The　power　amplifier　of　the　radio　repeater　often　works　in　the　nonlinear　regime　to　improve　its　efficiency,　which　will　not　only　cause　a　lower　SNR　and　mutual　interference　between　the　channels,　but　also　increase　the　error　rate　of　the　signals　transmitted　in　their　own　channels.　This　paper　utilizes　the　pre-distortion　technology　to　solve　the　problem　and　applies　the　QRD-RLS　self-adaptive　algorithm　to　realize　the　DPD　in　FPGA.　The　data　truncation　errors　in　FPGA　are　operated　and　stored　by　a　finite　floating　point.　Based　on　results　of　DPD,　the　rise　of　baseline　is　analyzed　in　this　paper.　This　paper　proves　that　error　is　the　leading　cause　to　the　rise　of　baseline.　Moreover,　the　errors　caused　by　the　truncate　operation　are　discussed,　and　the　method　of　reducing　truncation　errors　is　also　demonstrated.　After　optimization,　the　SNR　of　the　circuit　grows　more　than　35　dB,　the　ACPR　improves　20　dB　and　the　influence　of　errors　is　limited　to　merely　3dB.　©　2012　IEEE.