
Hold: stop ACL, SCO still possible, possibly
participate in another piconet
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.106
Example: Power consumption/CSR BlueCore2
Typical Average Current Consumption (1)
VDD=1.8V Temperature = 20°C
Mode
SCO connection HV3 (1s interval Sniff Mode) (Slave)
SCO connection HV3 (1s interval Sniff Mode) (Master)
SCO connection HV1 (Slave)
SCO connection HV1 (Master)
ACL data transfer 115.2kbps UART (Master)
ACL data transfer 720kbps USB (Slave)
ACL data transfer 720kbps USB (Master)
ACL connection, Sniff Mode 40ms interval, 38.4kbps UART
ACL connection, Sniff Mode 1.28s interval, 38.4kbps UART
Parked Slave, 1.28s beacon interval, 38.4kbps UART
Standby Mode (Connected to host, no RF activity)
Deep Sleep Mode(2)
Notes:
(1) Current consumption is the sum of both BC212015A and the flash.
(2) Current consumption is for the BC212015A device only.
(More: www.csr.com )
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
26.0 mA
26.0 mA
53.0 mA
53.0 mA
15.5 mA
53.0 mA
53.0 mA
4.0 mA
0.5 mA
0.6 mA
47.0 µA
20.0 µA
7.107
Example: Bluetooth/USB adapter (2002: 50€)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.108
L2CAP - Logical Link Control and Adaptation Protocol
Simple data link protocol on top of baseband
Connection oriented, connectionless, and signalling channels
Protocol multiplexing
RFCOMM, SDP, telephony control
Segmentation & reassembly
Up to 64kbyte user data, 16 bit CRC used from baseband
QoS flow specification per channel
Follows RFC 1363, specifies delay, jitter, bursts, bandwidth
Group abstraction
Create/close group, add/remove member
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.109
L2CAP logical channels
Master
Slave
L2CAP
Slave
L2CAP
2
d
1
1 d d d d 1
baseband
signalling
L2CAP
1
baseband
ACL
baseband
connectionless
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
connection-oriented
MC SS05
7.110
d
d
2
L2CAP packet formats
Connectionless PDU
2
2
2
0-65533
length
CID=2
PSM
payload
bytes
Connection-oriented PDU
2
2
0-65535
length
CID
payload
bytes
Signalling command PDU
2
2
length
CID=1
bytes
One or more commands
1
1
2
0
code
ID
length
data
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.111
Security
User input (initialization)
PIN (1-16 byte)
Pairing
PIN (1-16 byte)
E2
Authentication key generation
(possibly permanent storage)
E2
link key (128 bit)
Authentication
link key (128 bit)
E3
Encryption key generation
(temporary storage)
E3
encryption key (128 bit)
Encryption
encryption key (128 bit)
Keystream generator
Keystream generator
payload key
Ciphering
payload key
Cipher data
Data
Data
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.112
SDP – Service Discovery Protocol
Inquiry/response protocol for discovering services
Searching for and browsing services in radio proximity
Adapted to the highly dynamic environment
Can be complemented by others like SLP, Jini, Salutation, …
Defines discovery only, not the usage of services
Caching of discovered services
Gradual discovery
Service record format
Information about services provided by attributes
Attributes are composed of an 16 bit ID (name) and a value
values may be derived from 128 bit Universally Unique Identifiers (UUID)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.113
Additional protocols to support legacy protocols/apps.
