Logistics Case Study: China Post

May 28, 2014 Impinj

The China Post, the official postal service of the People's Republic of China, was in search of a way to sort boxes in a fast-paced environment.

The RFID solution delivers:

  • State-owned enterprise
  • Established in 1949
  • Manages and regulates national postal industry


The Nanjing Aeronautics distribution center, China’s largest express mail services (EMS) processing center, needed an efficient way to sort boxes of presorted mail packages according to intended location. Sorting these boxes of mail packages presented a few difficulties. First, the boxes moved along a conveyor very quickly, at the rate of one meter per second. The identification of these boxes would consequently have to occur extremely rapidly. Second, the boxes were situated very close to each other, with only ten to twenty centimeters between each. The identification technology would have to be quick and very sensitive to correctly identify and sort each box. Finally, the boxes were not uniformly placed on the conveyor, so the chosen solution would need to be able to recognize the box regardless of its position on the conveyor.

China Post asked the China Post Science & Technology Co. (CPST), a scientific and technical support provider for the postal industry, to select and implement a solution. CPST eliminated the idea of using bar code technology, because box spacing and variable placement of boxes on the conveyor made bar code recognition poor. When tested, this technology operated with only 95% accuracy. In order to make sure all boxes were correctly sorted, the distribution center would need to have workers to supervise the process and identify incorrectly sorted boxes, which would be slow, expensive, and make it difficult for the center to meet processing speed requirements.

Because an RFID label does not require line of sight and is not sensitive to direction and angle, CPST decided that the best solution would be UHF RFID technology. However, one serious challenge remained: how to properly identify and sort each consecutive box, given their speed and proximity to one another

How It Works

CPST chose Impinj Monza 4 tag chips and Impinj Speedway readers, due to their reputation for high performance and flexibility of use within customized applications. During installation and test of the RFID solution in May 2012, each box of mail was tagged with an Impinj Monza 4 tag chip. As the boxes traveled along the conveyor, a Speedway reader detected each tag and correctly identified each box’s destination. Impinj’s Mini-Guardrail antenna was used to limit the field of vision (FOV) of the reader to only 7.5cm, which ensured that only one box would be read at a time, and that no boxes would be skipped. By October 2012, the new box sorting system was fully operational and meeting the needs of China Post.


The implementation of this RFID solution has dramatically improved the efficiency of the box sorting system at the China Post Nanjing Aeronautics distribution center. The sorting system now functions with an unprecedented accuracy of 99.9%, which makes the sorting process quicker and cheaper, as the center does not have to spend time and money to have employees check for and correct sorting errors. As a result, China Post is able to provide more efficient express mail services.

Additionally, the RFID tags on the boxes have helped the distribution center automate the inventory and recycling of the boxes, which has improved management efficiency.

China Post

China Post, or the State Post Bureau of the People’s Republic of China, is the official postal service of the People’s Republic of China. It is a state-owned enterprise which regulates the national postal industry and the management of national postal enterprises. China Post is responsible for domestic and international mail delivery services, circulation of newspapers, journals and books, stamp issuing, confidential correspondence communication, postal express delivery and logistics services, and a variety of postal agency businesses. It supervises 82,116 postal offices and 236 mail processing centers throughout China.



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