Abstract: Sensor network is frequently deployed in rather complex environment, such as underground parking lots, coal mine channels, etc. which are full of obstacles or corners. Such complicated situation brought a big challenge for protocol design, and made unreliable short distance wireless communication less efficient. Earlier protocol design for WSN paid more attention to the connectivity in on/off characteristics, neglecting link quality often in a middle value of 0 and 1 in the real world. As more knowledge on link feature of short distance wireless communication is studied, people begin to recognize the big impact brought by this problem and try many methods to improve the forwarding performance of protocol, such as link estimation, disjoint multi-path, braided multi-path and multi-link strategies, etc. Both uni-link and multi-link forwarding strategies are modeled and analyzed, and a satisfying condition is deduced. If the condition were met, multi-link strategy should perform better than uni-link. By the way, collision model for both strategies is also established and studied, through which the funnel bottleneck is shown and the impact on the performance of both energy efficiency and delivery rate is analyzed. Finally, simulations are conducted on the NS2 platform, and the satisfying condition and collision characteristics derived from the model are verified over simulation network.