The document discusses open loop flow and congestion control. It describes how open loop flow control works, with the source describing its traffic behavior using a descriptor during call setup. The network then verifies if it can support the requested quality of service. Common traffic descriptors like peak rate, average rate, and linear bounded arrival process are covered. The document also discusses issues like traffic burstiness, self-similar traffic, and how traffic policing and shaping are used to control traffic and enforce compliance with the descriptor.
This document summarizes the evolution of mobile networks from 2G to 4G. It describes the key technologies and capabilities of 2G (9.6 Kbps speed), 2.5G/GPRS (up to 115 Kbps), 3G (2 Mbps, increased bandwidth to 2GHz, supports video/GPS), LTE (200 active clients per 5MHz cell, up to 2Gbps speed), and 4G (formally approved in 2009 as IMT-Advanced, 2Gbps speed, improved coverage and capacity). Each generation brought increased speeds and bandwidth as well as new multimedia capabilities.
This presentation discusses about the WCDMA air Interface used in 3G i.e. UMTS. This Radio Interface has great capability on which Third Generation of Mobile Communication is built, with backward compatibility.
The document summarizes key points from an 8th lecture on wireless sensor networks. It discusses various medium access control (MAC) protocols that control when nodes can access a shared wireless medium. These include contention-based protocols like MACA that use RTS/CTS handshaking and schedule-based protocols with fixed or dynamic scheduling. It also describes energy-efficient MAC protocols for low data rate sensor networks like S-MAC, T-MAC, and preamble sampling that increase sleep time to reduce energy use through synchronized sleep schedules or long preambles.
Mobile technology has evolved from 1G analog networks to today's 4G/5G digital networks. Early radio technologies developed in the late 19th/early 20th centuries led to the first commercial cellular networks in the late 1970s/early 1980s (1G) providing analog voice calls. 2G digital networks in the 1990s like GSM and CDMA enabled more efficient use of spectrum and supported multiple users per channel. 3G networks beginning in the late 1990s provided improved data services and higher speeds like EDGE while laying the foundation for today's 4G/5G networks that provide robust broadband connectivity and multimedia services.
The document discusses different types of handoffs in cellular networks including hard and soft handoffs. Hard handoffs involve disconnecting from the current base station before connecting to the new one, while soft handoffs allow the mobile device to connect to multiple base stations simultaneously during handoff. The document also describes different handoff protocols like network-controlled, mobile-assisted, and mobile-controlled handoffs which help provide continuous service quality during the transfer between base stations. Maintaining signal strength and proper cell structure design are important strategies for effective handoff management.
1. Wireless sensor networks consist of distributed sensor nodes that communicate wirelessly to monitor physical or environmental conditions, such as temperature, sound, or pollution levels.
2. The sensor nodes gather and route data back to a central sink/gateway node where the information can be analyzed.
3. Communication protocols and algorithms are required for efficient multi-hop routing of data between sensor nodes and the sink node.
This document discusses wireless sensor network applications and energy consumption. It provides examples of WSN applications including disaster relief, environment monitoring, healthcare, and more. It then discusses various factors that influence energy consumption in sensor nodes, including operation states, microcontroller usage, radio transceivers, memory, and the relationship between computation and communication. Specific power consumption numbers are given for different components like radios, sensors, and microprocessors. The goals of optimization for WSNs are discussed as quality of service, energy efficiency, scalability, and robustness.
The document summarizes contention-based MAC protocols for wireless sensor networks. It discusses the PAMAS protocol, which provides detailed overhearing avoidance and uses two channels - a data channel and control channel. Signaling packets like RTS, CTS, and busy tones are transmitted on the control channel. It also covers concepts like low duty cycles, wake up mechanisms, and protocols like S-MAC that coordinate node schedules to reduce idle listening. Quizzes are included to test understanding of discussed concepts.
This document summarizes the evolution of mobile networks from 2G to 4G. It describes the key technologies and capabilities of 2G (9.6 Kbps speed), 2.5G/GPRS (up to 115 Kbps), 3G (2 Mbps, increased bandwidth to 2GHz, supports video/GPS), LTE (200 active clients per 5MHz cell, up to 2Gbps speed), and 4G (formally approved in 2009 as IMT-Advanced, 2Gbps speed, improved coverage and capacity). Each generation brought increased speeds and bandwidth as well as new multimedia capabilities.
This presentation discusses about the WCDMA air Interface used in 3G i.e. UMTS. This Radio Interface has great capability on which Third Generation of Mobile Communication is built, with backward compatibility.
The document summarizes key points from an 8th lecture on wireless sensor networks. It discusses various medium access control (MAC) protocols that control when nodes can access a shared wireless medium. These include contention-based protocols like MACA that use RTS/CTS handshaking and schedule-based protocols with fixed or dynamic scheduling. It also describes energy-efficient MAC protocols for low data rate sensor networks like S-MAC, T-MAC, and preamble sampling that increase sleep time to reduce energy use through synchronized sleep schedules or long preambles.
Mobile technology has evolved from 1G analog networks to today's 4G/5G digital networks. Early radio technologies developed in the late 19th/early 20th centuries led to the first commercial cellular networks in the late 1970s/early 1980s (1G) providing analog voice calls. 2G digital networks in the 1990s like GSM and CDMA enabled more efficient use of spectrum and supported multiple users per channel. 3G networks beginning in the late 1990s provided improved data services and higher speeds like EDGE while laying the foundation for today's 4G/5G networks that provide robust broadband connectivity and multimedia services.
The document discusses different types of handoffs in cellular networks including hard and soft handoffs. Hard handoffs involve disconnecting from the current base station before connecting to the new one, while soft handoffs allow the mobile device to connect to multiple base stations simultaneously during handoff. The document also describes different handoff protocols like network-controlled, mobile-assisted, and mobile-controlled handoffs which help provide continuous service quality during the transfer between base stations. Maintaining signal strength and proper cell structure design are important strategies for effective handoff management.
