Figure 6.2: MAC protocols for ad hoc network 2009/11/4 8. Contention-Based Protocols. MACA Protocol. Multiple access collision avoidance protocol. MACA-BI is a receiver-initiated MAC protocol – Reduced the number of control packets in MACA protocol (uses three-way handshake mechanism). Receiver sends ready to receive (RTR) Sender. The medium access control (MAC) layer is a part of the data link layer which plays one of the most crucial roles in the communication protocol's overall energy efficiency. 2 have done a survey on energy efficient neighbour discovery in mobile ad hoc and wireless sensor networks.
IEEE 802 is a family of Institute of Electrical and Electronics Engineers (IEEE) standards for local area networks (LAN), personal area network (PAN), and metropolitan area networks (MAN). The IEEE 802 LAN/MAN Standards Committee (LMSC) maintains these standards. The IEEE 802 family of standards has twelve members, numbered 802.1 through 802.12, with a focus group of the LMSC devoted to each.
The IEEE 802 standards are restricted to networks carrying variable-size packets, unlike cell relay networks, for example, in which data is transmitted in short, uniformly sized units called cells. Isochronous signal networks, in which data is transmitted as a steady stream of octets, or groups of octets, at regular time intervals, are also outside the scope of the IEEE 802 standards.
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The number 802 has no significance: it was simply the next number in the sequence that the IEEE used for standards projects.[1]
The services and protocols specified in IEEE 802 map to the lower two layers (data link and physical) of the seven-layer Open Systems Interconnection (OSI) networking reference model. IEEE 802 divides the OSI data link layer into two sub-layers: logical link control (LLC) and medium access control (MAC), as follows:
- Data link layer
- LLC sublayer
- MAC sublayer
The most widely used of these standards are for the Ethernet family, token ring, wireless network protocols (including Wi-Fi), and bridging protocols.[citation needed] Jobmate manuals press drill.
Working groups[edit]
| Name | Description | Status |
|---|---|---|
| IEEE 802.1 | Higher Layer LAN Protocols Working Group | Active |
| IEEE 802.2 | LLC | Disbanded |
| IEEE 802.3 | Ethernet | Active |
| IEEE 802.4 | Token bus | Disbanded |
| IEEE 802.5 | Token ring MAC layer | Disbanded |
| IEEE 802.6 | MANs (DQDB) | Disbanded |
| IEEE 802.7 | Broadband LAN using Coaxial Cable | Disbanded |
| IEEE 802.8 | Fiber Optic TAG | Disbanded |
| IEEE 802.9 | Integrated Services LAN (ISLAN or isoEthernet) | Disbanded |
| IEEE 802.10 | Interoperable LAN Security | Disbanded |
| IEEE 802.11 | Wireless LAN (WLAN) & Mesh (Wi-Fi certification) | Active |
| IEEE 802.12 | 100BaseVG | Disbanded |
| IEEE 802.13 | Unused[2] | reserved for Fast Ethernet development[3] |
| IEEE 802.14 | Cable modems | Disbanded |
| IEEE 802.15 | Wireless PAN | Active |
| IEEE 802.15.1 | Bluetooth certification | Disbanded |
| IEEE 802.15.2 | IEEE 802.15 and IEEE 802.11 coexistence | Hibernating[4] |
| IEEE 802.15.3 | High-Rate wireless PAN (e.g., UWB, etc.) | ? |
| IEEE 802.15.4 | Low-Rate wireless PAN (e.g., ZigBee, WirelessHART, MiWi, etc.) | Active |
| IEEE 802.15.5 | Mesh networking for WPAN | ? |
| IEEE 802.15.6 | Body area network | Active |
| IEEE 802.15.7 | Visible light communications | ? |
| IEEE 802.16 | Broadband Wireless Access (WiMAX certification) | hibernating |
| IEEE 802.16.1 | Local Multipoint Distribution Service | hibernating |
| IEEE 802.16.2 | Coexistence wireless access | hibernating |
| IEEE 802.17 | Resilient packet ring | Disbanded |
| IEEE 802.18 | Radio Regulatory TAG | ? |
| IEEE 802.19 | Wireless Coexistence Working Group | ? |
| IEEE 802.20 | Mobile Broadband Wireless Access | Disbanded |
| IEEE 802.21 | Media Independent Handoff | hibernating |
| IEEE 802.22 | Wireless Regional Area Network | hibernating |
| IEEE 802.23 | Emergency Services Working Group | Disbanded |
| IEEE 802.24 | Vertical Applications TAG | ? |
See also[edit]
References[edit]
- IEEE Std 802-1990: IEEE standards for Local and Metropolitan Networks: Overview and Architecture New York:1990
- ^Institute of Electrical and Electronics Engineers (September 2004). 'Overview and Guide to the IEEE 802 LMSC'(PDF). Retrieved October 13, 2020.
