An overlaid mesh with unequal RF nodes placement has been introduced to improve network performance of wireless network-on-chip benefited from the greatly reduced network diameter. Traffic however can easily get crowded at big RF nodes due to the sharing and competition of multi-channel usage. To alleviate traffic congestion, a load adaptive channel distribution and arbitration scheme is proposed in this paper. The single UWB frequency band is efficiently shared among the nodes such that more bandwidth is allocated to more potentially congested nodes. Further, higher winning probability is granted to them so as to release earlier crowded traffic. Coping with the uniqueness of overlaid mesh, a three-tiered arbitration strategy is proposed to greatly reduce the contention overhead and improve the end-to-end performance. The optimization effectiveness and performance impact of the proposed approach is extensively studied and investigated.