Wireless Communications

1
Wireless Communications

• UniForum Chicago
• Bill Latura

2
Context

• Basic Concepts
• How a Cell Phone System Works
• The 3 Gs
• Cellular Data Networks
• Wireless Data

3
Circuit and Packet Switching

• Circuit-switched
• A physical path is obtained for and dedicated to
  a single connection between two end-points in the
  network for the duration of the connection.
  Ordinary voice phone service is circuit-switched.
  The phone company reserves a specific physical
  path to the number being called for the duration
  of the call. During that time, no one else can
  use the physical lines involved.
• Packet-switched
• Small units of data called packets are routed
  through a network based on the destination
  address contained within each packet. The same
  data path can be used by many users in the
  network. This type of communication between
  sender and receiver is known as connectionless
  (rather than dedicated). Most traffic over the
  Internet uses packet switching. The Internet is
  basically a connectionless network.

4
Spread Spectrum Transmission
Direct Sequence
Frequency Hopping

• Highest power consumption
• Highest potential data rates
• Lowest aggregate capacity using multiple physical
  layers than frequency hopping
• Smallest number of geographically separate radio
  cells due to limited channels
• Greater range than frequency hopping
• Slices transmission into small coded bits and
  spreads message across whole spectrum
• Utilizes wide signal channel

• Lower cost
• Lowest power consumption
• Most tolerant to signal interference
• Lower potential data rates
• Highest aggregate capacity using multiple
  physical layers
• Less range than direct sequence
• Concentrates power in very narrow spectrum
• Hops in random pattern 100 times/sec
• Spreads power across band instead of signal

5
CDMA and TDMA

• CDMA (Code-Division Multiple Access) a digital
  cellular technology that uses spread-spectrum
  techniques. Unlike systems that use TDMA, CDMA
  does not assign a specific frequency to each
  user. Instead, every channel uses the full
  available spectrum. Individual conversations are
  encoded with a pseudo-random digital sequence.
• TDMA (Time Division Multiple Access) a technology
  for delivering digital wireless service using
  time division multiplexing. TDMA works by
  dividing a radio frequency into time slots and
  then allocating slots to multiple calls. In this
  way, a single frequency can support multiple,
  simultaneous data channels. TDMA is used by the
  GSM digital cellular system.

6
Cellular Networks

• All BSs within a cluster are connected to a
  Mobile Switching Center(MSC).
• Each MSC of a cluster is then connected to the
  MSC of other clusters and a PSTN main switching
  center.
• The MSC stores information about the subscribers
  located within the cluster and is responsible for
  directing calls to them.

7
Making a Call

• Scan Control Channels Your cell phone needs to
  use the "closest" base station because that's the
  one with the strongest signal and the one that
  will give the best connection. To find the
  closest base station, your phone checks all 21
  control channels and determines which has the
  strongest signal.
• Choose Strongest Your cell phone chooses the
  strongest signal and decides to use that one for
  placing the call.
• Send Origination Message Your cell phone now
  transmits a very short message (about 1/4 second)
  that contains the MIN (Mobile Identification
  Number, aka your cell phone number), its ESN
  (Electronic Serial Number), and the number you
  just dialed.
• Get Channel Assignment After the cellular
  service provider verifies that you are a valid,
  paying customer (based on the MIN and ESN your
  phone sent), the base station sends a Channel
  Assignment message to your phone (also a short
  1/4-second burst). This message tells your phone
  where (that is, on which channel) the
  conversation will take place.
• Begin Conversation

8
Roaming

• A wireless roaming network has five components
  that make it work
• A database for storing customer profile
  information such as features, dialing
  capabilities, and the home serving area
  identification. This is called the home location
  register (HLR).
• A database of mobile numbers used by each switch
  on the network.
• A signaling network for transmitting data
  messages between switches.
• Routing specifications that direct the data
  messages to the appropriate destination.
• Public long-distance connections for call
  delivery

9
Roaming

• A registration cycle keeps track of a phone as it
  travels around the network. It begins when a
  wireless user powers on their phone. The general
  steps for this process are
• When the phone is powered on, it sends a data
  message to the cellsite. This data message
  contains the Mobile Identification Number (MIN or
  phone number) and the Electronic Serial Number
  (ESN). The cellsite forwards this information to
  the switch.
• The switch compares the MIN with a table of all
  MINs in the network. It will determine if the MIN
  belongs to a home customer, or to a visiting
  customer. In either case, the switch will request
  the subscriber's feature profile from the Home
  Location Register (HLR). The HLR for home
  customers may be integrated into the same switch
  or stored on a separate platform.

