DHL Supply Chain Primark – IT Network Installation

DHL Supply Chain

“The company’s technical report clearly highlighted the issues to my client and the team’s knowledge enabled the problems to be solved within days”

Kevin Townend – Business Unit Director, Operations


IT network installation involves a number of factors as illustrated in this case study. Signals were requested by Kevin Townend to investigate A DHL Primark 750,000 sq.ft warehouse with problems for both wireless hand scanners and The WiFi Network.

Mobile hand scanner latency issues were creating a delay of two minutes between data capture and transmission. Additionally, separate issues were indicated by the poor performance of the WiFi infrastructure

Signals were tasked to provide a root cause analysis on the latency issues and evaluate the wireless network. With vast experience in IT network installation, our network engineers responded quickly to the brief. A summary of our approach is outlined below.

The Fix:

Scanner Latency – Prior to arrival on site, Signals established that the cause of the transmission delay was a Microsoft issue within the scanners.  DHL and their incumbent were able to implement the patch speedily.

WiFi – The WiFi Network evaluation revealed a number of issues:

  1. Automated channel selection resulting in radio clash creating handover problems.
  2. Transmission power overlap – The APs were all set to maximum transmission power resulting in saturation. The scanners accessed twenty-one APs with no ability to lock on to any individual AP.
  3. One third of The Access Point Radios were turned off –indicating the network was over-populated with access points.
  4. Lack of redundancy (no fail-over protection) – Dumb access points managed by four smart switches, meaning should any smart switch fail, a quarter of the warehouse would have no Wi-Fi Coverage. The preferred method – To use smart access points with dumb switches.
  5. Incorrect omni-directional antennas were installed rather than directional and hi-gain antennas.
  6. APs were only accessing three frequencies, randomly, rather than all available frequencies in the UK.


The Result:

Signals were provided access to all areas, including the costings for hand scanners and infrastructure. We analysed the situation and recommended a complete replacement of The Wi-Fi Infrastructure. Our report highlighted over population of the network, overcharge for hand held devices and access points, and use of inappropriate hardware by the incumbent supplier with a total overcharge of approximately £150,000.

We recommended replacement with twenty four smart access points – twelve active and twelve back-up units. These should be configured to use specific channels enabling correct handover policy and utilise power management to control the signal strength on each antenna. In addition, Signals recommended the use of directional and hi-gain antennas.

DHL changed the network accordingly, received satisfactory compensation from the incumbent supplier and adopted a changed due diligence policy for all new installs

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