WiFi Successive Interference Cancellation : Channel Estimate for Unused Carriers ?

Hello, I am working on SIC between WiFi(802.11g) and ZigBee(802.15.4). First I am decoding the WiFi signal. Once decoded I have to regenerate the WiFi signal with the decoded bits and channel estimates. However the channel estimates are available only for 52 sub carriers (using LTS). How shall I put channel effects for the unused sub carriers i.e. -32 to -27 and 27 to 31 as well as the DC. Because for these sub carriers, I don't have nay channel estimate ? Am I doing something wrong ? Regards Sumit