WIRELESS NETWORKS _ BABU M_ unit 3 ,4 & 5 PPT
EC 6802 WIRELESS NETWORKS PPT
POWER POINT PRESENTAION ON WIRELESS NETWORKS
BABU M
ASST PROFESSOR/ ELECTRONICS AND COMMUNICATION ENGINEERING,
RMK COLLEGE OF ENGINEERING AND TECHNOLOGY
CHENNAI, THIRUVALLUR DISTRICT
Mobile Transport Layer protocols aim to address challenges with TCP over mobile networks. Traditional TCP uses congestion control like slow start and fast retransmit/recovery that can reduce performance over mobile. Indirect TCP splits the connection at the access point to avoid wireless errors affecting the wired segment. Snooping TCP buffers packets at the access point and performs local retransmissions on errors. Mobile TCP splits the connection and uses an optimized TCP between the supervisory host and mobile host, choking the sender when the mobile is disconnected to avoid buffering large amounts of undelivered data.
This document summarizes the Bluetooth protocol stack. It discusses the baseband protocols, link manager protocol, L2CAP, service discovery protocol, and various adopted protocols like RFCOMM, TCS, PPP, TCP/IP, WAP, and OBEX. The baseband and link control layer control the physical RF link and links can be either SCO or ACL. The link manager protocol handles link setup and power modes. L2CAP provides multiplexing and segmentation. Service discovery allows finding and searching for Bluetooth services. RFCOMM provides emulation and transport capabilities for cables replacement. TCS deals with telephony control and configurations. Adopted protocols allow communication with other Bluetooth devices and bringing internet to phones.
This document discusses multiplexing techniques used in mobile computing. It describes four types of multiplexing: frequency division multiplexing (FDM), time division multiplexing (TDM), code division multiplexing (CDM), and space division multiplexing (SDM). For each type, it provides details on how the technique works and its advantages and disadvantages. FDM uses different frequencies to transmit multiple signals simultaneously. TDM divides a signal into time slots to share a frequency. CDM assigns unique codes to signals sharing the same frequency. SDM splits a channel across physical locations.
The document discusses wireless local area networks (WLANs). It describes what a WLAN is and how to develop one. Key points include:
- A WLAN extends a wired LAN using radio frequency technology, allowing user mobility without wires.
- Developing a WLAN involves considering pros/cons, configurations, costs, standards, security, and specifications.
- Building a WLAN requires wireless LAN cards, access points, bridges/antennas, and following IEEE standards like 802.11b for speeds up to 11 Mbps and distances up to 1,000 feet.
This document discusses different types of networking devices used to connect local area networks (LANs). It describes hubs, repeaters, bridges, routers, and gateways. Hubs and repeaters operate at the physical layer, bridges operate at the physical and data link layers, and routers and gateways operate at the network layer and above to connect multiple networks and perform protocol conversion. The document provides details on the functions and characteristics of each type of device.
The document discusses various IEEE 802 standards for networking technologies including Ethernet, wireless LAN (802.11), and their variants and evolutions over time. It provides details on Ethernet standards and implementations such as 802.3, 10BASE5, 10BASE2, 10BASE-T, 10BASE-F, Fast Ethernet, and Gigabit Ethernet. It also summarizes key aspects of wireless networking standards such as 802.11 components, frame format, and physical layer specifications including FHSS, DSSS, OFDM, and associated data rates and frequencies.
The document discusses Ethernet networking technologies. It describes how Ethernet was developed in the 1970s and standardized. It outlines the evolution of Ethernet speeds from 2Mbps to 1Gbps. It discusses the physical layer standards for 10BaseT, 100BaseT, 1000BaseT, and 10GBase networking. It also provides an overview of Token Ring and FDDI technologies, including their operation, standards, and key features.
IP specifies the format of packets, also called #datagrams, and the addressing scheme. Most networks combine IP with a higher-level protocol called Transmission Control Protocol (TCP), which establishes a virtual connection between a destination and a source.
If you want to purchase the content e-mail me on dulith1989@gmail.com
Mobile Transport Layer protocols aim to address challenges with TCP over mobile networks. Traditional TCP uses congestion control like slow start and fast retransmit/recovery that can reduce performance over mobile. Indirect TCP splits the connection at the access point to avoid wireless errors affecting the wired segment. Snooping TCP buffers packets at the access point and performs local retransmissions on errors. Mobile TCP splits the connection and uses an optimized TCP between the supervisory host and mobile host, choking the sender when the mobile is disconnected to avoid buffering large amounts of undelivered data.
This document summarizes the Bluetooth protocol stack. It discusses the baseband protocols, link manager protocol, L2CAP, service discovery protocol, and various adopted protocols like RFCOMM, TCS, PPP, TCP/IP, WAP, and OBEX. The baseband and link control layer control the physical RF link and links can be either SCO or ACL. The link manager protocol handles link setup and power modes. L2CAP provides multiplexing and segmentation. Service discovery allows finding and searching for Bluetooth services. RFCOMM provides emulation and transport capabilities for cables replacement. TCS deals with telephony control and configurations. Adopted protocols allow communication with other Bluetooth devices and bringing internet to phones.
This document discusses multiplexing techniques used in mobile computing. It describes four types of multiplexing: frequency division multiplexing (FDM), time division multiplexing (TDM), code division multiplexing (CDM), and space division multiplexing (SDM). For each type, it provides details on how the technique works and its advantages and disadvantages. FDM uses different frequencies to transmit multiple signals simultaneously. TDM divides a signal into time slots to share a frequency. CDM assigns unique codes to signals sharing the same frequency. SDM splits a channel across physical locations.
The document discusses wireless local area networks (WLANs). It describes what a WLAN is and how to develop one. Key points include:
- A WLAN extends a wired LAN using radio frequency technology, allowing user mobility without wires.
- Developing a WLAN involves considering pros/cons, configurations, costs, standards, security, and specifications.
- Building a WLAN requires wireless LAN cards, access points, bridges/antennas, and following IEEE standards like 802.11b for speeds up to 11 Mbps and distances up to 1,000 feet.
This document discusses different types of networking devices used to connect local area networks (LANs). It describes hubs, repeaters, bridges, routers, and gateways. Hubs and repeaters operate at the physical layer, bridges operate at the physical and data link layers, and routers and gateways operate at the network layer and above to connect multiple networks and perform protocol conversion. The document provides details on the functions and characteristics of each type of device.
The document discusses various IEEE 802 standards for networking technologies including Ethernet, wireless LAN (802.11), and their variants and evolutions over time. It provides details on Ethernet standards and implementations such as 802.3, 10BASE5, 10BASE2, 10BASE-T, 10BASE-F, Fast Ethernet, and Gigabit Ethernet. It also summarizes key aspects of wireless networking standards such as 802.11 components, frame format, and physical layer specifications including FHSS, DSSS, OFDM, and associated data rates and frequencies.
The document discusses Ethernet networking technologies. It describes how Ethernet was developed in the 1970s and standardized. It outlines the evolution of Ethernet speeds from 2Mbps to 1Gbps. It discusses the physical layer standards for 10BaseT, 100BaseT, 1000BaseT, and 10GBase networking. It also provides an overview of Token Ring and FDDI technologies, including their operation, standards, and key features.
