1. AUTO3120 Enhancing WIMAX System Design Performance with FPGAs Seminar Presentation Samuel Ailen-Ubhi T94766 University of Vaasa
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2. Worldwide Interoperability for Microwave Access
WIMAX
Worldwide Interoperability for Microwave Access

3. Contents of WiMAX Seminar
WiMAX Overview
WiMAX Infrastructure
WiMAX and Standards
WiMAX Forum
WiMAX Protocol architecture
Physical layer
Medium Access layer
WiMAX System Design with FPGAs

4. What is WiMAX. - Protocol of communication network without wire
What is WiMAX? - Protocol of communication network without wire. - Allows communications over long distances with greater bandwidth than WiFi, and also a method for providing backhaul to WiFi.

5. WiMAX
Provides high-speed Internet access to home and business subscribers, without wires.
Frequency range of10-66 GHz LoS and additional range of GHz NLoS.
It Supports Legacy voice systems, voice over IP, TCP/IP, applications with different QoS requirements etc.
It consists of access point, BS(Base Station) and SSs (Subscriber Stations).
All data traffic goes through the BS, and the BS control the allocation of bandwidth on the radio channel.
During a communication, all the information coming from an SS go to the BS and are retransmitted back to the right SS.
Base stations (BS) can handle thousands of subscriber stations (SS).
Two type of link are defined:
The downlink: From the BS to the SS.
The uplink: From the SS to the BS.

6. WiMAX Infrastructure
A WIMAX tower: similar in concept to a cell-phone tower. A single WIMAX tower can provide coverage to a very large area (50 km).
A WIMAX receiver : The receiver and antenna could be a small box or PCMCIA card, or could be built into a laptop.

7. WiMAX and Standards IEEE 802.16 (2001)
Air Interface for Fixed Broadband Wireless Access System MAC and PHY Specifications for 10 – 66 GHZ (LoS)
One PHY: Single Carrier
Connection-oriented, TDM/TDMA MAC, QoS, Privacy
IEEE a (January 2003)
Amendment to , MAC Modifications and Additional PHY Specifications for 2 – 11 GHz (NLoS)
Three PHYs: OFDM, OFDMA, Single Carrier
Additional MAC functions: OFDM and OFDMA PHY support, Mesh topology support, ARQ
IEEE d (July 2004)
Combines both IEEE and a
Some modifications to the MAC and PHY
IEEE e (2005)
Amendment to
MAC Modifications for limited mobility

8. WiMAX and Standards
IEEE e-2005 improvements upon IEEE
Adding support for soft and hard handover between base stations (mobility)
Advanced antenna diversity schemes, and hybrid automatic repeat-request (HARQ)
Adaptive Antenna Systems (AAS) and MIMO technology
Introducing downlink sub-channelization,
allowing administrators to trade coverage for capacity or vice versa
Adding an extra QoS class for VoIP applications
IEEE e-2007: Management Plane Procedures and Services- in progress
IEEE e-2009: Air Interface for Fixed and Mobile Broadband Wireless Access System- in progress

9. WiMAX Forum Not-for-profit organization
Formed to certify and promote the compatibility and interoperability of broadband wireless products based upon the harmonized IEEE /ETSI Hiper MAN standard.
WiMAX Forum Certified™ products are fully interoperable and support broadband fixed, portable and mobile services.
The WiMAX Forum has hundreds of members, comprising the majority of operators, component vendors and equipment vendors in the communications ecosystem• AT&T, British Telecom, Fujitsu, Intel, Motorola, Nokia, Samsung, Lenovo, Sharp Corporation, LG Electronics etc
“WiMAX Forum” is aregistered trademark.

10. WiMAX Protocol architecture
Physical Layer
Medium Access Layer

11. Physical layer

12. Physical layer
The flow of bits is structured as a sequence of frames of equal length.
There is a downlink subframe and an uplink subframe and two modes of operation.
The duplex scheme is usually specified by regulatory bodies, e.g., FCC
Time-Division Duplex (TDD)
Downlink & Uplink time share the same RF channel
Dynamic asymmetry
does not transmit & receive simultaneously (low cost)
Frequency-Division Duplex (FDD)
Downlink & Uplink on separate RF channels
Full Duplexing (FDX): can Tx and Rx simultaneously;
Half-duplexing (HDX) SSs supported (low cost

13. Physical layer
Orthogonal Frequency Division Multiplexing Access(OFDM/OFDMA) where the spectrum is divided into many sub-carriers
Each sub-carrier then uses QPSK or QAM for modulation Scalable OFDMA (SOFDMA) to support scalable subcarrier bandwidths from 1.25 to 20 MHz
Sub-carrier spacing at kHz.
OFDMA spreads the energy of an impulse noise over a WiMAX-OFDMA burst. This means that instead of a few symbols being lost, the noise level slightly increases over a burst, which may not cause an increase in the error-rate.