1. Wireless sensor networks consist of distributed sensor nodes that communicate wirelessly to monitor physical or environmental conditions, such as temperature, sound, or pollution levels.
2. The sensor nodes gather and route data back to a central sink/gateway node where the information can be analyzed.
3. Communication protocols and algorithms are required for efficient multi-hop routing of data between sensor nodes and the sink node.
This document discusses wireless sensor network applications and energy consumption. It provides examples of WSN applications including disaster relief, environment monitoring, healthcare, and more. It then discusses various factors that influence energy consumption in sensor nodes, including operation states, microcontroller usage, radio transceivers, memory, and the relationship between computation and communication. Specific power consumption numbers are given for different components like radios, sensors, and microprocessors. The goals of optimization for WSNs are discussed as quality of service, energy efficiency, scalability, and robustness.
The document summarizes contention-based MAC protocols for wireless sensor networks. It discusses the PAMAS protocol, which provides detailed overhearing avoidance and uses two channels - a data channel and control channel. Signaling packets like RTS, CTS, and busy tones are transmitted on the control channel. It also covers concepts like low duty cycles, wake up mechanisms, and protocols like S-MAC that coordinate node schedules to reduce idle listening. Quizzes are included to test understanding of discussed concepts.
Lecture 19 22. transport protocol for ad-hoc Chandra Meena
This document discusses transport layer protocols for mobile ad hoc networks (MANETs). It begins with an introduction to MANETs and the need for new network architectures and protocols to support new types of networks. It then provides an overview of TCP/IP and how TCP works, including congestion control mechanisms. The document discusses challenges for TCP over wireless networks, where packet losses are often due to errors rather than congestion. It covers different versions of TCP and their approaches to congestion control. The goal is to design transport layer protocols that can address the unreliable links and frequent topology changes in MANETs.
RF signals are electromagnetic waves that propagate through the air and other materials, exhibiting behaviors like reflection, scattering, and multipath. Key characteristics of RF signals include wavelength, frequency, amplitude, and phase. Wavelength is inversely related to frequency, while amplitude determines signal strength. Phase describes the relationship between signals of the same frequency. RF behaviors can either increase or decrease signal strength through effects like multipath, attenuation, and amplification. Understanding these RF fundamentals provides context for wireless network performance.
The document discusses handoff in cellular networks. It begins by explaining that handoff is required when a mobile moves between coverage areas of different cells during a call. The main points are:
1) The MSC must identify a new BS to handle the call and seamlessly transfer control to it, assigning the call new forward and reverse channels.
2) Important performance metrics for handoff include it being seamless to the user, minimizing unnecessary handoffs, low probability of blocking new calls in the new cell, and handing off to a channel with good signal quality.
3) Handoff involves initiation when a need is identified, reserving resources in the new cell, executing the actual handoff, and free
This document discusses wireless sensor networks and routing protocols. It covers several key topics:
1) It describes single-hop and multihop data transmission in wireless sensor networks and the advantages of multihop in increasing network lifetime and reducing interference.
2) It discusses routing challenges in wireless sensor networks due to constraints like energy, bandwidth and changing environments. It also covers routing strategies like proactive, reactive and hybrid routing.
3) It provides details on common routing protocols for wireless sensor networks like flooding, gossiping, SPIN and LEACH, outlining their key mechanisms and advantages/disadvantages. LEACH uses clustering to improve energy efficiency.
Cellular systems use multiple low-power transmitters (base stations) rather than a single, high-power transmitter to increase capacity and coverage. Frequency reuse is used to allocate channels to nearby base stations to minimize interference. Handoff strategies are employed to transfer calls between base stations as users move. Interference and power control techniques aim to equalize signal power levels and improve capacity. Traffic engineering principles including Erlang formulas are applied to determine the optimal number of channels needed based on expected call volumes.
What is GSM?
The Global System for Mobile communications is a digital cellular communications system. It was developed in order to create a common European mobile telephone standard but it has been rapidly accepted worldwide.
Formerly it was “Groupe Spéciale Mobile” (founded in 1982)
now: Global System for Mobile Communication.
Services:
Tele-services
Bearer or Data Services
Supplementary services
Applications:
Mobile telephony
GSM-R
Telemetry System
- Fleet management
- Automatic meter reading
- Toll Collection
- Remote control and fault reporting of DG sets
Value Added Services
Advantages:
Better Quality of speech
Data transmission is supported
New services offered due to ISDN compatibility
International Roaming possible
Large market
Crisper, cleaner quieter calls
disadvantages:
Dropped and missed calls
Less Efficiency
Security Issues
conclusion
The mobile telephony industry rapidly growing and that has become backbone for business success and efficiency and a part of modern lifestyles all over the world.
In this session I have tried to give and over view of the GSM system. I hope that I gave the general flavor of GSM and the philosophy behind its design.
The GSM is standard that insures interoperability without stifling competition and innovation among the suppliers to the benefit of the public both in terms of cost and service quality.
cellular concepts in wireless communicationasadkhan1327
The document discusses the concept of frequency reuse in cellular networks. It explains that a limited radio spectrum is used to serve millions of subscribers by dividing the network coverage area into cells and reusing frequencies across spatially separated cells. Each cell is allocated a portion of the total available frequencies, and neighboring cells are assigned different frequencies to minimize interference. The frequency reuse factor is defined as the ratio of the minimum distance between co-channel cells to the cell radius. Larger frequency reuse factors provide better isolation between co-channel cells but reduce network capacity. The document also covers additional topics like different channel assignment strategies, handoff methods, interference calculation and optimization of frequency reuse networks.
The document describes the architecture of GSM networks. It discusses the key components including the mobile station, base station subsystem (BSS), and network subsystem (NSS). The mobile station consists of mobile equipment and a subscriber identity module (SIM) card. The BSS comprises base transceiver stations and a base station controller. The NSS combines switches like the mobile switching center with databases like the home location register and visitor location register that track subscriber locations and identities.