10
Roaming

• If the HLR is a separate platform, or if the
  customer is visiting from another system, the
  switch then sends a data message to the HLR
  across the signaling network. Routing
  specifications stored at Signaling Transfer
  Points (STPs) provide the necessary information
  to direct the message to the home location
  register.
• When the Home Location Register (HLR) receives
  the message, it checks the MIN the ESN. If the
  numbers are valid, the HLR records the location
  of the phone and returns a message containing the
  subscriber's feature list and calling
  restrictions to the visited switch.
• Once the visited switch receives the return
  message, it creates a Visitor Location Register
  (VLR) to store information about the roamer,
  including the MIN, ESN, features, etc... This
  register will be used by the roamer as long as
  they are registered in the visited system.

11
Hand-over

• During a call, the base station would monitor the
  signal level from the mobile phone. When the
  mobile phone is moving into a new cell, the
  signal level will fall to a critical value
  causing the base station to inform the Mobile
  Switching Center(MSC) about this event. The MSC
  would instruct all the surrounding base stations
  to measure the mobile phone's signal level and
  transfer control to the base station receiving
  the strongest signal level. This is known as
  hand-over and occurs within 400ms, so the phone
  user is hardly aware of a break.
• Registration is done again with the new base
  station. Location information stored in the MSC
  about this mobile telephone is updated. If the
  mobile telephone is moved into a cell belonging
  to a different cluster it would also have to
  register with the new MSC.

12
1G (Analog)

• Uses frequency division multiple access (FDMA) to
  communicate (every call in one area uses its own
  set of channels for communication)
• No support for wireless data
• NMT (Nordic Mobile Telephone) is an analog
  cellular phone system deployed in more than 40
  countries in Europe. NMT was the first analog
  cellular phone system (launched in the
  Scandinavian countries 1979). The system used
  originally 450 MHz band (NMT 450), but later when
  more capacity was needed, it was also adopted for
  900 MHz band (NMT 900).

13
1G (Analog)

• AMPS (Advanced Mobile Phone System) is the analog
  cellular phone system used in North and South
  America. AMPS uses FDMA and operates at 800 MHz
  band. AMPS was introduced in the USA in 1983.
• TACS (Total Access Communication System) was
  developed in Britain using the 900 MHz band. TACS
  was based on the AMPS system and was adopted in
  other countries such as Hong Kong and Japan.
• ETACS (Extended Total Access Communication
  System) was developed in the UK and is available
  in Europe and Asia.

14
2G (Digital)

• Uses digital encoding and includes CDMA, TDMA and
  GSM. Text messages can be sent on 2G networks,
  but more bandwidth hungry applications require
  2.5G.
• Circuit switched
• In the United States, GSM, TDMA, and CDMA are
  assigned two frequency ranges that include the
  frequency ranges assigned to analog cellular, 824
  MHz to 849 MHz and 869 MHz to 894 MHz, and also
  the frequency ranges of 1850 to 1910 MHz and 1930
  MHz to 1990 MHz.

15
2G (Digital)

• CDMA (Code Division Multiple Access) uses a
  spread spectrum technique to scatter a radio
  signal across a wide range of frequencies.
• IDEN, (Integrated Digital Enhanced Network) is a
  wireless technology from Motorola combining the
  capabilities of a digital cellular telephone,
  two-way radio, alphanumeric pager, and data/fax
  modem in a single network. iDEN operates in the
  800 MHz, 900MHz, and 1.5 GHz bands and is based
  on time division multiple access (TDMA) and GSM
  architecture.