RFCOMM
Emulation of a serial port (supports a large base of legacy applications)
Allows multiple ports over a single physical channel
Telephony Control Protocol Specification (TCS)
Call control (setup, release)
Group management
OBEX
Exchange of objects, IrDA replacement
WAP
Interacting with applications on cellular phones
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.114
Profiles
Represent default solutions for a certain usage model
Applications
Vertical slice through the protocol stack
Basis for interoperability
Protocols
Generic Access Profile
Service Discovery Application Profile
Cordless Telephony Profile
Intercom Profile
Serial Port Profile
Additional Profiles
Headset Profile
Advanced Audio Distribution
Dial-up Networking Profile
PAN
Fax Profile
Audio Video Remote Control
LAN Access Profile
Basic Printing
Generic Object Exchange Profile
Basic Imaging
Object Push Profile
Extended Service Discovery
File Transfer Profile
Generic Audio Video Distribution
Synchronization Profile
Hands Free
Hardcopy Cable Replacement
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.115
Profiles
WPAN: IEEE 802.15-1 – Bluetooth
Data rate
Connection set-up time
Synchronous, connection-oriented:
64 kbit/s
Asynchronous, connectionless
433.9 kbit/s symmetric
723.2 / 57.6 kbit/s asymmetric
Transmission range
Quality of Service
Free 2.4 GHz ISM-band
Security
Challenge/response (SAFER+),
hopping sequence
Availability
Public/private keys needed, key
management not specified, simple
system integration
Special Advantages/Disadvantages
Frequency
Guarantees, ARQ/FEC
Manageability
POS (Personal Operating Space)
up to 10 m
with special transceivers up to 100
m
Depends on power-mode
Max. 2.56s, avg. 0.64s
Integrated into many products,
several vendors
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
Advantage: already integrated into
several products, available worldwide,
free ISM-band, several vendors, simple
system, simple ad-hoc networking, peer
to peer, scatternets
Disadvantage: interference on ISM-band,
limited range, max. 8
devices/network&master, high set-up
latency
MC SS05
7.116
WPAN: IEEE 802.15
802.15-2: Coexistance
Coexistence of Wireless Personal Area Networks (802.15) and Wireless
Local Area Networks (802.11), quantify the mutual interference
802.15-3: High-Rate
Standard for high-rate (20Mbit/s or greater) WPANs, while still lowpower/low-cost
Data Rates: 11, 22, 33, 44, 55 Mbit/s
Quality of Service isochronous protocol
Ad hoc peer-to-peer networking
Security
Low power consumption
Low cost
Designed to meet the demanding requirements of portable consumer
imaging and multimedia applications
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.117
WPAN: IEEE 802.15 – future developments 2
Several working groups extend the 802.15.3 standard
802.15.3a:
Alternative PHY with higher data rate as extension to 802.15.3
Applications: multimedia, picture transmission
802.15.3b:
Enhanced interoperability of MAC
Correction of errors and ambiguities in the standard
802.15.3c:
Alternative PHY at 57-64 GHz
Goal: data rates above 2 Gbit/s
Not all these working groups really create a standard, not all standards
will be found in products later …
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.118
WPAN: IEEE 802.15 – future developments 3
802.15-4: Low-Rate, Very Low-Power
Low data rate solution with multi-month to multi-year battery life and very
low complexity
Potential applications are sensors, interactive toys, smart badges, remote
controls, and home automation
Data rates of 20-250 kbit/s, latency down to 15 ms
Master-Slave or Peer-to-Peer operation
Up to 254 devices or 64516 simpler nodes
Support for critical latency devices, such as joysticks
CSMA/CA channel access (data centric), slotted (beacon) or unslotted
Automatic network establishment by the PAN coordinator
Dynamic device addressing, flexible addressing format
Fully handshaked protocol for transfer reliability
Power management to ensure low power consumption
16 channels in the 2.4 GHz ISM band, 10 channels in the 915 MHz US ISM
band and one channel in the European 868 MHz band
Basis of the ZigBee technology – www.zigbee.org
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.119
ZigBee
Relation to 802.15.4 similar to Bluetooth / 802.15.1
Pushed by Chipcon, ember, freescale (Motorola), Honeywell, Mitsubishi,
Motorola, Philips, Samsung
More than 150 members
Promoter (40000$/Jahr), Participant (9500$/Jahr), Adopter (3500$/Jahr)
No free access to the specifications (only promoters and participants)
ZigBee platforms comprise
IEEE 802.15.4 for layers 1 and 2
ZigBee protocol stack up to the applications
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.120
WPAN: IEEE 802.15 – future developments 4
Several working groups extend the 802.15.4 standard
802.15.4a:
Alternative PHY with lower data rate as extension to 802.15.4
Properties: precise localization (< 1m precision), extremely low power consumption,
longer range
Two PHY alternatives
UWB (Ultra Wideband): ultra short pulses, communication and localization
CSS (Chirp Spread Spectrum): communication only
802.15.4b:
Extensions, corrections, and clarifications regarding 802.15.4
Usage of new bands, more flexible security mechanisms
802.15.5: Mesh Networking
Partial meshes, full meshes
Range extension, more robustness, longer battery live
Not all these working groups really create a standard, not all standards will be
found in products later …
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.121
Some more IEEE standards for mobile communications
IEEE 802.16: Broadband Wireless Access / WirelessMAN / WiMax
Wireless distribution system, e.g., for the last mile, alternative to DSL
75 Mbit/s up to 50 km LOS, up to 10 km NLOS; 2-66 GHz band
Initial standards without roaming or mobility support
802.16e adds mobility support, allows for roaming at 150 km/h
Unclear relation to 802.20, 802.16 started as fixed system…
IEEE 802.20: Mobile Broadband Wireless Access (MBWA)
Licensed bands < 3.5 GHz, optimized for IP traffic
Peak rate > 1 Mbit/s per user
Different mobility classes up to 250 km/h and ranges up to 15 km
IEEE 802.21: Media Independent Handover Interoperability
Standardize handover between different 802.x and/or non 802 networks
IEEE 802.22: Wireless Regional Area Networks (WRAN)
Radio-based PHY/MAC for use by license-exempt devices on a noninterfering basis in spectrum that is allocated to the TV Broadcast Service
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.122
WLAN: Home RF – yet another standard, no success
Data rate
0.8, 1.6, 5, 10 Mbit/s
Transmission range
Connection set-up time
Quality of Service
300m outdoor, 30m indoor
Frequency
2.4 GHz ISM
Strong encryption, no open access
Adapter 130€, base station 230€
Availability
Like DECT & 802-LANs
Special Advantages/Disadvantages
Cost
Up to 8 streams A/V, up to 8 voice
streams, priorities, best-effort
Manageability
Security
10 ms bounded latency
Several products from different
vendors, no more support
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
Advantage: extended QoS support,
host/client and peer/peer, power
saving, security
Disadvantage: future uncertain due
to DECT-only devices plus
802.11a/b for data
MC SS05
7.123
RF Controllers – ISM bands
Data rate
Typ. up to 115 kbit/s (serial
interface)
Transmission range
5-100 m, depending on power (typ.