- ^'802.3'. Data Communincation Standards and Protocols. EE Herald. Retrieved 2012-01-25.
- ^'The fate of 100 Mbps Ethernet now definitely two-fold'. FDDI News. Boston: Information Gatekeepers, Inc. 4 (7): 1–2. July 1993. ISSN1051-1903. Retrieved 2013-11-21.
- ^'IEEE 802.15 WPAN Task Group 2 (TG2)'. official web site. IEEE Standards Association. May 12, 2004. Retrieved June 30, 2011.
External links[edit]
- IEEE 802 Standards available via IEEE Get Program
The Data Link Layer is responsible for transmission of data between two nodes. Its main functions are-
- Data Link Control
- Multiple Access Control
Data Link control –
The data link control is responsible for reliable transmission of message over transmission channel by using techniques like framing, error control and flow control. For Data link control refer to – Stop and Wait ARQ
Multiple Access Control –
If there is a dedicated link between the sender and the receiver then data link control layer is sufficient, however if there is no dedicated link present then multiple stations can access the channel simultaneously. Hence multiple access protocols are required to decrease collision and avoid crosstalk. For example, in a classroom full of students, when a teacher asks a question and all the students (or stations) start answering simultaneously (send data at same time) then a lot of chaos is created( data overlap or data lost) then it is the job of the teacher (multiple access protocols) to manage the students and make them answer one at a time.
Thus, protocols are required for sharing data on non dedicated channels. Multiple access protocols can be subdivided further as –
Mac Protocols For Language
1. Random Access Protocol: In this, all stations have same superiority that is no station has more priority than another station. Any station can send data depending on medium's state( idle or busy). It has two features:
- There is no fixed time for sending data
- There is no fixed sequence of stations sending data
The Random access protocols are further subdivided as:
(a) ALOHA – It was designed for wireless LAN but is also applicable for shared medium. In this, multiple stations can transmit data at the same time and can hence lead to collision and data being garbled.
- Pure Aloha:
When a station sends data it waits for an acknowledgement. If the acknowledgement doesn't come within the allotted time then the station waits for a random amount of time called back-off time (Tb) and re-sends the data. Since different stations wait for different amount of time, the probability of further collision decreases. - Slotted Aloha:
It is similar to pure aloha, except that we divide time into slots and sending of data is allowed only at the beginning of these slots. If a station misses out the allowed time, it must wait for the next slot. This reduces the probability of collision.
Mechwarrior for mac. For more information on ALOHA refer – LAN Technologies
(b) CSMA – Carrier Sense Multiple Access ensures fewer collisions as the station is required to first sense the medium (for idle or busy) before transmitting data. If it is idle then it sends data, otherwise it waits till the channel becomes idle. However there is still chance of collision in CSMA due to propagation delay. For example, if station A wants to send data, it will first sense the medium.If it finds the channel idle, it will start sending data. However, by the time the first bit of data is transmitted (delayed due to propagation delay) from station A, if station B requests to send data and senses the medium it will also find it idle and will also send data. This will result in collision of data from station A and B.
Figure 6.2: MAC protocols for ad hoc network 2009/11/4 8. Contention-Based Protocols. MACA Protocol. Multiple access collision avoidance protocol. MACA-BI is a receiver-initiated MAC protocol – Reduced the number of control packets in MACA protocol (uses three-way handshake mechanism). Receiver sends ready to receive (RTR) Sender. The medium access control (MAC) layer is a part of the data link layer which plays one of the most crucial roles in the communication protocol's overall energy efficiency. 2 have done a survey on energy efficient neighbour discovery in mobile ad hoc and wireless sensor networks.
IEEE 802 is a family of Institute of Electrical and Electronics Engineers (IEEE) standards for local area networks (LAN), personal area network (PAN), and metropolitan area networks (MAN). The IEEE 802 LAN/MAN Standards Committee (LMSC) maintains these standards. The IEEE 802 family of standards has twelve members, numbered 802.1 through 802.12, with a focus group of the LMSC devoted to each.
The IEEE 802 standards are restricted to networks carrying variable-size packets, unlike cell relay networks, for example, in which data is transmitted in short, uniformly sized units called cells. Isochronous signal networks, in which data is transmitted as a steady stream of octets, or groups of octets, at regular time intervals, are also outside the scope of the IEEE 802 standards.
Torrent downloader for macbook. The feedback and comment system on KAT allows users to recommend good torrents and warn against bad ones. One of the things that makes this such a top torrent site for movies is that it has an excellent community. The website is still going and gets a surprising amount of regular visitors.
