Wi MAX IEEE 802 16 Standards Protocol Presented

Wi. MAX: IEEE 802. 16 Standards / Protocol Presented by Dr. Sim Moh Lim mlsim 2003@gmail. com Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 1

Agenda • Part 2: Wi. MAX: IEEE 802. 16 Standards / Protocol (2 h) – – – Concept of OFDM System Concept of OFDMA Physical layer MAC layer Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 2

Basic Features Concept of OFDM Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 3

Orthogonal Frequency Division Multiplexing (OFDM) • Frequency Division Multiplexing (FDM) technique that divides the channel into multiple orthogonal subchannels – Input data stream is divided into several substreams of a lower data rate (increased symbol duration) – each substream is modulated and simultaneously transmitted on a separate subchannel with carrier orthogonal to each other FDM OFDM n Source: CSCE 4520/5520 Fall 2006, Shori Fukatsu Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 OFDM is more spectral efficient as compared to FDM (allows more transmission channels) 4

Orthogonality Concept • Cross-correlation: – <x(t)y(t)> = 1/T∫T x(t)y(t)dt – Correlator: a device that does multiplying and the integration • Auto-correlation: – <x(t)x(t-d)> = 1/T∫T x(t)x(t-d)dt • If x(t) and y(t) are orthogonal over T – <x(t)y(t)> = 1/T∫T x(t)y(t)dt = 0 – 1/T∫T x(t)dt = 1/T∫T y(t)dt = C, constant Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 5

Application of Orthoganality • Send signal, s(t) = a. x(t) + b. y(t) – a and b are the messages; x and y are the carriers. • At the desired “receiver” of message a and carrier x(t), we can use a correlator to recover message: – < s(t)x(t)> = < [a. x(t)+b. y(t)]x(t) > = a<x(t)> + b<y(t)x(t)> = a. C + b. 0 =a (constant C can be set to 1) • Example: Chebyshev polynomial of the first kind, Jacobi polynomial, Legendre polynomial, and cosines. Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 6

OFDM Basics • Each subcarrier can be used to carry one complex QAM symbol, di of duration T – The send signal is given by: s(t) =Re{∑i di exp(j 2Π(fc+ iΔf)t)} for 0 < t < Tb Source: www. iec. org/online/ tutorials/ofdm/topic 04. html • • Δf Frequency Note that the subcarriers are orthogonal to each other However, shape will be distorted (becomes non-orthogonal) by – (i) Frequency Offset – (ii) Fading Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 – Its complex baseband is: s(t) =∑i di exp(j 2Π it/T) which is the Inverse Fourier Transform (IFT) of N symbols. – N is frequently called the FFT size – The discrete time equivalent is the inverse discrete Fourier Transform (IDFT) : s[n] =∑i di exp(j 2Πin/N) 7

Condition for Orthogonality in OFDM • To maintain orthogonality (no interference between subcarriers): – 1/Tb∫Tb cos(2Πfct)cos(2Π(fc+Δf)t)dt = 0 • 1/Tb∫Tb cos(2Πfct)cos(2Π(fc )t)dt = 1/2 – Which can be simplified to: 1/Tb = Δf where • Δf = sub-carrier spacing • Tb = symbol duration • If N-point IDFT (or DFT) is used – Total bandwidth (in Hz) , BW = NΔf – Ts = Tb + Tg = symbol duration after Cyclic Prefix addition Time Tb Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 Physical interpretation of orthogonality requirement: all sin-waves used must have integer number of cycles within Tb 8

OFDM and Multipath delay n Multipath causes n inter-carrier interference (ICI) n Delayed subcarrier #2 signal has no complete integer number of cycles within 1 OFDM symbol (integration time) n inter-symbol interference (ISI) n The phase transitions in the delayed path are causing problem Tb = integration time ICI Source: Book on OFDM by R. Prasad Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 ISI Solid line: first arriving path Dashed line: delayed path 9

OFDM and Multipath delay n through the operation of Cyclic Prefix insertion/ extraction n Interference from previous transmitted blocks is eliminated provided the delay spread is much smaller than Tg Source: EECS 228 a, Shyam Parekh Source: Book on OFDM by R. Prasad Cyclic Prefix in Time Domain Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 10

OFDM System Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 11

Generic OFDM Transmitter [d 1 d 2 d 3 … d. N bits FEC ]T Serial to Parallel Complex baseband OFDM symbol, s(t) IFFT Pulse shaper & Linear PA DAC add cyclic extension • fc From earlier analysis, each subcarrier can be used to carry one complex QAM symbol, di of duration T – The corresponding complex baseband of the OFDM signal is: s(t) =∑ di exp(j 2Π it/T) which is the Inverse Fourier Transform (IFT) of N symbols: can be implemented efficiently using IFFT Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 12

