doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 1 Technology Proposal IEEE P Wireless RANs Date: Authors: Notice: This document has been prepared to assist IEEE It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chairhttp://standards.ieee.org/guides/bylaws/sb-bylaws.pdf Carl R. StevensonCarl R. Stevenson as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE Working Group. If you have questions, contact the IEEE Patent Committee Administrator at >

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 2 Contributors SectionOrganizationContributors 1. WRAN sensingSamsung Advanced Institute of Technology (SAIT) Ashish Pandharipande, Duckdong Hwang 2. Interference managementSamsung Electronics Ltd.David 3. WRAN MACSAIT-Inha UniversitySang-Jo Yoo, Ashish Pandharipande 4. WRAN PHYInha UniversityJaehak Chung, Jae- Myung Kim 5. Misc MAC-PHY issuesSamsung Telecom AmericaBaowei

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 3 Abstract This document provides technology solutions to meet functional requirements of an IEEE based WRAN system. Keeping in view the unique requirements imposed on WRANs to operate while avoiding interference to licensed incumbents and coexistence among WRANs, we propose an OFDM(A) solution in conjunction with a set of MAC protocols, and provide distributed sensing and interference management solutions.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 4 WRAN Proposal Overview Sensing –Local detection algorithms –Information fusion in distributed sensing –Interference avoidance to licensed incumbents –Coexistence among WRANs MAC –Frame structure definitions –Sensing management –Initialization procedures –Connection management and QoS support –Dynamic frequency change –Inter-WRAN communication, coexistence and resource sharing Physical Layer –OFDM(A) air interface –Support for single channel TDD/Multi-channel FDD and TDD –Adaptive modulation and coding modes for variable data rate support –Multiple antenna technology at BS Sensing PHY MAC

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 5 Overview of WRAN Basic Architecture Wireless Regional Area Network (WRAN) –Point-Multipoint structure –Unlicensed operation over VHF-UHF spectrum range –Large service coverage (> 30 Kms) –Operation under interference avoidance to licensed services such as TV broadcasting –Coexistence among unlicensed systems WRAN BS Customer Premise Equipment (CPE) CPE

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 6 1.WRAN sensing Solutions to address requirements in the following sections of the FRD –General requirements of Sections 5, 14 and 15

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 7 Sensing and associated modules at WRAN BS TV usage database Sensing information module SG for Part 74 devices Dynamic map of Spectrum usage Interference management module WRAN radio resource allocation WRAN coexistence Licensed device protection Regional WRAN information base Inter-WRAN resource sharing module Local WRAN information base

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 8 Overview of WRAN distributed sensing WRAN BS has to determine –Whether a signal is present or not in a given TV channel –Binary hypothesis testing (signal present or signal absent) problem –If yes, which ones WRAN BS relies on a central sensing decision unit (CSDU) to make global decision on channel occupancy –Distributed local detection by CPEs followed by detection information fusion at CSDU to enhance reliability of sensing Signal types to be considered –Licensed incumbents TV signals Part 74 device signals –Unlicensed systems WRAN Others? Different interference management solutions apply depending on which signals are detected

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 9 Distributed sensing overview

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 10 Local detection problem formulation Local detection performed at each CPE Signal detection –Signal x(k), that is transmitted over channel h(k), to be detected in presence of AWGN n(k) h(k) is the impulse response of channel between Tx and CPE Rx

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 11 Cyclostationarity based signal detection Signal x(k) is cyclostationary with period P if Cyclic autocorrelation and cyclic power spectrum density Various forms of detectors can be derived from cyclic power spectrum density Sliding N-pt FFT x(n)Correlate and average sum Feature detector Signal attributes –Power –Modulation –Symbol frequency

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 12 Proposed local detection algorithm Detection based on cyclostationary properties exhibited by large class of signals (eg., PSK, QAM, VSB, OFDM, CDMA, …) Basic mode of detection algorithm –Energy detection –Used in high SNR regimes for pilot/carrier/signature detection type schemes Enhanced mode of detection algorithm –Feature detection –Used in low SNR regimes –Especially useful during initialization procedures where BS is looking for an empty channel in low SNR conditions

