Varying Checksum failures in WiMAX uplink

Hi,

I find that the checksum failures varies from WiMAX BTS to BTS with my
CPE(Customer Premise Equipment) and so are the ping drops which are
dependent largely on these checksums.

I find that the Checksum failures are present during the uplink from
CPE to the BTS and this is varying from BTS to BTS for the same CPE.
Strange :(:( . Some BTS show more that 50 % checksum failures.

Why this checksum failures vary from WiMAX BTS(Base Transceiver
Station) to BTS ?
Any ideas ?

Thx in advans,
Karthik Balaguru