Introduction to Bluetooth: The Wireless Connection Standard

1. Bluetooth

2. General Introduction • Bluetooth is a new standard developed by a group of electronics manufacturers that will allow any sort of electronic equipment -- from computers and cell phones to keyboards and headphones -- to make its own connections, without wires, cables or any direct action from a user. • This technology allows users to make ad hoc wireless connections between devices like mobile phones, desktop or notebook computers without any cable. • Devices carrying Bluetooth-enabled chips can easily transfer data at a speed of about 720Kbps within 50 meters of range. • A key difference with other existing wireless technologies is that Bluetooth enables combined usability models based on functions provided by different devices. • Present wireless technology like infra red data communication has two problems –1)Line of Sight 2) One to One • Using data synchronizing– e.g. hot sync on a PDA --- problem of using the right cradle and cable. • BLUETOOTH OVERCOMES THESE PROBLEMS

3. It provides agreement at the physical level -- Bluetooth is a radio-frequency standard. • Provides agreement at the data link level where products have to agree on • when bits are sent • how many will be sent at a time • how the parties in a conversation can be • sure that the message received is the same as the message sent • Bluetooth is a standard for a small , cheap radio chip to be plugged into computers, printers, mobile phones, etc.. • Bluetooth chip is designed to replace cables. Information normally carried by the cable, is transmitted at a special frequency to a receiver Bluetooth chip.

4. Bluetooth Protocol • Bluetooth uses the unlicensed 2.4 GHz ISM (Industrial Scientific and Medical) frequency band, there are 79 available Bluetooth channels spaced 1 MHz apart from 2.402GHz to 2.480 GHz. • Bluetooth allows power levels starting form 1mW covering 10cm to 100mW covering up to 100 meters. • Power levels are suitable for short devices zone to personal area networks within a home, Bluetooth supports both unicast (point-to-point) and multicast (point-to-multipoint) connections. • Bluetooth protocol uses the concept of master and slave, in this one a device cannot talk as and when they desire. They need to wait till the time the master allows them to talk. • The master and slaves together from a “piconet”, up to seven ‘slave’ devices can be set to communicate with a ‘master’. Several of these “piconets” can be linked together to from a larger network in an ad hoc manner.

5. Usage Models- Voice/Data Access Points • Connecting a computing device to a communicating device. • Allows any device with a Bluetooth chip to connect to the internet while located within the range of the access point. • Example- a notebook could link to the internet using a mobile phone as an access point. • Envisions public data access points

6. Usage models-Peripheral Interconnects • Standard peripheral devices like keyboard, mice, headsets etc working over a wireless link. • The same device can be used in multiple functions e.g. a headset can access phones while in the office and can interface with a cellular phone when mobile.

7. Usage model- Personal Area Networking.(PAN) • Allows dynamic formation and breakdown of “PICONETS”--ad-hoc personal networks.

8. Bluetooth Architecture/Protocol Stack • Core Specification -Deals with the lower layers of the architecture and describes how the technology works. • Profile Specification - • Focuses on how to build interoperating devices using the core technology.

9. Bluetooth Security • Authentication and encryption is provided at the Link Manager layer. • The PIN is translated into a 128 bit link key which is used for authentication. • After authentication the radios will settle on a suitable length encryption key to be used. • Bluetooth relies on PIN codes to establish trusted relationships between devices.

10. Bluetooth Application Models • Each application model in Bluetooth is realized through a profile. It define the protocols and features supporting a particular usage model. • File Transfer:- The file transfer usage model offers the ability to transfer data objects from one device to another, object types include all files, folders or directories or media formats. • Internet Bridge:- In this model, mobile phone or cordless modem acts as modem to the PC, providing dial-up networking and fax capabilities without need for physical connection to the PC. • LAN Access:- In this usage model multiple data terminals use a LAN access point as a wireless connection to an Ethernet LAN, once connected the terminals as if they were connected directly to the LAN. • Synchronization:- The synchronization usage model provides a device-to-device synchronization of data, E.g. personal information management (PIM) information, phonebook, calendar, message. • Headset:- The headset can be wirelessly connected for the purpose of acting as a remote device’s audio input and output interface.

