The document summarizes key aspects of wireless local area networks (WLANs) and the IEEE 802.11 standard. It describes the characteristics and design goals of WLANs. It provides an overview of the IEEE 802.11 standard including the physical layer specifications, MAC layer functions and frame formats, and access methods like CSMA/CA. It also discusses wireless network architectures including infrastructure and ad-hoc networks, and comparisons of different wireless transmission technologies.
Powerpoint exploring the locations used in television show Time Clash
Mobile Comms Chapter: Wireless LAN Standards
1. Mobile Communications
Chapter 7: Wireless LANs
Characteristics HIPERLAN
IEEE 802.11 Bluetooth / IEEE 802.15.x
PHY IEEE 802.16/.20/.21/.22
MAC RFID
Roaming
Comparison
.11a, b, g, h, i …
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
2. Mobile Communication Technology according to IEEE
WiFi
Local wireless networks 802.11a 802.11h
WLAN 802.11 802.11i/e/…/w
802.11b 802.11g
ZigBee
802.15.4 802.15.4a/b
Personal wireless nw
WPAN 802.15 802.15.5
802.15.2 802.15.3 802.15.3a/b
802.15.1
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/
3. 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/
4. 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/
5. Comparison: infrared vs. radio transmission
Infrared Radio
uses IR diodes, diffuse light, typically using the license free
multiple reflections (walls, ISM band at 2.4 GHz
furniture etc.) Advantages
Advantages experience from wireless WAN
simple, cheap, available in and mobile phones can be used
many mobile devices coverage of larger areas
no licenses needed possible (radio can penetrate
simple shielding possible walls, furniture etc.)
Disadvantages Disadvantages
interference by sunlight, heat very limited license free
sources etc. frequency bands
many things shield or absorb IR shielding more difficult,
light interference with other electrical
low bandwidth devices
Example Example
Many different products
IrDA (Infrared Data Association)
interface available everywhere
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
6. Comparison: infrastructure vs. ad-hoc networks
infrastructure
network
AP: Access Point
AP
AP wired network
AP
ad-hoc network
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
7. 802.11 - Architecture of an infrastructure network
Station (STA)
802.11 LAN terminal with access mechanisms
802.x LAN
to the wireless medium and radio
contact to the access point
STA1 Basic Service Set (BSS)
BSS1 group of stations using the same
Access Portal
radio frequency
Point
Access Point
Distribution System station integrated into the wireless
LAN and the distribution system
Access
ESS Point Portal
bridge to other (wired) networks
BSS2
Distribution System
interconnection network to form
one logical network (EES:
Extended Service Set) based
STA2 802.11 LAN STA3 on several BSS
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
8. 802.11 - Architecture of an ad-hoc network
Direct communication within a limited
802.11 LAN
range
Station (STA):
terminal with access mechanisms to
the wireless medium
STA1 Independent Basic Service Set
IBSS1 STA3
(IBSS):
group of stations using the same
radio frequency
STA2
IBSS2
STA5
STA4 802.11 LAN
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
9. 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/
10. 802.11 - Layers and functions
MAC PLCP Physical Layer Convergence Protocol
access mechanisms, fragmentation, clear channel assessment signal
encryption (carrier sense)
MAC Management PMD Physical Medium Dependent
synchronization, roaming, MIB, modulation, coding
power management PHY Management
channel selection, MIB
Station Management
coordination of all management
functions
LLC
DLC
MAC MAC Management
PLCP
PHY
PHY Management
PMD
a Mnot a S
i t
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
11. 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
chipping sequence: +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/
12. FHSS PHY packet format
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 16 12 4 16 variable bits
synchronization SFD PLW PSF HEC payload
PLCP preamble PLCP header
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
13. 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 16 8 8 16 16 variable bits
synchronization SFD signal service length HEC payload
PLCP preamble PLCP header
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
14. 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/
15. 802.11 - MAC layer II
