Cross Layer Design -Suparna

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

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

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

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

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

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

Cross Layer Signaling Methods Method I – Packet headers

Method II – ICMP Messages

Method III – Local Profiles

Method IV – Networks Services

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

Method I – Packet Headers Method II – ICMP Messages

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

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.

Method III – Local Profile

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.

Method IV – Networks Services

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

Application of CLD in AD-HOC Networks for

Real time Video Streaming

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

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

PSNR performance for video Streaming for two different Networks

Issue 1:Video 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).

Architecture of a cross layer QoS Management for video delivery over wireless

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.

GOP structure of MPEG video file

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)

Solution: Tree search approach

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.

Solution for Priority Transmission and Video Application Module

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.

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.

Issue:2 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.

CLD Architecture for a Wireless Network

Scheduler

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?

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.

Simulation Results for Traffic Mix Parameters

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.

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.

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.

Plain IEEE 802.11 protocol

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.

Destination Sequence Distant Vector

Comparison of Adaptive Rate MAC and Plain IEEE 802.11

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.

Questions?

References Introduction: http://www.iet.ntnu.no/projects/cuban/archive/1812041.pdf

http://www.tech.plym.ac.uk/see/research/cdma/Papers/QWang%20EPMCC03%20paper.pdf

Architecture: http://www.stanford.edu/~esetton/Wcomm.pdf http://ieeexplore.ieee.org/iel5/7742/32173/01497859.pdf?tp=&arnumber=

1497859&isnumber=32173 issue:1 http://ieeexplore.ieee.org/iel5/9692/30597/01417549.pdf?tp=&

arnumber=1417549&isnumber=30597 http://140.98.193.112/iel5/49/28068/01254584.pdf?tp=&arnumber

=1254584&isnumber=28068

References Issue2:

http://140.98.193.112/iel5/49/28068/01254584.pdf?tp=&arnumber=1254584&isnumber=28068

http://www.tech.plym.ac.uk/see/research/cdma/Papers/QWang%20EPMCC03%20paper.pdf

http://ieeexplore.ieee.org/iel5/35/27698/01235598.pdf?tp=&arnumber=1235598&isnumber=27698

Issue3: http://ieeexplore.ieee.org/iel5/7742/30466/01404568.pdf?tp=&arnumber=1404568&is%20%20%20number=30