11. RFID

12. Radio Frequency Identification (RFID) • RFID is a radio transponder carrying an ID that can be read through radio frequency (RF) interfaces. • These transponders are commonly known as RFID tags or simply tags, the object could be an entity in a manufacturing shop, goods in transit, item in a retail store, a vehicle in a parking lot, or a book in a library. • RFID for sometime to track animals for the purpose of studying animal behavior and conservation. • A RFID system comprises of different functional areas like: • Means of reading or interrogating the data in the tag • Mechanism to filter some of the data • Means to communicate the data in the tag with a host computer • For updating or entering customized data into the tag

13. RFID tags are categorized on three basic criteria, which are based o frequency, application area and the power level. • On Frequency:- there are 6 basic frequencies on which RFID operates, which are 132.4 KHz, 13.56 MHz, 433 MHz, 918 MHz, 2.4 GHz and 5.8 GHz. For some system have short reading ranges or low-frequency in this case tags are slow in data transfer and suitable for slow-moving. Commonly used in security access, asset tracking and animal identification applications. For high-frequency systems offer long read ranges and high data transfer speeds, this is require for fast moving objects like railway tracking and identification of vehicles on freeways. • On Application:- RFIDs are also grouped according to application and usage. Speed of the object and distance to read determines the type of tag to be used. RFID used for livestock will be different from the tag used in railroad. RFID tags can also be read at high speeds. In these cases RFIDs can respond within 100 milliseconds. A RFID tag contains two segments of memory. One segment is a factory-set and used to uniquely identify a tag. The other segment is usable by the application data can be written or stored in this portion of the tag.

14. Power-based grouping:- RFID can be grouped into two types based on power requirements. Which are active and passive tags. • Active tags at higher frequency range. • Passive tags are generally in low frequency range. • RFID tags are of different shapes and sizes. Animal tracking tags are inserted beneath the skin and are as small as a pencil lead. Plastic tags are attached to merchandise and used as anti-theft device, heavy-duty large tags are used to track containers or heavy machinery. • A basic RFIID system consist of three components: • A transponder programmed with unique information • A transceiver with decoder • An antenna or coil.

15. Areas of Application for RFID • Principal areas of application for RFID that can be currently identified include: • Transportation and logistics • Manufacturing and processing • Security • Animal tagging • Store in an enterprise • Retail store • Community library • Postal tracking • Road toll management • Airline baggage reconciliation • Standardization helped GSM and barcode technology to be widely accepted

16. Wireless broadband (WiMax) • The IEEE 802 committee set up the 802.16 working group in 1999 to develop wireless broad-band or Wireless MAN standards. • Wireless MAN offers an alternative to high bandwidth wire line access networks like fiber optic, cable modems and DSL. • Some technologies are generally referred to as Wireless local loop (WLL) or Wireless in local loop (Will). Wireless local loop is known as fixed-wire-less system. • The world is moving towards a convergence of voice, data and video. This will demands interoperability and high data rate.

17. 802.16 medium access control:- The IEEE 802.16 MAC protocol was designed for point-to-multipoint broadband wireless access. It addresses the need very high bit rates both uplink and downlink. This supports different services like multimedia and voice. • Broadband Applications:- Wireless broadband allows higher data rates in homes and offices. Therefore all the user applications in home and offices are potential candidates for wireless broadband. These include standards Ethernet LAN or Wi-Fi. One such system is mobile cellular system. • Broadband mobile cellular system:- In mobile cellular system the cellular network itself will be mobile. 3G system can provide high data rate. Wireless MAN is also geared up to support high data rate. Now these high data rates are possible with low speed mobility. So in terms of high-speed mobility specially designed for high-speed application.

18. Mobile IP Mobile IP architecture

19. Mobility is a application that user can continuously access data and services. • A data connection between two end-points through TCP/IP network requires a source IP address, source TCP port and a target IP address with a target TCP port. TCP port number is application-specific and remains constant. IP address, on the other hand, is network specific and varies form network to network.. IP address are assigned to a host form a set, of addresses assigned to network. • Suppose user is mobile and is using a laptop with Wi-Fi , the point of attachment will change from one subnet to another subnet resulting in a change of IP address. • What the reason why it continuously connected without disconnect, so this is ‘Mobile IP’. • ‘Mobile IP’ is that user connected to applications across the internet and the user’s point of attachment changes dynamically , all connection are maintained despite the change in network properties. • This is similar to the handoff/roaming situation in cellular network.

20. Internet protocol version 6 (IPv6) • Through internet we access variety of wireless devices offering IP connectivity, PDA, Palmtops, laptops, digital cellular phones. • IPv6 the successor to today’s IPv4, because 32-bit address space of TCP/IP is sufficient for number of devices connected to the internet. Expands the available address space. • IPv6 addresses both a short-term and long-term concern for network owners, service providers and users.