IP specifies the format of packets, also called #datagrams, and the addressing scheme. Most networks combine IP with a higher-level protocol called Transmission Control Protocol (TCP), which establishes a virtual connection between a destination and a source.
If you want to purchase the content e-mail me on dulith1989@gmail.com
This document discusses agent discovery and registration in mobile IP networks. It describes how mobile nodes use agent advertisements and solicitations to determine their network attachment and discover available foreign agents. It also explains the registration process, where a mobile node informs its home agent and foreign agent of its current location to setup packet forwarding. Key aspects covered are how registrations establish care-of addresses, are authenticated, and must be periodically renewed to remain valid.
The document summarizes key aspects of wireless local area networks (WLANs) and the IEEE 802.11 standard. It describes the characteristics and design goals of WLANs. It provides an overview of the IEEE 802.11 standard including the physical layer specifications, MAC layer functions and frame formats, and access methods like CSMA/CA. It also discusses wireless network architectures including infrastructure and ad-hoc networks, and comparisons of different wireless transmission technologies.
Routers and switches are networking devices that connect computers and networks, but they operate at different layers and have different functions. Routers operate at the network layer (layer 3) and use IP addresses to direct traffic between networks, while switches operate at the data link layer (layer 2) and use MAC addresses to direct traffic within a local area network. Some key differences are that routers can perform tasks like network address translation, have fewer ports, and take longer for routing decisions than switches.
The document discusses the differences between packets and frames, and provides details on the transport layer. It explains that the transport layer is responsible for process-to-process delivery and uses port numbers for addressing. Connection-oriented protocols like TCP use three-way handshaking for connection establishment and termination, and implement flow and error control using mechanisms like sliding windows. Connectionless protocols like UDP are simpler but unreliable, treating each packet independently.
BGP is the exterior gateway protocol that connects different autonomous systems on the internet. It allows for the exchange of routing and reachability information between these systems. BGP operates using a finite state machine to manage the states of connections between peers. It establishes TCP connections between routers to exchange routing updates and keep connections alive through regular keepalive messages. BGP version 4, defined in RFC 4271, is the current standard implementation which supports features like classless inter-domain routing and route aggregation.
This document provides an overview of wireless networks and the IEEE 802.11 standards. It discusses wireless LAN technologies including IEEE 802.11, HiperLAN, Bluetooth, and various amendments. It describes the infrastructure and ad-hoc modes of wireless LANs. It also summarizes key standards such as 802.11a, 802.11b, their architectures, protocols, and parameters. Finally, it provides details on the HiperLAN standard developed by ETSI for wireless local area networks in Europe.
The document provides an overview of basic networking concepts including computer networks, local area networks (LANs), wide area networks (WANs), common LAN topologies, LAN transmission methods, LAN infrastructure devices, common network cabling, Ethernet, and network models like OSI and TCP/IP. It describes key aspects of each layer in the OSI model from application to network layer.
Packet radio protocols allow multiple subscribers to access a shared channel for transmitting data packets. They use contention-based random access techniques like ALOHA. Pure ALOHA protocol has low efficiency due to partial packet collisions. Slotted ALOHA synchronizes transmissions to time slots to prevent partial collisions, improving efficiency. Performance is evaluated using metrics like throughput, which is highest at optimal channel load and drops off above and below this point.
Topics covered in this presentation:
1. RF spectrum and GSM specifications
2. FDMA and TDMA
3. Digital Voice Transmission
4. Channel coding, Interleaving and Burst formatting
5. GMSK
6. Frame structure of GSM
7. Corrective actions against multipath fading
This document discusses radio channels and interfaces in GSM networks. It covers topics like:
- The Um interface between the mobile station and base station subsystem.
- Processing of the voice signal from analog to digital conversion through encoding, interleaving and modulation for transmission.
- The different types of radio channels used including traffic channels, control channels, and their logical and physical combinations in bursts and frames.
- Technologies used for efficient transmission like frequency hopping, discontinuous transmission, and power control.
Wireless communication and its standardsM.k. Praveen
The document discusses wireless communication standards and cellular technology. It provides an agenda covering topics like wireless communication, cellular technology, standards evolution, modulation and multiplexing techniques, and cellular standards like GSM and CDMA. It also discusses frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and the differences between the 900MHz and 1800MHz frequency bands used in cellular networks.
The document discusses various topics related to wireless communication channels and networks. It provides details on wireline channels, fading effects, bit error rates for different mediums. It also summarizes key aspects of cellular systems, challenges in wireless communications, deployment of different generations of wireless networks, and traffic routing in wireless networks. The document is written by A.Sanyasi Rao and contains technical details on wireless communication concepts.
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.
Transmission media (data communication)Pritom Chaki
Transmission media is the material pathway that connects computers, different kinds of devices and people on a network. It can be compared to a superhighway carrying lots of information. Transmission media uses cables or electromagnetic signals to transmit data.
A wireless local area network (WLAN) uses radio frequency technology to transmit and receive data over the air, providing mobility and flexibility as an extension or alternative to wired networks. Key advantages of WLANs include productivity, convenience, lower installation costs and mobility. However, WLANs also have disadvantages such as higher costs for wireless network cards and access points, susceptibility to environmental interference, and lower bandwidth capacity compared to wired networks. Common applications of WLANs include use in corporate, education, medical and temporary settings.
The document discusses computer networks and networking concepts. It defines what a network is and explains the need for networking. It describes the components of a network including nodes, servers, network interface units. It covers the evolution of networks from ARPANET to the internet. It discusses different types of networks including LAN, MAN, WAN and their characteristics. It also covers topics like communication media, switching techniques, wireless networking and networking terms.
This document provides an overview of basic networking concepts including protocols, protocol layers, network interconnection, and the Internet. It describes how networks are defined and addressed. The key protocol layers of OSI and TCP/IP models are examined including physical, data link, network, transport, and application layers. Common network types, topologies, and connectivity options are also summarized.
Wireless local area networks (WLANs) use radio waves to connect devices in a building or campus wirelessly. They integrate with wired networks through access points that bridge wireless and wired traffic. WLANs operate similarly to wired LANs but have some differences like lower security, limited bandwidth, and variable performance depending on location within the network coverage area. Common devices that use WLANs include tablets, smartphones and laptops.
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.
TCP/IP is a set of protocols that defines how data is transmitted and formatted so that networked systems can communicate. It originated from ARPAnet, which was developed by the Department of Defense to create a decentralized network resilient to attacks. TCP/IP provides logical addressing, routing between networks, name resolution from names to addresses, error checking and flow control for reliable data transmission, and support for multiple applications simultaneously through the use of ports. It is overseen by various standards organizations to ensure interoperability.
1) Standard TCP performs poorly over wireless networks due to packet loss from errors and mobility rather than congestion. This causes unnecessary slow starts and window reductions.
2) Early approaches like Indirect TCP, Snooping TCP, and Mobile TCP split or modify the TCP connection to isolate the wireless link but lose end-to-end semantics or require changes.
3) Later techniques like forced fast retransmit and selective acknowledgements improve efficiency without changing TCP but require cooperation between layers. Overall no single solution is optimal due to the need to maintain compatibility with fixed networks.