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 13 Advantages of cyclostationary detection Cyclic spectrum domain a richer domain for signal analysis than conventional power spectrum Robust to noise –Stationary noise exhibits no cyclic correlations Better detector performance even in low SNR regions Signal classification ability –Different signals have different cycle frequencies and exhibit distinct spectral characteristics Can be used as an energy detector in alpha = 0 mode –Flexibility of operation

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 14 Feedback of sensing result and fusion rules Option 1: Data fusion –Each sensing element makes raw observations but does not make a decision as to whether a signal is present or not –It processes the raw observations and sends the processed information to the CSDU. For eg., each CPE may feed back quantized values of energy when in energy detector mode –At the CSDU, the sensing reports from the Q reporting CPEs is fused using the decision: Thresholds chosen so as to meet a pre-specified probability of false-alarm Option 2: Decision fusion –Each sensing element makes raw observations, processes these observations and makes a detection decision as to whether a signal is present or not –It then sends the decision bit D i (1/0) to the CSDU –At the CSDU, the individual decisions D i are fused into a final decision based on the following rule: Parameters chosen so as to meet a pre-specified probability of false-alarm

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 15 Detecting other WRANs Unique ID/spectral signature Regional WRAN information base –Attractive for its support for inter-WRAN communication Feature detection –Easy to detect OFDM signal with known symbol rate using cyclostationary methods

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 16 Dynamic map of collated sensing reports from CPEs CPE IDsCPE location CPE sensing and classification and classification report * [Characteristics of signals detected] Power of signal type 1 Spectrum occupancy of signal type 1 Power of signal type 2 Spectrum occupancy of signal type 2 … Channel number k Data fusion case; *In case of WRANs, report also WRAN ID CPE IDsCPE location CPE sensing report [Characteristics of signals detected] Power of signal type 1 Spectrum occupancy of signal type 1 Power of signal type 2 Spectrum occupancy of signal type 2 … Channel number k

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 17 Spectrum usage map Information fusion of distributed sensing results Sensing measurementsTV usage database Signal classification and footprint characteristics Licensed incumbentsOther WRANsOther licensed exempt Channel N Channel N type of incumbent spatial footprint spectral footprint BS ID spatial footprint spectral footprint BS ID spatial footprint spectral footprint Channel N

doc.: IEEE yy/xxxxr0 Submission November 2005 Ashish Pandharipande, SAITSlide 18 Local WRAN information base WRAN BS ID BS location CPE IDs CPE location CPE DLCPE ULQoS and resource allocation information SNRService requirement CPE MCS CPE Tx power … Information base contains current resource allocation of CPEs associated to the WRAN

doc.: IEEE yy/xxxxr0 Submission November 2005 Ashish Pandharipande, SAITSlide 19 Regional WRAN information base Operator IDWRAN BS ID WRAN BS location Currently occupied spectrum occupancy Spectrum resources available for sharing Other parameters to facilitate inter-WRAN resource sharing … Information base contains WRAN information that can be accessed by other WRANs for facilitating coexistence and resource sharing

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 20 2.WRAN maximum transmit power constraint for interference management and coexistence Solutions to address requirements in the following sections of the FRD –Requirements of Sections , and 15.2 (Coexistence and interference-mitigation) Algorithms for Avoidance of Interference to Incumbents Maximum Power for WRAN CPEs to Avoid Interference to TV Operation WRAN Systems Coexistence/Sharing

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 21 Place of proposed interference management module in the system Database Sensing measurements Set of minimum constraints for QoS scheduler optimization Radio map Footprints of incumbent and coexisting WRANs QoS scheduling & resource allocation (RRM): in opportunistic spectrum access channels in dedicated channels (for coexistence) Module that computes the constraints relative to coexistence Module that computes the constraints relative to the protection of incumbents Interference management module Constraints from WRANs negotiation outcome

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 22 Joint maximum power constraint rule in constraint areas

