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Physical Layer: Scalable OFDM (Orthogonal Frequency Division Multiplexing)Unlike CSMA, OFDM does not have contention and collisionsThe minimum time-frequency resource allocated per user is called a slotEach slot consists of one subchannel over one, two, or three OFDM symbolsA contiguous series of slots assigned to a given user is called the user’s data regionThe scheduler allocates data regions to users based on demand, QoS requirements, and channel conditions
ACCESS SERVICE NETWORK (ASN)Access gateway (ASN GW) – provides the micro-mobility anchor point and supports bearer services. Also supports the Foreign Agent.Base station (BS) – provides the radio dependent functions and has limited IP functionality
CORE SERVICES NETWORK (CSN)Home agent (HA) – provides the macro-mobility anchor point and supports bearer services, if roaming/mobility is desired. Other Network Elements such as AAA, DHCP servers and more are also in the CSN.
Profile A: Central radio resource management in ASN-GW approachProfile B: Closed interfaces favor radio network (BS) vendorsProfile C: Open interfaces with separation between radio and network functionality favors Cisco
PHY and partly MAC in BTSHandover-Control (RRM) in ASNGWRouting and AAA/Paging in ASN-GW
BSBSBS
ASNASN-GW
[BSC]
A
All radio-specific functions in BSHandover-Control (RRM) in BSRouting and AAA/Paging in ASN-GW
ASNGW
BSBSBS
ASNCBSBSBS
Most ASN functions in BSBS anchored by standard router Inter-BS control over Ethernet
WiMAX QoS and Scheduling SchemesSpecifications and Applications…
Service Flows:Mechanism defined in Mobile WiMAX to provide QoS
Uni-directional flow of packets associated with certain defined QoS parameters for traffic
Packet Classifiers:Each service flow also has packet classifiers associated with it to determine criteria used by the MAC layer to associate packets into service flows
Mobile WiMAX scheduling based on QoS service Flows associated with each packet
QoS Category Applications QoS Specifications
UGSUnsolicited Grant
Service
VoIP • Maximum Sustained Rate
• Maximum Latency• Jitter Tolerance
rtVRReal-Time Variable
Rate Service
Streaming Audio or Video
• Minimum Reserved Rate
• Maximum Sustained Rate
• Maximum Latency• Traffic Priority
ErtVRExtended Real-Time
Variable Rate Service
Voice with Activity Detection (VoIP)
• Minimum Reserved Rate
• Maximum Sustained Rate
• Maximum Latency• Jitter Tolerance• Traffic Priority
nrtVRNon-Real-Time Variable Rate
Service
FTPFile Transfer Protocol
• Minimum Reserved Rate
• Maximum Sustained Rate
• Traffic Priority
BEBest-Effort Service
Data, Web Browsing, etc.
• Maximum Sustained Rate
• Traffic Priority
*Not all of these QoS Categories are supported by Cisco Base station
Energy is dispersed across an entire 90° or 120° sectorGain decreases quickly with distance, degrading performanceLimited coverage. Cells must be tightly spaced for good performanceInter-cell interference adversely affects frequency reuse
Array is recalibrated every 5ms, energy is focused at individual subscribersGain (64x) remains high over long distances, improving performanceExpanded Coverage. Cells can be widely spaced while providing good performanceInter-cell interference is minimized, allowing maximum frequency reuse
Adaptive Beamforming Using Many Antenna Elements—A Cisco Leadership Technology—Is Most EffectiveSwitched Lobe Beamforming Adaptive Beamforming
Multiple directionalsub-sector antennasFixed, static lobesLobe selected based on received signal strength
4-element dynamic phased antenna arrayFixed, static beamsSingle beam selected based on angle of arrivalMultipath inhibits beam selection
8-element dynamic phased antenna arrayInfinite, dynamic beamsNew beams calculated every 5ms based on angle of arrival, phase, and signal strength for each userMultipath leveraged for optimum performance
Single-Input Single-OutputSingle antennas at both base station and subscriber deviceUsed in WiMAX Wave 1 deployments
TT RR
TT RR
TT RR
S2 S1
MIMO Matrix-A (Space Time Coding) Symbols are sent redundantly in both space and timeStreams are reconstructed using intact symbols at the receiverIncreases link reliability and fading margins (+3 dB)
MIMO Matrix-B (Spatial Multiplexing)Symbols are divided and multiplexed in spaceMultipath must exist to prevent signals from becoming coherent and therefore indistinguishable at the receiverIncreases throughput for stationary subscriber devices
S2
S1
TT RR
TT RR
S1S3
S4
MIMO Antenna Systems Enable Techniques that Improve Received Power Levels, Path Reliability, and Path Performance
S2
Cisco Broadband Wireless AccessMobile WiMAX MIMO Explained
Enables open Mobile WiMAX ASN architectures for maximum design & deployment flexibilityBuilt on the Cisco 7600 Series – the carrier-class converged services platform providing access to thousands of IOS featuresThe most powerful ASN-GW platform available –scalable from 5 to 45 GbpsMPLS and IPSec VPNs enables secure residential and business services over a common infrastructurePart of the Cisco Service Exchange Framework, enabling precise control over each subscriber’s quality of experience
Performance, scalability, and sophisticated features ensure maximum value for service providers
Cisco Broadband Wireless Gateway (BWG)—A High Performance Open Profile-C ASN Gateway for Mobile WiMAX Access
Business Services (Ethernet and MPLS Services)Centralized Control Plane FunctionDistributed bearer enables transport efficiency
Layer-2 switched locally at base station, or in Carrier Ethernet across bridge domainsLayer-3 controlled centrally, switching/routing inCarrier Ethernet
Traffic carried as Ethernet packets
Residential ServicesCentralized Control and Data Plane FunctionEnables control of subscriber traffic and servicesEnable Tiered Services and Flexible MeteringSimplifies the transport network designScales Ethernet based transport network
Enables flexible deployment, tight service control, and transport efficiency