Performance Comparison of DASH7 and ISO/IEC 18000-7 for Fast Tag Collection with an Enhanced CSMA/CA Protocol

ISO/IEC 18000-7 adopted Slotted ALOHA as MAC transmission protocol. However, this protocol cannot solve the collision problem when there is a need of collecting massive tags. To solve this problem, DASH7 adopted CSMA/CA for MAC protocol. It also proposed three kinds of collision avoidance models to implement the back off flexibly. AIND is the unsurpassed model as it can effectively use the contention period employing data transmission time back off. RAIND adopts random initialization and distribute access time of each tag in order to reduce the back off. And the last, RIGD does geometric decaying slot back off, minimizing the number of bakeoffs to reduce energy consumption. This paper presents tag collection scenario. We analyze the three CA models and Slotted ALOHA with tag collection time. We also suggest adaptive guard time method to improve the CA models. The aftermath of tag collection experiment is that CSMA/CA has exceptional performance than Slotted ALOHA. AIND has the best performance among CA models and its performance is 28.7% better than Slotted ALOHA. In addition, the adaptive guard time method enhances RAIND and RIGD which are based on random back-off. In particular, RIGD with adaptive guard time method(AG-RIGD) has similar performance as AIND. Besides, AG-RIGD is better than AIND in terms of energy efficiency because it consumes one third of energy than AIND during tag collection.