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 23 Justification of 150 m margin Calculations show that [2] A CPE transmitting at 4W with TV operation on channel N should be: At least 10 m away from noise-protected contour co-channel to DTV operation At least 150 m away from noise-protected contour on N-1 of DTV operation At least 44 m away from noise-protected contour on N+1 of DTV operation At least 4.7 km away from Grade B contour co-channel to NTSC operation At least 44 m away from Grade B contour on N-1 of NTSC operation At least 31 m away from Grade B contour on N+1 of NTSC operation Thus a 150 m margin beyond the Grade B/noise-protected contours can be given to take care of all but 1 constraints, and would only affect a marginal number of potential WRAN customers. An additional margin can be given if needed based on accuracy of distributed sensing measurements, and to take care of outage due to fading.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 24 Step by step process for the determination of the interference protection constraints Spectrum usage map Table 2 of max powers for all CPEs on all TV bands List of areas where simultaneous transmissions are critical List of CPEs in these areas and density of constraint area Computation of maximum transmit power control rules for the CPEs in each constraint area Possible set of rules: dedicated channels to some CPEs (respectively to WRANs) power control rule as a function of density of CPEs (per constraint area per TV band) below the critical density threshold where communication is not possible or channels cannot be shared by CPEs. simultaneous scheduling constraints by groups of CPEs within a WRAN Table 1 of max powers for each CPE on all TV bands Using flowchart #1 and EIRP information Negotiation between WRANs: sharing of density and area information result of negotiation: dedicated channels (operating and backup) shared channels Power density of other unlicensed users in each constraint area Distance/location information Incumbent presence information Distance and area information First layer of individual maximum transmit power constraints Second layer of individual maximum transmit power constraints Third layer of maximum transmit power constraints

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 25 Maximum power constraint for a single CPE operation (out-of-band emission mask is assumed to meet the functional requirement [1]) Table 1 (example) 1st layer of maximum power constraint 2nd layer of maximum power constraint All values assume a 6 MHz bandwidth used by the CPE. They need to be scaled down later to the bandwidth actually used by the CPE within a TV band. To Table 2

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 26 Table 2 (example) Joint power constraint rule applies whenever CPEs share the same frequency band.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 27 Flowchart to determine the first layer of maximum transmit power constraints  fill one cell of Table 1 For one given CPE, determine the constraints on all bands incurred by possible TV operation on band N

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 28 Simple description of the power rule A single transmitting CPE induces power at TV receiver: Where d is the distance of the CPE to the Grade B contour, and a is the path loss exponent. Let n be the density of CPEs in a local area (a few km 2 ). Multiple transmitting CPEs: effective path loss exponent is decreased Maximum transmit power rule: Power at the nearest TV receiver: One rule can address interference to incumbent from same and coexisting WRANs given the knowledge of the density of CPEs of all WRANs within a constraint area.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 29 3.WRAN MAC Solutions to address requirements in the following sections of the FRD –General requirements of Sections 5, 14 and 15

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 30 MAC Proposals WRAN unique MAC frame structure and messages –SystemInfo (to carry sensing related information) –BS Communication sub-channel (to provide a ranging and bandwidth request channel between WRAN base stations) –Modified UL, DL MAP –Additional management message BS – CPEs & BS – BS MAC procedures –WRAN initialization and channel sensing –Channel acquisition broadcasting –Sensing reporting –Dynamic frequency selection –Connection management –Inter-WRAN base station management Resource partitioning Dynamic resource renting

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 31 Basic PHY Architecture (Duplexing) UplinkDownlink TDD FDD TDD FDD

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 32 Physical frame structure SystemInfo (in every MAC frame) in BS downlink frame –This portion is used to carry some sensing related information to CPEs/other WRANs –It is also used by BS to send sensing management messages to CPEs or other BSs BS communication sub-channel –BS may set BS communication sub-channel periodically; Need not appear in every MAC frame –BS communication sub-channel is used for inter-base station communication –Base station that wants to share some frequency bands must send a request message without collision

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 33 MAC Frame Structure (Definition of New Portion) SystemInfo (in every MAC frame) in BS downlink frame Some important fields –CurrentBandList: includes the currently used bands by the BS –CandidateBandList: includes the bands that can be used in the case that currently used bands are not available any more –Sensing Information: includes some commands for CPE sensing Quiet time, …

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 34 MAC Management Message Additional message type –SensingReport –BandMoveRequest –BandChangeACK (1:1 case) –ResourcePartitionRequest –ResourceRentingRequest –ResourceRentingACK –ResourceAllocationACK –ResourceCollectionRequest –ResourceCollectionResponseACK –ResourceReturningRequest –ResourceReturningACK

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide WRAN Initialization (Option 1)