Priorities
defined through different inter frame spaces
no guaranteed, hard priorities
SIFS (Short Inter Frame Spacing)
highest priority, for ACK, CTS, polling response
PIFS (PCF IFS)
medium priority, for time-bounded service using PCF
DIFS (DCF, Distributed Coordination Function IFS)
lowest priority, for asynchronous data service
DIFS DIFS
PIFS
SIFS
medium busy contention next frame
t
direct access if
medium is free ≥ DIFS
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
16. 802.11 - CSMA/CA access method I
contention window
DIFS DIFS (randomized back-off
mechanism)
medium busy next frame
direct access if t
medium is free ≥ DIFS 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)
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/
17. 802.11 - competing stations - simple version
DIFS DIFS DIFS DIFS
boe bor boe bor boe busy
station1
boe busy
station2
busy
station3
boe busy boe bor
station4
boe bor boe busy boe bor
station5
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/
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
data
sender
SIFS
ACK
receiver
DIFS
other data
stations t
waiting time contention
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
19. 802.11 - DFWMAC
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
RTS data
sender
SIFS SIFS
CTS SIFS ACK
receiver
NAV (RTS) DIFS
other NAV (CTS) data
stations t
defer access contention
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
20. Fragmentation
DIFS
RTS frag1 frag2
sender
SIFS SIFS SIFS
CTS SIFS ACK1 SIFS ACK2
receiver
NAV (RTS)
NAV (CTS)
NAV (frag1) DIFS
other NAV (ACK1) data
stations t
contention
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
21. DFWMAC-PCF I
t0 t1
SuperFrame
medium busy PIFS SIFS SIFS
D1 D2
point
coordinator SIFS SIFS
U1 U2
wireless
stations
stations‘ NAV
NAV
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
22. DFWMAC-PCF II
t2 t3 t4
PIFS SIFS
D3 D4 CFend
point
coordinator SIFS
U4
wireless
stations
stations‘ NAV
NAV contention free period contention t
period
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
23. 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 0-2312 4
Frame Duration/ Address Address Address Sequence Address
Data CRC
Control ID 1 2 3 Control 4
bits 2 2 4 1 1 1 1 1 1 1 1
Protocol To From More Power More
Type Subtype Retry WEP Order
version DS DS Frag Mgmt Data
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
24. MAC address format
scenario to DS from address 1 address 2 address 3 address 4
DS
ad-hoc network 0 0 DA SA BSSID -
infrastructure 0 1 DA BSSID SA -
network, from AP
infrastructure 1 0 BSSID SA DA -
network, to AP
infrastructure 1 1 RA TA DA SA
network, within DS
DS: Distribution System
AP: Access Point
DA: Destination Address
SA: Source Address
BSSID: Basic Service Set Identifier
RA: Receiver Address
TA: Transmitter Address
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
25. Special Frames: ACK, RTS, CTS
Acknowledgement
bytes 2 2 6 4
ACK Frame Receiver
Duration CRC
Control Address
Request To Send
bytes 2 2 6 6 4
Frame Receiver Transmitter
RTS Duration CRC
Control Address Address
Clear To Send
bytes 2 2 6 4
Frame Receiver
CTS Duration CRC
Control Address
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
26. 802.11 - MAC management
Synchronization
try to find a LAN, try to stay within a LAN
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
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
27. Synchronization using a Beacon (infrastructure)
beacon interval
B B B B
access
point
busy busy busy busy
medium
t
value of the timestamp B beacon frame
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
28. Synchronization using a Beacon (ad-hoc)
beacon interval
B1 B1
station1
B2 B2
station2
busy busy busy busy
medium
t
value of the timestamp B beacon frame random delay
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
29. 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/
30. Power saving with wake-up patterns (infrastructure)
TIM interval DTIM interval
D B T T d D B
access
point
busy busy busy busy
medium
p d
station
t
T TIM D DTIM awake
B broadcast/multicast p PS poll d data transmission
to/from the station
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
31. Power saving with wake-up patterns (ad-hoc)
ATIM
window beacon interval
B1 A D B1
station1
B2 B2 a d
station2
t
B beacon frame random delay A transmit ATIM D transmit data
awake a acknowledge ATIM d acknowledge data
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
