In large heavy-duty resealable plastic food-storage bag, mix sugar, salt, orange peel, onion, peppercorns and 4 cups water. Seal bag and squeeze to mix until sugar and salt have dissolved. Place salmon in bag of brine; seal bag. Refrigerate at least 3 hours but no longer than 4 hours.
Cover wood chunks with water; soak at least 30 minutes.
Drain wood chunks. Prepare and heat smoker using wood chunks and adding water to water pan following manufacturer’s directions.
Meanwhile, remove salmon from brine; discard brine. Blot salmon dry with paper towels. Brush both sides of salmon with oil. Place salmon, skin side down. Sprinkle with paprika and pepper.
Place salmon, skin side down, on top grill rack in smoker. Cover and smoke about 1 hour or until salmon flakes easily with a fork. If smoking stops, add additional wood chunks through side door of smoker.
Place salmon, skin side up, on foil. Peel skin from fish and discard. Use foil to turn fish onto serving platter.