14. WiMAX Protocol architecture
The MAC is comprised of three sublayers.
The Service Specific Convergence Sublayer (CS) provides any transformation or mapping of external network data, received through the CS service access point (SAP), into MAC SDUs received by the MAC Common Part Sublayer (MAC CPS) through the MAC SAP.
The Common Part exchanges MAC service data units (SDUs) with the Convergence layer.
The Security sub layer addresses authentication, establishment of keys and encryption and exchanges MAC PDUs with the Physical layer.

15. Physical and MAC layers

16. Physical and MAC layers
Overview of PHY Layer functions in a typical WiMAX base station

17. Physical layer Security Threat
Jamming attack: achieved by introducing a source of noise strong enough to significantly reduce the capacity of the channel
Solution: prevent jamming attack by increasing the power of signals or by increasing the bandwidth of signals using spreading techniques such as frequency spread spectrum
Scrambling attack: scrambling is a kind of jamming but only provoked for short intervals of time and targeted to specific WiMAX frames or parts of frames at the PHY layer.
Solution: we can use anomalies monitoring beyond performance norm (or criteria) to detect scrambling
Water torture attack: this is also a typical attack in which an attacker force a SS to drain its battery or consume computing resources by sending a series of bogus frames.
Solution: a sophisticated mechanism is necessary to discard bogus frames, thus avoiding running out of battery or computational resources.

18. MAC Security Threat Eavesdropping of management messages.
BS or MS masquerading.
Management message modification.
Man in the middle attack.
Denial of Service attack.
Solutions: Key authentication. Countermeasures need to be devised for networks using the security options with critical or major risks. An intrusion detection system approach can be used to address some of the threats. More research is needed in this direction.

19. WiMAX System Design with FPGAs
Hardware Platform for WiMAX Implementation- Challenges
- Processing speed: Hardware platform must have significant processing capabilities to support high data rate.
- Flexibility: WiMAX is a relatively a new market and still undergoing it product life cycle in the development/deployment stage.
- Time to Market: This has a direct effect on the development life cycle and choice of hardware platform.
- Cost Reduction Path: Plans to use resources and to access the final stage after the initial uncertainty surrounding it should also be considered.

20. Field programmable gate arrays -Stratix II Device Floorplan
Altera’s Stratix II FPGA, are usually used at the heart of high-bandwidth systems to accelerate performance and enable new functionality
Stratix II devices improve on the features that set new standards in FPGAs

21. Field programmable gate arrays -Stratix II Device Floorplan
Up to 9 Mbits of memory in three block sizes: M-RAM, M4K, and M512 blocks
Includes parity bits for error checking
Performance up to 370 MHz
Mixed-width data and mixed-clock modes
Maximized performance of up to 370 MHz providing DSP throughput up to 284 GMACs
Up to 12 PLLs (four enhanced PLLs and eight fast PLLs) per device to provide spread sspectrum, programmable bandwidth, clock switchover, real-time PLL reconfiguration, and advanced multiplication and phase shifting
Remote system upgrades for reliable and safe deployment of in-system upgrades and bug fixes

22. WiMAX System Design-FPGA
Overcoming WiMAX system design implementation challenges with FPGAs.
Processing Speed:
- High performance FPGAs contain embedded DSP blocks, TriMatrix memory architecture, innovative logic structure, and high-speed interfaces.
- These features provide powerful and integrated platform to implement broadband wireless systems such as WiMAX.
- Each DSP block can support a variety of multiplier bit sizes and operation modes .

23. Stratix II DSP Block Architecture

24. WiMAX System Design-FPGA
Flexibility:
- Altera’s Stratix II FPGAs provide the ability to easily evolve WiMAX systems in accordance with changing market demands.
- These devices allow remote system upgrades to be transmitted over any communications network.
- Remote system upgrades are enabled using Stratix II devices and flash memory

25. WiMAX System Design-FPGA
Time-to-Market
- key differentiator for developing WiMAX compliant
products.
- To achieve this, designers need access to off-the-shelf IPs and reference designs that help accelerate their own development cycle
- some of the PHY layer solutions available from Altera :
a. Forward Error Correction (FEC)
b. OFDM modulation/demodulation
c. Multiple Antenna Techniques

26. WiMAX System Design-FPGA
Cost Reduction Path
- Altera provides this cost reduction path for its FPGAs through HardCopy devices.
- Altera HardCopy devices are the industry’s first structured ASICs that offer a comprehensive alternative to traditional
ASICs
- Altera provides FPGAs, development tools, intellectual property (IP), and a seamless migration path from the function-verified prototypes to high-volume production devices.

27. Conclusions
WiMAX is an emerging technology with significant potential broadband wireless internet access market
The diverse hardware requirements including processing speed, flexibility, integration and time-to market necessitate an FPGA based implementation platform.

28. Summary WiMAX Overview WiMAX Infrastructure WiMAX and Standards
WiMAX Forum
WiMAX Protocol architecture
Physical layer
Medium Access layer
WiMAX System Design with FPGAs

29. Thank You
Questions

30. References
IEEE
Alcatel White Paper: WiMAX, making ubiquitous high-speed data services a reality
Intel White Paper: Understanding WiMAX and 3G for Portable/Mobile Broadband Wireless
WiMAX Forum:
Stratix II Device Family Features: