Cognitive Radio Platform: from achievable performance to architecture design

Transcription

1 Cognitive Radio Platform: from achievable performance to architecture design Christian Bonnet 1, Hervé Callewaert 1, Merouane Debbah 1, Majed Haddad 1, Aawatif Menouni Hayar 1, Karim Khalfallah 1, Raymond Knopp 1, Najam-ul-Islam Muhammad 1, Dominique Nussbaum 1, Renaud Pacalet 2, Rizwan Rasheed 2 1 Mobile Communications Group, Institut Eurecom, 2 SOC Laboratory, ENST Sophia Antipolis 2229 Route des Crêtes, B.P. 193, Sophia Antipolis, France firstname.lastname@eurecom.fr ETSI Software Defined Radio (SDR) / Cognitive Radio (CR) Workshop Friday 9th February Sophia-Antipolis, France

2 Cognitive Radio Algorithms and architectures Sensing Algorithms Spectral efficiency issues Fundamental limits Reconfigurable architectures ETSI SDR/CR Workshop 2

3 How Does a Cognitive Radio Get So Smart? External Intelligence Sources Infer on Context Hierarchy Receive a Message Read Buttons Observe Outside World Pre-process Parse Prior States Orient Establish Priority New States Immediate Learn Act Send a Message Set Display Normal Plan Urgent Save Global States Register to Current Time Decide Initiate Process(es) (Isochronism Is Key) Generate Alternatives (Program Generation) Evaluate Alternatives Alternate Resources The Cognition Cycle Mitola, Cognitive Radio for Flexible Mobile Multimedia Communications, IEEE Mobile Multimedia Conference, 1999, pp3-10 ETSI SDR/CR Workshop 3

4 Cognitive radio perspectives for Open Air Interface Platform Licenced system Licenced system Meas. Report Cognitive Terminals/Sensors Control Center ETSI SDR/CR Workshop 4

5 Context Observing that in some locations or at some times of the day, 70 % of the allocated spectrum may be sitting idle, the FCC has recently recommended [1] that significantly greater spectral efficiency could be realized by de-ploying wireless devices that can coexist with the licensed (primary) users, generating minimal interference while taking advantage of the available resources. We investigate the idea of using cognitive radio to reuse locally unused spectrum to increase the total system capacity. We consider a multiband/wideband system in which users wish to communicate to the base station, subject to mutual interference. ETSI SDR/CR Workshop 5

6 System Model Fig. 1. Two-user cognitive radio TDD-uplink in a wideband/multiband context. ETSI SDR/CR Workshop 6

7 Cognitive Radio Protocol (1) Fig. 2: One primary user and two cognitive users in a system with N = 8 sub-bands. ETSI SDR/CR Workshop 7

8 Cognitive Radio Protocol (2) Under this scheme, a cognitive radio will listen to the channel and, if sensed idle, will transmit during the voids. Users successively transmit over available bands through proper water filling. Each user knows only his channel and the unused spectrum through adequate sensing. ETSI SDR/CR Workshop 8

9 Achievable Performance (1) Fig. 3. The maximum number of users for different number of sub-bands N. ETSI SDR/CR Workshop 9

10 Achievable Performance (2) Fig. 4. Sum spectral efficiencies of the system with 5 users. ETSI SDR/CR Workshop 10

11 Experimental Platforms Goal of OpenAirInterface platform Experiment with wideband RF tuning architectures (for wideband sensing, multichannel communications, etc.) High-performance reconfigurable computing architectures for DSP -> wireless orientation System-on-chip (SoC) approach using high-capacity switching network Open-source development (Linux, ecos, Leon3/GRLib) AdHoc and Cellular communications ETSI SDR/CR Workshop 11

12 OpenAirInterface SoC Target ETSI SDR/CR Workshop 12

13 Reconfigurability Through Generic Operators Ex: Front-End Processing Engine (I)DFT Engine max. max( Y i ) per subband argmax( Y i ) per subband X Y Σ Σ. 2 Y 2 Uses: H params OFDMA (TX,RX,Ch Est,Frame Sync) MC-CP (TX,RX,Ch Est, Frame Sync) TD-SCDMA (RX,Ch Est, Frame Sync, MF synthesis) WCDMA (TX,RX,Ch Est, Frame Sync, RAKE) SC (e.g. GSM) : RX, Ch Est, Frame Sync, Equalization ETSI SDR/CR Workshop 13

14 Reconfigurability Through Generic Operators DFT/IDFT : OFDM (LTE downlink, WIFI, WIMAX, DVB,DAB) Frequency-domain Equalization Filtering Digital FDM (LTE Uplink) Componentwise product with accumulation (vectorized): Frequency Domain channel estimation Channel compensation Spatio-temporal processing o MIMO channel estimation o Bit-metric generation (channel decoder/deinterleaver input) o Equalization Scalar-product (vectorized): WCDMA RAKE receiver Phase-offset compensation Max/argmax (vectorized): Synchronization (acquisition, tracking) Energy (vectorized): Computation of RX power/sinr (for measurements) ETSI SDR/CR Workshop 14

15 CardBus MIMO RF Antenna Module TX RX A/D D/A Antenna Module Antenna Module 4-way Wideband Tuners (4 7.6 GHz) TX RX TX RX A/D D/A A/D D/A Antenna Module Band Selection Modules (.4-1,1-2,2-4,4-7.6) TX RX A/D D/A 2 step U/D conversion fixed 10-bit (direct for >4GHz, dual 3.6 GHz 45 Ms/s ETSI SDR/CR transposition Workshop < 4GHz) 15

16 References [1]: Federal Communications Commission, Cognitive Radio Technologies Proceeding (CRTP), [2]: M. Haddad, A.M. Hayar and M. Debbah Fundamental limits of Cognitive Radio, submitted to Special Issue on Cognitive Radio Oriented Wireless Networks and Communications. ETSI SDR/CR Workshop 16