This document discusses challenges with TCP in mobile networks and various approaches to address them. It introduces indirect TCP, which splits the TCP connection to isolate the wireless link. Snooping TCP has the foreign agent snoop packets and acknowledgements to enable local retransmissions. Mobile TCP uses a supervisory host and window size adjustments to handle disconnections. Other optimizations discussed include forced fast retransmit after handovers, freezing TCP timers during disconnects, and selective retransmissions. The document compares the advantages and disadvantages of these different "mobile TCP" approaches.
This document discusses agent discovery and registration in mobile IP networks. It describes how mobile nodes use agent advertisements and solicitations to determine their network attachment and discover available foreign agents. It also explains the registration process, where a mobile node informs its home agent and foreign agent of its current location to setup packet forwarding. Key aspects covered are how registrations establish care-of addresses, are authenticated, and must be periodically renewed to remain valid.
The document summarizes key aspects of wireless local area networks (WLANs) and the IEEE 802.11 standard. It describes the characteristics and design goals of WLANs. It provides an overview of the IEEE 802.11 standard including the physical layer specifications, MAC layer functions and frame formats, and access methods like CSMA/CA. It also discusses wireless network architectures including infrastructure and ad-hoc networks, and comparisons of different wireless transmission technologies.
Routers and switches are networking devices that connect computers and networks, but they operate at different layers and have different functions. Routers operate at the network layer (layer 3) and use IP addresses to direct traffic between networks, while switches operate at the data link layer (layer 2) and use MAC addresses to direct traffic within a local area network. Some key differences are that routers can perform tasks like network address translation, have fewer ports, and take longer for routing decisions than switches.
The document discusses the differences between packets and frames, and provides details on the transport layer. It explains that the transport layer is responsible for process-to-process delivery and uses port numbers for addressing. Connection-oriented protocols like TCP use three-way handshaking for connection establishment and termination, and implement flow and error control using mechanisms like sliding windows. Connectionless protocols like UDP are simpler but unreliable, treating each packet independently.
BGP is the exterior gateway protocol that connects different autonomous systems on the internet. It allows for the exchange of routing and reachability information between these systems. BGP operates using a finite state machine to manage the states of connections between peers. It establishes TCP connections between routers to exchange routing updates and keep connections alive through regular keepalive messages. BGP version 4, defined in RFC 4271, is the current standard implementation which supports features like classless inter-domain routing and route aggregation.
This document provides an overview of wireless networks and the IEEE 802.11 standards. It discusses wireless LAN technologies including IEEE 802.11, HiperLAN, Bluetooth, and various amendments. It describes the infrastructure and ad-hoc modes of wireless LANs. It also summarizes key standards such as 802.11a, 802.11b, their architectures, protocols, and parameters. Finally, it provides details on the HiperLAN standard developed by ETSI for wireless local area networks in Europe.
The document provides an overview of basic networking concepts including computer networks, local area networks (LANs), wide area networks (WANs), common LAN topologies, LAN transmission methods, LAN infrastructure devices, common network cabling, Ethernet, and network models like OSI and TCP/IP. It describes key aspects of each layer in the OSI model from application to network layer.
Packet radio protocols allow multiple subscribers to access a shared channel for transmitting data packets. They use contention-based random access techniques like ALOHA. Pure ALOHA protocol has low efficiency due to partial packet collisions. Slotted ALOHA synchronizes transmissions to time slots to prevent partial collisions, improving efficiency. Performance is evaluated using metrics like throughput, which is highest at optimal channel load and drops off above and below this point.
Topics covered in this presentation:
1. RF spectrum and GSM specifications
2. FDMA and TDMA
3. Digital Voice Transmission
4. Channel coding, Interleaving and Burst formatting
5. GMSK
6. Frame structure of GSM
7. Corrective actions against multipath fading
This document discusses radio channels and interfaces in GSM networks. It covers topics like:
- The Um interface between the mobile station and base station subsystem.
- Processing of the voice signal from analog to digital conversion through encoding, interleaving and modulation for transmission.
- The different types of radio channels used including traffic channels, control channels, and their logical and physical combinations in bursts and frames.
- Technologies used for efficient transmission like frequency hopping, discontinuous transmission, and power control.
Wireless communication and its standardsM.k. Praveen
The document discusses wireless communication standards and cellular technology. It provides an agenda covering topics like wireless communication, cellular technology, standards evolution, modulation and multiplexing techniques, and cellular standards like GSM and CDMA. It also discusses frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and the differences between the 900MHz and 1800MHz frequency bands used in cellular networks.
The document discusses various topics related to wireless communication channels and networks. It provides details on wireline channels, fading effects, bit error rates for different mediums. It also summarizes key aspects of cellular systems, challenges in wireless communications, deployment of different generations of wireless networks, and traffic routing in wireless networks. The document is written by A.Sanyasi Rao and contains technical details on wireless communication concepts.
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.
Transmission media (data communication)Pritom Chaki
Transmission media is the material pathway that connects computers, different kinds of devices and people on a network. It can be compared to a superhighway carrying lots of information. Transmission media uses cables or electromagnetic signals to transmit data.
A wireless local area network (WLAN) uses radio frequency technology to transmit and receive data over the air, providing mobility and flexibility as an extension or alternative to wired networks. Key advantages of WLANs include productivity, convenience, lower installation costs and mobility. However, WLANs also have disadvantages such as higher costs for wireless network cards and access points, susceptibility to environmental interference, and lower bandwidth capacity compared to wired networks. Common applications of WLANs include use in corporate, education, medical and temporary settings.
The document discusses computer networks and networking concepts. It defines what a network is and explains the need for networking. It describes the components of a network including nodes, servers, network interface units. It covers the evolution of networks from ARPANET to the internet. It discusses different types of networks including LAN, MAN, WAN and their characteristics. It also covers topics like communication media, switching techniques, wireless networking and networking terms.
This document provides an overview of basic networking concepts including protocols, protocol layers, network interconnection, and the Internet. It describes how networks are defined and addressed. The key protocol layers of OSI and TCP/IP models are examined including physical, data link, network, transport, and application layers. Common network types, topologies, and connectivity options are also summarized.
Wireless local area networks (WLANs) use radio waves to connect devices in a building or campus wirelessly. They integrate with wired networks through access points that bridge wireless and wired traffic. WLANs operate similarly to wired LANs but have some differences like lower security, limited bandwidth, and variable performance depending on location within the network coverage area. Common devices that use WLANs include tablets, smartphones and laptops.
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.
TCP/IP is a set of protocols that defines how data is transmitted and formatted so that networked systems can communicate. It originated from ARPAnet, which was developed by the Department of Defense to create a decentralized network resilient to attacks. TCP/IP provides logical addressing, routing between networks, name resolution from names to addresses, error checking and flow control for reliable data transmission, and support for multiple applications simultaneously through the use of ports. It is overseen by various standards organizations to ensure interoperability.
1) Standard TCP performs poorly over wireless networks due to packet loss from errors and mobility rather than congestion. This causes unnecessary slow starts and window reductions.
2) Early approaches like Indirect TCP, Snooping TCP, and Mobile TCP split or modify the TCP connection to isolate the wireless link but lose end-to-end semantics or require changes.