16
2G (Digital)

• GSM (Global System for Mobile Communications) is
  the digital transmission technique widely adopted
  in Europe and supported in North America. GSM
  uses 900 MHz and 1800 MHz in Europe. In North
  America, GSM uses the 1900 MHz band.
• TDMA (Time Division Multiple Access) divides each
  cellular channel into three time slots in order
  to increase the amount of data that can be
  carried. GSM and D-AMPS use TDMA in one form or
  another. It is also generally used to describe
  what was formerly known as D-AMPS. TDMA networks
  are operated in the United States, Latin America,
  New Zealand, parts of Russia and Asia Pacific.

17
2G Vendor Support

• Cingular supports TDMA and GSM.
• Nextel relies on iDEN.
• T-Mobile supports GSM.
• ATT Wireless supports TDMA and GSM networks.
• Verizon Wireless uses CDMA.

18
2.5G

• An enhancement to 2G networks that allows them to
  operate in a "packet switched" manner
• 2.5G networks incorporate 2G technology with
  GPRS' higher speeds to support data transport.
  2.5G is a bridge from the voice-centric 2G
  networks to the data-centric 3G networks.
• GPRS (General Packet Radio Service) is a radio
  technology for GSM networks that adds
  packet-switching protocols. As a 2.5G technology,
  GPRS enables high-speed wireless Internet and
  other data communications. GPRS networks can
  deliver SMS, MMS, email, games, and WAP
  applications.

19
3G

• 3G networks promise next-generation service with
  transmission rates of 144Kbps and higher that can
  support multimedia applications, such as video,
  video conferencing and Internet access. Both UMTS
  (WCDMA) and EDGE will support 3G services. 3G
  networks operate on a different frequency than 2G
  networks.

20
3G

• UMTS (Universal Mobile Telecommunications System)
  or WCDM (Wideband Code Division Multiple Access)
  was selected as the successor to GSM. It is the
  European standard for 3G wideband digital radio
  communications, and it utilizes one 5 MHz channel
  for both voice and data, offering data speeds up
  to 2 Mbps.
• EDGE is a mobile network radio technology that
  allows current GSM networks to offer 3G services
  within existing frequencies. As an evolution of
  GSM/GPRS, EDGE is an upgrade to GPRS' data and
  GSM's voice networks. EDGE provides data speed
  three times that of GPRS.

21
Cellular Data Networks

• SMS
• Short Message Service
• MMS
• Multimedia Message Service
• GPRS
• General Packet Radio Service
• HSCSD
• High Speed Circuit Switched Data
• EDGE
• Enhanced Data Rates for Global Evolution

22
Short Message Service (SMS)

• Globally accepted wireless service that enables
  the transmission of alphanumeric messages between
  mobile devices and external systems
• Available in US on GSM-based PCS as well as TDMA
  and CDMA based cellular systems
• Short Message Service Center (SMSC) acts as a
  relay and store and forward system for messages
• Point to point delivery of messages
• Active mobile handset is able to receive or send
  a short message at any time, independent of
  whether a voice or data call is in progress
• Utilizes out-of-band packet delivery and
  low-bandwidth message delivery
• Guarantees delivery of the short message by the
  network. Temporary transmission failures are
  identified, and the message is stored in the
  network until the destination becomes available

23
MMS

• Multimedia Message Service, a store-and-forward
  method of transmitting graphics, video clips,
  sound files and short text messages over wireless
  networks using the WAP protocol. Carriers deploy
  special servers, dubbed MMS Centers (MMSCs) to
  implement the offerings on their systems.
• MMS also supports e-mail addressing, so the
  device can send e-mails directly to an e-mail
  address. The most common use of MMS is for
  communication between mobile phones. MMS,
  however, is not the same as e-mail. MMS is based
  on the concept of multimedia messaging. The
  presentation of the message is coded into the
  presentation file so that the images, sounds and
  text are displayed in a predetermined order as
  one singular message. MMS does not support
  attachments as e-mail does.
• To the end user, MMS is similar to SMS.

