August 13, 1999 TXAA Feedback Channel 1

August 13, 1999 TXAA Feedback Channel 2 Contents  Introduction  TXAA and Feedback Channel Description  Generation of Phase and Gain Feedback Commands

August 13, 1999 TXAA Feedback Channel 3 Introduction

August 13, 1999 TXAA Feedback Channel 4 Background  Code Multiplexed Users –These include voice and/or medium bandwidth data –Transmission of signals for multiple users (e.g., voice) from possibly multiple sectors from both TXAA antennas (i.e., main and diversity antennas) –Best policy is maximizing SNR while minimizing BTS transmit power per user –Feedback channel provides channel gain and phase for maximizing user capacity  Time Multiplexed Users –High Speed Data Applications on a Dedicated Carrier –Time-multiplexing users onto a single (or few) code channels on a CDMA carrier for high- bandwidth, bursty traffic –Best policy for maximizing throughput is transmission of full power from BTS antenna(s) –Feedback channel provides ability to select strongest sector for management of resources between sectors

August 13, 1999 TXAA Feedback Channel 5 TXAA Feedback Channel Objectives  The TXAA feedback should provide flexibility for efficient support of differing services and environments  Efficient support of applications with many code multiplexed users such as voice and medium bandwidth data  Efficient support of applications which are time multiplexed, such as high speed data  Flexibility for efficient support of various soft handoff scenarios  Feedback data rates to support high or low mobile velocities  Minimal feedback channel overhead on RL

August 13, 1999 TXAA Feedback Channel 6 TXAA and Feedback Channel Description

August 13, 1999 TXAA Feedback Channel 7 Feedback Channel and Operational Modes  Code Multiplexed Users –  cmd, 1-bit per soft-handoff leg, specifies relative antenna power at the BTS –  cmd, 1-bit per soft-handoff leg, specifies relative antenna phase at the BTS  Time Multiplexed Users –  S, 1-bit per 2 Sectors, specifies strongest received sector for sector selection –  cmd 1-bit per Tx antenna pair, specifies relative antenna power at the BTS –  cmd, 1-bit per Tx antenna pair, specifies relative antenna phase  Combined modes can be defined

August 13, 1999 TXAA Feedback Channel 8 TXAA General Description  TX TXAA Parameters –  designates relative power on each Tx Antenna –  designates relative phase on each Tx Antenna  Feedback parameters  cmd,  cmd sent from RL to base station for optimal setting of Tx Parameters  Transmitter  Radio Channel  Mobile Receiver  cmd (k),  cmd (k) Feedback Channel xtxt

August 13, 1999 TXAA Feedback Channel 9 General Description of Feedback Commands   cmd –Separate power control bit is transmitted besides  cmd –Send 1-bit  cmd per soft handoff leg indicating relative gain of each TX antenna –  cmd indicates a step up/down in power based on estimation from Rx Pilot and Auxiliary Pilot –Step up/down in  indicates that the main antenna increases/decreases power by a fixed step size –Delta-modulation provides robust performance in case of feedback errors   cmd –Send 1-bit  cmd per soft handoff leg indicating relative phase of each TX antenna –  cmd indicates a step up/down in phase on estimation from Rx Pilot and Auxiliary Pilot –Step up/down in  indicates that the main antenna increases/decreases phase by a fixed step size relative to the diversity antenna –Delta-modulation provides robust performance in case of feedback errors  Alternatively complex coefficients can be feedback in a similar manner for possibly less mobile computational complexity   S –Send 1-bit  S per 2 sectors leg indicating strongest received sector based on pilot strengths –Base station decides on a transmit sector based on received  S commands over some period of time

August 13, 1999 TXAA Feedback Channel 10 Generation of Phase and Gain Feedback Commands

August 13, 1999 TXAA Feedback Channel 11 Received Signal (1-path)  Rx Traffic  SNR

August 13, 1999 TXAA Feedback Channel 12 TXAA Antenna Coefficients  Antenna Coefficients  Mobile estimates  (k) and  (k) at k-th time interval

August 13, 1999 TXAA Feedback Channel 13 Generation of Feedback Commands  Make use of Delta Modulation techniques for generation of binary up/down commands