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What is Dense Reader Mode in RFID Readers? How the RFID Anti-collision technique works?

  • Akansha Sharma
  • Mar 06, 2024
  • RFID
What is Dense Reader Mode in RFID Readers?

"DRM solves the RFID reader collision issues by letting RFID scanners communicate with several RFID tags at the same time, while overcoming the Reader collision, resulting in increased read efficiency and lower collision rates"

RFID (Radio Frequency Identification) technology's fast growth has enabled widespread adoption and increased deployments of RFID solutions in varied contexts under varying situations and limits. These limits range from the number of readers deployed to their mobility, which has a significant impact on the quality of the RFID system, resulting in reading collisions.

Imagine you have a large warehouse where multiple fixed readers are installed at various checkpoints and there are hundreds of workers often roaming around with portable RFID readers in close proximity, looking for inventory assets, tracking consignments, and reconciling inward and outward movement of assets. What happens is that when multiple RFID readers are deployed nearby, the RF interrogation signals that are supposed to be picked up by RFID tags, these signals are picked up by another reader in the proximity. Now we have an RFID reader collision problem.

With various wireless technologies working on radio frequency, the collision has become a big issue, leading to inefficiency and errors in data collection and transmission.

The limitations of barcodes in terms of reading distance, complexity, errors, and the requirement for a straight line of sight prompted the introduction and advancement of RFID (Radio Frequency Identification) technology as a better-performing AIDC solution. The RFID enables contactless identification without the necessity for a direct line of sight, leveraging RFID Readers and Tags.

What is The Dense Reader Mode (DRM)?

Dense Reader Mode (DRM) is an RFID reader function that improves tag recognition performance in settings with a high RFID tag density where multiple RFID Readers are deployed and functioning simultaneously.

Utilizing dense reader mode, simply by adjusting the antenna settings to Dense Reader Mode, allows a reader to overcome interrogator interference, not allowing the strong RFID reader signals to overcome weak tag response on selected communication channels. The Dense Read Mode also ensures that tags and readers are separated by their ability to communicate on different channels.

DRM solves the RFID reader collision issue by letting RFID scanners communicate with several RFID tags at the same time efficiently while overcoming the Reader collision, resulting in increased read efficiency and lower collision rates. In DRM, the reader uses enhanced anti-collision algorithms to better detect and handle tag replies, ensuring that all tags within its range are queried and recognized, even with a weak transponder response.

Most readers by Zebra, Impinj, Chainway, and other RFID companies are EPCglobal gen 2 v2 compliant and support the Dense Reader Mode to ensure efficient AIDC applications in high-volume tag scanning facilities.

What is Dense Reader Mode in RFID Readers? How the RFID Anti-collision technique works?

(Pic Credit: Zebra Technologies)

Understanding Anti-collision Techniques other than DRM 

Anti-collision methods are key components of RFID systems that solve the difficulty of recognizing numerous RFID tags within the reader's range. These strategies optimize tag interrogation, reduce data collisions, and improve overall system efficiency.

In RFID systems, there are two basic anti-collision methods other than DRM:

Tree-Based Protocol

1. In this mechanism, the reader issues a query command, and tags inside its range answer concurrently.

2. Tags wait for the command and answer using their unique identification number (UID).

3. The reader then separates the tag population into groups depending on their replies and queries each group until all tags are found.

4. It continues recursively, similar to the structure of a tree until all tags are recognized.

Aloha protocol

1. The Aloha protocol allows tags to answer the reader's query command at random.

2. When a tag gets a query command, it waits a random time before replying to prevent colliding with another tag.

3. If a collision occurs, the tags involved wait a random amount of time before attempting to react again.

4. The process will continue until all tags have been correctly recognized.

Key Considerations for Implementing Dense Reader Mode

When installing Dense Reader Mode (DRM) for RFID systems, numerous factors must be considered to achieve maximum performance and efficiency:

1. Hardware Requirements: Ensure that the RFID reader and antennas utilized can support Dense Reader Mode. Specific reader models or firmware updates are sometimes required to activate DRM capabilities. 

2. Tag Population Density: Determine the estimated tag population density for the reader's range. DRM is particularly effective in areas with a large number of RFID tags, such as warehouses, distribution facilities, and retail stores.

3. Antenna location: Proper antenna location is essential for maximizing read speeds while minimizing interference. Antennas should be properly placed to cover the target read area uniformly while avoiding signal interference. 

4. Reader Configuration: Change the RFID reader settings to enable Dense Reader Mode and optimize characteristics including read power, sensitivity, and anti-collision algorithms. Fine-tuning these variables can improve read performance while reducing collisions.

5. Network Infrastructure: Make sure the network infrastructure can accommodate the extra data traffic caused by DRM-enabled RFID readers. It might include increasing network capacity or improving network topologies to avoid bottlenecks. 

6. Testing and Validation: Thorough testing and validation are required to confirm the usefulness of Dense Reader Mode in real-world circumstances. Conduct field testing to evaluate scan rates, tag detection accuracy, and overall system performance under a variety of situations.

Benefits of Dense Reader Mode as an Anti-Collision Technique 

Dense Reader Mode (DRM) provides various advantages for RFID systems, particularly in circumstances where a large number of tags must be scanned concurrently. Some major benefits of Dense Reader Mode include:

1. Overcoming RFID Reader collision issues

2. Optimizing Tag Reading Efficiency with Dense Reader Mode

3. Managing Tag Collisions with Dense Reader Mode

4. Maximizing Throughput with DRM

5. Scalability of DRM

1. Enhanced Tag Reading Efficiency: DRM enables RFID readers to read numerous tags within their range of operation at once. It is essential in situations with tightly packed objects or a large number of tagged assets, such as warehouses, retail stores, or industrial facilities.

2. Improved Tag Collision Handling: In instances when many RFID tags answer the reader's query at the same time, DRM uses improved anti-collision algorithms to successfully manage tag collisions. DRM promotes consistent and accurate data capture in demanding circumstances by reducing data collisions and optimizing tag identification.

3. Increased Throughput: By streamlining tag interrogation operations, DRM can significantly boost RFID systems' throughput. It allows for quicker and more effective inventory management, asset monitoring, and supply chain activities, resulting in increased overall productivity and efficiency. 

4. Scalability: DRM is very scalable, allowing for a large number of tags within the reader's range without sacrificing speed. It is essential for applications that need the simultaneous recognition of thousands, if not millions, of RFID tags, such as large-scale logistics or inventory management systems.

5. Enhanced Reader Flexibility: Many current RFID readers enable Dense Reader Mode, which allows RFID systems to be used in a variety of situations and applications. Organizations can apply DRM-enabled readers to adjust their RFID infrastructure to changing business demands and efficiently grow their operations.

Finally, Dense Reader Mode (DRM) is a sophisticated anti-collision technology that is essential for improving RFID system performance, especially in situations with high tag density and frequent reader-to-tag contacts where multiple readers are also deployed. DRM allows RFID readers to efficiently manage multiple tag signals, reducing collisions with other readers and increasing data capture speeds with high accuracy.

Disclaimer: The information presented here is for general information purposes only and true to best of our understanding. Users are requested to use any information as per their own understanding and knowledge. Before using any of the information, please refer to our Privacy Policy and Terms and Conditions.


  • Created on Mar 06, 2024
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