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Mobile ad hoc networking with a view of 4G wireless: Imperatives

and challenges

Myungchul Kim

mckim@icu.ac.kr

Tel: 042-866-6127

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by J. Liu and Imrich Chlamtac, Ch 1 of Mobile Ad Hoc Networking, Wiley-Interscience, 2004.

• Introduction– Mobile devices– The worldwide number of cellular users has been

doubling every 11/2 years.– The number of mobile connections and the number of

shipments of mobile and Internet terminals will grow by another 20-50%. -> the total number of mobile Internet users soon to exceed that of fixed-line Internet users.

– Situations in which user-required infrastructure is not available, cannot be installed, or cannot be installed in time in a given geographic area. -> mobile ad hoc network.

– Ad hoc networking: the 4G network architecture.

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• Review of wireless network evolution– Wireless communication characteristics

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• Review of wireless network evolution– Wireless communication characteristics

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– Types of wireless networks• By network formation and architecture: infrastructure-

based network, Infrastructureless (ad hoc) network.• By communication coverage area:

– wireless wide area networks (Wireless WANs) e.g., cellular networks

– wireless metropolitan area networks (Wireless MANs) e.g., local multipoint distribution services (LMDS), multichannel multipoint distribution services (MMDS) and IEEE 802.16

– wireless LANs e.g., 802.11 (Wi-Fi) and Hiperlan2 – wireless personal area networks (Wireless PANs): 10

meter range, e.g., Bluetooth and infrared light.• By access technology

– GSM, TDMA, CDMA, Sattellite, Wi-Fi, Hiperlan2, Bluetooth, Infrared.

• By network applications– Enterprise, Home, Tactical, Sensor, Pervasive, Wearable

Computing, Automated Vehicle Networks.

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– Table 1.1

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– Table 1.1 – cont’

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– Forces driving wireless technology evolution• The need to integrate various types of wirless

networks• The need to integrate wireless platforms with fixed

network backbone infrastructure• The need to support high-speed multimedia services• The need for convergence in network infrastructure• The need to support high mobility and device

portability• The need to support noninfrastructure-based

networks• The need to add location intelligence• The need to lower the cost of wireless services• The need for greater standard interoperability.

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– 4G wireless architecture and capabilities• ]integrating different types of wireless networks

with wireline backbone networks seamlessly and the convergence of voice, multimedia, and data traffic over a single IP-based core network.

• Network integration• All-IP networks, e.g., VoIP• Lower cost and higher efficiency• Ultrahigh speed and multimedia applications• Ubiquitous computing• Support of Ad Hoc networking (MANET)• Location intelligence

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– Fig 1.1

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• Mobile Ad Hoc Networks– Characteristics and advantages

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– Table 1.2

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– Table 1.2 – cont’

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– Design issues and constraints• They are infrastructureless: brings added difficulty

in fault detection and management.• Dynamically changing network topologies• Physical layer limitation: hidden terminal

problem, collisions, packet loss• Limited link bandwidth and quality• Variation in link and node capabilities• Energy constrained operation• Network robustness and reliability• Network security• Network scalability• Quality of Service

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• Technical challenges and research overview

– Fig 1.3

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• Technical challenges and research overview

– Media access control and optimization• Fig 1.4 and Fig 1.5

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– Media access control and optimization• RTS and CTS before the data transmission has

actually taken place.-> virtual carrier sensing• loss/collision of RTS and CTS -> wait for a

random backoff duration– Multicasting and broadcasting

• Avoid the significant delays in route recovery caused by link failures

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– Ad hoc routing• Frequent changes and unpredicability in network

topologies• Proactive routing protocols and reactive on-

demand routing protocols• Fig 6.1

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• Fig 6.2 and Fig 6.3

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– TCP issues• Packet losses <- congestion (wired), wireless

medium, frequent disconnection from mobility, ….

• Measurements using 2Mbps 802.11 MAC have shown that TCP throughput decreases by 50% when the traffic moves from the one-hop to the two-hop path.

– Energy conservation• The wireless interface consumes nearly the same

amount of energy in the receive, transmit, and idle states, whereas in the sleep state, an interface cannot transmit or receive, and its power consumption is highly reduced.

– Network security

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– Simulation and performance evaluation• OPNET, NS-2, Glomosim -> different results

– QoS and Optimization• May be impossible if the nodes are highly mobile

– Future research directions• Routing protocol optimization: GPS, multicasting• QoS support• Simulation: do not exceed networks of hundred

nodes in size• Security• Standardization and interoperability