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide WRAN Initialization (Option 2) Initialization of WRAN system not simple –BS consults TV usage database and regional WRAN information base to find potentially empty channels –BS performs sensing over these channels to check if they are indeed empty –Before using these channels, BS has to get sensing reports from CPEs to enhance channel occupancy figure –BS broadcasts a “sensing request signal” on channels found empty by it –On receiving sensing request signal on a particular channel, CPEs perform sensing and send a channel report signal if it finds channel is empty

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide Channel Acquisition Broadcasting BS broadcasts a special carrier pattern after it acquires a channel (every time) –We may use PHY pilots –Easy to detect CR WRAN BS signals by CPEs (simple frequency scanning) –Let the other BSs know that the channel is already acquired by a certain CR WRAN BS –Use special carrier signature (each BS may have different signature) 6MHz6 TV in useCR WRAN in use Acquisition broadcasting

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide Sensing reports when CPEs detect interference BS performs sensing via collation of detection results from CPEs Periodic sensing by BS –BS periodically senses current used bands and other available bands –BS periodically broadcasts some candidate bands with CandidateBandList in SystemInfo portion Periodic sensing by CPEs –BS can request sensing requests to CPEs (periodic, not every frame) Sensing Information in SystemInfo includes some commands for CPE sensing If CPE receives the sensing request, it checks whether the current bands and some other requested bands are available or not CPE responds with Sensing Report –Sensing Report = {empty/occupied, (if occupied) licensed incumbent/other WRAN, …} Sensing request (in Sensing Information) Sensing Report Sensing Information Sensing Report Down Frame UP Frame Sensing Information

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 39 State transition diagram for sending CPE sensing report

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide Frequency Changing by BS BS should move to new empty bands if a primary system appears –BS starts frequency sensing. –Before it actually moves to new bands, it should broadcast its frequency changing to CPEs. Need a new message (use SystemInfo portion) –BandChange message –Include up and/or down frequency changing, new frequency info, …. –CPEs reply with Sensing Report message immediately. CPE checks (senses) whether the new frequency band is empty or not. If the new band was already occupied, then it sends a Sensing Report to BS (with the current up-link band) – BS should wait a sufficient time before it moves. Sensing Report may includes –Available Band list (if it has) Sensing Report is sent –Piggybacking on the data burst –Request a channel for sensing report (use CDMA codes) BandChange Sensing Report Signal from the new band

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 41 State transition diagram of frequency changing – BS, CPE

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 42 Frequency changing failure happens when –CPE does not receive BandChange message –BS did not receive Sensing Report message during the DFS procedure Impossible for some CPEs to decode the WRAN BS’s message –if the signal strength from the primary system that suddenly appeared is quite strong Sudden death procedure deals with such problems –There will be two possibilities First: BS could not recognize the primary system and continuously uses the current bands or BS couldn’t receive the sensing report from CPE during DFS Second: BS recognized the primary system appearance. BS will move to new bands (the CPE could not hear BandChange message from BS) –For both cases, CPEs should search all frequency bands to find out the BS. WRAN TV Tx WRAN TV Tx Frequency Change 3.5 Sudden Death Resolution Procedure CPE

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 43 –For the first case, if BS is serving with several bands and the CPE is served with one of the bands of BS, then (FDD case example) BS maintains a service table for each CPE –CPE={uplink band, downlink band} When the CPE cannot hear BS signal with the current band, it moves to one of the other downlink bands of BS and tries to connect to BS –After the CPE got a synch with the new band, it sends BandMove message to BS. –BandMove (down2) is sent with the up link band indicated in down2 (in this example, up2). –BandMoveACK message is sent by BS with the new downlink band (down2) –If CPE cannot receive the BandMoveACK within the given time, it tries to hear different downlink band. To do that, BS should broadcast its CurrentBandList in SystemInfo of all its downlink bands frequency up1 up2 down1 down2down3 CPE Uplink band problem can be easily detected by BS. BS handles this (e.g., BandChange). CPE={up1, down1} CPE={up2, down2}

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 44 –If CPE fails to synchronize to BS with all current down link bands in the previous CurrentBandList, it may mean that BS changed its service bands into entirely new bands. CPE should search all frequency bands until it finds out the BS. –To reduce this searching effort by CPEs, BS periodically broadcasts some candidate bands to move (BS periodically performs spectrum sensing) Candidate bands are not used now, but if BS cannot use the current bands, then it will try to move to the candidate bands first. CandidateBandList message is included in SystemInfo portion. When CPE entirely lost the connection with the BS, then it first searches the BS from the candidate bands. frequency up1 up2 down1 down2down3 CPE up1 Pre- amble FCH UL- MAP DL - Burst System Info DL- MAP DL - Burst DL – Burst DL - Burst MAC frame of down1 CurrentBandList ={down1,down2,down3, up1, up2, up3}