There are 3 main propagation mechanisms in mobile communication systems:
1. Reflection occurs when signals bounce off surfaces like buildings and earth.
2. Diffraction is when signals bend around obstacles like hills and buildings.
3. Scattering is when signals are deflected in many directions by small obstacles like trees and signs. These 3 mechanisms impact the received power and must be considered in propagation models.
5G Interview Questions: 50 Questions on Spectrum3G4G
These slides are for information purposes only. The questions asked in this has been covered in other tutorials and opinion videos. The latest PDF version of this document can be downloaded from here: https://www.3g4g.co.uk/5G/5Gtech_Interview0001_Spectrum.pdf
All our #3G4G5G slides and videos are available at:
Videos: https://www.youtube.com/3G4G5G
Slides: https://www.slideshare.net/3G4GLtd
5G Page: https://www.3g4g.co.uk/5G/
Free Training Videos: https://www.3g4g.co.uk/Training/
1) MIMO systems use multiple antennas at both the transmitter and receiver to improve wireless communication capabilities. This allows for increased data rates and signal strength.
2) Traditional wireless systems use a single antenna at both ends (SISO) while MIMO can have multiple at both, known as MISO, SIMO, or fully multiple-input multiple-output (MIMO).
3) MIMO provides higher capacity through spatial multiplexing and increases spectrum efficiency. The Shannon capacity can increase linearly with the number of antennas or data streams.
The document discusses wireless sensor networks and their applications. It describes wireless sensor networks as consisting of individual nodes that can interact with their environment by sensing or controlling physical parameters. It then discusses several applications of wireless sensor networks, including disaster relief, environment monitoring, intelligent buildings, facility management, machine maintenance, agriculture, healthcare, and logistics. Finally, it outlines some key requirements and mechanisms needed to implement wireless sensor networks, including communication, energy efficiency, self-configuration, collaboration, data-centric operation, and exploiting tradeoffs between different needs.
CDMA Technology & IS-95
- CDMA uses spread spectrum techniques where signals are spread over a wide frequency band before transmission. IS-95 is a 2G mobile telecommunications standard that uses CDMA.
- IS-95 defines forward and reverse air interfaces with different channel structures using techniques like orthogonal codes, power control, and RAKE receivers.
- The document discusses the technical details of the IS-95 forward and reverse channel structures including the pilot, sync, paging and traffic channels.
3G cellular networks aimed to provide higher bandwidth and data rates, global roaming, and support for multimedia services. The ITU defined the IMT-2000 standard to enable these capabilities. Major 3G technologies included W-CDMA, CDMA2000, and UWC-136. Early 3G networks rolled out starting in 2001, with the Japanese and Koreans among the first to offer services meeting IMT-2000 specifications. Key technologies like higher bandwidths, packet switching, coherent modulation, smart antennas, and interference management helped 3G networks provide improved performance over 2G networks.
Mobile Originated Call Process in Simple WordsAssim Mubder
Call Setup
Different procedures are necessary depending on the initiating and terminating party:
Mobile Originating Call MOC: Call setup, which are initiated by an MS
Mobile Terminating Call MTC: Call setup, where an MS is the called party
Mobile Mobile Call MMC: Call: setup between two mobile subscribers; MMC thus consists of the execution of a MOC and a MTC one after the other.
Mobile Internal Call MIC: a special case of MMC; both MSs are in the same MSC area, possibly even in the same cell.
GPRS Architecture and its components are covered extensively.
The slides give a little information about gprs and also gets into deeper explanation of its architecture.
Directed diffusion for wireless sensor networkingHabibur Rahman
This document summarizes the key ideas of the "Directed Diffusion for Wireless Sensor Networking" paper. It introduces directed diffusion as a data-centric paradigm for wireless sensor networks that is designed for robustness, scalability, and energy efficiency. The core concepts of directed diffusion are interests, data, gradients, and reinforcement, which work together to efficiently route queries to sensor data in the network. Through localized interactions and data aggregation, directed diffusion is shown to significantly reduce energy consumption compared to flooding-based approaches in wireless sensor networks.
This document provides an introduction to the IEEE 802.11 wireless LAN standard. It outlines the standard's architecture including components like stations, basic service sets, extended service sets, and access points. It describes the medium access control sublayer which uses distributed coordination function and point coordination function to provide reliable data delivery and fair medium sharing. It also briefly discusses the physical layer and typical wireless LAN products.
Mac protocols for ad hoc wireless networks Divya Tiwari
The document discusses MAC protocols for ad hoc wireless networks. It addresses key issues in designing MAC protocols including limited bandwidth, quality of service support, synchronization, hidden and exposed terminal problems, error-prone shared channels, distributed coordination without centralized control, and node mobility. Common MAC protocol classifications and examples are also presented, such as contention-based protocols, sender-initiated versus receiver-initiated protocols, and protocols using techniques like reservation, scheduling, and directional antennas.
Michael D. Schneickert supports various philanthropic organizations including the Armory Center for the Arts in Pasadena, California. The Armory offers field trips for kindergarten through high school students to view exhibitions and develop an appreciation for art through guided activities and opportunities to create art themselves. In the first half of 2015, the Armory will offer field trips for exhibitions on mysticism and contemporary art showcasing the work of over 10 artists.
Lecture 19 22. transport protocol for ad-hoc Chandra Meena
This document discusses transport layer protocols for mobile ad hoc networks (MANETs). It begins with an introduction to MANETs and the need for new network architectures and protocols to support new types of networks. It then provides an overview of TCP/IP and how TCP works, including congestion control mechanisms. The document discusses challenges for TCP over wireless networks, where packet losses are often due to errors rather than congestion. It covers different versions of TCP and their approaches to congestion control. The goal is to design transport layer protocols that can address the unreliable links and frequent topology changes in MANETs.
RF signals are electromagnetic waves that propagate through the air and other materials, exhibiting behaviors like reflection, scattering, and multipath. Key characteristics of RF signals include wavelength, frequency, amplitude, and phase. Wavelength is inversely related to frequency, while amplitude determines signal strength. Phase describes the relationship between signals of the same frequency. RF behaviors can either increase or decrease signal strength through effects like multipath, attenuation, and amplification. Understanding these RF fundamentals provides context for wireless network performance.
