Channel estimation and interpolation by vector in OFDM
You can use various methods to interpolate the channel - Linear, Polynomial, Sinc Interpolation etc. But what you need to keep in mind is synchronization. You have to make sure that frequency and timing offsets are eliminated or accounted for. Otherwise you will see an error floor in the Channel Estimation Error. Means your Mean Square Error (MSE) for Channel estimate will not go down even if SNR increases. It will go down for lower SNR but will flatten out for higher SNR. The residual errors due to timing/frequency offsets will spill over to channel estimation. See this paper (https://ir.nctu.edu.tw/bitstream/11536/32821/1/000072736100027.pdf). A simple search in google scholar with 'Channel Interpolation in OFDM' will reveal lot of good references.