10-500 mW)
Connection set-up time
Quality of Service
Typ. 27 (EU, US), 315 (US), 418
(EU), 426 (Japan), 433 (EU), 868
(EU), 915 (US) MHz (depending on
regulations)
Some products with added
processors
Cost
Very simple, same as serial
interface
Special Advantages/Disadvantages
Security
none
Manageability
Frequency
N/A
Cheap: 10€-50€
Advantage: very low cost, large
experience, high volume available
Disadvantage: no QoS, crowded
ISM bands (particularly 27 and 433
MHz), typ. no Medium Access
Control, 418 MHz experiences
interference with TETRA
Availability
Many products, many vendors
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.124
RFID – Radio Frequency Identification (1)
Data rate
Transmission of ID only (e.g., 48 bit,
64kbit, 1 Mbit)
9.6 – 115 kbit/s
Transmission range
Passive: up to 3 m
Active: up to 30-100 m
Simultaneous detection of up to, e.g.,
256 tags, scanning of, e.g., 40 tags/s
Connection set-up time
Quality of Service
125 kHz, 13.56 MHz, 433 MHz, 2.4 GHz,
5.8 GHz and many others
Application dependent, typ. no crypt. on
RFID device
Cost
Very simple, same as serial interface
Special Advantages/Disadvantages
Security
none
Manageability
Frequency
Depends on product/medium access
scheme (typ. 2 ms per device)
Very cheap tags, down to 1€ (passive)
Advantage: extremely low cost, large
experience, high volume available, no
power for passive RFIDs needed, large
variety of products, relative speeds up to
300 km/h, broad temp. range
Disadvantage: no QoS, simple denial of
service, crowded ISM bands, typ. oneway (activation/ transmission of ID)
Availability
Many products, many vendors
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.125
RFID – Radio Frequency Identification (2)
Function
Standard: In response to a radio interrogation signal from a reader (base
station) the RFID tags transmit their ID
Enhanced: additionally data can be sent to the tags, different media access
schemes (collision avoidance)
Features
No line-of sight required (compared to, e.g., laser scanners)
RFID tags withstand difficult environmental conditions (sunlight, cold, frost,
dirt etc.)
Products available with read/write memory, smart-card capabilities
Categories
Passive RFID: operating power comes from the reader over the air which is
feasible up to distances of 3 m, low price (1€)
Active RFID: battery powered, distances up to 100 m
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.126
RFID – Radio Frequency Identification (3)
Applications
Total asset visibility: tracking of goods during manufacturing, localization of
pallets, goods etc.
Loyalty cards: customers use RFID tags for payment at, e.g., gas stations,
collection of buying patterns
Automated toll collection: RFIDs mounted in windshields allow commuters
to drive through toll plazas without stopping
Others: access control, animal identification, tracking of hazardous
material, inventory control, warehouse management, ...