The document discusses handoff in cellular networks. It begins by explaining that handoff is required when a mobile moves between coverage areas of different cells during a call. The main points are:
1) The MSC must identify a new BS to handle the call and seamlessly transfer control to it, assigning the call new forward and reverse channels.
2) Important performance metrics for handoff include it being seamless to the user, minimizing unnecessary handoffs, low probability of blocking new calls in the new cell, and handing off to a channel with good signal quality.
3) Handoff involves initiation when a need is identified, reserving resources in the new cell, executing the actual handoff, and free
This document discusses wireless sensor networks and routing protocols. It covers several key topics:
1) It describes single-hop and multihop data transmission in wireless sensor networks and the advantages of multihop in increasing network lifetime and reducing interference.
2) It discusses routing challenges in wireless sensor networks due to constraints like energy, bandwidth and changing environments. It also covers routing strategies like proactive, reactive and hybrid routing.
3) It provides details on common routing protocols for wireless sensor networks like flooding, gossiping, SPIN and LEACH, outlining their key mechanisms and advantages/disadvantages. LEACH uses clustering to improve energy efficiency.
Cellular systems use multiple low-power transmitters (base stations) rather than a single, high-power transmitter to increase capacity and coverage. Frequency reuse is used to allocate channels to nearby base stations to minimize interference. Handoff strategies are employed to transfer calls between base stations as users move. Interference and power control techniques aim to equalize signal power levels and improve capacity. Traffic engineering principles including Erlang formulas are applied to determine the optimal number of channels needed based on expected call volumes.
What is GSM?
The Global System for Mobile communications is a digital cellular communications system. It was developed in order to create a common European mobile telephone standard but it has been rapidly accepted worldwide.
Formerly it was “Groupe Spéciale Mobile” (founded in 1982)
now: Global System for Mobile Communication.
Services:
Tele-services
Bearer or Data Services
Supplementary services
Applications:
Mobile telephony
GSM-R
Telemetry System
- Fleet management
- Automatic meter reading
- Toll Collection
- Remote control and fault reporting of DG sets
Value Added Services
Advantages:
Better Quality of speech
Data transmission is supported
New services offered due to ISDN compatibility
International Roaming possible
Large market
Crisper, cleaner quieter calls
disadvantages:
Dropped and missed calls
Less Efficiency
Security Issues
conclusion
The mobile telephony industry rapidly growing and that has become backbone for business success and efficiency and a part of modern lifestyles all over the world.
In this session I have tried to give and over view of the GSM system. I hope that I gave the general flavor of GSM and the philosophy behind its design.
The GSM is standard that insures interoperability without stifling competition and innovation among the suppliers to the benefit of the public both in terms of cost and service quality.
cellular concepts in wireless communicationasadkhan1327
The document discusses the concept of frequency reuse in cellular networks. It explains that a limited radio spectrum is used to serve millions of subscribers by dividing the network coverage area into cells and reusing frequencies across spatially separated cells. Each cell is allocated a portion of the total available frequencies, and neighboring cells are assigned different frequencies to minimize interference. The frequency reuse factor is defined as the ratio of the minimum distance between co-channel cells to the cell radius. Larger frequency reuse factors provide better isolation between co-channel cells but reduce network capacity. The document also covers additional topics like different channel assignment strategies, handoff methods, interference calculation and optimization of frequency reuse networks.
The document describes the architecture of GSM networks. It discusses the key components including the mobile station, base station subsystem (BSS), and network subsystem (NSS). The mobile station consists of mobile equipment and a subscriber identity module (SIM) card. The BSS comprises base transceiver stations and a base station controller. The NSS combines switches like the mobile switching center with databases like the home location register and visitor location register that track subscriber locations and identities.
There are 3 main propagation mechanisms in mobile communication systems:
1. Reflection occurs when signals bounce off surfaces like buildings and earth.
2. Diffraction is when signals bend around obstacles like hills and buildings.
3. Scattering is when signals are deflected in many directions by small obstacles like trees and signs. These 3 mechanisms impact the received power and must be considered in propagation models.
5G Interview Questions: 50 Questions on Spectrum3G4G
These slides are for information purposes only. The questions asked in this has been covered in other tutorials and opinion videos. The latest PDF version of this document can be downloaded from here: https://www.3g4g.co.uk/5G/5Gtech_Interview0001_Spectrum.pdf
All our #3G4G5G slides and videos are available at:
Videos: https://www.youtube.com/3G4G5G
Slides: https://www.slideshare.net/3G4GLtd
5G Page: https://www.3g4g.co.uk/5G/
Free Training Videos: https://www.3g4g.co.uk/Training/
1) MIMO systems use multiple antennas at both the transmitter and receiver to improve wireless communication capabilities. This allows for increased data rates and signal strength.
2) Traditional wireless systems use a single antenna at both ends (SISO) while MIMO can have multiple at both, known as MISO, SIMO, or fully multiple-input multiple-output (MIMO).
3) MIMO provides higher capacity through spatial multiplexing and increases spectrum efficiency. The Shannon capacity can increase linearly with the number of antennas or data streams.
The document discusses wireless sensor networks and their applications. It describes wireless sensor networks as consisting of individual nodes that can interact with their environment by sensing or controlling physical parameters. It then discusses several applications of wireless sensor networks, including disaster relief, environment monitoring, intelligent buildings, facility management, machine maintenance, agriculture, healthcare, and logistics. Finally, it outlines some key requirements and mechanisms needed to implement wireless sensor networks, including communication, energy efficiency, self-configuration, collaboration, data-centric operation, and exploiting tradeoffs between different needs.
CDMA Technology & IS-95
- CDMA uses spread spectrum techniques where signals are spread over a wide frequency band before transmission. IS-95 is a 2G mobile telecommunications standard that uses CDMA.
- IS-95 defines forward and reverse air interfaces with different channel structures using techniques like orthogonal codes, power control, and RAKE receivers.