24
GPRS

• GPRS (General Packet Radio Service) is a
  specification for data transfer on TDMA and GSM
  networks. The theoretical limit for packet
  switched data is approx. 170 kb/s. A realistic
  bit rate is 30-70 kb/s. . GPRS supports both
  TCP/IP and X.25 communications.
• It provides moderate speed data transfer, by
  using unused TDMA channels on a GSM network.
• GSM circuit switch connections are still used for
  voice, but data is sent and received in "packets"
  in the same way as it would be in the fixed
  internet environment.
• The advantage is that network resources are used
  more efficiently. Rather than maintaining a
  circuit for the duration of the connection, which
  ties up resources regardless of whether anything
  is actually being sent or received, GPRS only
  consumes resource when information packets are
  transmitted.

25
HSCSD

• HSCSD (High Speed Circuit Switched Data) is a
  specification for data transfer over GSM
  networks. HSCSD utilizes up to four 9.6Kb or
  14.4Kb time slots, for a total bandwidth of
  38.4Kb or 57.6Kb.
• 14.4Kb time slots are only available on GSM
  networks that operate at 1,800Mhz. 900Mhz GSM
  networks are limited to 9.6Kb time slots.
  Therefore, HSCSD is limited to 38.4Kbps on 900Mhz
  GSM networks. HSCSD can only achieve 57.6Kbps on
  1,800Mhz GSM networks.

26
HSCSD vs. GPRS

• HSCSD has an advantage over GPRS in that HSCSD
  supports guaranteed quality of service because of
  the dedicated circuit-switched communications
  channel. This makes HSCSD a better protocol for
  timing-sensitive applications such as image or
  video transfer.
• GPRS has the advantage over HSCSD for most data
  transfer because HSCSD, which is
  circuit-switched, is less bandwidth efficient
  with expensive wireless links than GPRS, which is
  packet-switched.
• For an application such as downloading, HSCSD may
  be preferred, since circuit-switched data is
  usually given priority over packet-switched data
  on a mobile network, and there are few seconds
  when no data is being transferred.

27
EDGE

• Enhanced Data Rates for Global Evolution (EDGE)
  is a bolt-on enhancement to 2G and GPRS networks.
  This technology is compatible with TDMA and GSM
  networks. EDGE uses the same spectrum allocated
  for GSM850, GSM900, GSM1800 and GSM1900
  operation.
• Instead of employing GMSK (Gaussian minimum-shift
  keying) EDGE uses 8PSK (8 Phase Shift Keying)
  producing a 3bit word for every change in carrier
  phase. This effectively triples the gross data
  rate offered by GSM. EDGE, like GPRS, uses a rate
  adaptation algorithm that adapts the modulation
  and coding scheme (MCS) used to the quality of
  the radio channel, and thus the bit rate and
  robustness of data transmission. It introduces a
  new technology not found in GPRS, Incremental
  Redundancy, which, instead of retransmitting
  disturbed packets, sends more redundancy
  information to be combined in the receiver. This
  increases the probability of correct decoding.

28
Wireless Data

• 802.11x
• Bluetooth
• ZigBee
• UltraWideBand

29
WAP

• Wireless Application Protocol
• An application communication protocol
• Used to access services and information
• Inherited from Internet standards
• Used for handheld devices such as mobile phones
• A protocol designed for micro browsers
• Enables the creating of web applications for
  mobile devices.
• Uses the mark-up language WML (not HTML)
• WML is defined as an XML 1.0 application

30
WAP

• The WAP standard is based on HTML, XML and
  TCP/IP. It consists of a WML language
  specification, a WMLScript specification, and a
  Wireless Telephony Application Interface (WTAI)
  specification.
• WML stands for Wireless Markup Language. It is a
  mark-up language inherited from HTML, but WML is
  based on XML, so it is much stricter than HTML.
• WML uses WMLScript to run simple code on the
  client. WMLScript is a light JavaScript language.
  WML scripts are not embedded in the WML pages.
  WML pages only contain references to script URLs.
  WML scripts need to be compiled into byte code on
  a server before they can run in a WAP browser.

31
ISM Frequency Bands
The three ISM frequency bands are the only ones
available for unlicensed wireless transmission in
the US. Only one band has world-wide availability.