3) Later techniques like forced fast retransmit and selective acknowledgements improve efficiency without changing TCP but require cooperation between layers. Overall no single solution is optimal due to the need to maintain compatibility with fixed networks.
This document discusses challenges with TCP in mobile networks and various approaches to address them. It introduces indirect TCP, which splits the TCP connection to isolate the wireless link. Snooping TCP has the foreign agent snoop packets and acknowledgements to enable local retransmissions. Mobile TCP uses a supervisory host and window size adjustments to handle disconnections. Other optimizations discussed include forced fast retransmit after handovers, freezing TCP timers during disconnects, and selective retransmissions. The document compares the advantages and disadvantages of these different "mobile TCP" approaches.
This document discusses several proposals to modify TCP for use in mobile environments:
1. Indirect TCP splits the TCP connection to isolate the wireless link but loses end-to-end semantics.
2. Snooping TCP allows local retransmissions through buffering and "snooping" but does not fully isolate the wireless link.
3. Mobile TCP handles disconnections through a supervisory host but does not isolate wireless link losses.
4. Fast retransmit/recovery avoids the slow start algorithm after handovers but mixes network layers.
The approaches vary in their ability to isolate the wireless link, efficiency, and amount of modification required to TCP.
Mobile transport layer - traditional TCPVishal Tandel
This document summarizes several mechanisms proposed to improve TCP performance in wireless networks. It discusses approaches like indirect TCP, snooping TCP, and mobile TCP that split the TCP connection to isolate the wireless link. It also covers fast retransmit/recovery techniques, transmission freezing, and selective retransmission to more efficiently handle packet losses due to mobility. While each approach aims to address TCP issues in wireless networks, they often do so by mixing layers or requiring changes to the basic TCP protocol stack.
The document discusses several mechanisms used in TCP for mobile computing. It describes:
1) TCP congestion control mechanisms like slow-start and fast retransmit/fast recovery which are designed to address packet loss. However, these can be inappropriate for wireless networks where packet loss is often due to errors rather than congestion.
2) Approaches like Indirect TCP, Snooping TCP, and Mobile TCP which modify TCP for mobile networks by splitting connections or having a supervisory host monitor the connection to enable local retransmissions and avoid unnecessary window reductions when the mobile host disconnects.
3) Other TCP optimizations for mobile like forced fast retransmit after handovers and transmission timeout freezing to avoid slow-start
This document discusses various approaches to improving TCP performance over mobile networks. It describes Indirect TCP, Snooping TCP, Mobile TCP, optimizations like fast retransmit/recovery and transmission freezing, and transaction-oriented TCP. Each approach is summarized in terms of its key mechanisms, advantages, and disadvantages. Overall, the document evaluates different ways TCP has been adapted to better support mobility and address challenges like frequent disconnections, packet losses during handovers, and high bit error rates over wireless links.
The document discusses various approaches to improving TCP performance over mobile networks. Indirect TCP splits the TCP connection at the foreign agent to isolate the wireless link. Snooping TCP has the foreign agent buffer packets and retransmit lost packets locally. Mobile TCP uses a supervisory host to monitor connections and choke the sender window during disconnections. Other techniques discussed include fast retransmit/recovery after handovers, freezing TCP states during interruptions, selective retransmission of only lost packets, and transaction-oriented TCP to reduce overhead of short messages. Each approach has advantages but also disadvantages related to compatibility, transparency, and complexity.
The document discusses various approaches to modifying TCP for use in mobile networks. Indirect TCP splits the TCP connection at the foreign agent, keeping the fixed network unchanged but losing end-to-end semantics. Snooping TCP has the foreign agent snoop packets and retransmit lost packets locally without changing TCP. Mobile TCP uses a supervisory host to monitor disconnections and choke senders. Other approaches include forced fast retransmit after handovers, freezing TCP timers during disconnects, selective retransmission of only lost packets, and transaction-oriented TCP to combine connection setup in fewer packets. Each approach has advantages like efficiency or compatibility but also disadvantages like overhead or non-transparency.
This document discusses various transport layer protocols for mobile networks. It begins with an overview of TCP and UDP, and then describes several strategies for improving TCP performance over mobile networks, including indirect TCP (I-TCP), snooping TCP, and Mobile TCP. It also discusses congestion control strategies like slow start and fast retransmit. Overall, the document analyzes how TCP can be optimized through techniques like connection splitting, buffering, and selective retransmission to better accommodate the characteristics of wireless networks.
The document discusses various transport layer protocols for mobile networks, including traditional TCP, Indirect TCP, Snooping TCP, and Mobile TCP. Traditional TCP was designed for fixed networks and experiences issues in mobile networks due to factors like packet loss from handoffs. Indirect TCP splits the TCP connection at the access point to isolate the wireless link. Snooping TCP has the access point buffer packets and detect losses to enable local retransmissions. Mobile TCP uses a supervisory host to handle disconnections and restart the connection when needed. Each approach aims to improve TCP performance over mobile networks while maintaining compatibility with traditional TCP.
This document discusses several approaches to improving TCP performance over mobile networks:
Traditional TCP uses slow start and congestion control mechanisms that reduce efficiency over mobile networks. Indirect TCP segments connections and uses a proxy to improve performance. Snooping TCP buffers packets to enable fast retransmissions without changing endpoints. Mobile TCP freezes the sender's window on disconnection to avoid unnecessary retransmissions. These methods aim to isolate wireless losses from congestion responses and enable fast recovery from errors and handovers.
This document discusses various transport layer protocols for mobile networks. It begins by describing TCP and its mechanisms for congestion avoidance, flow control, slow start, and retransmission. It then covers several TCP variants including Tahoe, Reno, and Vegas. It also discusses indirect TCP, Snoop TCP, and Mobile TCP which aim to optimize TCP for wireless networks by handling retransmissions locally or splitting the connection. The document provides details on the algorithms and functioning of these different protocols.
AN EXPLICIT LOSS AND HANDOFF NOTIFICATION SCHEME IN TCP FOR CELLULAR MOBILE S...IJCNCJournal
With the proliferation of mobile and wireless computing devices, the demand for continuous network connectivity exits for various wired-and-wireless integrated networks. Since Transmission Control Protocol (TCP) is the standard network protocol for communication on the Interne, any wireless network with Internet service need to be compatible with TCP. TCP is tuned to perform well in traditional wired
networks, where packet losses occur mostly because of congestion. However cellular wireless network
suffers from significant losses due to high bit errors and mobile handoff. TCP responds to all losses by
invoking congestion control and avoidance algorithms, resulting in degraded end-to-end performance. This
paper presents an improved Explicit Loss Notification algorithm to distinguish between packet loss due to congestion and packet loss due to wireless errors and handoffs. Simulation results show that the proposed protocol significantly improves the performance of TCP over cellular wireless network in terms of throughput and congestion window dynamics.
The document discusses various approaches to improving TCP performance over mobile networks, including:
1. Indirect TCP which splits the TCP connection to isolate errors on the wireless link. This requires no changes to fixed network hosts but loses end-to-end semantics.
2. Snooping TCP where the foreign agent buffers packets and retransmits lost packets transparently. This maintains end-to-end semantics but does not fully isolate the wireless link.
3. Mobile TCP which splits the connection and supports lengthy disconnections by freezing transmission at disconnected base stations. However, it propagates wireless losses into the fixed network.