32. 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/
33. WLAN: IEEE 802.11b
Data rate Connection set-up time
1, 2, 5.5, 11 Mbit/s, depending on Connectionless/always on
SNR Quality of Service
User data rate max. approx. 6 Typ. Best effort, no guarantees
Mbit/s (unless polling is used, limited
support in products)
Transmission range
Manageability
300m outdoor, 30m indoor Limited (no automated key
Max. data rate ~10m indoor
distribution, sym. Encryption)
Frequency Special Advantages/Disadvantages
Free 2.4 GHz ISM-band Advantage: many installed systems,
lot of experience, available
Security worldwide, free ISM-band, many
Limited, WEP insecure, SSID vendors, integrated in laptops,
Availability simple system
Disadvantage: heavy interference
Many products, many vendors
on ISM-band, no service
guarantees, slow relative speed
only
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
34. IEEE 802.11b – PHY frame formats
Long PLCP PPDU format
128 16 8 8 16 16 variable bits
synchronization SFD signal service length HEC payload
PLCP preamble PLCP header
192 µs at 1 Mbit/s DBPSK 1, 2, 5.5 or 11 Mbit/s
Short PLCP PPDU format (optional)
56 16 8 8 16 16 variable bits
short synch. SFD signal service length HEC payload
PLCP preamble PLCP header
(1 Mbit/s, DBPSK) (2 Mbit/s, DQPSK)
96 µs 2, 5.5 or 11 Mbit/s
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
36. WLAN: IEEE 802.11a
Data rate Connection set-up time
6, 9, 12, 18, 24, 36, 48, 54 Mbit/s, Connectionless/always on
depending on SNR
User throughput (1500 byte packets): 5.3
Quality of Service
(6), 18 (24), 24 (36), 32 (54) Typ. best effort, no guarantees (same as
6, 12, 24 Mbit/s mandatory all 802.11 products)
Transmission range Manageability
100m outdoor, 10m indoor Limited (no automated key distribution,
E.g., 54 Mbit/s up to 5 m, 48 up to 12 m, sym. Encryption)
36 up to 25 m, 24 up to 30m, 18 up to 40
m, 12 up to 60 m Special Advantages/Disadvantages
Frequency Advantage: fits into 802.x standards, free
Free 5.15-5.25, 5.25-5.35, 5.725-5.825 ISM-band, available, simple system,
GHz ISM-band uses less crowded 5 GHz band
Security Disadvantage: stronger shading due to
Limited, WEP insecure, SSID higher frequency, no QoS
Availability
Some products, some vendors
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
37. IEEE 802.11a – PHY frame format
4 1 12 1 6 16 variable 6 variable bits
rate reserved length parity tail service payload tail pad
PLCP header
PLCP preamble signal data
12 1 variable symbols
6 Mbit/s 6, 9, 12, 18, 24, 36, 48, 54 Mbit/s
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
38. Operating channels for 802.11a / US U-NII
36 40 44 48 52 56 60 64 channel
5150 5180 5200 5220 5240 5260 5280 5300 5320 5350 [MHz]
16.6 MHz
center frequency =
5000 + 5*channel number [MHz]
149 153 157 161 channel
5725 5745 5765 5785 5805 5825 [MHz]
16.6 MHz
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
39. 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
pilot 312.5 kHz
-26 -21 -7 -1 1 7 21 26 subcarrier
channel center frequency number
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
40. WLAN: IEEE 802.11 – future 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
Currently unclear to which extend manufacturers will follow this suggestion
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/
41. WLAN: IEEE 802.11– future 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/
42. 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/
43. ETSI – HIPERLAN (historical)
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 logical link
network layer
control layer control layer
channel access medium access
data link layer
control layer control layer
physical layer physical layer physical layer
HIPERLAN layers OSI layers IEEE 802.x layers
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
44. Overview: original HIPERLAN protocol family
HIPERLAN 1 HIPERLAN 2 HIPERLAN 3 HIPERLAN 4
Application wireless LAN access to ATM wireless local point-to-point
fixed networks loop wireless ATM
connections
Frequency 5.1-5.3GHz 17.2-17.3GHz
Topology decentralized ad- cellular, point-to- point-to-point
hoc/infrastructure centralized multipoint
Antenna omni-directional directional
Range 50 m 50-100 m 5000 m 150 m
QoS statistical ATM traffic classes (VBR, CBR, ABR, UBR)
Mobility <10m/s stationary
Interface conventional LAN ATM networks
Data rate 23.5 Mbit/s >20 Mbit/s 155 Mbit/s
Power yes not necessary
conservation
HIPERLAN 1 never reached product status,
the other standards have been renamed/modfied !