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 45 State transition diagram of CPE (sudden death resolution)

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide Resource Partition Request by other BSs Network environment –Multiple WRAN service providers (Base Stations) may need to share available resources One BS (prior BS) already acquired TV channels, and if other BSs cannot secure the required resource (additional TV bands are not available) –Other BSs can request a resource partition to the prior BS Using a special sub-channel or slot of the prior BS’s UP link Resource partition ratio between different BSs is outside of this proposal (pre-determined) Downlink RPREQ (Uplink) Prior BS RPREP (Downlink) New BS

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 47 MAC frame structure for resource partition request –For OFDMA PHY: define BS Communication Sub-channel –BS Communication Sub-channel does not appear in every frame, BS communication sub-channel appearance and symbol length is defined in UL-MAP BS communication sub-channel appears periodically but not in every frame DL - Burst DL – Burst DL - Burst DL- MA P DL - Burst UL- MA P FCH Ranging Subchannel UL- Burst Preamble OFDMA symbol number Subchannel logical number Syst em Info BSCommunication_IE BSCommunication Sub-channel Downlink Uplink

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 48 –Each BSs should be able to send the resource partition requests to the prior BS without (or little) collisions –And, the resource partition requests sent by other BSs should be treated with higher priority than ranging or bandwidth requests sent by CPEs of the prior BS BS Communication Sub-Channel (OFDMA case) BS Communication SubChannel Ranging and BW requests from CPEs of the prior BS Prior BS UP Link OFDM symbol sub-channel number Each BS selects one of possible CDMA codes; because the number of BSs is small, there will be little collisions UL-Burst

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 49 State transition diagram of resource partition request – Other BSs

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 50 Prior BS Send UL-MAP without BSCommunication_IE [Time to send next map] Send UL-MAP containing BSCommunication_IE [Receive CDMA code] Send UL-MAP containing CDMA_Allocation_IE [Receive RPREQ] Send RPREP [Time to send next map] Send UL-MAP New BS Wait Confirm whether BSCommunication_IE exists Transmit randomly selected CDMA code in BSCommunication Sub-Channel Send RPREQ UL- MAP RPREP UL- MAP CDMA code RPREQ Message flows of resource partition request

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide Dynamic Resource Renting Procedure One regional area, multiple BSs share available resources –Resource partition ratio between BSs is usually fixed based on agreement Example : BS1 (50%), BS2(50%) However –The number of subscribers of each service provider may be different –The total traffic volume of each BS is also different and time varying Dynamic resource renting procedure between BSs 1) Offeror broadcasts its unused resource in terms of (subchannels and time slots in a frame) 2) Renter requests its desired resource and duration 3) Offeror broadcast its allocation 4) Renter sends an ACK 5) Renter may return the borrowed resource before the rental time ends 6) Offeror may collect the resource before the rental time ends

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 52 Resource definition for rent: Resource Advertisement message in SystemInfo portion –OFDMA case: (sub-channels, symbol number (time)) Rent request by other BSs –Use offeror BS’s UP link channel OFDMA case: BS communication sub-channel FCH UL- MAP DL - Burst System Info DL- MAP DL - Burst DL – Burst (resource for renting) DL – Burst (resource for renting) DL - Burst Resource Advertisement MAC message (format and syntax) To be determined Offeror Down Link Offeror UP Link Renter BS sends a CDMA code with offeror’s UL ranging subchannel to be allocated for resource BS Communication SubChannel UL-BURST

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 53 Renting Procedure Collecting Procedure Returning procedure Resource Advertisement Offeror Renter Resource Renting Request Resource Renting Response Resource Renting ACK Offeror DL (SystemInfo) Offeror UL Offeror Renter Resource Collection Request Resource Collection Response Resource Collection Response ACK Resource Collection ACK Renter UL Renter DL (SystemInfo) Resource Advertisement Resource Renting Request Resource Renting Response Resource Renting ACK Resource Collection Request Resource Collection Response Resource Collection Response ACK Resource Collection ACK To be determined Offeror Renter Resource Returning Request Resource Returning Response Resource Returning ACK Offeror DL (SystemInfo) Offeror UL Resource Returning Request Resource Returning Response Resource Returning ACK To be determined