A THROUGHPUT ANALYSIS OF TCP IN ADHOC NETWORKScsandit
This document analyzes the throughput of TCP in mobile ad hoc networks through simulations. It finds that TCP throughput decreases initially as the number of hops increases, then stabilizes at higher hop counts. This is due to hidden terminal problems at low hops. The number of retransmissions increases with payloads and flows due to buffering and congestion. TCP performance degrades in wireless networks because it cannot differentiate between congestion and non-congestion packet losses. Mobility, interference, and dynamic topology changes specific to wireless networks cause unnecessary triggering of TCP congestion control mechanisms.
A throughput analysis of tcp in adhoc networkscsandit
Transmission Control Protocol (TCP) is a connection oriented end-end reliable byte stream
transport layer protocol. It is widely used in the Internet.TCP is fine tuned to perform well in
wired networks. However the performance degrades in mobile ad hoc networks. This is due to
the characteristics specific to wireless networks, such as signal fading, mobility, unavailability
of routes. This leads to loss of packets which may arise either from congestion or due to other
non-congestion events. However TCP assumes every loss as loss due to congestion and invokes
the congestion control procedures. TCP reduces congestion window in response, causing unnecessary
degradation in throughput. In mobile ad hoc networks multi-hop path forwarding further
worsens the packet loss and throughput. To understand the TCP behavior and improve the
TCP performance over mobile ad hoc networks considerable research has been carried out. As
the research is still active in this area a comprehensive and in-depth study on the TCP throughput
and the various parameters that degrade the performance of TCP have been analyzed. The
analysis is done using simulations in Qualnet 5.0
1. Early approaches to optimize TCP for mobile networks included indirect TCP, snooping TCP, and mobile TCP. These attempted to isolate the wireless link from the fixed network or handle frequent disconnections.
2. Additional techniques explored were fast retransmit/recovery, transmission freezing, selective acknowledgements, and transaction-oriented TCP to improve efficiency over mobile links.
3. Current TCP over 2.5G/3G networks focuses on fine-tuning parameters like large windows and MTU sizes. Performance enhancing proxies are also used but break end-to-end security semantics. Open issues remain around header compression and congestion control over slow, lossy links.
The document discusses various protocols and approaches for improving the performance of TCP over wireless networks. It notes that wireless networks have higher bit error rates, lower bandwidth, and mobility issues compared to wired networks. Several protocols are described that aim to distinguish wireless losses from congestion losses to avoid unnecessary TCP reactions:
- Indirect TCP splits the connection and handles losses locally at the base station. Snoop caches packets at the base station for retransmission.
- Mobile TCP further splits the connection and has the base station defer acknowledgments. It can also inform the sender about handoffs versus interface switches.
- Multiple acknowledgments uses two types of ACKs to isolate the wireless and wired portions of the network.
-
Hardware multithreading allows multiple threads to share the functional units of a single processor by switching between threads when one thread is stalled. There are three main types of hardware multithreading: coarse-grained multithreading switches threads on long latency events like L2 cache misses; fine-grained multithreading switches threads every clock cycle in a round-robin fashion for high throughput but poor single-thread performance; simultaneous multithreading combines fine-grained multithreading with superscalar processing to further improve throughput by hiding memory latency but increases conflicts for shared resources.
Introduction to Advance Computer Architecturebabuece
Audio Version available in YouTube Link : https://www.youtube.com/AKSHARAM?sub_confirmation=1
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Audio Version available in YouTube Link : https://www.youtube.com/AKSHARAM?sub_confirmation=1
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Audio Version available in YouTube Link : https://www.youtube.com/AKSHARAM?sub_confirmation=1
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Audio Version available in YouTube Link : https://www.youtube.com/AKSHARAM?sub_confirmation=1
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Audio Version available in YouTube Link : https://www.youtube.com/AKSHARAM?sub_confirmation=1
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Exception | How Exceptions are Handled in MIPS architecturebabuece
Audio Version available in YouTube Link : https://www.youtube.com/AKSHARAM?sub_confirmation=1
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Introduction to Embedded Laboratory EC 8711 babuece
The document discusses ARM processors and provides information about why they are widely used, their history and design. It notes that ARM is one of the most licensed processor cores in the world and is used in many portable devices due to its low power consumption and reasonable performance. It provides brief descriptions of some ARM cores and their features. Finally, it lists some example equipment that incorporates ARM cores.
Pipeline hazards | Structural Hazard, Data Hazard & Control Hazardbabuece
Audio Version available in YouTube Link : https://www.youtube.com/AKSHARAM?sub_confirmation=1
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Audio Version available in YouTube Link : https://www.youtube.com/AKSHARAM?sub_confirmation=1
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Audio Version available in YouTube Link : www.youtube.com/Aksharam
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Audio Version available in YouTube Link : www.youtube.com/Aksharam
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Audio Version available in YouTube Link : www.youtube.com/Aksharam
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Audio Version available in YouTube Link : www.youtube.com/Aksharam
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Audio Version available in YouTube Link : www.youtube.com/Aksharam
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Audio Version available in YouTube Link : www.youtube.com/Aksharam
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
The document describes Booth's algorithm for multiplying two binary numbers in two's complement notation. It was invented by Andrew Booth in 1950 to increase the speed of calculations on desk calculators that were faster at shifting than adding. The algorithm handles both positive and negative multipliers uniformly. It then provides an example of multiplying two positive binary numbers (+13 x +7) using Booth's algorithm in four steps: 1) representing the numbers in binary, 2) recoding the multiplier, 3) performing the multiplication, and 4) verifying the result.
Audio Version available in YouTube Link : www.youtube.com/Aksharam
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
Booth's algorithm allows for the binary multiplication of a positive multiplicand and negative multiplier. It involves 3 steps:
1) Representing the multiplicand and multiplier in binary, with the negative multiplier represented in 2's complement form.
2) Recoding the bits of the multiplier according to Booth's recoding table to translate it into a signed-digit form.
3) Multiplying the multiplicand by the recoded multiplier through successive additions or subtractions of the multiplicand according to the recoded bits. The result is the binary product of the positive and negative values.
Audio Version available in YouTube Link : www.youtube.com/Aksharam
subscribe the channel
Computer Architecture and Organization
V semester
Anna University
By
Babu M, Assistant Professor
Department of ECE
RMK College of Engineering and Technology
Chennai
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
How to Fix the Import Error in the Odoo 17Celine George
An import error occurs when a program fails to import a module or library, disrupting its execution. In languages like Python, this issue arises when the specified module cannot be found or accessed, hindering the program's functionality. Resolving import errors is crucial for maintaining smooth software operation and uninterrupted development processes.
Physiology and chemistry of skin and pigmentation, hairs, scalp, lips and nail, Cleansing cream, Lotions, Face powders, Face packs, Lipsticks, Bath products, soaps and baby product,
Preparation and standardization of the following : Tonic, Bleaches, Dentifrices and Mouth washes & Tooth Pastes, Cosmetics for Nails.
Assessment and Planning in Educational technology.pptxKavitha Krishnan
In an education system, it is understood that assessment is only for the students, but on the other hand, the Assessment of teachers is also an important aspect of the education system that ensures teachers are providing high-quality instruction to students. The assessment process can be used to provide feedback and support for professional development, to inform decisions about teacher retention or promotion, or to evaluate teacher effectiveness for accountability purposes.
