1. IEEE e/Mobile WiMAX
Moise Effo

2. IEEE Overview

3. IEEE e Protocol Stack

4. Network architecture

5. PHYSICAL Layer Description
The Mobile Wimax adopts Orthogonal Frequency Division Multiple Access (OFDMA) for improved multi-path performance in non-line-of-sight environments by:
Multiplexing operation of data streams from multiple users
Dynamically assign a subset of sub-channels to individual users.
Scalable OFDMA (SOFDMA) is introduced in the IEEE e an amendment to support scalable channel bandwidths from 1.25 to 20 MHz.
Scalability is supported by adjusting the FFT size while fixing the sub-carrier frequency spacing at kHz.

6. PHYSICAL Layer Description
Since the resource unit sub-carrier bandwidth and symbol duration is fixed, the impact to higher layers is minimal when scaling the bandwidth.
802.16e systems offer scalability in both radio access technology and network architecture, thus providing a great deal of flexibility in network deployment options and service offerings.
802.16e supports TDD and Full and Half-Duplex FDD operation.

7. PHYSICAL Layer Description
Adaptive modulation and coding (AMC) is the matching of the modulation, coding and  signal strength and protocol parameters to the conditions on the radio link.
Hybrid Automatic Repeat Request (HARQ) is a combination of high-rate forward error-correcting coding (FEC), and ARQ (Automatic Repeat-reQuest) error-control for detectable-but-uncorrectable errors.
Fast Channel Feedback (CQICH) is a method of communicating feedback information between a mobile station and a base station by determining a need to request bandwidth allocation.

8. MAC Layer Description
Quality of service (QoS) is provided via service flows. This is a unidirectional flow of packets that is provided with a particular set of QoS parameters
Service
Definition
Typical Applications
QoS Specifications
Unsolicited Grant Service (UGS)
Real-time data streams comprising fixed-size data packets issued at periodic intervals.
T1/E1 transport, VoIP without silence suppression.
-Maximum Sustained Rate
-Maximum Latency
Tolerance
-Jitter Tolerance
Extended Real-time Polling Service (ErtPS)
Real-time service flows that generate variable-sized data packets on a periodic basis.
VoIP with silence suppression.
-Minimum Reserved Rate
-Traffic Priority
Real-time Polling Service (rtPS)
Real-time data streams comprising variable-sized data packets that are issued at periodic intervals.
MPEG Video.
Non-real-time Polling Service (nrtPS).
Delay-tolerant data streams comprising variable-sized data packets for which minimum data rate is required.
FTP with guaranteed minimum throughout.
Best Effort (BE)
Data streams for which no minimum service level is required and therefore may be handled on a space-available basis.
HTTP.

9. MAC Layer Description
Scheduling service is designed to efficiently deliver broadband data services including voice, data, and video over time-varying broadband wireless channel. The MAC scheduling service has the following properties that enable the broadband data service:
Fast Data Scheduler
Scheduling for both DL and UL
Dynamic Resource Allocation
QoS Oriented
Frequency Selective Scheduling

10. MAC Layer Description Mobility management
Power management Mobile Wimax supports the two modes for power efficient operation:
- Sleep Mode
- Idle Mode
Handoff there are handoffs methods supported by the mobile Wimax:
- Hard Handoff (HHO)
- Fast Base Station Switching (FBSS)
- Macro Diversity Handover (MDHO)

11. MAC Layer Description Security
Key Management Protocol for Traffic Encryption Control, Handoff Key Exchange and Multicast/Broadcast security messages.
Device/User Authentication by providing support for credential that are SIM-based.
Traffic Encryption, a cipher is used for the protection all the user data over the Mobil Wimax MAC interface. (AES-CCM)
Control Message Protection using AES Based CMAC.
Fast Handover Support there is a 3-way Handshake scheme to optimize the re-authentication mechanisms for fast handovers.

12. Advanced features of mobile wimax
Smart antenna technologies:
typically involve complex vector or matrix operations on signals due to multiple antennas. OFDMA allows smart antenna operations to be performed on vector-flat sub-carriers. Complex equalizers are not required to compensate for frequency selective fading.
Mobile Wimax supports a full range of smart antenna technologies to enhance system performance.
Beamforming for a better coverage and capacity of the system and reduce outage probability.
Space-Time Code(STC) transmit diversity codes are used to provide spatial diversity and reduce fade margin.

13. Advanced features of mobile wimax
Smart antenna technologies
Spatial Multiplexing(SM) is to take advantage of higher peak rates and increases throughput.
multiple streams are transmitted over multiple antennas
both receiver and transmitter must have multiple antennas to achieve higher throughput.
The inclusion of MIMO antenna techniques along with flexible sub-channelization schemes, Advanced Coding and Modulation all enable the802.16e technology to support a high data rate:
•peak DL data rates up to 63 Mbps per sector and
•peak UL data rates up to 28 Mbps per sector
in a 10 MHz channel.

14. Advanced features of mobile wimax
Fractional Frequency reuse
All cells/sectors operate on the same frequency channel to maximize spectral efficiency.
Users operate on sub-channels, which only occupy a small fraction of the whole channel bandwidth
The flexible sub-channel reuse is facilitated by sub-channel segmentation and permutation zone

15. Advanced features of mobile wimax
Multicast and Broadcast Service (MBS)
combines the best features of DVB-H, MediaFLO and 3GPP
E-UTRA and satisfies the following requirements:
High data rate and coverage using a Single Frequency Network (SFN)
Flexible allocation of radio resources
Low MS power consumption
Support of data-casting in addition to audio and video streams
Low channel switching time

16. Key advantages of Mobile WIMAX
Tolerance to Multipath and Self-Interference
Scalable Channel Bandwidth
Orthogonal Uplink Multiple Access
Support for Spectrally-Efficient TDD
Frequency-Selective Scheduling
Fractional Frequency Reuse
Fine Quality of Service (QoS)
Advanced Antenna Technology

17. summarize
Mobile Wimax can be considered as a real competitor for 3G for example in IP-traffic(VoIP/ IPTV).
Mobile Wimax supports seamless handoff which provides switching between base stations in vehicular speeds.
Mobile Wimax uses Scalable OFDMA multiplexing which maximizes the spectral efficiency.

18. IEEE e/Mobile WiMAX
Questions