and compares the gross weight of the tagged items against the gross weight stored in a backend database (as a new field) that is only accessed through properly read tags. Although there are many positives of using multiple tagging to avoid errors, there are also a few drawbacks which have to be kept in mind. Following are few of the drawbacks related to reading multiple tags in one location: It has independency from the tag’s type as everything is set and controlled in the backend database It is easy to deploy as there is no additional software/hardware configuration but computing the total weight of tagged items It is applicable to multiple domains without limitation It has no irrational high expense as the weighting machine is cheaper compared to the cost of RFID readers and antennas The weighting process shown in figure 5.1.1  can be explained by the following steps: Tags are attached and fixed on items under consideration The computed gross weight of the RFID tagged items is saved and stored in the backend database. RELIABILITY ANALYSIS OF RFID READABILITY Final Report Figure 5.1.1 –RFID Weighting Machine
Page 14 The operation starts with items passing the read -zone without any prior awareness of the amount of items entering. Once tags are read, they are weighed by the weighing machine that has a small RFID attached to it. If the number doesn’t match, an alarm will sound coming from the database. 5.2 Redundancy Techniques One other technique that has been recommended in order to improve RFID reliability is using redundancy. RFID redundancy techniques involve using multiple antennas, multiple readers and tags that can significantly enhance the reliability. During our research study, we came across many such authors that have conducted extensive research on RFID system redundancy which we have tried to cover in great length in this section.  There are several approaches that have been used to implement redundancy in RFID systems. A few of these are stated below: Multiple antennas per portal: This is a widely used technique, since it makes readers capable of handling two or more antennas in a single zone or portal. Multiple readers per portal: This is not a very applicable solution for old RFID versions, primarily because it requires dense reader modes in order to work properly. Multiple readers are difficult to implement since reader-to-reader RF interference can also occur. Multiple tags per object: Multiple tags can be placed on different sides of an object or with different orientations. However as mentioned before if the tags are too close to one another the read reliability will drop. One other issue is that if the number of tags attached to one object is too large, there will be an excess amount of interference, leading to a decrease in read reliability.  While reviewing our literature, it was determined that the multiple tag technique is by far the best among the three suggested types of redundancy techniques. The fact that Multi-tags are very
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