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In the multiple-reader environment (MRE) of radio frequency identification (RFID) system, multiple readers are often scheduled to interrogate the randomized tags via operating at different time slots or frequency channels to decrease the signal interferences. Based on this, a Geometric Distribution-based Multiple-reader Scheduling Optimization Algorithm using Artificial Immune System (GD-MRSOA-AIS) is proposed to fairly and optimally schedule the readers operating from the viewpoint of resource allocations. GD-MRSOA-AIS is composed of two parts, where a geometric distribution function combined with the fairness consideration is first introduced to generate the feasible scheduling schemes for reader operation. After that, artificial immune system (including immune clone, immune mutation and immune suppression) quickly optimize these feasible ones as the optimal scheduling scheme to ensure that readers are fairly operating with larger effective interrogation range and lower interferences. Compared with the state-of-the-art algorithm, the simulation results indicate that GD-MRSOA-AIS could efficiently schedules the multiple readers operating with a fairer resource allocation scheme, performing in larger effective interrogation range.

In a Radio Frequency Identification (RFID) System, collision between tags is one of the core problems that we must consider about. In general, a collision will occur when more than one tag communicates with the reader simultaneously, reducing the system efficiency. To solve this, dynamic frame slotted ALOHA (DFSA) is widely adopted nowadays, and as a variant of DFSA algorithm, Q-algorithm is accepted by the EPCglobal specifications for RFID air interface Class1 Gen2 protocol. Based on this, we provide a new algorithm called EPP-Q to adjust the parameter Q more accurate as well as maintain high system efficiency when tags are no more than 2 Q-1(Q belongs to 0 to 15). The simulation provides an obvious improvement when EPP-Q is compared with other two mainstream algorithms, not only in system efficiency, but also in the quantity of time slots used.

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