The wireless mesh network (WMN) is a promising solution to support wireless broadband applications. However, mesh networks face the power unfairness issue. Compared to the users far away from the gateway, the users near the gateway have to relay more traffic and consume more power. This paper proposes a scalable ring-based WMN that can ensure power fairness among users by adjusting its ring widths. On top of the ring-based cell structure, frequency planning is suggested to reduce the contending users, thereby making the system more scalable to accommodate more users. To investigate the overall tradeoffs among power fairness, capacity, and coverage, we develop an analytical model to evaluate the throughput and power consumption of the ring-based WMN using carrier sense multiple access (CSMA) medium access control (MAC) protocol in the unsaturated situation. Then, the optimization approach is applied to determine the best number of rings and the optimal ring widths, aiming to maximize cell capacity and coverage subject to the requirement of power fairness. Numerical results show that compared to the uniform ring-width strategy, the variable ring- width design criterion can improve cell capacity and coverage.