“…Unfortunately, it is, in general, difficult to obtain a closed-form expression of the stationary distribution of 2D-RRWs. This is primarily why the tail asymptotics of 2D-RRWs and their generalizations have been extensively studied (see [2,8,10,11,16,15,19,20,21,22] and the references therein). These studies focus on identifying the decay rate of the stationary distribution, though they make a limited contribution to the performance evaluation of the queueing systems mentioned above.…”