Generic OFDM Receiver Slot & Timing Sync. AGC Sampler fc FFT P/S and Detection Error Recovery VCO Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 13

Baseband of OFDM System • Baseband portion of OFDM system x[i] X[k] Y[k] h[i] y[i] Remarks: i is time domain index, k is frequency domain index • y[i] = x[i] © h[i] where © = circular convolution – h[i] represents the channel impulse response • Y[k] = X[k]. H[k] • Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 where H[k] is the channel freq response 14

OFDM Transmitter Serial/ Parallel X[n, k] Add IFFT x[n, i] Cyclic Prefix Parallel/ Serial • S/P acts as Time/Frequency mapper • IFFT generates the required Time domain waveform • Cyclic Prefix acts like guard interval and makes “equalization” easy (FFT-cyclic convolution vs channel-linear convolution) Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 15

OFDM Receiver Serial/ Parallel Remove Cyclic Prefix y[n, i] FFT Parallel/ Y [ n , k] Serial • Cyclic Prefix is discarded • FFT generates the required Frequency Domain signal • P/S acts like a Frequency/Time Mapper Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 16

OFDM Basics • If the Cyclic Prefix > Max. Delay Spread, then the received signal after FFT, at the kth tone for the nth OFDM block can be expressed as – Y[n, k] = X[n, k] H[n, k] + W[n, k] where – W[n, k] is the additive noise – H[n, k] is the channel frequency response • Estimated X[n, k] = Y[n, k]H-1[n, k] = X[n, k] + W[n, k] H-1[n, k] Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 17

OFDMA Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 18

Orthogonal Frequency Division Multiple Access (OFDMA) • Orthogonal Frequency Division Multiple Access (OFDMA) is a multi-user version of the popular OFDM digital modulation scheme. • A subset of subcarriers is grouped together to form a subchannel • Multiple access is achieved in OFDMA by dynamically assigning subsets of subchannels to individual users. • This allows simultaneous low data rate transmission from several users. • Wireless. MAN-OFDMA is based on scalable OFDMA (SOFDMA) – Support scalable channel bandwidths from 1. 25 to 20 MHz Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 19

OFDM vs OFDMA OFDM • Only one user can transmit during an OFDM symbol Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 OFDMA • Sub-channelization enables several users to transmit at the same time 20

OFDMA Subchannels n n A subscriber can be assigned one or more subchannels Subchannels provide interference averaging benefits for aggressive frequency reuse systems Source: IEEE Tutorial Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 21

OFDMA Features • adaptive user-to-subcarrier assignment – Based on feedback information about the channel conditions • possible to achieve even better system spectral efficiency. – If the assignment is done sufficiently fast, this further improves the OFDM robustness to fast fading and narrowband cochannel interference • support differentiated Quality of Service (Qo. S), i. e. to control the data rate and error probability individually for each user. – Different number of sub-carriers can be assigned to different users Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 22

Multiuser diversity: adaptive user-to-subcarrier Source: Jungnam Yun and Mohsen Kavehrad, PHY/MAC CROSS-LAYER ISSUES IN MOBILE Wi. MAX • Each MS/subscriber faces a different fading channel; hence, radio resource management can use multiuser diversity to maximize system throughput. – Allocate logical channel numbers (subcarriers) and symbol numbers based on the channel strength Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 23

Wi. Max Protocol Overview Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 24

Scope of 802 standards Source: Internet • • Physical (Layer 1) – Concern physical interface and the rules by which bits are passed from one to another. Data Link (Layer 2) – Provides means of activating, maintaining and deactivating a reliable point-to-point link IEEE 802 model Source: IEEE Medium Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 25

IEEE 802. 16 protocol layering ATM transport IP transport MAC Service Specific Convergence Sublayer (CS) MAC Common Part Sublayer (MAC CPS) Security sublayer Like typical IEEE 802 standards, IEEE 802. 16 specifies the Medium Access Control (MAC) [Layer 2] and PHY [Layer 1] layers of the wireless transmission system. Physical Layer (PHY) Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 26