- The document discusses the technical details of the IS-95 forward and reverse channel structures including the pilot, sync, paging and traffic channels.
3G cellular networks aimed to provide higher bandwidth and data rates, global roaming, and support for multimedia services. The ITU defined the IMT-2000 standard to enable these capabilities. Major 3G technologies included W-CDMA, CDMA2000, and UWC-136. Early 3G networks rolled out starting in 2001, with the Japanese and Koreans among the first to offer services meeting IMT-2000 specifications. Key technologies like higher bandwidths, packet switching, coherent modulation, smart antennas, and interference management helped 3G networks provide improved performance over 2G networks.
Mobile Originated Call Process in Simple WordsAssim Mubder
Call Setup
Different procedures are necessary depending on the initiating and terminating party:
Mobile Originating Call MOC: Call setup, which are initiated by an MS
Mobile Terminating Call MTC: Call setup, where an MS is the called party
Mobile Mobile Call MMC: Call: setup between two mobile subscribers; MMC thus consists of the execution of a MOC and a MTC one after the other.
Mobile Internal Call MIC: a special case of MMC; both MSs are in the same MSC area, possibly even in the same cell.
GPRS Architecture and its components are covered extensively.
The slides give a little information about gprs and also gets into deeper explanation of its architecture.
Directed diffusion for wireless sensor networkingHabibur Rahman
This document summarizes the key ideas of the "Directed Diffusion for Wireless Sensor Networking" paper. It introduces directed diffusion as a data-centric paradigm for wireless sensor networks that is designed for robustness, scalability, and energy efficiency. The core concepts of directed diffusion are interests, data, gradients, and reinforcement, which work together to efficiently route queries to sensor data in the network. Through localized interactions and data aggregation, directed diffusion is shown to significantly reduce energy consumption compared to flooding-based approaches in wireless sensor networks.
This document provides an introduction to the IEEE 802.11 wireless LAN standard. It outlines the standard's architecture including components like stations, basic service sets, extended service sets, and access points. It describes the medium access control sublayer which uses distributed coordination function and point coordination function to provide reliable data delivery and fair medium sharing. It also briefly discusses the physical layer and typical wireless LAN products.
Mac protocols for ad hoc wireless networks Divya Tiwari
The document discusses MAC protocols for ad hoc wireless networks. It addresses key issues in designing MAC protocols including limited bandwidth, quality of service support, synchronization, hidden and exposed terminal problems, error-prone shared channels, distributed coordination without centralized control, and node mobility. Common MAC protocol classifications and examples are also presented, such as contention-based protocols, sender-initiated versus receiver-initiated protocols, and protocols using techniques like reservation, scheduling, and directional antennas.
Michael D. Schneickert supports various philanthropic organizations including the Armory Center for the Arts in Pasadena, California. The Armory offers field trips for kindergarten through high school students to view exhibitions and develop an appreciation for art through guided activities and opportunities to create art themselves. In the first half of 2015, the Armory will offer field trips for exhibitions on mysticism and contemporary art showcasing the work of over 10 artists.
ΤΣΙΚΝΟΠΕΜΠΤΗ 2015 στο ΕΠΑΛ ΣΙΔΗΡΟΚΑΣΤΡΟΥd tampouris
Ευθυμία, χαρά και με πολλά χαμόγελα πραγματοποιήθηκε από τους μαθητές του ΕΠΑΛ Σιδηροκάστρου, ένα μικρό γλέντι για να τιμήσουν την ημέρα της Τσικνοπέμπτης. Η τσίκνα ήταν απαραίτητη καθώς και η ευρηματικότητα των μαθητών στις μεταμφιέσεις τους.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise causes chemical changes in the brain that may help boost feelings of calmness, happiness and focus.
"Liberate your voice, be a legend", a very unique and empowering programme designed specially for singers to unlock the real essence and true potential.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
The document describes an experiment to determine if larger magnets have stronger magnetic force than smaller magnets. Various sized magnets were positioned at increasing distances above paper clips. The number of paper clips attracted to each magnet was recorded. At 1 inch, the large magnet attracted the most paper clips and the extra small magnet the least. This trend continued at 2 inches, although fewer clips were attracted. At 3 inches, only the large magnet attracted clips. It was concluded that big magnets have stronger magnetic force than smaller magnets.
The document describes a mobile application called "Great" that allows users to rate various places, items, dishes, etc. on a scale of 1 to 5. It differentiates itself from other rating apps by having an easy-to-use mobile interface, leveraging social media followings to influence ratings, and allowing users to "tag" items with hashtags. The app aims to grow an active user base initially and then plans to monetize through sponsored search results and custom business pages with additional information and the ability to follow updates.
The system was tested with identical twins, registering one but not the other; only the registered twin could enter the facility with biometric verification, showing the system could distinguish between the twins. Contact the sales team at 67377 268 for more details on the biometric verification system.
Sacha Elizabeth Cato was born in London in 1985 to parents who immigrated from Grenada. She attended primary and secondary school in London where she engaged in various activities like ballet, piano, gymnastics, and football. She went on to study Business Studies, Information Technology, and Media Studies at A Levels and a degree in Accounting Management and Information Systems at the University of Hertfordshire. After graduating, she gained work experience in project management and finance roles, and now works as a Reporting Financial Analyst for a major PR agency. In her personal life, she enjoys traveling, spending time with family in the Caribbean, and has diverse interests in music, films, and television shows.
Van inzicht in medewerker betrokkenheid tot positieve peer-to-peer feedback. 2daysmood Pulse Features zorgt ervoor dat je altijd waardevolle informatie genereert over de onderwerpen die in focus zijn. Het Administrator Panel biedt een selectie van interessante features die op elk moment ingezet kunnen worden. Daarnaast worden continue nieuwe features ontwikkeld en aangeboden via het Administrator Panel.
