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課程名稱︰無線多媒體系統研究
課程性質︰多媒體
課程教師︰吳曉光
開課學院：電資
開課系所︰資工
考試日期（年月日）︰2011.01.16
考試時限（分鐘）：180
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
1. Mobile Ad hoc Networks
(a) Describe two main motivations for the Terminal Project: Toward Self-
Organized MObile Ad Hoc Networks.
(b) Describe Ad hoc network evolutions from early stage to the future.
(c) Describe the characteristics of ad hoc networks
(d) In the early stage, two representative kinds of routing schemes are:(1)
table driven routing scheme (such as DSDV) (2) on demand routing scheme (such
as AODV). Explain the differences between them. (3) Different from traditional
routing schemes, recently, geographical methods have been utilized for routing.
.Describe how geographic information can be helpful for the routing function.
(4) For large scale ad hoc networks, describe the problems and possible
solutions for the routing schemes.
(e) Describe the similarities and differences between ad hoc networks and
vehicular Ad Hoc networks (VANET).
2. MANET Routing Protocols
MANETs are basically peer-to-peer, multihop wireless networks in which information
packets are transmitted in a store-and-forward manner from a source to an
arbitrary destination, via intermidiate nodes. (A) Describe the looping
problem by Figure 1 example. (B) In ad hoc networks, it is sometimes desirable
to transmit packets of a single message using multiple paths. Can you think of
any specific reasons for this? If you need to employ two alternative paths,how
would you revise AODV or DSR protocols to obtain two alternative paths?
(C) What are the similarities and differences between ad hoc networks and
sensor networks?
3. QoS routing for MANETS
Providing real time services such as voice or video over ad hoc network is a
challenge. Usually QoS routing will be required for real time connections.(a)
Describe the difference between QoS routing and shortest path routing. (b)
Usually bandwidth constraint must be satisfied for the required voice and
video. How do you calculate the available bandwidth for an ad hoc node if you
have 2M bits per second(e.g. 802.11b) bandwidth and each requested video stream
require 50K bit per second bandwidth. As Figure 2, the video connection is
constructed from sender to receiver, how many bandwidth resources could be
consumed for each node (sender, R1,R2,and receiver).(c) If you need to employ
two alternative paths, how woulf you extend DSR algorithm? (d) Multipath
routing has been proposed to satisfy QoS requirements. Can you describe
the advantages and disadvantages for multipath routing? (e) QoS routing
protocols assumed that all nodes had the same capacity. In practice, since
the wireless medium is shared and collision-based, different nodes may have
different capacities, depending on their densities of contending nodes.
Descibe hidden routing problem and the corresponding possible solution for
QoS routing.
4. VANET Routing
(A) Explain why current routing solutions (such as AODV) developed for Mobile
Ad hoc Networks happen to be highly inappropiate for VANETs. (B) However,
location based stateless routing schemes such as Greedy Perimeter Stateless
Routing (GPSR) are particularly efficient on highly dynamic networks. Using
geo-localization information, packets are greedily forwarded to the vehicle
bringing the maximum progress towards the destination. In some cases, there
might not be such a vehicle and a recovery strategy, called perimeter routing
in GPSR, is used to find an appropriate next relay. Explain specifically
how they work. (C) Design a location based QoS routing solution for Vehicular
Ad hoc Network given than location-based stateless routing protocols (such as
GPSR) are efficient on highly dynamic networks.
5. Mobile Multicast
The mobile multicast protocl must deal not only with dynamic group monagement
but also with dynamic member location. The current version of mobile IP
proposed two approaches to support mobile multicast, i.e. bidirectional
tunneling and remote subscription. (A) Can these two approaches (bidirectional
tunneling and remote subscription) handle source mobility and recipient
mobility? (B) A direct mechanism for achieving multicast reception on MHs is to
let HA handle mutlicast routing by executing IGMP and delivering multicasts to
the MHs as if it was at home. In Current IETF mobile multicast, is it qualified
as remote subscription or bi-direction tunnel multicast? Advantage?
Disadvantage? (C) What is the duplication problem? (D) What is the tunnel
convergent problem? (E) Can you describe what is "combined routing"?
Advantage? Disadvantage?
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