Ubiquitous Wireless Communication ~Possibility of Software Defined Radio~

Transcription

1 1 Ubiquitous Wireless Communication ~Possibility of Software Defined Radio~ Yukitoshi Sanada Dept. of Electronics and Electrical Engineering Keio University

2 2 Outline Definition and background of software defined radio Research issues Direct Conversion Receiver RF MEMs Multiband Antenna Operating System and API Concluding Remarks

3 3 What is Software Defined Radio? Coffee Shop Cellular Hot Spot WPAN WLAN Multiband/Multimode,Wideband Wireless Terminal Ubiquitous Wireless Communications

4 4 Merits of Software Defined Radio Comfortable Mobile Computing Environment Frequency Utilization Efficiency FCC has been thought of renting out frequency bands. Ecology No need to replace all terminals when new service is launched Low Cost Shorten the development period No cost for adjustment of analog circuits Debugging with software download

5 Background of SDR 5 Reduction of budget for US military (early 90 s) Needs of flexible terminals with multiple modes IMT-2000 Standard(1999) CDMA: 3 standards, TDMA: 2standards, Multiple frequency band assignment(800m/1.7g/2.5ghz) Beyond 3G Popularity of WLAN 2.4GHz band,5.2ghz band Multiple standards Needs for Multiband/Multimode Terminals Software Defined Radio

6 Ideal Configuration of Software Defined Radio 6 Multiband operation with multiband antenna elements, variable response filter and amplifier A/D conversion with ultra high speed converter Reconfigurable device such as DSP or FPGA RF Signal Analog Digital BPF LNA A/D Conversion Digital Signal Processing 出力 Impossible!

7 7 Realization of SDR Terminal Reconstruction of Hardware Architecture Down Conversion Frequency Filtering Dependency Antenna & Flexibility High speed signal processing FPGA Low cost & DSP Low power Construction of Software Architecture Operating System API Protocol Security Software Module

8 8 Down Conversion and Filtering Heterodyne Receiver Long history and reliability Require sharp RF or IF band pass filter for elimination of image frequency signal SAW filter (not reconfigurable) RF BPF LNA IF BPF Amp. A/D Conv. Demod. RF Lo. IF Lo.

9 9 Down Conversion and Filtering (Cnt d) Direct Conversion Receiver Elimination of IF modules No IF filter=reduction of cost and size Flexibility RF Signal LPF Amp. LPF A/D Conv. I BPF LNA 90 DSP LPF Amp. LPF A/D Conv. Q Lo.

10 Principle of the Direct Conversion Receiver 10 Power Convert to Base Band Directly RF Filter Base Band Signal IF RF Signal Frequency

11 Direct Conversion with Multi-port Junction No mixer is required for down conversion Multiband capability (2.4 and 5.2 GHz) Power of LO signal can be reduced Low DC offset 11 RF Signal Directional Coupler Divider Phase Shifte ψ Divider LO Signal ADC PD P 1 ADC PD ADC PD P 2 P 3 PD:Power Detector

12 12 Principles of demodulation P2 Phase Shifted Lo. Local Signal Received Signal ψ P1 ψ P3 Phase Shifted Lo. I Q h h i0 hi 1P1 hi 2P2 hi 3P3 q0 hq 1P1 hq 2P2 hq 3P3 Multiband Capability Demodulation Technique

13 13 RF Filter (Image Rejection Filter) Microstrip Filters Fixed Frequency Response

14 14 RF Filter RF MEMS Maximum Frequency MEMS Minimum Frequency

15 15 Multiband Antenna Needs to cover frequency bands for cellular and WLAN May not be need to be ultra wideband antenna Reconfigurable antenna? Fractal antenna? Higher frequency utilization may be possible with SPACE, TIME, FREQUNCY selection for transmission

16 16 Array Antenna (MIMO) Adaptive signal processing based on Channel characteristics Physical layer MAC layer Cognitive Radio Software Modules Antenna Processing Adaptive Signal Processing

17 17 Standardization of Software Defined Radio SDR forum (1996~) Standardization of API between software modules Recommending VxWorks as Operating System Dealing with security issues Software Application Antenna Specific Modules RF Specific Modules Modem Specific Modules Opt. Link Proc Specific Modules INFOSEC Specific Modules Msg & I/O Specific Modules User I/O Specific Modules Common Software Common Software Common Software Common Software Common Software Common Software Common Software OS Firmware OS Firmware OS Firmware OS Firmware OS Firmware OS Firmware User I/O Hardware Antenna Hardware RF Hardware Modem Hardware Link Proc Hardware INFOSEC Hardware Msg Proc & I/O HW Open Interface

18 18 FCC Sept. 2001: FCC adopts SDR first report and order proposed by SDR Forum Allow manufacturers and operators to reconfigure devices after they have been deployed in the filed 3 rd parties can make and sell softwares for the terminals with the corroboration with the original hardware manufactures

19 19 Concluding Remarks Software defined radio is absolutely necessary to realize ubiquitous wireless communication environments. Multiband and multimode capabilities are required. They leads to higher efficiency of frequency utilization. With the collaboration of multiple software modules, cognitive radio can be realized. Standardization of operating system and software APIs enables communication between software modules. Multiband Antenna (Wideband Antenna) and MIMO are key technologies for SDR.

20 20 IEICE SR Technical Group 12 th Technical Meeting Date: Dec. 13, Place: 8 Presentations and 2 Invited Talks The FCC SDR Policy or about the FCC Spectrum Policy Task Force Report by Mike Marcus(FCC,USA) Prof. Ryuji Kohno URL: Special Issue Software Defined Radio Technology and Its Applications Issue: Dec Submission deadline: March 28 URL: Info: Y. Sanada(sanada@elec.keio.ac.jp)

21 Complex Filter Bank Parallel A/D Conversion 21 Reduction of A/D conversion rate with decimator Frequency division with an analysis filter bank Reduction of required resolution RF Signal N Amp. ^ d 0 ADC y 0 BPF s 0 BPF LNA Lo. D D N Analysis Filter Bank Amp. ^ d 1 ADC Decorrelator y 1 BPF s 1 D N Amp. ^ d N-1 ADC y N-1 BPF s N-1 Proposed Filter Bank Parallel A/D Converter

22 22 IEEE MAC IEEE MAC (1) Authenticate and associate with AP1 AP1 (3) Re-associate with AP2 (2) Pre-authenticate with AP2 AP2 (4) Termination of the station s previous association Multiple Channel Reception with SDR Technology

23 Multiple Channel Reception 23 Power IEEE b Channel 1 IEEE b Channel 2 IEEE a Channel 2 IEEE a Channel 2 Frequency