The number 802 has no significance: it was simply the next number in the sequence that the IEEE used for standards projects.[1]
The services and protocols specified in IEEE 802 map to the lower two layers (data link and physical) of the seven-layer Open Systems Interconnection (OSI) networking reference model. IEEE 802 divides the OSI data link layer into two sub-layers: logical link control (LLC) and medium access control (MAC), as follows:
- Data link layer
- LLC sublayer
- MAC sublayer
The most widely used of these standards are for the Ethernet family, token ring, wireless network protocols (including Wi-Fi), and bridging protocols.[citation needed] Jobmate manuals press drill.
Working groups[edit]
| Name | Description | Status |
|---|---|---|
| IEEE 802.1 | Higher Layer LAN Protocols Working Group | Active |
| IEEE 802.2 | LLC | Disbanded |
| IEEE 802.3 | Ethernet | Active |
| IEEE 802.4 | Token bus | Disbanded |
| IEEE 802.5 | Token ring MAC layer | Disbanded |
| IEEE 802.6 | MANs (DQDB) | Disbanded |
| IEEE 802.7 | Broadband LAN using Coaxial Cable | Disbanded |
| IEEE 802.8 | Fiber Optic TAG | Disbanded |
| IEEE 802.9 | Integrated Services LAN (ISLAN or isoEthernet) | Disbanded |
| IEEE 802.10 | Interoperable LAN Security | Disbanded |
| IEEE 802.11 | Wireless LAN (WLAN) & Mesh (Wi-Fi certification) | Active |
| IEEE 802.12 | 100BaseVG | Disbanded |
| IEEE 802.13 | Unused[2] | reserved for Fast Ethernet development[3] |
| IEEE 802.14 | Cable modems | Disbanded |
| IEEE 802.15 | Wireless PAN | Active |
| IEEE 802.15.1 | Bluetooth certification | Disbanded |
| IEEE 802.15.2 | IEEE 802.15 and IEEE 802.11 coexistence | Hibernating[4] |
| IEEE 802.15.3 | High-Rate wireless PAN (e.g., UWB, etc.) | ? |
| IEEE 802.15.4 | Low-Rate wireless PAN (e.g., ZigBee, WirelessHART, MiWi, etc.) | Active |
| IEEE 802.15.5 | Mesh networking for WPAN | ? |
| IEEE 802.15.6 | Body area network | Active |
| IEEE 802.15.7 | Visible light communications | ? |
| IEEE 802.16 | Broadband Wireless Access (WiMAX certification) | hibernating |
| IEEE 802.16.1 | Local Multipoint Distribution Service | hibernating |
| IEEE 802.16.2 | Coexistence wireless access | hibernating |
| IEEE 802.17 | Resilient packet ring | Disbanded |
| IEEE 802.18 | Radio Regulatory TAG | ? |
| IEEE 802.19 | Wireless Coexistence Working Group | ? |
| IEEE 802.20 | Mobile Broadband Wireless Access | Disbanded |
| IEEE 802.21 | Media Independent Handoff | hibernating |
| IEEE 802.22 | Wireless Regional Area Network | hibernating |
| IEEE 802.23 | Emergency Services Working Group | Disbanded |
| IEEE 802.24 | Vertical Applications TAG | ? |
See also[edit]
References[edit]
- IEEE Std 802-1990: IEEE standards for Local and Metropolitan Networks: Overview and Architecture New York:1990
- ^Institute of Electrical and Electronics Engineers (September 2004). 'Overview and Guide to the IEEE 802 LMSC'(PDF). Retrieved October 13, 2020.
- ^'802.3'. Data Communincation Standards and Protocols. EE Herald. Retrieved 2012-01-25.
- ^'The fate of 100 Mbps Ethernet now definitely two-fold'. FDDI News. Boston: Information Gatekeepers, Inc. 4 (7): 1–2. July 1993. ISSN1051-1903. Retrieved 2013-11-21.
- ^'IEEE 802.15 WPAN Task Group 2 (TG2)'. official web site. IEEE Standards Association. May 12, 2004. Retrieved June 30, 2011.
External links[edit]
- IEEE 802 Standards available via IEEE Get Program
The Data Link Layer is responsible for transmission of data between two nodes. Its main functions are-
- Data Link Control
- Multiple Access Control
Data Link control –
The data link control is responsible for reliable transmission of message over transmission channel by using techniques like framing, error control and flow control. For Data link control refer to – Stop and Wait ARQ
Multiple Access Control –
If there is a dedicated link between the sender and the receiver then data link control layer is sufficient, however if there is no dedicated link present then multiple stations can access the channel simultaneously. Hence multiple access protocols are required to decrease collision and avoid crosstalk. For example, in a classroom full of students, when a teacher asks a question and all the students (or stations) start answering simultaneously (send data at same time) then a lot of chaos is created( data overlap or data lost) then it is the job of the teacher (multiple access protocols) to manage the students and make them answer one at a time.