This document outlines a Christmas lead time project for a limited edition sweatshirt collaboration between French retailer Colette and electronic music duo Daft Punk. The sweatshirt would feature silver and gold laminated prints referencing Daft Punk's signature aesthetic and 2013 album release. A proposed production timeline is provided, with an order deadline of November 8th and deliveries to Colette in Paris by December 11th to be available for the Christmas season.
This very short document contains a single word "CARTOONS!!!!" expressing excitement about cartoons, followed by a statement hoping that the reader likes cartoons. No other information is provided in the document.
The :Jeti Titan challenges perceptions of what a printer can do for your business,
delivering high resolution quality, high production speeds and uniquely the ability
to increase the speed and capabilities of your Titan as your business grows. The
:Jeti Titan introduces a host of new advanced features, without compromising its
true fl atbed capabilities and delivering an unbeatable return on your investment.
This document describes a pedagogical experiment conducted with undergraduate medical students at Universidade Federal do Estado do Rio de Janeiro (UNIRIO) in Brazil. The experiment uses problem-based learning to have students research and present case reports on metabolic diseases using real patient medical records. The goals are to stimulate students' interest in cell biology, biochemistry, and research skills while connecting these basic science subjects to clinical practice. Results found increased classroom participation and more students volunteering to participate, indicating this approach improved student engagement with the course material. The conclusion is that case reports enrich learning by transforming the teacher-centered method into collaborative student-teacher learning.
The :Jeti 5024 with 24 Spectra print heads is unquestionably
the fastest 5.1 m (16’6”) grand-format printer on the market
today. True 600 dpi (1200 apparent) and 6 colors graphics on the
:Jeti 5024 puts it in a class of its own, producing quality that
competes with conventional large format inkjet printers at far
lesser cost.
This document discusses several economic concepts including finance, economics, factors that influence prices of petrol, gold and vegetables, fluctuations in currency exchange rates, career prospects in economics, reasons to understand economic principles, and different states of an economy such as recession, depression and slowdowns. It also asks how one would like their money to appear visually.
APNIC Chief Scientist Geoff Huston gives a presentation on Buffers, Buffer Bloat and BBR at NZNOG 2020 in Christchurch, New Zealand, from 28 to 31 January 2020.
Congestion control and quality of service focus on managing data traffic by avoiding congestion and ensuring appropriate network conditions. Traffic is characterized by descriptors like data rate and burst size. Congestion occurs when network load exceeds capacity and is controlled using open-loop prevention or closed-loop removal techniques. Quality of service provides classifications, scheduling, and resource reservation to meet flow requirements for reliability, delay, bandwidth and more. Integrated and differentiated services are QoS frameworks for IP that use signaling, admission control, and per-hop behaviors.
This document discusses computer networks and congestion control techniques. It provides information on routing algorithms, causes of congestion, effects of congestion, and open-loop and closed-loop congestion control methods. Specifically, it describes the leaky bucket algorithm and token bucket algorithm for traffic shaping, and how they regulate data flow rates to prevent network congestion.
This document discusses TCP and a new flow control algorithm called BBR. It provides background on TCP and how its sending rate is controlled via ACK pacing. While TCP rates increased from kilobits to gigabits per second over time, it is not keeping up with optical transmission speeds approaching terabits. BBR aims to be more efficient than TCP by probing the network to detect the onset of queueing rather than relying on packet loss. Testing shows BBR can crowd out other flows and operate inefficiently against itself. While promising for high speeds, BBR may not scale well if widely adopted and requires further research to improve fairness against other flows.
This document discusses approaches for providing quality of service (QoS) on the Internet. It describes two main service types: Integrated Services (IntServ) which uses resource reservation on a per-flow basis, and Differentiated Services (DiffServ) which prioritizes aggregates of traffic based on packet markings. While IntServ allows for strict QoS guarantees through signaling and per-flow state, it does not scale well. DiffServ aims to provide QoS for traffic classes through simple packet classification and queuing at network edges and core routers, avoiding per-flow state for better scalability. The document also covers challenges with end-to-end QoS and outlines components needed for a DiffServ architecture.
This document discusses quality of service (QoS) networking. It will cover topics like queue management, traffic shaping, admission control, routing protocols, Integrated Services, Differentiated Services, MPLS, and traffic engineering. The course will include proposals, paper presentations, quizzes, and participation. QoS aims to provide predictable network performance by prioritizing some types of traffic over others. It allows resources to be allocated to high priority services at the expense of lower priority traffic. The document discusses challenges in providing these guarantees and techniques like resource reservation, traffic contracts, scheduling algorithms, and statistical approaches.
What is Quality of Service?
-Basic mechanisms
-Leaky and token buckets
-Integrated Services (IntServ)
-Differentiated Services (DiffServ)
-Economics and Social factors facing QoS
-QoS Vs. Over Provisioning
The document discusses congestion control in computer networks. It defines congestion as occurring when the load on a network is greater than the network's capacity. Congestion control aims to control congestion and keep the load below capacity. The document separates congestion control mechanisms into two categories: open-loop control, which aims to prevent congestion; and closed-loop control, which detects congestion and takes corrective actions through feedback. Specific open-loop techniques discussed are admission control, traffic shaping using leaky bucket and token bucket algorithms, and traffic scheduling.
The document discusses congestion control in computer networks. It defines congestion as occurring when the load on a network is greater than the network's capacity. Congestion control aims to control congestion and keep the load below capacity. The document outlines two categories of congestion control: open-loop control, which aims to prevent congestion; and closed-loop control, which detects congestion and takes corrective action using feedback from the network. Specific open-loop techniques discussed include admission control, traffic shaping using leaky bucket and token bucket algorithms, and traffic scheduling.
The document discusses various congestion control algorithms and quality of service techniques used in computer networks. It describes approaches like traffic-aware routing, admission control, traffic throttling, and load shedding to control congestion. It also explains how quality of service is achieved through integrated services, differentiated services, and techniques like traffic shaping, packet scheduling, buffering, and jitter control.