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 54 For communication between WRAN BSs –When a BS sends its messages using other WRAN BS’s uplink channel, the BS should request other BS’s up link resource first –Example scenario BS1 periodically (need not in every frame) broadcasts the appearance of BS Communication sub-Channel and its position in UL-MAP with BS1’s downlink If BS2 wants to send a message to BS1, BS2 decodes BS1’s UL-MAP to see if the next up link channel of BS1 BS Communication sub- channel is available BS2 sends a CDMA code in BS Communication sub-channel of BS1’s up link BS1 allocates up link resource to BS2 with UL-MAP BS2 sends a message for the dynamic resource renting procedure

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 55 4.WRAN PHY Solutions to address requirements in the following sections of the FRD –General requirements of Sections 5, 8 and 10

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 56 Overview of OFDMA A variation on OFDM Multiple access is realized by providing each user with a fraction of the available number of subcarriers OFDMA avoids the relatively large guard bands necessary in FDMA to separate different users

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 57 System parameters Basic parameters –FFT Size : 1024, 2048, 4096 –Coding : Convolutional Turbo Codes –Modulation : QPSK, 16QAM, 64QAM –Channel BW : 6, 7, 8 MHz (TV band) –Operation Channel : Single or Multi Channel –Duplexing Mode : Full duplex FDD and TDD system

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 58 WRAN physical layer parameters # of subcarrier1 K mode2 K mode4 K mode Subcarrier spacing (KHz) 6MHz MHz MHz Effective Subcarrier 864 (null carrier : left 80, right 79, DC 1) 1728 (null carrier : left 160,right 159, DC 1) 3408 (null carrier : left 343, right 344, DC 1) FFT duration (  s) 6MHz MHz MHz Duration of GI (  s) 6Mhz Mhz Mhz Symbol Duration (  s) 6MHz MHz MHz

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 59 TDD TDD parameter define(6MHz case) ParameterValue DuplexTDD Multiple AccessOFDMA System Bandwidth6 MHz Sampling frequency6 MHz 1K mode2K mode4K mode Number of used tones864 out of 1, out of 2,0483,456 out of 4,096 Number of data tones ,072 Number of pilot tones Tone spacing kHz kHz kHz Signal bandwidth MHz MHz MHz FFT duration μs μs μs Cyclic prefix time μs μs μs μs μs μs OFDMA symbol time μs μs μs μs μs μs TDD frame length4 ms5 ms6 ms4 ms 5 ms6 ms4 ms5 ms6 ms Number of symbols in a frame

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 60 TDD TDD Time duration parameter (6MHz case) Frame structure (ref: duty ratio 1:1 / 2:1 / 3:1) 1K mode2K mode4K mode DLULDLULDLUL Time duration Tx duration (T Trans ) 4ms /2.253 /2.662 ms 1.638/ 1.228/ ms ms /3.072 /3.481 ms /3.891 /4.301ms / /- -- 6ms /3.891 /4.301 ms /1.638 /1.229 ms /3.755 /4.130 ms /1.877 /1.502 ms /3.584 ms /1.434 Ms TDD Gap time (T guard ) 4ms μs ( ) -- 5ms μs ( ) μs ( ) - 6ms μs (TTG + RTG = μs μs) μs (TTG + RTG = μs μs) μs (TTG + RTG = μs μs)

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 61 TDD Frame Structure

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 62 FDD 1K /2K / 4K mode FDD parameter define Parameter1K2K4K DuplexFDD Multiple AccessOFDMA System Bandwidth6MHz Sampling frequency6MHz Number of used tones864 of 1, out of 2, out of 4,096 Number of data tones Number of pilot tones Tone spacing KHz kHz kHz Signal bandwidth5.0625MHz MHz MHz Basic OFDMA symbol time μs μs μs Cyclic prefix time μs μs OFDMA symbol time μs μs μs TDD frame length3 / 4 / 5 / 6 ms Number of symbols in a frame 14 / 19 / 24 / 297 / 10 / 13 / 154 / 5 / 6 / 8

