17-03-2014, 09:15 PM
Abstract- Multimedia transmissions over wireless
networks need continuous media play out. In order to
meet best Quality of Services, higher layers data depend
on lower layer parameters. That is readily known as
cross-layer design. Our cross-layer design model
optimizes the physical layer, MAC layer and application
layer. Video summary frames are transmitted via
MIMO transmit/receive diversity with AMC at the
physical layer and Payload and data rate adaptation at
the MAC link layer and source coding at the application
layer. We, first model the finite-state Markov chain
(FSMC) for the physical layer service and based on
that, we then characterize the Lagrangian relaxation
and Dynamic programming to find the optimal shortest
path. The source coding as well as retransmission
requests are based on the channel-state information
(CSI) and the system controller is implemented in all
the three physical, MAC layer and application layers.
The numerical results revealed that our proposed crosslayer
design can efficiently achieve the effective
throughput and distortion gain.
Index Terms- Cross-layer design, quality-ofservice(
QoS), adaptive modulation and coding (AMC),
multiple input multiple output (MIMO), automatic
repeat request (ARQ), rate distortion, mobile wireless
networks.
I INTRODUCTION
Rapid Growth in wireless networks
increases the demand of services that traditionally
available only in wired networks. The users are in
need of best Quality of Services with in the available
bandwidth. In wireless networks, Communication
takes place over a time-varying and unreliable
channel. So transmission of data over unreliable
networks has been an active field of research.
Depending on the type of data, QoS parameters will
vary, like voice data is constrained by delay
parameter where as video is constrained by loss and
distortion factors. Though the Shannon’s source and
channel coding theorems works well, it would not
fulfill the current challenging network conditions.
Most network designs do not provide
mechanisms for protocol layers to optimally adapt
to underlying channel conditions and specific
application requirements. While protocol layering
is an important abstraction that reduces network
design completely, it is not well suited to wireless
networks since the nature of the wireless medium
makes it difficult to decouple the layers. Moreover,
meeting the end-to-end performance requirements
of demanding applications is extremely challenging
without interaction between protocol layers. Video
streaming over wireless networks can benefit
substantially from a cross-layer design. In this
design, interdependencies between layers are
characterized and exploited by adapting the
information exchanged between layers and
building the appropriate amount of robustness into
each layer. So the joint optimization of application
layers with lower layers is necessary to meet
certain QoS requirements.
Wireless communication systems with
multiple transmit antenna and receiving antennas
exploit the scattering propagation environment and
increase the channel capacity. The channel capacity
is increases linearly with the number of transmitter
and receiver antennas, for an equal number of
transmitter and receiver antennas. In general, there
are two categories of multiple input multiple output
(MIMO) techniques. The first approach improves
the power efficiency by maximizing spatial
diversity. Such techniques include delay diversity,
space-time block codes (STBC) and space time
trellis codes (STTC).The other category uses linear
processing to increase the data rate. Such
techniques include BLAST, where full spatial
diversity is usually not achieved.