• Industrial, Scientific, and Medical (ISM) spread
  spectrum modulation
• 902-928 MHz
• 2.4-2.4835 GHz (home of microwave oven band)
• 5.725-5.850 GHz
• under 1 watt transmitter output power
• more bandwidth with higher frequencies, which
  support higher data rates.

32
802.11x (Wi-Fi)

• Standards
• The following standards exist
• IEEE 802.11 - The original 2 Mbit/s, 2.4 GHz
  standard
• IEEE 802.11a - 54 Mbit/s, 5 GHz standard
• IEEE 802.11b - Enhancements to 802.11 to support
  5.5 and 11 Mbit/s
• IEEE 802.11d - New countries
• IEEE 802.11e - Enhancements QoS, including
  packet bursting
• IEEE 802.11f - Inter-Access Point Protocol (IAPP)
• IEEE 802.11g - 54 Mbit/s, 2.4 GHz (backwards
  compatible with b)
• IEEE 802.11h - 5 GHz spectrum, Dynamic
  Channel/Frequency Selection (DCS/DFS) and
  Transmit Power Control (TPC) for European
  compatibility
• IEEE 802.11i - Enhanced security
• IEEE 802.11j - Extensions for Japan
• IEEE 802.11n - Higher throughput improvements
• IEEE 802.11p - Adding wireless capabilities to
  mobile vehicles such as ambulances and passenger
  cars

33
802.11b

• 802.11b has a range of about 50 meters with the
  low-gain omnidirectional antennas typically used
  in 802.11b devices. 802.11b has a maximum
  throughput of 11 Mbit/s, however a significant
  percentage of this bandwidth is used for
  communications overhead in practice the maximum
  throughput is about 5.5 Mbit/s. Metal, water, and
  thick walls absorb 802.11b signals and decrease
  the range drastically. 802.11 runs in the 2.4 GHz
  spectrum and uses Carrier Sense Multiple Access
  with Collision Avoidance (CSMA/CA) as its media
  access method.
• With high-gain external antennas, the protocol
  can also be used in fixed point-to-point
  arrangements, typically at ranges up to 8
  kilometers (although some report success at
  ranges up to 80-120 km where line of sight can be
  established). This is usually done to replace
  leased lines, or in place of microwave
  communications equipment. Current cards can
  operate at 11 Mbit/s, but will scale back to 5.5,
  then 2, then 1, if signal strength becomes an
  issue.

34
802.11a

• The 802.11a standard uses the 5 GHz band, and
  operates at a raw speed of 54 Mbit/s, and more
  realistic net achievable speeds in the mid-20
  Mbit/s. The speed is reduced to 48, 36, 34, 18,
  12, 9 then 6 Mbit/s if required. 802.11a has 12
  non-overlapping channels, 8 dedicated to indoor
  and 4 to point to point.
• 802.11a has not seen wide adoption because of the
  high adoption rate of 802.11b, and because of
  concerns about range at 5 GHz, 802.11a cannot
  reach as far as 802.11b, other things (such as
  same power limitations) being equal it is also
  absorbed more readily. Most manufacturers of
  802.11a equipment countered the lack of market
  success by releasing dual-band or
  dual-mode/tri-mode cards that can automatically
  handle 802.11a and b or a, b and g as available.
  Access point equipment which can support all
  these standards simultaneously is also available.

35
802.11g

• 802.11g works in the 2.4 GHz band (like 802.11b)
  but operates at 54 Mbit/s raw, or about 24.7
  Mbit/s net, throughput like 802.11a. It is fully
  backwards compatible with b and uses the same
  frequencies. In older equipment, however, the
  presence of an 802.11b participant significantly
  reduces the speed of an 802.11g network.
• A new feature called Super G is now integrated in
  certain access points. These can boost network
  speeds up to 108 Mbit/s by using channel bonding.
  This feature may interfere with other networks
  and may not support all b and g client cards. In
  addition, packet bursting techniques are also
  available in some chipsets and products which
  will also considerably increase speeds. Again,
  they may not be compatible with some equipment.

