Cross Layer Design

1
Cross Layer Design

• -Suparna

2
Agenda

• Introduction
• Signaling Methods
• Architecture
• Applications
• Issues
• Proposed solutions
• Conclusion Future Work
• References

3
What lead to CLD?

• Advanced applications like VOIP, Web browsing ,
  multimedia conferences video streaming demanded
• Widely varying and diverse QoS guarantees
• Adaptability to dynamically varying networks
  traffic
• Modest Buffer requirements
• High and effective Capacity utilization
• Low processing overhead per packet
• Video streaming high bandwidth requirements are
  coupled with tight delay constraints

4
What lead to CLD?

• The approach of any layered network is to treat
  different layers as different entities and
  perform layer specific operation independent of
  other layers
• TCP is a point-to-point protocol that sets up a
  connection bet two endpoints using a handshake
  signal, hence it cannot be used in multicast
  environment
• QoS was not an issue for the application using
  Layered approach for providing multi vendor
  interface
• FIFO buffers were used for resource handling and
  sharing

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Cross Layer Design

• CLD is a way of achieving information sharing
  between all the layers in order to obtain
  highest possible adaptivity of any network.
• This is required to meet the challenging Data
  rates, higher performance gains and Quality of
  Services requirements for various real time and
  non real time applications.
• CLD is a co-operation between multiple layers to
  combine the resources and create a network that
  is highly adaptive

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Cross Layer Design

• This approach allows upper layers to better adapt
  their strategies to varying link and network
  conditions.
• This helps to improve the end-to-end performance
  given networks resources.
• Each layer is characterized by some key
  parameters, that are passed to the adjacent
  layers to help them determine the best operation
  modes that best suit the current channel, network
  and application conditions

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Cross Layer Design

• Wireless Networking
• Architecture Connection Vs Connectionless
• Energy efficient analysis of manets
• Traffic theory protocols
• Signal processing
• Increasing the spectral efficiency
• Reducing Bit Error Rate
• Reducing transmission energy
• Information Theory
• Developing capacity limits
• Designing efficient source coding and channel
  algorithms

8
Cross Layer Signaling Methods

• Method I Packet headers
• Method II ICMP Messages
• Method III Local Profiles
• Method IV Networks Services

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Method I Packet headers

• Interlayer signaling pipe stores the cross layer
  information of the Headers of theIPv6 packets
• It makes use of IP data packets as in-band
  message carriers
• There is no need to use a dedicated message
  protocol

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Method I Packet Headers Method II ICMP
Messages
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Method II ICMP Messages

• A message can be generated at any layer and
  propagated to any upper layer, thus a message is
  transferred using these holes rather than a pipe
  as in method I
• The messages are propagated through the layers
  using the Internet Control Message Protocol
  (ICMP)
• This is more flexible and efficient method.
• But, ICMP encapsulated message have to pass by
  network layer even if the signaling is requires
  between link and application layer.
• Only upward ICMP messages are reported

12
Method III Local Profiles

• Cross layer information is abstracted from
  related layer and stored in separate profiles
  within a Mobile Host (MH).
• Interested layers can select profiles to fetch
  desired information.
• This is not suitable for time-stringent tasks
  like real time applications.

13
Method III Local Profile
14
Method IV Networks Services

• Channel and link information from physical
  layer and link layer are gathered, abstracted and
  managed by WCI Wireless channel Information
  Servers.

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Method IV Networks Services
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Some applications of CLD

• QoS support in the 3Gpp2 Wireless Systems
• AD-HOC networks for real-time video streaming
• QoS mapping architecture for video delivery in
  wireless network
• Multimedia over wireless
• Multi hop wireless networks

17
Application of CLD in AD-HOC Networks for Real
time Video Streaming
18
CLD for Real Time Video Streaming

• Link Layer Adaptive techniques are used to
  maximize the link rates under varying channel
  conditions.
• MAC Layer Assigns time slots, codes or frequency
  bands to each links.
• Network Layer Network layer operates jointly
  with MAC layer to determine the set of network
  flows that minimizes congestion.
• Transport Layer Congestion-Distortion optimized
  scheduling is performed to control the
  transmission and retransmission of packets. It
  uses a CoDiO Scheduler which selects the most
  important packet in terms of video distortion and
  transmits it in an order that minimizes
  congestion. It avoids transmitting packets in
  large bursts.
• Application Layer It determines the most
  efficient encoding rate that will suite the given
  requirements for that application

