Considerations for SDR Implementations in Commercial Radio Networks

Transcription

1 Considerations for SDR Implementations in Commercial Radio Networks Hans-Otto Scheck Nokia Networks P.O.Box 301 FIN Nokia Group ETSI Software Defined Radio (SDR) / Cognitive Radio (CR) Workshop Friday 9th February Sophia-Antipolis, France Nokia SDR ETSI Nokia.ppt / / HOS

2 End to end reconfigurability E²R Vision Nokia SDR ETSI Nokia.ppt / / HOS

3 Why Software Defined Radio? UMTS the Universal Mobile Telecom Standard isn t the all universal solution Even if there would be an universal standard it would not necessarily be the single dominating standard To have a standard, open and flexible architecture for a wide range of communication products - life cycle cost reductions. Enhanced wireless roaming by extending the capabilities of current and emerging commercial air-interface standards. Over-the-air download of new features and services as well as S/W patches. Joint Tactical Radio DoD initiative: Unified communication across commercial, civil, federal and military organizations Nokia SDR ETSI Nokia.ppt / / HOS

4 The SDR BTS and its components The RF Block: Software Defined RF From antenna to digital interface (OBSAI & CPRI) Analog & digital signal processing Frequency specific components The BaseBand Block: Software Defined BB From digital interface (OBSAI, CPRI) to digital interface (transport) Pure digital signal processing Frequency independent The Transport Block: End to end service Cellular specific networks (E1/T1 transmission, RNC, ) IP networks Nokia SDR ETSI Nokia.ppt / / HOS

5 The SDR for commercial and consumer radio networks Cellular industry: Consumer industry: Growing number of incompatible radio technologies Call for technology agnostic spectrum allocation Growing number of different applications. From low rate RFID to high speed WLAN Fundamental difference between wide area and local area systems: Wide Area Spectral efficiency and cell planning Coordinated spectrum usage (minimize interference by design) High performance RF (TX power, RX sensitivity & blocking) Is SDR and cognitive radio feasible? Local Area No cell planning Uncoordinated spectrum usage Short term spectrum allocation BTS (WLAN) listens before transmit Low performance TRX SDR and cognitive radio essential Nokia SDR ETSI Nokia.ppt / / HOS

6 BTS Throughput vs. Interference Min. throughput at the cell edge UL traffic on DPCH Node- B Avg. SINR - > avg. cell throughput There is no tolerable interference level! Low interference affects the BTS similar like increased noise Every minute amount of interference reduces the capacity of a system. The effect might be tolerable in the beginning, but increases gradually with usage of the interfering system Gradually decreasing capacity is difficult to detect Will be compensated with TX power and/or additional sites Increases gradually both CAPEX and OPEX With fatal effects on the competitiveness of the network Clean spectrum is an essential asset! Nokia SDR ETSI Nokia.ppt / / HOS

7 HW limits the capacity Radio Radiotelegraphy : Transmission of news by radiation of electromagnetic waves. C = W log 2 (1 + S/N) (Shannon) E = mc 2 (Einstein) Software Immaterial ware, non-apparative (m=0) functional parts of an installation. The downlink power (PA) is shared between the users GSM: # of timeslots per carrier, # of carriers per TRX WCDMA: Service (BW) used by each user, noise (interference, network load) Relative cell size 100% Cell breathing is a SDR feature! Nokia SDR ETSI Nokia.ppt / / HOS 80% 60% 40% 20% 0% 8 kbps 128 kbps 64 kbps Low load 200 kbps Large coverage Traffic load has direct effect on the cell size Radio Resource Management provides means to control cell breathing in network optimisation Traffic load factor 144 kbps 144 kbps 64 kbps 64 kbps 144 kbps 64 kbps 64 kbps Increased load 800 kbps Decreased coverage

8 Spectrum Usage 1 Power (W) GSM1800 GSM1900 WCDMA RX filter to protect the GSM1800 RX from it s TX GSM 1800 UL GSM 1900 UL WCDMA UL RX filter to protect the GSM1900 RX from it s TX WCDMA RX filter GPS RX filter GP S GSM 1800 DL GSM 1900 DL WCDMA DL A wideband RF filter would leave the vulnerable RX LNAs unprotected from the high TX power! Frequency (MHz) HOS Nokia SDR ETSI Nokia.ppt / / HOS

9 Why do we need RF Antenna Filters? Violent, non-standard compliant transmitters Commonly agreed radio rules Within GSM band Power (dbm) >25dB of additional blocking robustness RX filter GSM blocking spec Intermodulation Wanted channel HOS 100kHz GSM band 12GHz Frequency Nokia SDR ETSI Nokia.ppt / / HOS

10 Noise in the TX Modulator & Digital Digital filter filter D/A D/A Up-conversion to to RF RF RF RF filter filter PA PA Antenna filter filter Noise floor: -165dBm/Hz -155dBm/Hz -115dBm/Hz -100dBm/Hz Power: -10dBm 30dBm 43dBm Noise (dbm/hz) -100 RF & antenna filter PA noise floor -173 TX band RX band RX noise floor Frequency Nokia SDR ETSI Nokia.ppt / / HOS

11 RF filters in wireless local area systems Wide Area Radio Local Area Radio Noise (dbm/hz) -100 RF & antenna filter PA noise floor Reduced TX power (20W to 20mW) -130dBm/Hz -145dBm/Hz -173 TX band RX noise floor RX band Reduced RX sensitivity (<3dB to ~40dB) Nokia SDR ETSI Nokia.ppt / / HOS

12 Filter technology esonator Q / Filter 2GHz l Wide area RF filter (1.5l) l ml Coaxial duplex filter IL < 0.5dB Att. >70dB P max ~100W Conductor loaded ceramic resonator Multimode ceramic resonator BAW filter IL = 3 db Att.= 25dB P max ~2W 100 1µl Local area RF filter Local area RF filter (<75µl) Nokia SDR ETSI Nokia.ppt / / HOS Pictures not in scale!

13 Cellular Standard Development Complexity 1G Radio 2G Radio Three radio generations Over Over ten ten S/W S/W releases within w ithin years of of cellular development Voice Rel.99 Rel.4 HSDPA 3G Radio Rel.5 Rel.6 Multi- Standard HSUPA Rel.7 LTE WB channel equalization, MIMO Voice Data Frequency Hopping GSM P1 Analog Cellular GSM P2 GPRS Variable Data Rates EDGE Variable modulation HOS Nokia SDR ETSI Nokia.ppt / / HOS

14 Signal processing flexibility has its price Pow er consumption (mw/mops) ASIC Dedicated logic logic Minimize size & H/W cost Mem ory FPGA µ Processor Sat elli t e Processor Sat elli t e Processor Sat elli t e Processor Mem ory µprocessor MAC DSP Addr. Memory µprocessor Maximize flexibility CPU Flexibility 0% (H/W) HOS 100% (S/W) Nokia SDR ETSI Nokia.ppt / / HOS

15 Conclusions 1. SDR is already implemented in existing cellular systems. 2. Cellular networks provides us with a country / continent wide coverage and uninterrupted services. 3. Local area and peer to peer radio networks provide high speed in-building coverage. 4. RF requirements for wide area and local area networks are not compatible Wide area: clean spectrum, network planning, high performance RF Local area: ad-hoc spectrum usage, cognitive radio, low cost RF 5. End to end services require a seamless handover between different radio access networks Nokia SDR ETSI Nokia.ppt / / HOS