36
802.11n

• In January 2004, IEEE announced that it will
  develop a new standard for wide-area wireless
  networks. The real speed would be 100 Mbit/s
  (even 250 Mbit/s in PHY level), and so up to 4-5
  times faster than 802.11g, and perhaps 50 times
  faster than 802.11b.
• As projected, 802.11n will also offer a better
  operating distance than current networks. The
  standardization progress is expected to be
  completed by the end of 2006.

37
802.11 Security (WEP)

• Wired Equivalent Privacy
• A security protocol for wireless local area
  networks defined in the 802.11b standard. WEP is
  designed to provide the same level of security as
  that of a wired LAN. LANs are inherently more
  secure than WLANs because LANs are somewhat
  protected by the physical properties of their
  structure, having some or all part of the network
  inside a building that can be protected from
  unauthorized access. WLANs, which operate over
  radio waves, do not have the same physical
  structure and therefore are more vulnerable to
  tampering. WEP aims to provide security by
  encrypting data over radio waves so that it is
  protected as it is transmitted from one end point
  to another.
• Data encryption protects the vulnerable wireless
  link between clients and access points once this
  measure has been taken, other typical LAN
  security mechanisms such as password protection,
  end-to-end encryption, virtual private networks
  (VPNs), and authentication can be put in place to
  ensure privacy.

38
802.11 Security (WEP)

• Some versions use the 40-bit key that was
  originally used to formulate the standard, while
  other newer versions use a 128-bit (104 in
  reality) key to each is added a 24-bit
  initialization vector (IV) which is transmitted
  in the clear.
• When WEP is active in a wireless LAN, each 802.11
  packet is encrypted separately with an RC4 cipher
  stream generated by an RC4 key. This key is
  composed of a 24-bit initialization vector (IV)
  and the 40 (or 104)-bit WEP key. The encrypted
  packet is generated with a bitwise exclusive OR
  (XOR) of the original packet and the RC4 stream.
  The IV is chosen by the sender and can be changed
  periodically so every packet won't be encrypted
  with the same cipher stream. The IV is sent in
  the clear with each packet. An additional 4-byte
  Integrity Check Value (ICV) is computed on the
  original packet and appended to the end. The ICV
  (be careful not to confuse this with the IV) is
  also encrypted with the RC4 cipher stream.

39
802.11 Security (WEP Weaknesses)

• WEP has been widely criticized for a number of
  weaknesses
• A high percentage of wireless networks have WEP
  disabled because of the administrative overhead
  of maintaining a shared WEP key.
• WEP has the same problem as all systems based
  upon shared keys any secret held by more than
  one person soon becomes public knowledge. Take
  for example an employee who leaves a company -
  they still know the shared WEP key. The
  ex-employee could sit outside the company with an
  802.11 NIC and sniff network traffic or even
  attack the internal network.
• The ICV algorithm is not appropriate The WEP ICV
  is based on CRC-32, an algorithm for detecting
  noise and common errors in transmission. CRC-32
  is an excellent checksum for detecting errors,
  but an awful choice for a cryptographic hash.
  Better-designed encryption systems use algorithms
  such as MD5 or SHA-1 for their ICVs.
• The initialization vector that seeds the WEP
  algorithm is sent in the clear.
• The WEP checksum is linear and predictable.

40
802.11 Security (WPA)

• Wi-Fi Protected Access
• The Wi-Fi Alliance has taken a subset of the
  draft 802.11i standard, calling it WPA, and now
  certifies devices that meet the requirements.
• WPA uses Temporal Key Integrity Protocol (TKIP)
  as the protocol and algorithm to improve security
  of keys used with WEP. It changes the way keys
  are derived and rotates keys more often for
  security. It also adds a message-integrity-check
  function to prevent packet forgeries.
• While WPA goes a long way toward addressing the
  shortcomings of WEP, not all users will be able
  to take advantage of it. That's because WPA might
  not be backward-compatible with some legacy
  devices and operating systems. Moreover, not all
  users can share the same security infrastructure.
  Some users will have a PDA and lack the
  processing resources of a PC.
• TKIP/WPA will degrade performance unless a WLAN
  system has hardware that will run and accelerate
  the WPA protocol. For most WLANs, there's
  currently a trade-off between security and
  performance without the presence of hardware
  acceleration in the access point.