Local Positioning Systems
GPS useless indoors or underground, problematic in cities with high
buildings
RFID tags transmit signals, receivers estimate the tag location by
measuring the signal‘s time of flight
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.127
RFID – Radio Frequency Identification (4)
Security
Denial-of-Service attacks are always possible
Interference of the wireless transmission, shielding of transceivers
IDs via manufacturing or one time programming
Key exchange via, e.g., RSA possible, encryption via, e.g., AES
Future Trends
RTLS: Real-Time Locating System – big efforts to make total asset visibility
come true
Integration of RFID technology into the manufacturing, distribution and
logistics chain
Creation of „electronic manifests“ at item or package level (embedded
inexpensive passive RFID tags)
3D tracking of children, patients
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.128
RFID – Radio Frequency Identification (5)
Devices and Companies
AXCESS Inc., www.axcessinc.com
Checkpoint Systems Group, www.checkpointsystems.com
GEMPLUS, www.gemplus.com/app/smart_tracking
Intermec/Intellitag, www.intermec.com
I-Ray Technologies, www.i-ray.com
RF Code, www.rfcode.com
Texas Instruments, www.ti-rfid.com/id
WhereNet, www.wherenet.com
Wireless Mountain, www.wirelessmountain.com
XCI, www.xci-inc.com
Only a very small selection…
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.129
RFID – Radio Frequency Identification (6)
Example Product: Intermec RFID UHF OEM Reader
Read range up to 7m
Anticollision algorithm allows for scanning of 40 tags per second regardless
of the number of tags within the reading zone
US: unlicensed 915 MHz, Frequency Hopping
Read: 8 byte < 32 ms
Write: 1 byte < 100ms
Example Product: Wireless Mountain Spider
Proprietary sparse code anti-collision algorithm
Detection range 15 m indoor, 100 m line-of-sight
> 1 billion distinct codes
Read rate > 75 tags/s
Operates at 308 MHz
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.130
RFID – Radio Frequency Identification (7)
Relevant Standards
American National Standards Institute
Automatic Identification and Data Capture Techniques
ISO TC 104 / SC 4, www.autoid.org/tc104_sc4_wg2.htm,
www.aimglobal.org/standards/rfidstds/TC104.htm
Road Transport and Traffic Telematics
JTC 1/SC 17, www.sc17.com, www.aimglobal.org/standards/rfidstds/sc17.htm,
Identification and communication
ETSI, www.etsi.org, www.aimglobal.org/standards/rfidstds/ETSI.htm
Identification Cards and related devices
ERO, www.ero.dk, www.aimglobal.org/standards/rfidstds/ERO.htm
European Telecommunications Standards Institute
JTC 1/SC 31, www.uc-council.com/sc31/home.htm,
www.aimglobal.org/standards/rfidstds/sc31.htm
European Radiocommunications Office
ANSI, www.ansi.org, www.aimglobal.org/standards/rfidstds/ANSIT6.html
CEN TC 278, www.nni.nl, www.aimglobal.org/standards/rfidstds/CENTC278.htm
Transport Information and Control Systems
ISO/TC204, www.sae.org/technicalcommittees/gits.htm,
www.aimglobal.org/standards/rfidstds/ISOTC204.htm
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.131
RFID – Radio Frequency Identification (8)
ISO Standards
ISO 15418
MH10.8.2 Data Identifiers
EAN.UCC Application Identifiers
ISO 15434 - Syntax for High Capacity ADC Media
ISO 15962 - Transfer Syntax
ISO 18000
Part 2, 125-135 kHz
Part 3, 13.56 MHz
Part 4, 2.45 GHz
Part 5, 5.8 GHz
Part 6, UHF (860-930 MHz, 433 MHz)
ISO 18047 - RFID Device Conformance Test Methods
ISO 18046 - RF Tag and Interrogator Performance Test Methods
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.132
ISM band interference
OLD
Many sources of interference
Microwave ovens, microwave lightning
802.11, 802.11b, 802.11g, 802.15, Home RF
Even analog TV transmission, surveillance
Unlicensed metropolitan area networks
…
NEW
Levels of interference
Physical layer: interference acts like noise
Spread spectrum tries to minimize this
FEC/interleaving tries to correct
MAC layer: algorithms not harmonized
© Fusion Lighting, Inc.
E.g., Bluetooth might confuse 802.11
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.133
802.11 vs.(?) 802.15/Bluetooth
Bluetooth may act like a rogue member of the 802.11 network
DIFS
500 byte
100
byte
802.15.1
79 channels
SIFS
ACK
SIFS
ACK
100
byte
(separated by
installation)
DIFS
SIFS
ACK
DIFS
SIFS
ACK
DIFS
100
byte
SIFS
ACK
DIFS
SIFS
ACK
DIFS
100
byte
500 byte
SIFS
ACK
100
byte
SIFS
ACK
DIFS
500 byte
DIFS
DIFS
DIFS
f [MHz] Does not know anything about gaps, inter frame spacing etc.
802.11b
2480
3 channels
1000 byte
(separated by
hopping pattern)
2402
t
IEEE 802.15-2 discusses these problems
Proposal: Adaptive Frequency Hopping
a non-collaborative Coexistence Mechanism
Real effects? Many different opinions, publications, tests, formulae, …
Results from complete breakdown to almost no effect
Bluetooth (FHSS) seems more robust than 802.11b (DSSS)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
MC SS05
7.134