This document discusses switching, routing, and flow control in interconnection networks. It covers different switching mechanisms like packet switching and circuit switching. It also discusses routing algorithms and techniques to avoid deadlocks like virtual channels and deadlock-free routing. The key topics are how packets are routed through switches, challenges like tree saturation and deadlocks, and approaches to provide reliable communication while matching the capabilities of the network hardware.
This paper proposes Core-Stateless Fair Queueing (CSFQ), a scheme that achieves approximately fair bandwidth allocation across high-speed networks without per-flow state in core routers. CSFQ decomposes routers into edge and core roles, with edge routers maintaining per-flow state to estimate rates and label packets, while core routers use these labels and estimated fair rates to probabilistically drop packets. Evaluation shows CSFQ provides fairness comparable to other schemes like FRED while significantly reducing complexity for core routers.
1. The document discusses quality of service (QoS) mechanisms in computer networks. It covers topics like best effort vs. QoS service, resource reservation using leaky and token buckets, Integrated Services (IntServ) and Differentiated Services (DiffServ) architectures, and economics of QoS.
2. It provides details on basic QoS mechanisms like leaky and token buckets that are used to police resource reservations. It also describes the IntServ and RSVP signaling protocol that is used for per-flow reservation in the IntServ architecture.
3. The document outlines different reservation styles in RSVP like fixed, shared explicit, and wildcard filters that determine how reservations can be shared among multiple
1. The document discusses quality of service (QoS) mechanisms in computer networks. It describes the differences between best effort service and QoS, which aims to provide guarantees for bandwidth, latency, and jitter.
2. The document outlines two main QoS architectures - Integrated Services (IntServ) which provides per-flow reservations and Differentiated Services (DiffServ) which uses traffic classes. It also discusses resource reservation using leaky and token bucket algorithms.
3. RSVP is described as the signaling protocol used to establish per-flow state through PATH and RESV messages. It supports different reservation styles like fixed, shared explicit, and wildcard filters to efficiently share resources among senders.
1. The document discusses quality of service (QoS) mechanisms in computer networks. It describes the differences between best effort and QoS networks and outlines two styles of QoS - worst-case and average-case.
2. It then covers basic QoS mechanisms like leaky buckets and token buckets that are used to police traffic entering the network. Integrated Services (IntServ) and Differentiated Services (DiffServ) models for providing QoS are also introduced.
3. Resource reservation protocols like RSVP are explained, including how they set up reservation state along network paths using PATH and RESV messages to signal bandwidth requirements from end hosts to routers.
1. The document discusses quality of service (QoS) mechanisms in computer networks, including leaky and token buckets used to police traffic and provide bandwidth guarantees.
2. It describes Integrated Services (IntServ) and Differentiated Services (DiffServ) approaches to implementing QoS.
3. Key aspects of QoS covered include resource reservation, admission control, scheduling, and the use of RSVP signaling to set up reservations along network paths.
Data link control involves framing data, flow and error control, and common protocols like HDLC and PPP. Framing involves adding source/destination addresses to frames for transmission. Flow control restricts how much data the sender sends before waiting for acknowledgment. Error control uses techniques like automatic repeat request to retransmit lost data frames. HDLC and PPP are protocols that define frame formats and control procedures for point-to-point links.
Contents:
Data Traffic
Congestion
Congestion Control
Quality of Service
Techniques to improve QOS
How QOS is implemented within the Internet
References..
1. Open Loop Flow and
Congestion Control
TELCOM2321 – CS2520
Wide Area Networks
Dr. Walter Cerroni
University of Bologna – Italy
Visiting Assistant Professor at SIS, Telecom Program
Slides based on Dr. Znati’s material
2. Reading
1. About self-similar traffic:
Textbook, Chap. 9, Sections 9.1, 9.3, 9.4
and subsection of 9.2 on heavy-tailed
distributions
2
3. Flow and congestion control implementation
• Provided at different layers
• Data Link Layer Flow and Error Control
– Stop-And-Wait ARQ
– Continuous ARQ
• End-to-End Flow and Congestion Control
– Closed Loop
– Open Loop
3
4. Open Loop Flow Control
1. During call setup, the source describes its behavior
using a traffic descriptor
– bandwidth and buffer requirements
– QoS requirements, in terms of delay, jitter and loss
2. Network nodes, along the path, verify the feasibility of
supporting QoS requirements
– renegotiation of parameters, if call not acceptable, with
potential rejection
– reservation of resources in case of acceptance
3. During data transfer, the source shapes its traffic to
match descriptor
4. Network nodes schedule traffic from admitted calls
– to meet bandwidth, buffer and QoS requirements
– verifying actual compliance with traffic descriptor
4
5. Open Loop Flow Control: Design Issues
• Traffic descriptor
– universal descriptor for different types of applications is not likely
• Call admission control scheme
– QoS guarantees of newly accepted connections should not affect
currently supported connections
• too conservative schemes, based on worst case scenario, are
resource wasteful
• too optimistic schemes may fail to meet QoS guarantees
– traffic must be controlled
– specific scheduling discipline at intermediate nodes is required
• tradeoff between efficiency, simplicity and capability of supporting
delay bounds
5
6. Traffic Descriptor
• It provides behavioral information
– it usually describes the worst case behavior rather
than the exact behavior
• It represents the basis of a traffic contract
– source agrees not to violate traffic descriptor
– network guarantees the negotiated level of QoS
• A traffic policing mechanism is used to verify that
the source adheres to its traffic specification
6
7. Traffic Descriptor Properties
• Usability
– source must be able to describe its traffic easily
– network must be able to perform admissibility test easily
• Verifiability
– policing mechanism must be able to verify the source compliance
