1 SMART ANTENNAS FOR TDMA Jack H. Winters AT&T Labs - Research Red Bank, NJ September 7, 2000

Aggressive frequency re-use(7/21,4/12,1/3)  High spectrum efficiency  Increased co-channel interference Downlink Switched Beam Antenna SIGNAL OUTPUT INTERFERENCE SIGNAL OUTPUT BEAMFORMER WEIGHTS Uplink Adaptive Antenna SIGNAL INTERFERENCE BEAMFORMER BEAM SELECT Smart antennas provide substantial interference suppression for enhanced performance Smart Antennas for TDMA Key enhancement technique to improve system capacity and user experience Leverage Smart Antennas currently in development/deployment for IS-136 TDMA

3 Smart Antennas Rooftop Base Station Antennas 11.3 ft Prototype Dual Antenna Handset Prototype Smart Antenna for Laptops

4 SMART ANTENNAS IN SECOND GENERATION SYSTEMS IS-136 TDMA: –On uplink, with two receive antennas, in 1999 changed from maximal ratio combining to optimum combining Software change only - provided 3-4 dB gain in interference- limited environments Combined with power control on downlink (software change only) - increased capacity through frequency reuse reduction –Use of 4 antennas (adaptive array uplink/multibeam, with power control, downlink) extends range and/or doubles capacity (N=7 to 4 or 3) Clears spectrum for EDGE deployment (2002) Limited deployment at base stations

5 IS-136 Smart Antenna System ADAPTIVE ANTENNA RECEIVER 4 Branches TRANSMITTER RADIO UNIT RSSI, BER DUPLEXERS BEAM SCANNING RECEIVER 1 per N radios SPLITTER Power ControlShared LPAs Atten 4 Branch adaptive antenna uplink for range extension and interference suppression Fixed switched beam downlink with power control for increased coverage and capacity Uplink and downlink are independent Shared linear power amplifiers reduce amplifier requirements to handle maximum traffic load

6 Smart Antenna System Dual-polarized slant 45° PCS antennas separated by 10 feet and fixed multibeam antenna with ° beams 4 coherent 1900 MHz receivers with real-time baseband processing using 4 TI TMS320C40 DSPs

7 Spatial Diversity: S/I = 0dB, AAA with 4 antennas vs. REF with 2 antennas INTERFERENCE SUPPRESSION - OFFSET INTERFERER BER AAA(avg.) REF (avg.) AAA (data) ·REF (data) SNR (dB)

8 ADAPTIVE ARRAYS IN EDGE Spatial-Temporal processing using DDFSE for interference suppression

9 ADAPTIVE ARRAYS IN EDGE

DDFSE Equalizer Channel Decoder Rx Output Data EDGE Smart Antenna Processing Dual Diversity Receiver Using Delayed Decision Feedback Sequence Estimator for Joint Intersymbol Interference and Co-channel Interference Suppression Simulation results show a 15 to 30 dB improvement in S/I with 2 receive antennas Real-time EDGE Test Bed supports laboratory and field link level tests to demonstrate improved performance Wireless Systems Research Block Error Rate Signal -to-Interference Ratio (dB) EDGE with Interference Suppression in a Typical Urban Environment

11 MIMO-EDGE Goal: 4 transmit / 4 receive antennas in EDGE can theoretically increase capacity 4-fold with the same total transmit power (3.77X384 kbps = 1.45 Mbps is actual theoretical increase) Issues: –Joint spatial-temporal equalization –Weight adaptation –Mobile channel characteristics to support MIMO-EDGE Our approach: –Development of multi-antenna EDGE testbed –Development of 2X2 and 4X4 DDFSE architecture with MMSE combining using successive interference cancellation –Mobile channel measurements

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13 EDGE with Wideband OFDM - MIMO Downlink High data rates (>1 Mbps) required on downlink only OFDM eliminates need for temporal processing => simplified MIMO processing for much higher data rates With 1.25 MHz bandwidth, QPSK, OFDM- MIMO with 4 antennas at base station and terminal => 10 Mbps downlink

14 SMART ANTENNA EVOLUTION IS-136: Optimum combining uplink / power control downlink at all base stations with existing 2Rx/1Tx antennas 4Rx/4Tx antenna upgrade (adaptive uplink/multibeam downlink) for N=7 to 4 to clear spectrum for EDGE EDGE: S-T processing with IS-136 smart antennas (Data followed by VoIP) MIMO-EDGE (1.5 –2.4 Mbps) Wideband OFDM-MIMO downlink (10-40 Mbps)