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AUTOMATION & ROBOTICS S
ince the global pandemic, ever increasing demands on fulfillment have resulted in a sharp rise in warehousing productivity initiatives. Technology often plays a central role
in these initiatives. This has led warehouse management and their IT teams to look for better networking options to improve operations and maximise the utilisation of their assets. The connection of various devices and people in one automated ecosystem is paramount, as is the consistent communication between them. But coverage and connectivity are two common problems which seem to be at odds in many wireless networks in warehouses. That is why identifying and deploying a wireless network to support everything, is essential to productivity. As warehouses involve many moving parts:
personnel, vehicles, and stock, they need a communications network that keeps operations moving 24/7, 365 days a year. However, traditional networks often prove insufficient to the demands of autonomous AGVs, dismounted workers, and logistical systems being implemented to scale with ever increasing demands on fulfilment operations. This is only made harder because warehouses are so dynamic, and ever-changing environments. Many warehouse operators avoid addressing
the problems with their current network for a number of reasons. They may not realise more reliable and capable network options exist. Alternatively, they may confuse a network communications issue with a robotics or automation issue. Or, they may worry that a network upgrade will be too difficult, too expensive or take too long. However, they are at a crossroads. They either improve operational efficiency and warehouse utilisation, or risk facing the consequences of not meeting the challenges of their role. The good news is, there are great options which are likely far easier to deploy than they imagine, and won’t break the bank.
OBSTACLES TO ACHIEVING AUTONOMOUS OPERATIONS Autonomous systems enhance productivity, speed, and accuracy. But they require continuous mobile connectivity to run effectively. If they lose connectivity even momentarily, it can stop them from working and negate their expected efficiency gains. A wireless network should be reliable and run in a way that they are invisible to the people and machines relying on them. However, far too often, wireless communications are a source of frustration and an obstruction to achieving operational goals and objectives. Traditional Wi-Fi networks in particular
struggle in a warehouse environment. Inconsistent throughput, high latency and dropouts are common. Fundamentally it is not the brand of Wi-Fi which operators chose, but rather the Wi-Fi networking protocol which is to blame. The protocol limits each client to a single connection to one access point. So, whenever an AGV or person walks around the end of an aisle, the shelving creates obstructions which at best
KEEPING AUTONOMOUS WAREHOUSE OPERATIONS MOVING WITH MESH NETWORKING
By Todd Rigby, director of sales at Rajant Corporation
decreases network performance and at worst blocks the signal altogether. In large areas, Wi-Fi clients roam from access
point to access point. This roaming is a hard break. The Wi-Fi client literally drops the active connection before making a new connection to the next access point. If the handoff does not complete in 10ms or less, most AGVs will stop as a safety measure and wait for a person to restart them. Alternatively, if a dismounted worker’s device doesn’t reconnect, valuable time is wasted while they manually reconnect. Additionally, the fixed infrastructure can only transmit data as fast as the weakest client connection. Because connected clients are always moving, a Wi-Fi network will almost never operate at optimum data rates. There are simply too many operational variables which cannot be designed or configured away. Besides mobility, these also include inventory, racking, and other equipment. This past March, I attended the Promat conference in Chicago and had the opportunity to speak with hundreds of people. Every single person I spoke to had one or more chronic Wi-Fi issues in their warehouse. Some warehouses have adopted Private Long
Term Evolution (LTE) networks. Private LTE networks are more sophisticated and performs more elegant roaming, however that sophistication and elegance comes with a very high price tag. Don’t be surprised by a 10x jump in cost. Like Wi- Fi, Private LTE also only allows for one active connection between a client and infrastructure. In order to deal with all the physical obstruction in a warehouse, much more infrastructure is required.
Despite all the hype around 5G networks, Private LTE does not deliver the same throughput as the highest performing mesh network options. This comes down to simple physics.
LESS IS ALWAYS LESS Bad English aside, Private LTE uses the CBRS spectrum in the 3.6 GHz range. This spectrum is a narrower band than the unlicensed spectrum which Wi-Fi and mesh networks utilise. In short, narrow band means less bandwidth. And while we all love to stream video on our smartphones, do not assume your AGVs will have the same user experience. LTE by design has more download capacity than upload capacity. This is perfect for smartphones, but bad in industrial environments where the capacity most needed is on the upload stream from your AGVs and dismounted workers to the file servers. Both Wi-Fi and Private LTE require LAN
connections at each infrastructure point. For new warehouse construction, this will add to the cost of deploying either of these network options. Do you remember playing with walkie- talkies as a kid? Remember how only one person could talk at a time? In networking parlance, this is called half-duplex. Whereas talking on a telephone is full-duplex. Both Wi-Fi mesh and LTE data networks are half-duplex.
NAVIGATING RF BLOCKAGES Throughput, or the amount of data you can transmit over a connection is directly correlated to signal quality. Radio Frequency (RF) signal interference is commonplace, causing indoor
14 NOVEMBER 2023 | FACTORY&HANDLINGSOLUTIONS
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