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 63 FDD Frame Structure Down Link Frame Structure UP Link Frame Structure

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 64 System Capacity TDD / FDD capacity comparison Whole Frame Capacity 1 frame duration – TDD : 6ms / FDD : 3ms, single symbol transmission case unit : Mbps FFT Size1K2K Modulation DL UL DLUL TDDFDDTDDFDDTDDFDDTDDFDD Q P S K 1 / / / / QAM 1 / / / / QAM 1 / / / /

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide Other considerations on WRAN PHY and MAC Solutions to address requirements in the following sections of the FRD –General requirements of Sections 5 and 15.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide WRAN Pilot Relevant sections of the Functional Requirements Document [1] 5.5.1: The base station SHALL serve as a radio resource supervisor and controller for its “cell,” including all associated CPEs and/or optional repeaters, if implemented, in its cell. A Master/Slave relationship between the base station and the CPEs SHALL be established whereby all the RF characteristics of the CPEs are remotely controlled by the base station. The proposal of including RACH channel ID guarantees the reliability of Channel Sensing and Initialization described in Section 3.1 in this document.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 67 WRAN Pilot Pilot definition (in terms of function) –Frequency synchronization (sync LO) –Cell timing synchronization (sync timing) –WRAN ID and BS ID (cell identification) –RACH ID (UL transmission, mandatory for FDD, optional for TDD) For a fresh-started CPE to be able to start the first transmission, the BS must include in its pilot the information of the channel ID of the reverse access channel (RACH).

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide Smart antenna for sensing, cell searching, packet transmitting and receiving, and soft combining. Relevant sections of the Functional Requirements Document [1] –5: The base station radio SHALL be P-MP, capable of radiating its downstream signal (forward) toward the CPEs with an omni- directional, a shaped sector, or optionally an adaptive array (spatial reuse) antenna achieving broad azimuthal beam width to serve a number of prospective subscribers. – : The base station and the CPEs SHALL sense licensed transmissions using an omni-directional antenna with a gain of 0 dBi or greater (where all losses between the antenna and the input to the receiver are included) in any azimuthal direction and polarization.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 69 Sensing: omni, 0dBi Cell searching: Beamforming (one beam, but space-sweeping), highest gain: Packet transmitting and receiving: Beamforming (one fixed beam), highest gain Soft combining: Beamforming (multiple beams), highest gain BS

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide Spectrum Classification at BS Relevant sections of the Functional Requirements Document [1] : The system SHALL provide a way to populate a table of channels that characterizes channel availability – such as disallowed, occupied, available, available at reduced power, etc., and to update that table at any time. The base station, and optionally the CPEs, SHOULD maintain a "list" of backup channel(s) in case a new incumbent is detected and a channel has to be quickly vacated. The exact scheme can be left to the proposers, as different approaches could be suggested to address this issue. The proposal of spectrum classification at BS make it smoother and more reliable of the Frequency Changing described in Section 3.4 in this document.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 71 Spectrum Classification (State transitions) Active SetCandidate SetObserving Set Disallowed Set C/I < S 1 C/I < S 2 Needed C/I > S 1 C/I > S 2 C/I > S 1 Frequency Changing

