By

D. Jayasakthi

Student ID No. 100998001

Advisor : Prof Dr. Kai-Wei ke

Wireless And Broadband Networks Lab

National Taipei University of Technology,

Taipei, Taiwan-106. (ROC)

WiMAX

(Worldwide Interoperability for Microwave Access)

1

Contents Introduction Wimax Research Article

Abstract Quality of service Call Admission Control (CAC) Mechanism Proposed Scheme Results Conclusion

References

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IEEE 802.16 Overview

IEEE 802.16 is a series of Wireless Broadband standards authored by the Institute of Electrical and Electronics Engineers (IEEE).

The IEEE Standards Board established a working group in 1999 to develop standards for broadband Wireless Metropolitan Area Networks.

The Workgroup is a unit of the IEEE 802 local area network and metropolitan area network standards committee.

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IEEE 802.16 Overview Scope :

Specifies the air interface, MAC (Medium Access Control), PHY(Physical layer)

Purpose : To enable rapid worldwide deployment of cost-effective broadband

wireless access products.

To facilitate competition in broadband access by providing alternatives to wire line broadband access

Main advantage : Fast deployment, dynamic sharing of radio resources and low cost.

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WiMax

Although the 802.16 family of standards is officially called WirelessMAN in IEEE, it has been commercialized under the name “WiMAX” (from "Worldwide Interoperability for Microwave Access") by the WiMAX Forum industry alliance.

The Forum promotes and certifies compatibility and interoperability of products based on the IEEE 802.16 standards.

Provide broadband (i.e., voice, data, video) connectivity

802.16e is an amendment to 802.16d (fixed or nomadic wireless broadband) to support mobility

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WiMax WiMAX (Worldwide Interoperability for Microwave Access) is a

communication technology for wirelessly delivering high-speed Internet service to large geographical areas.

The 2005 WiMAX revision provided bit rates up to 40 Mbit/s with the 2011 update up to 1 Gbit/s for fixed stations.

It is a part of a “fourth generation,” or 4G, of wireless-communication technology.

WiMax offers data-transfer rates of up to 75 Mbit/s, which is superior to conventional cable-modem and DSL connections.

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Roadmap for WiMAX

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Basic WiMAX Network Architecture

• Fixed/Mobile wireless broadband network to replace “last mile” w/ properties of lower cost and easier to deploy

Subscribe Station (SS)

SS

Radio tow er

Wireless link

Radio tow er

Radio tow er

Radio tow er

Base Station (BS)

SS

Core netwo

rk

Users

• BS/SS interfaces: Hub, Wi-Fi

Mobile WiMAX enables convergence of mobile and fixed broadband networks through a common wide area broadband radio access technology and flexible network architecture

Adopt OFDMA for improved multi-path performance in NLOS

Scalable OFDMA (SOFDMA) is introduced in IEEE 802.16e to support scalable channel bandwidths from 1.25 to 20 MHz

Release-1 will cover 5, 7, 8.75, and 10 MHz channel bandwidths for licensed worldwide spectrum allocations in the 2.3, 2.5, 3.3, and 3.5 GHz frequency bands

Mobile WiMAX

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Features of Mobile WiMAX High Date Rates

Peak DL data rates up to 63 Mbps per sector and peak UL data rates up to 28 Mbps per sector in the 10 MHz channel.

QoS

Fundamental characteristic of MAC architecture. Supports a wide range of data services and applications with varied QoS requirements.

Scalability

Able to scale to function in different channelizations from 1.25 to 20 MHz to comply with varied worldwide requirements.

Security

Flexible key management schemes assures that security is maintained during handovers.

Mobility

Support optimized handover schemes with latencies less than 50 ms.

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Bandwidth and Delay Guaranteed Call AdmissionControl Scheme for QoS Provisioning in IEEE

802.16e Mobile WiMAX

K. Suresh , I. S. Misra and K Saha,

IEEE GLOBECOM 2008, Page no(1-6),

DOI- 10.1109/GLOCOM.2008.ECP.246

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Abstract An efficient Call Admission Control (CAC) scheme for IEEE 802.16e

Mobile WiMAX that satisfies both bandwidth and delay guarantee to the admitted connections has been proposed in this paper.

The proposed CAC scheme provides higher priority to Handoff connections, because it is more annoying to drop an ongoing connection than blocking a newly originated connection.

Also UGS connections are given higher priority because UGS is the most common service used by the people for communication in everyday life.

An analytical model is developed to evaluate the performance of the CAC scheme using Continuous Time Markov Chain Model.