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Adaptive Link Layer Technique

• The data rate of the link is improved by adapting
  the link layer variation to the variation of the
  channel like transmitter power, target BER and
  Symbol rate.
• Adapting the Packet length depending on the SINR
  and the link layer parameters to optimize
  throughput.
• The optimal packet length L is calculated as

20
PSNR performance for video Streaming for two
different Networks
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Issue 1Video Delivery in Wireless Networks(Link
layer, Transport Layer Application Layer)

• Providing better quality of service QoS mapping
  techniques so that each video layer is optimally
  mapped to its corresponding priority class.
• There should be a proper coordination mechanism
  between priority transmission system and video
  applications. This is because in transmission
  layer the QoS is expressed in terms of
  probability of buffer overflow and the
  probability of delay violation at the link
  layer. Whereas, in Video application layer QoS is
  measured by mean squared error (MSE) and Peak
  signal-to-noise ratio (PSNR).

22
Architecture of a cross layer QoS Management for
video delivery over wireless
23
QoS Mapping Technique

• The QoS mapping and the Adaptation Module are the
  key factors of the cross layer design.
• It has to be designed to optimally match
  application layer QoS and the link (Transmission
  layer) QoS.
• The video application layer QoS and link-layer
  QoS are allowed to interact with each other and
  adapt along with the wireless channel condition.

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GOP structure of MPEG video file
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QoS Mapping Issues

• Packets from the same GOP structure have to
  placed on the same QoS class.
• The video playback frame rate at the end user is
  F frames/sec. And if the mobile terminal starts
  to play back the first video frame of GOP at time
  Tp, then for uninterrupted playback the video
  frame n in the same GOP should be received before
  
• Td(n) Tp ((n-1)/F)

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Solution Tree search approach
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Tree approach for optimal Mapping

• Find out the number of the video layers and mark
  them as the stages of the tree
• Mark the priority classes as the nodes of the
  stages
• Create all the possible branches in order to
  account for all the accumulated buffer
  occupancies.
• Compute the accumulated distortion reduction to
  each mapping and after that the optimal mapping
  solution will be the route from the leaf node to
  the tree root which had the minimum accumulated
  distortion reduction.

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Solution for Priority Transmission and Video
Application Module
29
Solution for Priority Transmission and Video
Application Module

• Video coding module sets up a QoS bound r(t) in
  terms of expected video distortion (PSNR). It
  then send a transmit request (Txreq) to
  transmission module
• Transmission Module offers a set of statistical
  Qos guarantees for each priority class. The QoS
  parameters that provide the lowest distortion and
  satisfy the range of video quality requirement
  r(t) will be chosen as the QoS parameters for the
  transmission.
• The transmission module requests the video coding
  module to adjust itself to the lower value.

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Solution for Priority Transmission and Video
Application Module

• The video coding module sends the selected QoS
  parameters to set up the QoS parameters for each
  priority class of the network. In the next step
  the transmission module acknowledges this after
  set up is complete.
• The prioritized video bit stream is uploaded onto
  the network based on the QoS parameters and the
  video layer mapping policy.
• Upon the change of the channel service rate,
  parameters have to rearranged by using the same
  procedure.

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Issue2 Providing Multi User Gain

• In cross Layer Design for wireless networks on of
  the important issue is related to providing multi
  user gain without compensating for the QoS
  requirements of the users.

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CLD Architecture for a Wireless Network
33
Scheduler
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Related Issues

• How to support real time data users
  simultaneously with good QoS, with packet delays
  not exceeding given thresholds ?
• How to support a mixture of real time and non
  real time data users simultaneously with real
  time user receiving their desired QoS and non
  real time users receiving maximum throughput ?
• How to fairly allocated Bandwidth among various
  user?