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide WRAN Coexistence (Spectrum Etiquette) Relevant sections of the Functional Requirements Document [1] : Systems SHALL have means to coordinate with each other to facilitate sharing, coexistence, and interference mitigation amongst neighbors. The proposal of spectrum etiquette is for inter-WRAN coexistence. It is an alternative of the Dynamic Resource Renting Procedure described in Section 3.7 in this document.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 73 Spectrum Etiquette (Definitions) We are proposing a distributed interference-management scheme. Hence, the central sector/cell and neighbor sectors/cells are relative concept. If there is no sectorization, one central cell has 6 neighbor cells. The scheme is illustrated using a 6-sector per cell scenario. F usable, ID := the frequencies that won’t interfere incumbent uses. F used, ID := the frequencies that the central sector has picked up. This could include some backup frequencies. F pool := the frequencies that are usable and are not used by neighbor cells := F usable, ID \ (F used,n1 U F used,n2 U F used,n3 ) F local := F pool \ {F usable,n1 U F usable, n2 U F usable, n3 } Notes: –symbols U, ∩, and \ mean union, intersection, and exclude. –ID means the sector ID. Neighbor sectors are further denoted as n1, n2, and n3.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 74 Spectrum Etiquette (Procedure) 1.The central sector decides its F usable, and F pool. 2.The central sector picks up frequencies from the F pool according to the following etiquette principles. i.Try to the frequencies that won’t be used by neighbor cells at all. In other words, use first the frequencies in F local ii.If the central sector is satisfied, go to Step 3. Otherwise, try to pick up frequencies from the rest of F pool with the consideration of avoid using the frequencies that will affect a single neighbor cell most. For example, Use first the frequencies that are not shared by more than one neighbor cells, then other frequencies that may affect more and more neighbor cells. iii.If the central sector is satisfied, go to Step 3. Otherwise, go back to Step 1 and try later. (an optional step can be taken here is trying to ask help from neighbor cells so they could release some frequencies.) 3.If needed, update neighbor cells of its F usable, and F used. Go back to Step 1. Note: the procedure can be done periodically, or can be triggered by a certain predefined events.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 75 Example N3: 1,4,8 N2: 1,5,6 N1: 1,2,3 1,3,4,6,7 Neighbor 1Neighbor 2Neighbor 3Central F usable 1,2,31,5,61,4,81,3,4,6,7 F used 258 F pool 1,3,4,6,7 1st Selection7 2nd Selection4 (randomly from 3,4,6) Final Selection3 (randomly from 3,,6)

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide Coexistence with other LE systems (Contention-Based Protocol) Relevant sections of the Functional Requirements Document [1] 15: Furthermore, these protocols SHALL also include means to allow coexistence among multiple WRAN systems and with other license- exempt systems in these bands for fair and efficient use of the spectrum.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 77 DL Contention-Based Coexistence with LE Devices (Call Flow) CPE Primary BS Detect LE devices Normal data transmitting Data transmitting in contention manner Contention needed Contention

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 78 UL Contention-Based Coexistence with LE Devices (Call Flow) CPE Primary BS Detect LE devices Contention needed Normal data transmitting Contend with LE at the next TXOP Data transmitting in contention manner

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide Soft Combining While it is not required in FRD, Soft Combing does have the following advantages: –Extend coverage: Multiple BSs work together and support edge CPEs –Reduce interference: Neither BSs nor CPE needs to increase power in order to support a certain data rate. –It is very possible for OFDM-based WRAN given the fixed P-MP topology.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 80 Soft-combining Call Flow (DL) CPE Primary BSSupportive BS SC Req. (S-BS ID) SC Req. Ranging SC Accepted Data

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 81 Soft-combining Call Flow (UL) CPE Primary BSSupportive BS SC Req. (S-BS ID) SC Req. Ranging SC Accepted Data Data Extraction

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide Flexible CPE Operation Modes This is not a scheduling issue, rather an issue on system flexibility. CPEs of different categories can satisfy different customers. For example, SME and SOHO customers may want to pay for more expensive CPEs than a regular home owner would do. We propose the procedure for supporting various categories of CPEs. For example, –CPEs with various bandwidth: 1.25 MHz, 2.5 MHz, 5 MHz, 6 MHz or 20 MHz. –CPEs with different service level agreements. BS perspective: there are several groups of CPEs, each with a certain bandwidth. CPE perspective: multiple channels are available from BS

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 83 Procedures Initial acquisition –CPE send the request of bandwidth and service level agreement. –BS assigns the CPE a bandwidth based on the SLA and availability of system resources. CPE scans other spectrum under the direction of BS, reports back channel condition information (CQI) and the request for channel change. If it is beneficial for the CPE and other users, BS confirms the center frequency that user should tune into, based on the CQI feedback, user profile, and SLA. CPE may repeat Steps 2 and 3 occasionally, e.g., when the link conditions in the current channel deteriorates. Besides the request from CPE, BS may inform CPE to tune into a different channel for load balancing or other purposes (e.g., strategic sensing). Dependent on other users’ profile and the SLAs, BS may reserve a certain frequencies for higher priorities applications and for users with higher privilege.

doc.: IEEE Submission November 2005 Ashish Pandharipande, SAITSlide 84 References [1] Functional Requirements for the WRAN Standard, doc.: IEEE /0007r46. [2] WRAN Reference Model, doc.: IEEE /0002r12.