Thus, protocols are required for sharing data on non dedicated channels. Multiple access protocols can be subdivided further as –
Mac Protocols For Language
1. Random Access Protocol: In this, all stations have same superiority that is no station has more priority than another station. Any station can send data depending on medium's state( idle or busy). It has two features:
- There is no fixed time for sending data
- There is no fixed sequence of stations sending data
The Random access protocols are further subdivided as:
(a) ALOHA – It was designed for wireless LAN but is also applicable for shared medium. In this, multiple stations can transmit data at the same time and can hence lead to collision and data being garbled.
- Pure Aloha:
When a station sends data it waits for an acknowledgement. If the acknowledgement doesn't come within the allotted time then the station waits for a random amount of time called back-off time (Tb) and re-sends the data. Since different stations wait for different amount of time, the probability of further collision decreases. - Slotted Aloha:
It is similar to pure aloha, except that we divide time into slots and sending of data is allowed only at the beginning of these slots. If a station misses out the allowed time, it must wait for the next slot. This reduces the probability of collision.
Mechwarrior for mac. For more information on ALOHA refer – LAN Technologies
(b) CSMA – Carrier Sense Multiple Access ensures fewer collisions as the station is required to first sense the medium (for idle or busy) before transmitting data. If it is idle then it sends data, otherwise it waits till the channel becomes idle. However there is still chance of collision in CSMA due to propagation delay. For example, if station A wants to send data, it will first sense the medium.If it finds the channel idle, it will start sending data. However, by the time the first bit of data is transmitted (delayed due to propagation delay) from station A, if station B requests to send data and senses the medium it will also find it idle and will also send data. This will result in collision of data from station A and B.
CSMA access modes-
- 1-persistent: The node senses the channel, if idle it sends the data, otherwise it continuously keeps on checking the medium for being idle and transmits unconditionally(with 1 probability) as soon as the channel gets idle.
- Non-Persistent: The node senses the channel, if idle it sends the data, otherwise it checks the medium after a random amount of time (not continuously) and transmits when found idle.
- P-persistent: The node senses the medium, if idle it sends the data with p probability. If the data is not transmitted ((1-p) probability) then it waits for some time and checks the medium again, now if it is found idle then it send with p probability. This repeat continues until the frame is sent. It is used in Wifi and packet radio systems.
- O-persistent: Superiority of nodes is decided beforehand and transmission occurs in that order. If the medium is idle, node waits for its time slot to send data.
(c) CSMA/CD – Carrier sense multiple access with collision detection. Stations can terminate transmission of data if collision is detected. For more details refer – Efficiency of CSMA/CD
(d) CSMA/CA – Carrier sense multiple access with collision avoidance. The process of collisions detection involves sender receiving acknowledgement signals. If there is just one signal(its own) then the data is successfully sent but if there are two signals(its own and the one with which it has collided) then it means a collision has occurred. To distinguish between these two cases, collision must have a lot of impact on received signal. However it is not so in wired networks, so CSMA/CA is used in this case.
CSMA/CA avoids collision by:
- Interframe space – Station waits for medium to become idle and if found idle it does not immediately send data (to avoid collision due to propagation delay) rather it waits for a period of time called Interframe space or IFS. After this time it again checks the medium for being idle. The IFS duration depends on the priority of station.
- Contention Window – It is the amount of time divided into slots. If the sender is ready to send data, it chooses a random number of slots as wait time which doubles every time medium is not found idle. If the medium is found busy it does not restart the entire process, rather it restarts the timer when the channel is found idle again.
- Acknowledgement – The sender re-transmits the data if acknowledgement is not received before time-out.
Lan Protocols Vs Wan Protocols
2. Controlled Access:
In this, the data is sent by that station which is approved by all other stations. For further details refer – Controlled Access Protocols
3. Channelization:
In this, the available bandwidth of the link is shared in time, frequency and code to multiple stations to access channel simultaneously.
- Frequency Division Multiple Access (FDMA) – The available bandwidth is divided into equal bands so that each station can be allocated its own band. Guard bands are also added so that no to bands overlap to avoid crosstalk and noise.
- Time Division Multiple Access (TDMA) – In this, the bandwidth is shared between multiple stations. To avoid collision time is divided into slots and stations are allotted these slots to transmit data. However there is a overhead of synchronization as each station needs to know its time slot. This is resolved by adding synchronization bits to each slot. Another issue with TDMA is propagation delay which is resolved by addition of guard bands.
For more details refer – Circuit Switching - Code Division Multiple Access (CDMA) – One channel carries all transmissions simultaneously. There is neither division of bandwidth nor division of time. For example, if there are many people in a room all speaking at the same time, then also perfect reception of data is possible if only two person speak the same language. Similarly data from different stations can be transmitted simultaneously in different code languages.
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Lan Network Protocols