IEEE 802. 16 Physical layer • IEEE 802. 16 offers 5 PHY options ATM transport IP transport MAC Service Specific Convergence Sublayer (CS) MAC Common Part Sublayer (MAC CPS) Security sublayer Physical Layer (PHY) Designation Applicability Wireless. MAN-SC 10 -66 GHz Wireless. MAN-SCa Below 11 GHz Licensed bands Wireless. MANOFDMA Below 11 GHz Licensed bands Wireless. HUMAN Below 11 GHz Licensed-exempt bands Source: S-72. 3240 WMAN Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 27

IEEE 802. 16 MAC layer ATM transport IP transport MAC Service Specific Convergence Sublayer (CS) The IEEE 802. 16 MAC layer consists of three sublayers. MAC Common Part Sublayer (MAC CPS) Security sublayer Physical Layer (PHY) Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 28

IEEE 802. 16 MAC layer ATM transport IP transport MAC Service Specific Convergence Sublayer (CS) MAC Common Part Sublayer (MAC CPS) Security sublayer Physical Layer (PHY) Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 CS adapts higher layer protocols to MAC CPS. CS maps data (ATM cells or IP packets) to a certain unidirectional connection identified by the Connection Identifier (CID) and associated with a certain Qo. S. May also offer payload header suppression. 29

IEEE 802. 16 MAC layer ATM transport IP transport MAC Service Specific Convergence Sublayer (CS) MAC Common Part Sublayer (MAC CPS) Security sublayer Physical Layer (PHY) Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 MAC CPS provides the core MAC functionality: • System access • Bandwidth allocation • Connection control Note: Qo. S control is applied dynamically to every connection individually. 30

IEEE 802. 16 MAC layer ATM transport IP transport MAC Service Specific Convergence Sublayer (CS) MAC Common Part Sublayer (MAC CPS) Security sublayer Physical Layer (PHY) Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 The privacy sublayer provides authentication, key management and encryption. 31

Summary of MAC Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 32

Phy & MAC processing Upper MAC (UMAC): General processor, eg. ARM 926 • ARQ, • Handoff, • Idle mode protocol, • Sleep mode protocol, • MBS, • Session/ Connection management, • RRM/RLC, • Qo. S Lower MAC (LMAC): DSP / ARC processor • H-ARQ, • Ranging (Access), • Scheduling, Framing, Control, Signaling, • Qo. S, • MBS, • Security Mix/ Analog/ RF IC Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 Upper layers PHY Baseband Processing Bit level symbol level DDC/ DUC PHY A/D or D/A RF Front-end 33

Base /Subscriber station block diagram Baseband IC I/O devices, etc Peripheral controller DMA controller External memory Memory controller RISC Engine: UMAC and general control Radio control and measure ment Power, etc Ethernet controller TDM controller External processor controller OSC, PA, LNA, Amp ctr DSP Engine: LMAC and PHY RF IC ADC/ DAC Power supply Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 34

Thank You Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 35

Wi. Max Physical Layer Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 36

PHY Layer Features of IEEE 802. 16 -2004 Feature Benefit 256 point FFT OFDM Built in support for addressing multi-path waveform in outdoor LOS and NLOS environments. Adaptive Modulation Ensures a robust RF link while maximizing and variable error the number of bits/second for each correction encoding subscriber unit. per RF burst TDD and FDD support Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 Addresses varying worldwide regulations when one or both may be allowed 37

PHY Layer Features of IEEE 802. 16 -2004 (Continued) Feature Benefit Flexible Channel Sizes (Can be an integer multiple of 1. 25 MHz, 1. 5 MHz, and 1. 75 MHz with a maximum of 28 MHz. Provides the flexibility to operate in many different frequency bands with varying channel requirements around the world. Designed to support Smart antennas can suppress adaptive antenna systems interference and increase system (AAS). gain. They are becoming important to BWA deployment as their costs come down. Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 38

Wi. Max Data Link Layer Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 39

MAC Layer Features of IEEE 802. 16 -2004 Feature Benefit TDM/TDMA Scheduled Uplink/Downlink frames. Efficient bandwidth usage Scalable from 1 to hundreds/ thousands of subscribers Allows cost effective deployments by supporting enough subscribers to deliver a robust business case Connection-oriented • Per Connection Qo. S • Faster packet routing and forwarding Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 40

MAC Layer Features of IEEE 802. 16 -2004 (Continued) Feature Qo. S Benefit • Low latency for delay sensitive services • Optimal transport for video, Data prioritization ARQ • Improves end-to-end performance by hiding RF layer induced errors from upper layer protocols Adaptive Modulation • Enables highest data rates allowed by channel conditions, improving system capacity Security and Encryption • Protects user privacy • Minimizes self interference Automatic Power Control Public Use MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 41