How to Manage Your Lost Opportunities in Odoo 17 CRMCeline George
Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
আমাদের সবার জন্য খুব খুব গুরুত্বপূর্ণ একটি বই ..বিসিএস, ব্যাংক, ইউনিভার্সিটি ভর্তি ও যে কোন প্রতিযোগিতা মূলক পরীক্ষার জন্য এর খুব ইম্পরট্যান্ট একটি বিষয় ...তাছাড়া বাংলাদেশের সাম্প্রতিক যে কোন ডাটা বা তথ্য এই বইতে পাবেন ...
তাই একজন নাগরিক হিসাবে এই তথ্য গুলো আপনার জানা প্রয়োজন ...।
বিসিএস ও ব্যাংক এর লিখিত পরীক্ষা ...+এছাড়া মাধ্যমিক ও উচ্চমাধ্যমিকের স্টুডেন্টদের জন্য অনেক কাজে আসবে ...
How to Build a Module in Odoo 17 Using the Scaffold MethodCeline George
Odoo provides an option for creating a module by using a single line command. By using this command the user can make a whole structure of a module. It is very easy for a beginner to make a module. There is no need to make each file manually. This slide will show how to create a module using the scaffold method.
This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.
A workshop hosted by the South African Journal of Science aimed at postgraduate students and early career researchers with little or no experience in writing and publishing journal articles.
The simplified electron and muon model, Oscillating Spacetime: The Foundation...RitikBhardwaj56
Discover the Simplified Electron and Muon Model: A New Wave-Based Approach to Understanding Particles delves into a groundbreaking theory that presents electrons and muons as rotating soliton waves within oscillating spacetime. Geared towards students, researchers, and science buffs, this book breaks down complex ideas into simple explanations. It covers topics such as electron waves, temporal dynamics, and the implications of this model on particle physics. With clear illustrations and easy-to-follow explanations, readers will gain a new outlook on the universe's fundamental nature.
3. Contents
Traditional TCP
Congestion control
Slow start
fast retransmit/fast recovery
Implications on mobility
Classical TCP improvements
Indirect TCP
Snooping TCP
Mobile TCP
Time out freezing
Selective retransmission
3
4. Transport Layer
E.g. HTTP (used by web services)
typically uses TCP
Reliable transport between
client and server required
TCP
Steam oriented, not
transaction oriented
Network friendly: time-out
congestion
slow down transmission
Well known – TCP guesses quite
often wrong in wireless and mobile
networks
Packet loss due to
transmission errors
Packet loss due to change of
network
Result
Severe performance
Client Server
Connection
setup
Data
transmission
Connection
release
TCP SYN
TCP SYN/ACK
TCP ACK
HTTP request
HTTP response
GPRS: 500ms!
>15 s
no data
5. Congestion Control
Transport protocols typically designed for
Fixed end-systems
Fixed, wired networks
TCP congestion control
packet loss in fixed networks typically due
to (temporary) overload situations
router have to discard packets as soon as
the buffers are full
TCP recognizes congestion only indirect
via missing acknowledgements,
retransmissions unwise, they would only
5
6. Slow-start Algorithm
sender calculates a congestion window for
a receiver and start with a congestion
window size equal to one segment
exponential increase of the congestion
window up to the congestion threshold,
then linear increase
missing acknowledgement causes the
reduction of the congestion threshold to
6
7. Fast Retransmit/Fast Recovery
TCP sends an acknowledgement only after receiving
a packet
if a sender receives several acknowledgements for
the same packet, this is due to a gap in received
packets at the receiver
however, the receiver got all packets up to the gap
and is actually receiving packets
therefore, packet loss is not due to congestion,
continue with current congestion window (do not use
slow-start)
7
8. Implications on mobility
TCP assumes congestion if packets are dropped
typically wrong in wireless networks, here we often
have packet loss due to transmission errors
furthermore, mobility itself can cause packet loss, if
e.g. a mobile node roams from one access point
(e.g. foreign agent in Mobile IP) to another while
there are still packets in transit to the wrong access
point and forwarding is not possible
The performance of an unchanged TCP degrades severely
however, TCP cannot be changed fundamentally
due to the large base of installation in the fixed
network, TCP for mobility has to remain compatible
the basic TCP mechanisms keep the whole Internet
together
8
9. Indirect TCP
Indirect TCP or I-TCP segments the connection
no changes to the TCP protocol for hosts connected to the
wired Internet, millions of computers use (variants of) this
protocol
optimized TCP protocol for mobile hosts
splitting of the TCP connection at, e.g., the foreign agent
into 2 TCP connections, no real end-to-end connection
any longer
hosts in the fixed part of the net do not notice the
characteristics of the wireless part
mobile host
access point
(foreign agent) „wired“ Internet
„wireless“ TCP standard TCP
9
10. I-TCP Socket and State Migration
mobile host
access point2
Internet
access point1
socket migration
and state transfer
10
11. Indirect TCP
Advantages
no changes in the fixed network necessary, no changes
for the hosts (TCP protocol) necessary, all current
optimizations to TCP still work
transmission errors on the wireless link do not propagate
into the fixed network
simple to control, mobile TCP is used only for one hop
between, e.g., a foreign agent and mobile host
therefore, a very fast retransmission of packets is possible,
the short delay on the mobile hop is known
Disadvantages
loss of end-to-end semantics, an acknowledgement to a
sender does now not any longer mean that a receiver
really got a packet, foreign agents might crash
higher latency possible due to buffering of data within the
foreign agent and forwarding to a new foreign agent
11
12. Snooping TCP
Transparent extension of TCP within the foreign agent
buffering of packets sent to the mobile host
lost packets on the wireless link (both directions!) will be
retransmitted immediately by the mobile host or foreign
agent, respectively (so called “local” retransmission)
the foreign agent therefore “snoops” the packet flow and
recognizes acknowledgements in both directions, it also
filters ACKs
changes of TCP only within the foreign agent
„wired“ Internet
buffering of data
end-to-end TCP connection
local retransmission correspondent
hostforeign
agent
mobile
host
snooping of ACKs
12
13. Snooping TCP
Data transfer to the mobile host
FA buffers data until it receives ACK of the MH, FA detects packet
loss via duplicated ACKs or time-out
fast retransmission possible, transparent for the fixed network
Data transfer from the mobile host
FA detects packet loss on the wireless link via sequence numbers,
FA answers directly with a NACK to the MH
MH can now retransmit data with only a very short delay
Integration of the MAC layer
MAC layer often has similar mechanisms to those of TCP
thus, the MAC layer can already detect duplicated packets due
to retransmissions and discard them
Problems
snooping TCP does not isolate the wireless link as good as I-TCP
snooping might be useless depending on encryption schemes
13
14. Mobile TCP
Special handling of lengthy and/or frequent disconnections
M-TCP splits as I-TCP does
unmodified TCP fixed network to supervisory host (SH)
optimized TCP SH to MH
Supervisory host
no caching, no retransmission
monitors all packets, if disconnection detected
set sender window size to 0
sender automatically goes into persistent mode
old or new SH reopen the window
Advantages
maintains semantics, supports disconnection, no buffer
forwarding
Disadvantages
loss on wireless link propagated into fixed network
adapted TCP on wireless link
14
15. Fast retransmit/fast recovery
Change of foreign agent often results in packet loss
TCP reacts with slow-start although there is no congestion
Forced fast retransmit
as soon as the mobile host has registered with a new
foreign agent, the MH sends duplicated
acknowledgements on purpose
this forces the fast retransmit mode at the communication
partners
additionally, the TCP on the MH is forced to continue
sending with the actual window size and not to go into
slow-start after registration
Advantage
simple changes result in significant higher performance
Disadvantage
further mix of IP and TCP, no transparent approach
15
16. Transmission/time-out freezing
Mobile hosts can be disconnected for a longer time
no packet exchange possible, e.g., in a tunnel, disconnection
due to overloaded cells or mux. with higher priority traffic
TCP disconnects after time-out completely
TCP freezing
MAC layer is often able to detect interruption in advance
MAC can inform TCP layer of upcoming loss of connection
TCP stops sending, but does now not assume a congested link
MAC layer signals again if reconnected
Advantage
scheme is independent of data
Disadvantage
TCP on mobile host has to be changed, mechanism depends on
MAC layer
16
17. Selective retransmission
TCP acknowledgements are often cumulative
ACK n acknowledges correct and in-sequence receipt of
packets up to n
if single packets are missing quite often a whole packet
sequence beginning at the gap has to be retransmitted
(go-back-n), thus wasting bandwidth
Selective retransmission as one solution
RFC2018 allows for acknowledgements of single packets,
not only acknowledgements of in-sequence packet
streams without gaps
sender can now retransmit only the missing packets
Advantage
much higher efficiency
Disadvantage
more complex software in a receiver, more buffer needed
at the receiver
17
18. Transaction oriented TCP
TCP phases
connection setup, data transmission, connection release
using 3-way-handshake needs 3 packets for setup and release,
respectively
thus, even short messages need a minimum of 7 packets!
