What are the advantages and disadvantages for a MIMO system with or without the knowledge of channel state information? The TTL field of an IP packet is subtracted by 1 when the IP packet passes...

What are the advantages and disadvantages for a MIMO system with or without the knowledge of channel state information?

The TTL field of an IP packet is subtracted by 1 when the IP packet passes through a router, and thus the checksum value after the subtraction must be changed. Please find an efficient algorithm to recompute the new checksum value. (Hint: See RFC 1071 and 1141.)