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Connection Types

Base station receives 2 types of connection:

New Originating Connection

Handoff Connection

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Quality of Service (QoS) Supports a wide range of data services and applications with varied QoS

requirements. These are summarized in Table 1

Source: “Mobile WiMAX – Part I: A Technical Overview and Performance Evaluation,” WiMAX Forum, August, 2006

Table 1: Mobile WiMAX Applications and QoS

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Quality of Service(QoS)

The QoS parameters specified in the standard are

Maximum Sustained Traffic Rate (MSTR)

Minimum Reserved Traffic Rate (MRTR)

Maximum Latency (ML)

Tolerated Jitter (TJ)

Request/Transmission Policy.

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Different Types of Connections

Newly originated UGS connection Handoff UGS connection

Newly originated Rtps connection Handoff Rtps connection

Newly originated nrtPS connection Handoff nrtPS connection

Therefore the priority order of different types of service flows is H-UGS > H-rtPS > O-UGS > O-rtPS> H-nrtPS> O-nrtPS where H stands for Handoff and O stand for newly originated connections respectively.

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Call Admission Control(CAC) Mechanism CAC plays an important role in QoS provisioning for IEEE 802.16 networks

The MAC of IEEE 802.16 is connection oriented; therefore the Subscriber Station(SS) should establish an end-to-end connection with the Base Station(BS), before actually transmitting the data.

For this the SS should send a request with the required QoS parameters for connection admission, to the Base Station (BS).

The BS upon receiving the request will check whether it can provide the required QoS for that connection, if the request was accepted and at the same time verifies whether the QoS of all the ongoing connections can be maintained

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Interaction Between Base Station and Subscriber Station

Subscriber Station

Base Station

1. SS begins scanning presets frequency for base station.2. BS responds. Synchronizes with SS.

3. SS send a request with the required QoS parameters for connection admission

4. The BS will check whether it can provide the required QoS and accept the connection

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New UGS Connection

Bugs

If(Bre

m>Bug

s

If(delay guarantees of admitted

rtps connection )

satisfied

Admit the connection

Not satisfied Reject connectio

n

A

B Yes

No

Proposed Bandwidth and Delay Guaranteed CAC Scheme

If(Bre

m<Bug

s

A

Degrade Bandwidth in steps of

δ

If (max degradation level

reached)

yes

B

NO

Reject the connection

NO

yes If(Bre

m<Bug

s

Proposed Bandwidth and Delay Guaranteed CAC Scheme

Results

In the figure ugs1 is obtained using the proposed CAC scheme in this paper and ugs2 and ugs3 represent CAC schemes proposed in the reference papers.

From figure, we can notice that the BPs of UGS connection are less in the case of the ugs1 compared to ugs2 and ugs3.

Also there is a negligible difference in DPs of UGS connection in between the three models.

Blocking Probabilities (BPs) and Dropping Probabilities (DPs) of UGS.

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In the figure rtps1 is the proposed CAC scheme in this paper and rtps2 and rtps3 represent CAC schemes proposed in the reference papers.

From figure, we can notice that the BPs of rtPS connection are less in the case of the rtps1 compared to rtps2 and rtps3.

Also there is a negligible difference in DPs of rtPS connection in between the three models.

Blocking Probabilities (BPs) and Dropping Probabilities (DPs) of rtPS.

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From figure we can see that, the BP of nrtPS connections is slightly higher than nrtps3, but BPs are still less than nrtps2.

The only disadvantage of this scheme is that DPs of nrtPS connections are higher than nrtps2 and nrtps3.

But this does not have much effect on the performance of the system considering the priority of real time connections over the nonreal time connections.

Blocking Probabilities (BPs) and Dropping Probabilities (DPs) of nrtPS.

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The figure shows the Comparison of the bandwidth utilization of the system.

The Bandwidth Utilization is more in case of the proposed scheme compared to BU2 and BU3

Bandwidth Utilization of the system

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It is seen that for a system, there is a threshold limit above which no variation of BU occur.

It indicates the delay guarantee is automatically satisfied after reaching the threshold.

Bandwidth Utilization of the System for Different Delays.

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Conclusion

From the numerical results we can conclude that the proposed CAC scheme could be the better choice for admission control in Mobile WiMAX in terms of NCBP and HCDP of different types of connections and the bandwidth utilization of the system.

The threshold limit for delay guarantee for the mobile WiMAX system may be obtained from this scheme.

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References IEEE 802.16-2004, “IEEE Standard for Local and Metro-politan Area

Networks. Part 16: Air Interface for Fixed Broadband Wireless Access Systems,” Rev. of IEEE 802.16-2001, pp.1-857.

Kitti Wongthavarawat, and Aura Ganz, “Packet schedul-ing for QoS support in IEEE 802.16 broadband wireless ac-cess systems”, International Journal of Communication Sys-tems, vol. 16, issue 1, February 2003, pp. 81- 96.

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Thank you

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Q & A

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