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
45. 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/
47. 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/
48. 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/
49. 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
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
elimination survival
elimination burst
priority detection
priority assertion
yield listening
user data
verification
not az no hc nys
transmission prioritization contention transmission t
i i r
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
50. 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/
51. HIPERLAN 1 - DT-HCPDU/AK-HCPDU
0 1 2 3 4 5 6 7 bit
LBR 1 0 1 0 1 0 1 0
0 1 2 3 4 5 6 7 bit 0 1 HI AID
LBR 1 0 1 0 1 0 1 0 AID AIDCS
0 1 HI HDA
HDA HDACS Acknowledgement HCPDU
BLIR = n BL-
HI: HBR-part Indicator
IRCS 1
bit
HDA: Hashed Destination HCSAP Address
0 1 2 3 4 5 6 7 byte HDACS: HDA CheckSum
HBR TI BLI = n 1 BLIR: Block Length Indicator
PLI = m 2 BLIRCS: BLIR CheckSum
HID 3-6 TI: Type Indicator
DA 7 - 12 BLI: Block Length Indicator
SA 13 - 18
HID: HIPERLAN IDentifier
UD 19 - (52n-m-4)
DA: Destination Address
PAD (52n-m-3) - (52n-4)
SA: Source Address
CS (52n-3) - 52n
UD: User Data (1-2422 byte)
PAD: PADding
Data HCPDU CS: CheckSum
AID: Acknowledgement IDentifier
AIDS: AID CheckSum
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
52. 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/
53. HIPERLAN 1 - DT-HMPDU
bit LI: Length Indicator
0 1 2 3 4 5 6 7 byte
LI = n 1-2
TI: Type Indicator
TI = 1 3 RL: Residual Lifetime
RL 4-5
PSN: Sequence Number
PSN 6-7
DA 8 - 13 DA: Destination Address
SA 14 - 19
SA: Source Address
ADA 20 - 25
ASA 26 - 31 ADA: Alias Destination Address
UP ML 32 ASA: Alias Source Address
ML 33
UP: User Priority
KID IV 34
IV 35 - 37 ML: MSDU Lifetime
UD 38 - (n-2)