21. Address space:- IPv6 uses 128 bit addresses for each packet, creating a virtually infinite number of IP addresses, as to IPv4. in IPv6 there are global addresses and local addresses. Global addresses are used for routing of global Internet. IPv6 uses hierarchical addressing with three-level of addresses. This includes a public topology, a site topology, and an interface identifier. • IPv6 Security:- Differences between IPv6 and IPv4 is that all IPv6 nodes are expected to implement strong authentication and encryption features to improve internet security. Many vendors adapted IPSec as a part of IPv4. IPSec protocol is a standards based method of providing privacy, integrity and authenticity to information transferred across IP networks. Different security technologies: • Diffie-Hellman key exchange mechanism for deriving key between peers on a public network. • Public key cryptography to guarantee the identity of the two parties and avoid man in the middle attacks. • Bulk encryption algorithms. • Keyed hash algorithms • Digital certificates signed by a certificate authority to act as digital ID cards.

22. Mobile IP Home Agent Registration and Registration MessagesOnce a mobile node has completed agent discovery, it knows whether it is on its home network or a foreign network. If on its home network it communicates as a regular IP device, but if on a foreign network it must activate Mobile IP. This requires that it communicate with its home agent so information and instructions can be exchanged between the two. This process is called home agent registration. • The main purpose of registration is to actually start Mobile IP working. The mobile node must contact the home agent and tell it that it is on a foreign network and request that datagram forwarding be turned on. It also must let the home agent know its care-of address so the home agent knows where to send the forwarded datagrams. The home agent in turn needs to communicate various types of information back to the mobile node when registration is performed.

23. The goal of IP Mobility is to maintain the TCP connection between a mobile host and a static host while reducing the effects of location changes while the mobile host is moving around, without having to change the underlying TCP/IP. • Mobile node has two addresses – home address and a care-of address (CoA), which is associated with the network the mobile node is visiting. Two kinds of entities comprise a Mobile IP implementation: A home agent (HA) stores information about mobile nodes whose permanent home address is in the home agent's network. The HA acts as a router on a mobile host's home network which tunnels datagrams for delivery to the MH when it is away from home, maintains a location directory for the MH. A foreign agent (FA) stores information about mobile nodes visiting its network. Foreign agents also advertise care-of addresses, which are used by Mobile IP. If there is no foreign agent in the host network, the mobile device has to take care of getting an address and advertising that address by its own means. The FA acts as a router on a MH’s visited network which provides routing services to the MH while registered. FA detunnels and delivers datagrams to the MH that were tunneled by the MH’s HA

24. The so-called Care of Address is a termination point of a tunnel toward a MH, for datagrams forwarded to the MH while it is away from home. Foreign agent care-of address: the address of a foreign agent that MH registers with co-located care-of address: an externally obtained local address that a MH gets. • What exactly is a TCP connection? I understand there isn't a physical connection from the client to server. Is this connection just the client's socket being linked with the new socket created by the server after the three-way-handshake? Then once the "connection" is set up, the sockets on either ends of the connection then know where to send their packets. • How does this differ from the way UDP functions? Other than the initial handshake with TCP, is it that each server socket only has one client that sends packets to that particular socket? • What are some possible advantages of having a dedicated connection between hosts? My understanding of TCP and UDP is still very basic, so broad generalizations should suffice.

25. Congestion Control A transport layer protocol such as TCP has been designed for fixed networks with fixedend- systems. Congestion may appear from time to time even in carefully designed networks.The packet buffers of a router are filled and the router cannot forward the packets fast enoughbecause the sum of the input rates of packets destined for one output link is higher than thecapacity of the output link. The only thing a router can do in this situation is to drop packets. Adropped packet is lost for the transmission, and the receiver notices a gap in the packet stream.Now the receiver does not directly tell the sender which packet is missing, but continues toacknowledge all in-sequence packets up to the missing one.The sender notices the missing acknowledgement for the lost packet and assumes apacket loss due to congestion. Retransmitting the missing packet and continuing at full sendingrate would now be unwise, as this might only increase the congestion. To mitigate congestion,TCP slows down the transmission rate dramatically. All other TCP connections experiencing thesame congestion do exactly the same so the congestion is soon resolved.

26. Slow start TCP’s reaction to a missing acknowledgement is quite drastic, but it is necessary to get rid of  congestion quickly. The behavior TCP shows after the detection of congestion is called slowstart. The sender always calculates a congestion window for a receiver. The start size of thecongestion window is one segment (TCP packet). The sender sends one packet and waits foracknowledgement. If this acknowledgement arrives, the sender increases the congestionwindow by one, now sending two packets (congestion window = 2). This scheme doubles thecongestion window every time the acknowledgements come back, which takes one round triptime (RTT). This is called the exponential growth of the congestion window in the slow startmechanism.But doubling the congestion windowis too dangerous. The exponentialgrowth stops at the congestionthreshold. As soon as the congestionwindow reaches the congestionthreshold, further increase of thetransmission rate is only linear byadding 1 to the congestion windoweach time the acknowledgementscome back.