Transaction oriented TCP
RFC1644, T-TCP, describes a TCP version to avoid this overhead
connection setup, data transfer and connection release can be
combined
thus, only 2 or 3 packets are needed
Advantage
efficiency
Disadvantage
requires changed TCP
mobility not longer transparent
18
19. Comparison Of Different
ApproachesApproach Mechanism Advantages Disadvantages
Indirect TCP splits TCP connection
into two connections
isolation of wireless
link, simple
loss of TCP semantics,
higher latency at
handover
Snooping TCP “snoops” data and
acknowledgements, local
retransmission
transparent for end-to-
end connection, MAC
integration possible
problematic with
encryption, bad isolation
of wireless link
M-TCP splits TCP connection,
chokes sender via
window size
Maintains end-to-end
semantics, handles
long term and frequent
disconnections
Bad isolation of wireless
link, processing
overhead due to
bandwidth management
Fast retransmit/
fast recovery
avoids slow-start after
roaming
simple and efficient mixed layers, not
transparent
Transmission/
time-out freezing
freezes TCP state at
disconnect, resumes
after reconnection
independent of content
or encryption, works for
longer interrupts
changes in TCP
required, MAC
dependant
Selective
retransmission
retransmit only lost data very efficient slightly more complex
receiver software, more
buffer needed
Transaction
oriented TCP
combine connection
setup/release and data
transmission
Efficient for certain
applications
changes in TCP
required, not transparent
20. TCP Improvements I
Initial research work
Indirect TCP, Snoop TCP, M-TCP, T/TCP,
SACK, Transmission/time-out freezing, …
TCP over 2.5/3G wireless networks
Fine tuning today’s TCP
Learn to live with
Data rates: 64 kbit/s up, 115-384 kbit/s down; asymmetry: 3-6, but also up to 1000
(broadcast systems), periodic allocation/release of channels
High latency, high jitter, packet loss
Suggestions
Large (initial) sending windows, large maximum transfer unit, selective
acknowledgement, explicit congestion notification, time stamp, no header
compression
Already in use
i-mode running over FOMA
WAP 2.0 (“TCP with wireless profile”)
pRTT
MSS
BW
*
*93.0
• max. TCP BandWidth
• Max. Segment Size
• Round Trip Time
• loss probability
20
21. TCP Improvements II
Performance enhancing proxies (PEP, RFC 3135)
Transport layer
Local retransmissions and acknowledgements
Additionally on the application layer
Content filtering, compression, picture downscaling
E.g., Internet/WAP gateways
Web service gateways?
Big problem: breaks end-to-end semantics
Disables use of IP security
Choose between PEP and security!
More open issues
RFC 3150 (slow links)
Recommends header compression, no timestamp
RFC 3155 (links with errors)
States that explicit congestion notification cannot be used
In contrast to 2.5G/3G recommendations!
Mobile system
PEP
Comm. partner
wireless
Internet
21
23. SYLABUS
Introduction To 4G Networks
4G Vision
4G Features And Challenges
Benefits
Applications Of 4G
4G Technologies
Multicarrier Modulation
Smart Antenna Techniques
OFDM - MIMO Systems
Adaptive Modulation And Coding With Time Slot
Scheduler
Cognitive Radio
25. Future technology – Mobile and Wireless communications.
It is a heterogeneous network
Expectation of 4G:
Top quality audio /video over finish to finish net protocol
Introduction to 4G Networks
26. Technology moving towards
4G
26
Mobility
Data Rates
High speed
Medium
speed
Low speed
1995 2000 2005 2010+
~14.4 kbps 144 kbps 384 kbps <50 Mbps <100 Mbps
1G
(Analog)
2G
(Digital)
3G
(IMT2000)
3G LTE
4G
2.4 GHz
WLAN
5 GHz
WLAN
High Speed
WLAN
Mobile
WiMAX
(WiBRO)
Bluetooth
WPAN
CDMA/GSM/TDMA
CDMA/GSM/TDMA
29. 3G - concentrate in standards & hardware implementation.
4G
-encompass all networks
- interoperable with 2G,3G and other service.
- provides seamless integration of various technologies.
- IP based heterogeneous network.(IPv6 Core)
- OFDM used instead of CDMA
Why 3G to 4G?
30. Wireless World Research Forum defines 4G as:
-A network that operates on Internet technology, combines it with
other applications and technologies such as Wi-Fi, and runs at
speeds ranging from 100 Mbps (in cell-phone networks-Outdoor)
to 1 Gbps(in local Wi-Fi networks-Indoor).
4G Fourth generation Mobile
Communications
31. 4G -Objective
4G is being developed to accommodate the Quality
of Service (QOS) and rate requirements set by forth
coming applications like
1. MMS (Multimedia Messaging Service).
2. Wireless Broadband Service.
3. Video Chat.
4. Mobile TV.
5. Digital Video Broadcasting.
6. High Network Capacity.
7. Data Rate of 100 Mbps for mobile and 1 Gbps while
stationary .
8. Smooth handoff across heterogeneous network..
9. Seamless Connectivity and Global Roaming across
multiple networks.