KID: Key Identifier
SC (n-1) - n
IV: Initialization Vector
n= 40–2422 UD: User Data, 1–2383 byte
Data HMPDU
SC: Sanity Check (for the
unencrypted PDU)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
54. 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/
56. Some history: Why wireless ATM?
seamless connection to wired ATM, a integrated services high-
performance 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/
57. 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/
58. 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/
59. B-ISDN protocol reference model
3 dimensional reference model
three vertical planes (columns)
user plane
control plane
management plane
three hierarchical layers management plane
physical layer
plane management
control user
ATM layer
layer management
plane plane
ATM adaptation layer
higher higher
Out-of-Band-Signaling: user data is layers layers
transmitted separately from control
information ATM adaptation layer
ATM layer
physical layer
layers
planes
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
60. 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/
61. 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/
62. ATM and AAL connections
end-system A end-system B
service dependent
AAL AAL connections
AAL
service independent
ATM ATM
ATM connections
physical physical
layer layer
ATM layer: ATM network
service independent transport of ATM cells application
multiplex and demultiplex functionality
AAL layer: support of different services
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
63. 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 Mobile ATM Protocol Extensions
radio access layer handover signaling
wireless media access control location management
wireless data link control mobile routing
radio resource control traffic and QoS Control
handover issues network management
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
64. 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/
65. 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/
66. 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/
67. User plane protocol layers
radio segment fixed network segment
MATM WATM fixed
EMAS EMAS ATM-
termi- terminal RAS end
-E -N Switch
nal adapter system
user
user process
process
AAL AAL
ATM
ATM ATM ATM ATM ATM
ATM- ATM-
CL CL
RAL RAL PHY PHY PHY PHY PHY PHY PHY PHY
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
68. Control plane protocol layers
radio segment fixed network segment
MATM WATM fixed
EMAS EMAS ATM-
termi- terminal RAS end
-E -N Switch
nal adapter system
SIG, SIG,
SIG, SIG, SIG,
M-UNI, PNNI,
M-UNI M-PNNI UNI
M-PNNI UNI
SAAL SAAL SAAL SAAL SAAL
M-ATM
ATM ATM ATM ATM ATM
ATM- ATM-
CL CL
RAL RAL PHY PHY PHY PHY PHY PHY PHY PHY
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
69. 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/
70. Reference model with further access scenarios II
1 WMT
RAS ACT WMT
2 EMAS EMAS
T 5
WMT RAS -E -N
EMAS
-E 6
MT
3 RAS WT
NMAS
MS
RAS
RAS
T
4
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
71. 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/
72. 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/
73. 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 core network IETF (TCP/IP)
ATM IP
ATM forum (ATM)
network convergence sublayer ETSI (UMTS)
CEPT, ITU-R, ...
BRAN data link control (radio frequencies)
BRAN PHY-1 BRAN PHY-2 ...
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
74. 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
No products – but several mechanisms have been
Plug and Play Adopted by other standards (e.g. 802.11a)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
75. HiperLAN2 architecture and handover scenarios
AP
MT1
APT APC Core
1 Network
MT2 (Ethernet,
Firewire,
3 AP ATM,
MT3 APT
UMTS)
APC
2
MT4 APT
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
76. Centralized vs. direct mode
AP AP/CC
control control
control
data
data
MT1 MT2 MT1 MT2 MT1 MT2 +CC
data control
Centralized Direct
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
77. HiperLAN2 protocol stack
Higher layers
DLC control Convergence layer DLC user
SAP SAP
Radio link control sublayer Data link control -
basic data
Radio DLC
resource
Assoc.
conn.
transport function
control Scope of
control control
HiperLAN2
Error
standards
control
Radio link control
Medium access control
Physical layer
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
78. Physical layer reference configuration
PDU train from DLC
(PSDU)
scrambling FEC coding interleaving
PHY bursts radio
mapping OFDM
(PPDU) transmitter
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
79. Operating channels of HiperLAN2 in Europe
36 40 44 48 52 56 60 64 channel
5150 5180 5200 5220 5240 5260 5280 5300 5320 5350 [MHz]
16.6 MHz
100 104 108 112 116 120 124 128 132 136 140 channel
5470 5500 5520 5540 5560 5580 5600 5620 5640 5660 5680 5700 5725
16.6 MHz [MHz]
center frequency =
5000 + 5*channel number [MHz]
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
80. Basic structure of HiperLAN2 MAC frames
2 ms 2 ms 2 ms 2 ms TDD,
MAC frame MAC frame MAC frame MAC frame 500 OFDM
...
symbols
per frame
random
broadcast phase downlink phase uplink phase
access phase
variable variable variable
2 406 24 bit
LCH PDU type payload CRC LCH transfer syntax
2 10 396 24 bit
sequence UDCH transfer syntax
LCH PDU type payload CRC
number (long PDU)
54 byte
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
81. Valid configurations of HiperLAN2 MAC frames
2 ms 2 ms 2 ms 2 ms
MAC frame MAC frame MAC frame MAC frame ...