with its traffic descriptor
• Preservability
– network nodes must be able to preserve the traffic characteristics
along the path, if necessary
• Three traffic descriptors are commonly used
– Peak Rate
– Average Rate
– Linear Bounded Arrival Process (LBAP)
7
8. Traffic Descriptor: Peak Rate
• Highest rate allowed of traffic generation
– network with fixed size packets
• peak rate measured in pps or bps
• peak rate in pps is the inverse of the closest spacing between the
starting times of consecutive packets
– network with variable size packets
• peak rate measured in bps
• it defines an upper bound on the total number of packets generated
over all window intervals of a specified size
• Descriptor easy to compute an police
• It is a loose boundary measure
• Highly affected by large deviations from average
• Useful for sources with smooth traffic only
8
9. Traffic Descriptor: Average Rate
• Objective is to reduce the effect of outliers
• Transmission rate is averaged over a specified
period of time
• Two parameters are defined
– t = time window over which rate is measured
– N = number of bits/packets to be sent over t
• Two mechanisms are used to compute the
average rate
– jumping window
– moving window
9
10. Traffic Descriptor: Average Rate
• Jumping Window
– source claims that no more than N bits/packets will be
transmitted to the network over t
– a new time window starts immediately after the last
one
– jumping window is sensitive to the starting time of the
first window
• Moving Window
– source claims that no more than N bits/packets will be
submitted to the network over all windows of size t
– time window moves continuously
– enforces tighter bounds on spikes in the input traffic
10
11. Traffic Descriptor: LBAP
• Linear Bounded Arrival Process
• Source bounds the number N of bits/packets it
transmits in any interval of length t by a linear
function of t
N≤ρt+σ
– ρ is the long term average rate allocated by the
network
– σ is the longest burst a source is allowed to sent
– source has an intrinsic long-term average rate ρ, but
can sometimes deviate from this rate, as specified by
σ
11
12. Traffic Descriptor and Burstiness
• One of the main causes of the congestion is that
traffic is often bursty
• Traffic descriptor must be chosen based on
source behavior
– peak rate is enough for CBR traffic
– average rate is enough for VBR traffic with relatively
limited rate variability
– LBAP is better if VBR traffic has higher variability
• Data bursts should be controlled to comply with
descriptor
• But what exactly is traffic burstiness
12
13. Traffic Burstiness
• Takes into account the variability of source rate
• No universal definition
– Peak rate / Average rate
– Average source rate / Average rate of reference source
– ...
• Poisson arrivals are “less regular” than CBR
• M/D/1 input traffic is smoother that M/M/1
• Markov-Modulated Poisson Process (MMPP) is
bursty compared to a simple Poisson source
• Real-life traffic traces show even higher burstiness
– self-similar behavior
13
14. Self-Similar Traffic
W.E. Leland et al., On the Self-similar Nature of Ethernet Traffic (Extended Version),
IEEE/ACM Transactions On Networking, Vol. 2, No. 1, February 1994.
14
15. Self-Similar Traffic
• Different kinds of network traffic show self-similar
behavior
– Ethernet, WWW, ...
• High variability leads to strong autocorrelation
also for large time scales
– Long-Range Dependence
• Modeling with Heavy-Tailed Distributions
– ex. superposition of many Pareto-distributed ON/OFF
sources with 1 < α < 2
– Pareto distribution with parameters
15
16. Heavy-Tailed Distributions
α>2 finite mean, finite variance
1<α≤2 finite mean, infinite variance
0<α≤1 infinite mean, infinite variance
Probability density function
16
17. Effect on queue size
H: Hurst parameter
Self-similarity when
0.5 < H < 1
17
18. Traffic Policing
• Source behavior must comply with traffic descriptor
• Traffic policing is performed at network edges to detect
violations to contract
• Packets conforming to agreed bounds are forwarded to
the network
– required resources are guaranteed
• Packets exceeding the agreed bounds can be
– dropped at edge
– marked as non-conforming packets and forwarded to the network
• resources are not guaranteed
• dropped at any point in case of congestion
18
19. Traffic Shaping
• In order to comply with descriptor, source traffic could be
shaped to a predictable pattern
– smoothing burstiness out
– applied at source or network edges
• Exceeding packets are delayed
– sent later when they eventually conform to descriptor
– buffer required
• buffer limit may cause loss/marking
– latency introduced
• Traffic policing must still be enforced if shaping is left to
the source
19
20. Traffic Policing vs. Traffic Shaping
Example based on peak rate
policing
Rate
Peak rate Time
Rate
Rate
Time
shaping
Time 20
21. Traffic Shaping: Leaky Bucket
• Purpose is to shape bursty traffic into a data
regular stream of packets
– flow is characterized by a rate ρ
– bucket is characterized by a size β
• Packets are drained out at rate ρ by a
regulator at the bottom of the bucket β
• When bucket is full, incoming packets are
discarded or marked
• The effect of β is to
– limit the maximum bucket size
– bound the amount of delay a packet can incur
• Given β loss/marking rate vs. ρ tradeoff ρ
• β = 0 for peak rate policing
21
22. Traffic Shaping: Leaky Bucket
• Traffic shaping using leaky bucket generates
fixed-rate data flows
– QoS requirements easily guaranteed
• Suitable for smoothing small rate variations
– depending on β
• Highly variable rate sources must choose rate ρ
very close to their peak rate
– wasteful solution
– bursts are not permitted
– a shaper allowing limited rate variation at the output
would be better
22
23. Traffic Shaping: Token Bucket
• Bucket collects tokens
• Tokens are generated at rate ρ
– discarded when bucket is full
ρ tokens
• Each packet requires a token to be sent
σ
• A burst lesser than or equal to the number of
tokens available can be transmitted (up to σ)
data
β
• When bucket is empty, packets are buffered
and sent at rate ρ
23
24. Traffic Shaping: Token Bucket
• Number of packets sent in interval of length t
N≤ρt+σ LBAP regulator
• β = 0 for LBAP policing
• Given β and the maximum loss/marking rate allowed, the
minimal LBAP descriptor is not unique
– ρ and σ must be chosen
– average rate A ≥ ρ buffer grows without bound avoiding
packet losses would require σ to be infinite
– peak rate P ≤ ρ there are always tokens available σ can
be small at will
– as ρ increases in the range [ A, P ], the minimum σ needed to
meet the loss bounds decreases
– any ρ and its corresponding σ is a minimal LDAP descriptor
24