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Proposed Solution

• The optimal scheduling for a wireless networks
  consists of N queues and a single server is
  serving all the queues.
• The arrival process to each of the queues is
  assumed to be i.i.d (independent n identical
  distribution) bernoulli process and the channel
  perceived by each queue is also i.i.d ON-OFF
  process.
• Then it has been proved that the policy which
  minimizes the number of packets in the system is
  when the server serves the user whose channel is
  On and has the longest queue.

36
Simulation Results for Traffic Mix Parameters
37
Issue 3

• Whenever Cross Layer design is implemented
  problems like Time Separation, Stability and
  unintended interactions between the layers have
  to be taken care of.
• This issue deals with these problems with the
  help of some examples like Adaptive Rate MAC
  Layer.

38
Rate Adaptive MAC and Minimum Hop Routing Problem

• The rate adaptive protocol is a simple variation
  of IEEE 802.11 MAC Protocol.
• The idea behind rate-adaptive MAC protocols is to
  send data at higher rates when the channel
  quality is good. And such higher rates can be
  achieved by changing the modulation scheme.

39
Rate Adaptive MAC and Minimum Hop Routing Problem

• The transmission rate can be set as required
  depending on the Modulation scheme
• The RTS/CTS are always transmitted at Base rate
• At receiver, it measures the signal strength and
  figures out the maximum rate at which the Data
  can be received given that signal strength
• This rate is then communicated through CTS
• Then the transmitter send the subsequent ACK and
  DATA packets at this data rate.

40
Plain IEEE 802.11 protocol
41
Rate Adaptive Mac Protocol

• Using minimum Hop Routing Protocol with higher
  layers protocol like Destination Sequenced
  Distance Vector (DSDV), then it had some
  undesirable effects.
• DSDV builds routing tables by sending hello
  packets to neighbors. Hello packets are broadcast
  packets that contain cumulative routing
  information.
• Since hello packets are broadcast packets, they
  are sent at the base rate, and thus have a large
  range.
• Minimum-hop routing thus chooses the longest
  possible hops on the path, which causes low
  received signal strength, which in turn implies a
  low data rate.

42
Destination Sequence Distant Vector
43
Comparison of Adaptive Rate MAC and Plain IEEE
802.11
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Conclusion Future Work

• CLD is one of the most rapidly growing
  technologies which involves cooperation and state
  information sharing between all layers, thus
  bringing a revolutionary approach.
• CLD creates some interactions between the layers.
  Some of these are intentional but some are
  unintentional resulting into the poor performance
  of the system which is contradictory to why CLD
  is used in first place?
• As the CLD architecture is not a modular one,
  everything is interconnected to other, more
  complex algorithms have to be designed.
• A system wide CLD can lead to spaghetti
  implementations which in turn will hamper further
  innovations and it becomes difficult to maintain.

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Questions?
46
References

• Introduction
• http//www.iet.ntnu.no/projects/cuban/archive/1812
  041.pdf http//www.tech.plym.ac.uk/see/research/cd
  ma/Papers/QWang20EPMCC0320paper.pdf
• Architecture
• http//www.stanford.edu/esetton/Wcomm.pdf
• http//ieeexplore.ieee.org/iel5/7742/32173/0149785
  9.pdf?tparnumber1497859isnumber32173
• issue1 http//ieeexplore.ieee.org/iel5/9692/30597
  /01417549.pdf?tparnumber1417549isnumber30597
  
• http//140.98.193.112/iel5/49/28068/01254584.pdf?t
  parnumber1254584isnumber28068

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References

• Issue2 http//140.98.193.112/iel5/49/28068/012545
  84.pdf?tparnumber1254584isnumber28068
• http//www.tech.plym.ac.uk/see/research/cdma/Paper
  s/QWang20EPMCC0320paper.pdf
• http//ieeexplore.ieee.org/iel5/35/27698/01235598.
  pdf?tparnumber1235598isnumber27698
• Issue3 http//ieeexplore.ieee.org/iel5/7742/
  30466/01404568.pdf?tparnumber1404568is20202
  0number30