random
broadcast downlink uplink access
BCH FCH ACH DL phase DiL phase UL phase RCHs Valid
combinations
BCH FCH ACH DiL phase UL phase RCHs of MAC frames
for a single
BCH FCH ACH DL phase UL phase RCHs sector AP
BCH FCH ACH UL phase RCHs
BCH FCH ACH DL phase DiL phase RCHs
BCH FCH ACH DiL phase RCHs
BCH FCH ACH DL phase RCHs
BCH FCH ACH RCHs
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
82. Mapping of logical and transport channels
BCCH FCCH RFCH LCCH RBCH DCCH UDCH UBCH UMCH
downlink
BCH FCH ACH SCH LCH
UDCH DCCH LCCH ASCH UDCH UBCH UMCH DCCH RBCH LCCH
LCH SCH RCH LCH SCH
uplink direct link
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
83. 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/
84. 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
1998: foundation of Bluetooth SIG, www.bluetooth.org (was: )
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/
85. 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/
86. …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 This could be the “original” colors
the Danes to Christianity." of the stone.
Inscription:
Btw: Blåtand means “of dark complexion” “auk tani karthi kristna” (and
(not having a blue tooth…) made the Danes Christians)
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
87. 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, point-
to-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/
88. Piconet
Collection of devices connected in an ad hoc
fashion
P
S
One unit acts as master and the others as slaves
for the lifetime of the piconet S
M P
Master determines hopping pattern, slaves have
to synchronize SB S
P SB
Each piconet has a unique hopping pattern
Participation in a piconet = synchronization to
hopping sequence M=Master P=Parked
S=Slave 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/
89. 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)
P S
SB
SB S
SB M P
SB SB
SB S
SB SB P
SB SB
SB
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
90. 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
Piconets
(each with a
capacity of
P
S S 720 kbit/s)
S
P
P
M
M
SB S
M=Master P SB SB
S=Slave
P=Parked S
SB=Standby
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
91. Bluetooth protocol stack
audio apps. NW apps. vCal/vCard telephony apps. mgmnt. apps.
TCP/UDP OBEX
AT modem
IP
commands
TCS BIN SDP
BNEP PPP Control
RFCOMM (serial line interface)
Audio Logical Link Control and Adaptation Protocol (L2CAP) Host
Controller
Link Manager Interface
Baseband
Radio
AT: attention sequence SDP: service discovery protocol
OBEX: object exchange RFCOMM: radio frequency comm.
TCS BIN: telephony control protocol specification – binary
BNEP: Bluetooth network encapsulation protocol
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
92. Frequency selection during data transmission
625 µs
fk fk+1 fk+2 fk+3 fk+4 fk+5 fk+6
M 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 fk+6
M S M
t
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
93. Baseband
Piconet/channel definition
Low-level packet definition
Access code
Channel, device access, e.g., derived from master
Packet header
1/3-FEC, active member address (broadcast + 7 slaves), link type, alternating
bit ARQ/SEQ, checksum
68(72) 54 0-2745 bits
access code packet header payload
4 64 (4) 3 4 1 1 1 8 bits
preamble sync. (trailer) AM address type flow ARQN SEQN HEC
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
98. Robustness
Slow frequency hopping with hopping patterns determined by a master
Protection from interference on certain frequencies
Separation from other piconets (FH-CDMA)
Retransmission
ACL only, very fast Error in payload
(not header!)