32. Providing new service with high quality voice,high
definition video with high data rate
4G is defined as MAGIC
MAGIC – Mobile multimedia, Anytime anywhere, Global
mobility support, Integrated wireless solution and Customized
Personal services
4G Vision
33. 4G is IP based - Various network using IP as a Common Protocol
"Seamless" and "wireless," when put together, represent a
technology of wireless Internet that hands you off to another
network without interruption so you may continue your activities
online without even noticing that you connected into another
network. Another name for it is "seamless roaming."
Seamless Connection
35. Features of 4G
Autonomous Networks
Software Independence
Fully coated service(Entirely packet – switched
network).
Scalability
Interoperability and simple roaming
Support for multimedia services like
teleconferencing and wireless internet
Wider band width and higher bitrates
Global mobility and service portability
High internet speed
Tight network security
36.
37. a) Convergence of cellular mobile networks and WLANs
Benefits for Operators:
Higher bandwidths.
Lower cost of networks and equipment.
The use of license-exempt spectrum.
Higher capacity and QoS enhancement.
Benefits for Users:
Access to broadband multimedia
services with lower cost and where
mostly needed.
Inter-network roaming.
b) Convergence of mobile communications and broadcasting
From broadcaster point of view
From the cellular mobile operator point of view:
c) Convergence benefits
Benefits of 4G
38. Various categories of Challenges
Based on Mobile Station
Based on System
Based on Service
Mobile Station Challenges
Multimedia User terminals
Discovery of Wireless System
Selection of Wireless System
Incompatible roaming Frequencies
System Challenges
Terminal Mobility
QOS support and Network Infrastructure
Privacy and Security issues
Fault Tolerance and Survivability
Service Challenges
Service and Charge
Personal Mobility
Meeting Consumer Expectation
Challenges of 4G
39. The applications of 4G are called “KILLER APPLICATIONs” as it is going to bring
to revolution in the internet world.
Virtual Presence – User service at all times
Virtual Navigation -User can access a database of the streets and
buildings
Tele-Geoprocessing Applications – GIS + GPS
(Geographical Information System) + (Global Positioning System)
Tele-Medicine and Education –Support remote health Monitoring of
patients and Education in online
Gaming – High Speed Multi user gaming
Cloud Computing – Safe and Secure
Crisis Management – restore crisis issues in a few hours
Applications of 4G
41. Multi carrier Modulation (MCM)
Smart Antenna techniques
OFDM-MIMO Systems
Adaptive modulation and Coding
with Time slot Scheduler
Cognitive Radio
UWB(Ultra Wide Band)
Software defined radio
KEY 4G TECHNOLOGIES
42. It is a derivative of FDM
MCM derivative:
Digital Audio and Video Broadcasting (DAB/DVB)
Digital Subscriber Loop Modems (DSL)
Principle
A transmitted bit stream is divided into many different sub
streams, which are sent in parallel over many sub channels.
Sub channels are typically orthogonal
MCM efficiently implemented digitally using the FFT(OFDM)
Multicarrier Modulation(MCM)
45. Consider a MC system with a total passband bandwidth of 1 MHz.
Suppose the channel delay-spread is Tm = 20µs. How many
subchannels are needed to obtain approximately flat fading in each
subchannel?
The channel coherence bandwidth is
Bc = 1/Tm = 1/0.00002 = 50 KHz
To ensure flat fading on each subchannel, we take
BN = B/N = 0.1 x Bc
Hence,
N = B/(0.1 x Bc) = 1000000/5000 = 200 subcarriers.
An example
46. MC Modulated Signal
2 types of MCM for 4G
MC-CDMA – QPSK
modulation
OFDM with TDMA – QAM
modulation
48. The data rate on each of the subcarriers is much lower than the
total data rate
Subchannels experience flat fading.
Small ISI in each subchannel
Avoidance of single frequency interference
MCM
Advantages
MCM Drawbacks
Increase PAPR.
To overcome ISI, a cyclic extension (Guard
bit) is to be added
50. A smart antenna is a multi-element antenna where the signals received
at each antenna element are intelligently combined to improve the
performance of the wireless system.
Technologies Combined to design smart antenna systems
Antenna design
Signal processing
Hardware implementation
Smart Antenna Techniques
51. • Smart Antenna
Beam radio signals directly at a users to follow the
users as they move.
•Allow the same radio frequency to be used for
other users without worry of interference.
•Seamless handoff between towers/access points.
•One transmit antenna, two receive antennas.
–Allows connection to two access points at once.
51
53. Reduction in Co channel Interfernce
Range improvement
Increase in Capacity
Reduction in transmitted power
Reduction in Handoff
Benefits
54. MIMO supports multiple independent channel in the same BW,
Provided multipath environment.
Single-Input, Single Output (SISO)
Single-Input, Multiple Output (SIMO)
Multiple –Input, Single Output (MISO)
Multiple -Input, Multiple Output(MIMO)
Smart Antenna Technique- MIMO
57. Smart antenna Strategy
Level of Intelligence
Switched Lobe – Switching function between separate
directive antennas
Dynamically phased array (PA)–DOA algorithm is
included
Adaptive array - DOA is used to determine
interference sources
58.
59. Orthogonal Frequency Division Modulation (OFDM)
Basic idea:
Using a large number of parallel narrow-band subcarriers instead of a
single wide-band carrier to transport information.
Advantages:
-Very easy and efficient in dealing with multi-path.
-Robust again narrow-band interference
59
60. Enhancement in data rate and spectral efficiency.
Both schemes are indeed parallel transmission
technologies (Space & Frequency Domain).
MIMO -OFDM helps to achieve
Diversity
High gain
Implementation is based on
FFT/IFFT algorithm
MIMO Encoding
MIMO -OFDM
62. Time Slot Scheduler:
To share the spectrum efficiency between the users by satisfying QoS
requirements
Adaptive Modulation and Coding
with Time Slot Scheduler
FCC defined
A radio that is “aware of its
surroundings and adapts
intelligently”
63. Cognitive Radio Means “Smart” and “Alert”
Cognitive Radio* is Built on SDR*
D
Cognitive
Radio
Adaptive Radio
Intelligent
radio
Functions
Spectrum Sensing
Spectrum Management
Spectrum Mobility
Spectrum Sharing
65. Optimal Diversity
Spectral Efficiency
Improved QoS
Benefits to the Service provider
Benefits to the Regulator
Emergency Radio System
Covert Military radio
Multi technology Phone
Mobile video services
Open Air events
Extending mobile networks
Benefits
66. Software defined ratio(SDR)
A software defined radio is one that can be configured to any
radio or frequency standard through the use of software.
The phone should automatically switch from operating on a
CDMA frequency to a TDMA frequency whenever it is required.
Roaming can be an issue with different standards, but with a
software defined radio, users can just download the interface
upon entering new territory, or the software could just
download automatically.
67. G4
Earth's population stands at around 6.6 billion.
The Internet has a population of just 1.3 billion.
IPv6 uses 128 bits for IPv6 addresses which allows for 340 billion billion
billion billion (3.4x1038) unique addresses.
67
22%
69. FUTURE OF 4G:5G
The idea of WWWW, World Wide Wireless Web, is started
from 4G technologies. The following evolution will based on 4G
and completed its idea to form a Real wireless world.
Thus, 5G should make an important difference and add more
services and benefit to the world over 4G. 5G should be a
more intelligent technology that interconnects the entire world
without limits.