41
802.11 Security (RSN)

• Robust Security Network
• RSN uses dynamic negotiation of authentication
  and encryption algorithms between access points
  and mobile devices. The authentication schemes
  proposed in the draft standard are based on
  802.1X and Extensible Authentication Protocol
  (EAP). The encryption algorithm is Advanced
  Encryption Standard (AES).
• Dynamic negotiation of authentication and
  encryption algorithms lets RSN evolve with the
  state of the art in security, adding algorithms
  to address new threats and continuing to provide
  the security necessary to protect information
  that WLANs carry.
• Using dynamic negotiation, 802.1X, EAP and AES,
  RSN is significantly stronger than WEP and WPA.
  However, RSN will run very poorly on legacy
  devices. Only the latest devices have the
  hardware required to accelerate the algorithms in
  clients and access points, providing the
  performance expected of today's WLAN products.
• WPA will improve security of legacy devices to a
  minimally acceptable level, but RSN is the future
  of over-the-air security for 802.11.

42
Bluetooth

• Royalty free operation
• 721 kbps plus three voice channels
• 2.402-2.480 GHz unlicensed ISM band
• Frequency hopping spread spectrum
• 79 hops separated by 1 MHz
• Range lt 20 feet
• Transmit power 0.1mW

Bluetooth supports both point-to-point and point
to multi-point connections. Several Piconets can
be established and linked together ad hoc. Each
Piconet is identified by a different frequency
hopping sequence.
43
Bluetooth

• Moderate duty cycle, secondary battery lasts same
  as master
• Very high QoS and very low, guaranteed latency
• Quasi-static star network up to seven clients
  with ability to participate in more than one
  network
• Frequency Hopping Spread Spectrum is extremely
  difficult to create extended networks without
  large synchronization cost

44
ZigBee

• ZigBee-compliant products take full advantage of
  a powerful IEEE 802.15.4 physical radio standard
  and operate in unlicensed bands worldwide at
  2.4GHz (global), 915Mhz (Americas) and 868Mhz
  (Europe).
• Raw data throughput rates of 250Kbs can be
  achieved at 2.4GHz (16 channels), 40Kbs at 915Mhz
  (10 channels) and 20Kbs at 868Mhz (1 channel).
• Transmission distances range from 10 to 100
  meters, depending on power output and
  environmental characteristics

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ZigBee

• Very low duty cycle, very long primary battery
  life
• Static and dynamic star and mesh networks,
  gt65,000 nodes, with low latency available
• Ability to remain quiescent for long periods
  without communications
• Direct Sequence Spread Spectrum allows devices to
  sleep without the requirement for close
  synchronization

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ZigBee Applications

• Lighting controls
• Automatic Meter Reading
• Wireless smoke and CO detectors
• HVAC control
• Heating control
• Home security
• Environmental controls
• Blind, drapery and shade controls
• Medical sensing and monitoring
• Universal Remote Control to a Set-Top Box which
  includes Home Control
• Industrial and building automation

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UltraWideBand

• Bluetooth on steroids
• Designed for short-range, wireless personal area
  networks (WPANs) enabling wireless connection of
  multiple devices for transmission of video, audio
  and other high-bandwidth data.
• Its use will be to relay data from a host device
  to other devices in the immediate area (up to 10
  meters or 30 feet).
• UWB uses very low-powered, short-pulse radio
  signals many times in the picosecond duration
  range to transfer data over a very wide range of
  frequencies. A UWB transmission involves billions
  of pulses spread over several gigahertz.

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UltraWideBand

• UWB should deliver bandwidths from about 40Mbps
  to 600Mbps, and eventually data rates could be up
  to gigabits-per-second (with higher power).
• UWB systems consume very little power, around one
  ten-thousandth of that of cell phones. This makes
  UWB practical for use in smaller devices, such as
  cell phones and PDAs, that users carry at all
  times.
• Because UWB operates at such low power, it has
  very little interference impact on other systems.
  UWB causes less interference than conventional
  radio-network solutions. In addition, the
  relatively wide spectrum that UWB utilizes
  significantly minimizes the impact of
  interference from other systems as well.