Leaky coaxial (LCX) cable can provide high-speed wireless transmission and wireless power transmission for communication systems when used as antennas. Due to the constant power loss over cable, we have proposed a simple method of power allocation for LCX-MIMO system using the correct positional information (PI) of the user. Our proposed method largely improves its capacity with a low computational complexity. However, it is impossible and impractical to obtain the correct PI. In this paper, we will study the capacity performance of the LCX-MIMO channel considering the position detection error. The capacity result shows that the capacity loss of the MIMO channel is minor when the location error is within 1 m. The capacity of proposed power allocation is still better than that of equal power allocation even though the location error is within 2 m.