Behind Mobile WiMAX Chenxi Zhu, Ph.D. Fujitsu Labs of America College Park, MD Email: czhu@ieee.org
What is mobile WiMAX? � Mobile broadband wireless access � Defined by IEEE and WiMAX Forum. � IEEE 802.16e_2005: wireless MAN-OFDMA � PHY and MAC layer. � WiMAX Forum: � System profiles, testing, networking protocols, applications, certification, etc. � Marketing and promotion.
Mobile WiMAX network Mobile IP-based Networking layer Core Network TDD or FDD 802.16e air interface: spectrum • OFDMA-based PHY, • QoS-oriented MAC Cellular deployment Radio Access Network
� OFDMA PHY layer � QoS oriented MAC layer � Mobile IP-based networking layer � Future of WiMAX
OFDM PHY layer Frequency domain Time domain � Frequency domain signaling. � ICI-free: orthogonal between subcarriers. � ISI-free: guard interval between symbols. � Robust against multiple paths. � No equalization required at receiver.
OFDMA: OFDM for multiple access User 1 User 2 User 3 User 4 Base station assigns the subcarriers to users in DL and UL. � Radio resources (subcarriers, transmission powers) are � allocated based on user channel quality and BW requirement (QoS).
Scalable PHY layer TDD or FDD, variable frame length (2—20 ms). � Different FFT sizes (128, 512, 1024, 2048) for variable BW � (1.25MHz--20MHz). Variable CP length (1/32,1/16,1/8,1/4) for different cell size. � Same inter-subcarrier spacing (97.2KHz). � Multi-modes supported with a single SoC. � Adaptive modulation and coding. � QPSK, 16QAM, 64QAM. � CC, CTC, BTC, LDPC (1/2, 2/3, ¾, 5/6). � Beamforming and MIMO. � Common or dedicated pilots. � HARQ (Chase, IR). �
Different subchannelization for different mobility. Diversity permutation Contiguous permutation (PUSC, FUSC) (AMC)
TDD Frame structure Preamble: power boosted for BS identification and � synchronization. Control channel (FCH, DL-MAP, UL-MAP): assign � subchannels to users, power level, modulation/coding. DL/UL Burst: data packets BS �� MS. �
Multiple antennas (MIMO) MIMO SC de-mapping IFFT FFT MIMO SC mapping MIMO encoder MIMO decoder IFFT FFT IFFT FFT IFFT FFT � Close loop transmitter beamforming. � Space time code (Alamouti scheme). � Spatial multiplexing. � Up link: virtual MIMO.
� OFDMA PHY layer � QoS oriented MAC layer � Mobile IP-based networking layer � Future of WiMAX
QoS support by connection- oriented scheduled MAC Service Flow over QoS connection
WiMAX QoS classes QoS Category Applications QoS Specifications UGS (CBR) VoIP Maximum Rate, Maximum Delay (Unsolicited Grant Jitter Tolerance Service) RT-VR Streaming Audio Minimum Rate, Maximum Rate, or Video Maximum Delay, Traffic Priority (Real-Time Variable Rate service) ERT-VR VoIP with Minimum Rate, Maximum Rate, Activity Maximum Delay, Jitter Tolerance, Traffic (Extended Real-Time Detection Priority Variable Rate service) NRT-VR FTP Minimum Rate, Maximum Rate, Traffic Priority (Non-Real-Time Variable Rate) BE Data Transfer, Maximum Rate, Traffic Priority Web browsing (Best Effort Service)
� OFDMA PHY layer � QoS oriented MAC layer � MIP-based networking layer � defined by WiMAX Forum NWG � Future of WiMAX
Mobile IP-based network architecture MIP FA
� OFDMA PHY layer � QoS oriented MAC layer � Mobile IP-based networking layer � Future of WiMAX
Current development of 802.16 � 802.16j: multi-hop relay � Enhance coverage and capacity of 802.16e with relay stations. � 802.16m: targeting IMT-Advanced � Support BW ≥ 20MHz. � Backward compactable with 802.16e. � 100 Mbps at high mobility. � 1 Gbps for fixed user.
Industry synergy � System vendors � Samsung, Motorola, Alcatel-Lucent, Nortel, Nokia-Siemens, Huawei, ZTE, … � Chip manufactures � Intel, Fujitsu, Runcom, Beecem, … � Device manufactures � Nokia, Samsung, Motorola, Sony-Ericsson,… � Service providers � Sprint, AT&T, Nextwave, SK-Telecom, KDDI, French- telecom, Telecom-Italia, DirectTV, …. � Content provider � Disney
Roadmap to market
Who may deploy WiMAX? Fixed point-to-point (LOS): 802.16d-OFDM � Wireless backhaul � Fixed point-to-multipoint (NLOS): 802.16d/e-OFDM/OFDMA � DSL/cable replacement � CCTV � Nomadic data application (Laptop, Handhold): OFDM/OFDMA � Better coverage than WiFi Hotspot � Mobile data, data/voice (OFDMA) � 4G? � Intelligent transportation system (OFDMA) � Transportation infrastructure � Vehicle to curb �
World wide WiMAX trials
Further information � www.wimaxforum.org � www.wimaxtrends.com � Google!
Backup slides
Scalable OFDMA PHY layer 4 FFT sizes (128, 512, 1024, 2048) for variable Bandwidth. Adaptive Modulation and coding for different channel quality
802.16e Subcarrier allocation Pilot sub-carrier for channel estimation. � Data sub-carrier for data transmission. � No transmission in Null sub-carriers (DC, guard-band). �
Air Interface Protocol Stack
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