Bluetooth 802.15.1

Bluetooth 802.15.1

1. Wireless network using uhf radio waves Invented by Ericson in 1994 
2. Operate in Ism band 2.4
3. Bluetooth uses a radio technology called frequency-hopping spread spectrum . The
   transmitted data are divided into packets and each packet istransmitted on one of the 79
   designated Bluetooth channels.
4. Gaussian frequency-shift keying (GFSK) modulation but 8dpsk technique may also be used.

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Spraed spectrum methods FHSS and DSSS

Spread spectrum method used for digital tx over air

1. DSSS
2. FHSS

Fhss

• the data signal is modulated with a narrowband carrier signal that "hops" in a random but predictable sequence from frequency to frequency.
•  The signal energy is spread in time domain rather than frequency domain.
• This technique reduces interference because a signal from a narrowband system will only affect the spread spectrum signal if both are transmitting at the same frequency at the same time.

DSSS

•  Also known as direct sequence code division multiple access (DS-CDMA),
• Stream of information to be transmitted is divided into small pieces, each of which is allocated across to a frequency channel across the spectrum.
• Data signal is combined with high bit rate sequence also called chipping code ,divides the data according to a spreading ratio.
• The redundant chipping code helps the signal resist interference and also enables the original data to be recovered if data bits are damaged during transmission.

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LLC and Mac

Llc

1. Logical link control layer is upper subleases of data link layer.
2. Provide multiplexing
3. Provide flow control and error management contribute like ARQ Automatically repeat request.
4. The LLC sublayer acts as an interface between the media access control (MAC) sublayer and the network layer .

•  The LLC sublayer follows the IEEE 802.2 Where's in network like 802.11 Mac layer controls the error and flow control. Like Csma/ca
• PPP can be considered as LLC protocols.
•  

Mac ( Media access control)

1. Sublayer of 2 layer
2. Control the addressing and channel access control.
3. Provide communication between shared network like ethernet
4. Acts as interface between llc and physical layer.

This channel may provide unicast , multicast or broadcast communication service.


Examples of common statistical time division multiplexing multiple access protocols for wired multi-
drop networks are:

• CSMA/CD (used in Ethernet and
• IEEE 802.3)
• Token bus (IEEE 802.4 )
• Token ring ( IEEE 802.5 )
• Token passing (used in FDDI)

Examples of common multiple access protocols that may be used

• CSMA/CA (used in IEEE 802.11 /
• WiFi WLANs )
• Slotted ALOHA
• Dynamic TDMA
• Reservation ALOHA (R-ALOHA)
• Mobile Slotted Aloha (MS-
• ALOHA)
• CDMA
• OFDMAs

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802.11 WLAN

Wlan
A wireless local area network ( WLAN ) is a wireless computer network that links two or more devices using a wireless distribution method  within a limited area such as a home, school, computer laboratory, or office building.

Use 802.11 also called wifi


Wi-Fi

• Wi-Fi is a WLAN (Wireless Local Area
• Network) technology.
• The older variant of Wi-Fi, 802.11g speeds of up to
• 54Mbps

 802.11b (providing up to 11Mbps).

802.11n

The more recent standard is called 802.11n (offering speeds of up to150Mbps per channel or up to 600Mbps in total). It can be used in the 2.4 GHz or 5 GHz frequency bands, 

Wi-Fi 802.11ac

latest (so far) Wi-Fi ac standard. It allows for speeds of up to 500 Mbps per channel and over 1Gbps in total.  Wi-Fi 802.11ac operates only on the 5GHz band.

Wi-Fi is much faster than any data cellular network like GPRS, EDGE and even UMTS and HSDPA.

The range 

 is from 30 to 100 meters indoors
while outdoors  can cover about 650 meters.

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List of Protocols of OSI layers

Protocols of Osi
Physical layer

• 802.11wifi
• DSL digital subscriber line.
• ADSL  Asynchronoues
• ISDN Integrated service for digital network.
• Ethernet
• Bluetooth 802.15

Data link layer protocols

• CDP Cisco discovery protocol
• Ethernet
• IEEE 802.11 WiFi
• IEEE 802.16 WiMAX
• PPP Point-to-Point Protocol
• PPTP Point-to-Point Tunneling Protocol
• ARP Address Resolution Protocol
• RARP Reverse Address
• Resolution Protocol
• ATM Asynchronous Transfer
• Mode

Network layer

• Tcp/ip ip protocols

Transport layer

• Tcp
• UDP User Datagram Protocol
• DCCP Datagram Congestion
• Control Protocol
• Ah authentication header over ip

Session layer

• NCP NetWare Core Protocol
• NFS Network File System
• SMB Server Message Block

Presntation layer

• TLS Transport Layer Security
• SSL

Application layer

• Adc
• Bittorrent
• DNS
• Dhcp Dynamic Host Configuration Protocol
• FTP HTTP HTTPS
• IMAP , Internet Message Access
• Protocol
• NNTP , Network News Transfer
• Protocol
• NTP , Network Time Protocol
• POP3 Post Office Protocol Version 3
• SMTP , Simple Mail Transfer
• Protocol
• Telnet , a remote terminal access
• protocol

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TCp and UDP protocols

Tcp/udp

TCP/IP or UDP/IP (User Datagram Protocol )  are just protocols of Internet. They are in the 4th Layer of OSI. TCP or UDP are used to determine what kind of connection is to be established whether Connection-Oriented or Connection-Less.

Connection Oriented which uses TCP/IP: protocol is used when there is a need to establish a session and where lost packets have to be retransmitted if lost like when you use email, you dont want to send a mail with uncertainty of whether the mail will reach its destination or not and moreover with uncertainty of sending incomplete mail with lost packets.

Connectio-Less which: uses the UDP/IP protocol is used when you dont want waste time on establishing a connection and you don’t want to retransmit the lost packets as the latest packet is more necessary to reach the destination like when using chat, you dont want to resend the old packets or data later or else it will be like you are talking on some other topic and the earlier packet reaches later out of nowhere. Same can be said for buffering of a video.

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