英语翻译4.2 Results and Analysis4.2.1 Scalability StudyIn this s

英语翻译
4.2 Results and Analysis
4.2.1 Scalability Study
In this set of simulations,we studied the performance of
DOA when the network size varied from 100 nodes to
1,400 nodes.The network sizes and the respective network
areas are shown in Table 1.The size and the area were
selected so that the node density was approximately
constant,which would properly reflect the scalability of
routing protocols.For each performance metric,we compared
DOA with DSR and AODV.The results are shown in
Figs.6a,6b,6c,6d,and 6e.
Control Overhead.The main purpose of using hierarchy
in MANETs is to reduce the routing overhead.Fig.6a
shows the control overhead of DOA,DSR,and AODV.We
observe that DOA has much less control overhead than
AODV when the network size increases while supporting
high PDR (Fig.6b).For networks with 100 nodes,three
protocols incur approximately the same amount of control
overhead; for networks with 600 nodes,DOA saves
68 percent control packets compared to AODV; for networks
with 1,400 nodes,DOA saves 80 percent control
packets compared to AODV.The larger the network size is,
the more control packets are saved by DOA.DSR incurs
slightly less control overhead than DOA.However,the PDR
of DSR is much less than DOA and AODV (Fig.6b).
Control overhead in DOA is significantly reduced
because of the use of the waypoint routing hierarchy.
WPR enables the localization of route maintenance activities.
For example,a broken route can be repaired at the
intrasegment level or at the intersegment level.The low
control overhead is critical for DOA to scale to large
MANETs.
Three optimizations to AODV have been studied [25]
(which will be discussed in Section 5),including expanding
ring search,query localization,and local repair.These
optimizations can be incorporated in DOA to reduce the
intrasegment routing overhead further.
Packet Delivery Ratio.Fig.6b shows the PDRs of DOA,
DSR,and AODV.We observe that DSR cannot scale to
networks beyond a few hundred nodes.For networks with
600 nodes,DSR delivers 50 percent data packets.On the
other hand,both DOA and AODV show high PDRs even for
networks with more than 1,000 nodes.For all network sizes
from 100 nodes to 1,400 nodes,DOA consistently delivers
about 2 percent-3 percent more data packets than AODV.
DOA maintains routes hierarchically and repairs a
broken route locally.Thus,an active route in DOA usually
lasts longer and more data packets can be delivered.AODV
shows very comparable PDR to DOA.However,the control
overhead of AODV is significantly higher.DSR does not
scale well because it has higher packet header overhead and
keeps routing information in nondistributed manner,as
discussed in Section 2.1.

4.2结果和分析
4.2.1可测量性研究
In这套模仿,我们学习了表现 DOA,当网络大小从100个结变化了到
1,400结.网络大小和各自网络
areas在表1.显示.大小和区域是
selected,以便结密度大约是
constant,将适当地反射的可测量性routing协议.为公尺每表现,我们比较了与DSR和AODV的DOA.结果显示
Figs.6a、6b、6c、6d和6e.顶上的Control.使用阶层的主要目的in MANETs是减少发送天花板.图6a
shows控制天花板DOA、DSR和AODV.我们
observe DOA比有较少控制天花板AODV,当网络大小增加,当支持时high PDR (图6b).为与100个结的网络,三
protocols大约招致相同数量控制
overhead; 为与600个结的网络,DOA保存
68百分之控制小包与AODV比较; 为网络
with 1,400结,DOA保存80%控制
packets与AODV比较.越大网络大小是,
the更多控制小包由DOA保存.DSR招致
slightly顶上较少的控制比DOA.然而,PDR
of DSR比DOA和AODV (图6b)是较少.顶上在DOA显著减少Control由于使用的小站发送阶层.
WPR使能路线维护活动的地方化.
例如,一条残破的路线可以被修理在
intrasegment水平或在intersegment水平.低
control天花板是重要为了DOA能称对大
MANETs.对AODV的Three优化是被学习的[25] 在第5)部分将被谈论的 (包括扩展
ring查寻、询问地方化和地方修理.这些
optimizations在DOA可以被合并减少
intrasegment发送顶上更加进一步.
Packet交付比率.图6b显示DOA,PDRs DSR和AODV.我们观察DSR不可能称到在几百个结之外的networks.为与的网络600结,DSR交付50%数据包.在
other手,DOA和AODV显示高PDRs甚而的与超过1,000个结的networks.为所有网络估量
from 100结到1,400个结,DOA一贯地提供
about 2百分之3百分之多数据包比AODV.
DOA分层地维护路线并且修理地方broken路线.因此,在通常DOA 的一条活跃路线可以交付lasts和长期更多数据包.AODV
shows非常对DOA的可比较的PDR.然而,控制AODV overhead显着更高.DSR不因为它有更高的包标头天花板和,scale涌出keeps路由选择信息以非分布的方式,作为在第2.1部分的discussed.