Forward Error Correction
SCO and ACL NAK ACK
MASTER A C C F H
SLAVE 1 B D E
SLAVE 2 G G
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
99. Baseband states of a Bluetooth device
standby unconnected
detach inquiry page connecting
transmit connected active
AMA AMA
park hold sniff low power
PMA AMA AMA
Standby: do nothing Park: release AMA, get PMA
Inquire: search for other devices Sniff: listen periodically, not each slot
Page: connect to a specific device Hold: stop ACL, SCO still possible, possibly
Connected: participate in a piconet participate in another piconet
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
100. 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) 26.0 mA
SCO connection HV3 (1s interval Sniff Mode) (Master) 26.0 mA
SCO connection HV1 (Slave) 53.0 mA
SCO connection HV1 (Master) 53.0 mA
ACL data transfer 115.2kbps UART (Master) 15.5 mA
ACL data transfer 720kbps USB (Slave) 53.0 mA
ACL data transfer 720kbps USB (Master) 53.0 mA
ACL connection, Sniff Mode 40ms interval, 38.4kbps UART 4.0 mA
ACL connection, Sniff Mode 1.28s interval, 38.4kbps UART 0.5 mA
Parked Slave, 1.28s beacon interval, 38.4kbps UART 0.6 mA
Standby Mode (Connected to host, no RF activity) 47.0 µA
Deep Sleep Mode(2) 20.0 µA
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/
102. 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/
103. L2CAP logical channels
Slave Master Slave
L2CAP L2CAP L2CAP
2 d 1 1 d d d d 1 1 d d 2
baseband baseband baseband
signalling ACL connectionless connection-oriented
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
104. L2CAP packet formats
Connectionless PDU
2 2 ≥2 0-65533 bytes
length CID=2 PSM payload
Connection-oriented PDU
2 2 0-65535 bytes
length CID payload
Signalling command PDU
2 2 bytes
length CID=1 One or more commands
1 1 2 ≥0
code ID length data
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
105. Security
User input (initialization)
PIN (1-16 byte) Pairing PIN (1-16 byte)
Authentication key generation
E2 E2
(possibly permanent storage)
link key (128 bit) Authentication link key (128 bit)
Encryption key generation
E3 E3
(temporary storage)
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/
106. 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/
107. 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/
108. Profiles
Represent default solutions for a certain usage model Applications
Vertical slice through the protocol stack
Basis for interoperability
Generic Access Profile
Service Discovery Application Profile
s oc o o P
Cordless Telephony Profile
t r
Intercom Profile
l
Serial Port Profile Profiles
Headset Profile Additional Profiles
Dial-up Networking Profile Advanced Audio Distribution
Fax Profile PAN
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/
109. WPAN: IEEE 802.15-1 – Bluetooth
Data rate Connection set-up time
Synchronous, connection-oriented: Depends on power-mode
64 kbit/s Max. 2.56s, avg. 0.64s
Asynchronous, connectionless Quality of Service
433.9 kbit/s symmetric Guarantees, ARQ/FEC
723.2 / 57.6 kbit/s asymmetric
Manageability
Transmission range Public/private keys needed, key
POS (Personal Operating Space) management not specified, simple
up to 10 m system integration
with special transceivers up to 100 Special Advantages/Disadvantages
m Advantage: already integrated into
Frequency several products, available worldwide,
Free 2.4 GHz ISM-band free ISM-band, several vendors, simple
system, simple ad-hoc networking, peer
Security to peer, scatternets
Challenge/response (SAFER+), Disadvantage: interference on ISM-band,
hopping sequence limited range, max. 8
Availability devices/network&master, high set-up
latency
Integrated into many products,
several vendors
Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/
110. WPAN: IEEE 802.15 – future developments 1
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 low-
power/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/
111. 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/
Editor's Notes
Prof. Dr.-Ing. Jochen Schiller Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 9
Prof. Dr.-Ing. Jochen Schiller Freie Universität Berlin Institut of Computer Science Mobile Communications 2002 12
Prof. Dr.-Ing. Jochen Schiller Freie Universität Berlin Institut of Computer Science Mobile Communications 2002
Prof. Dr.-Ing. Jochen Schiller Freie Universität Berlin Institut of Computer Science Mobile Communications 2002
Prof. Dr.-Ing. Jochen Schiller Freie Universität Berlin Institut of Computer Science Mobile Communications 2002
Prof. Dr.-Ing. Jochen Schiller Freie Universität Berlin Institut of Computer Science Mobile Communications 2002