## 2 Theoretical Background
### Logistics Operator in Multi-Channels
Among the tasks of 3 PLs in the field of multi-channel are also the handling of drop shipping logistics and supporting companies in resource management, e.g., using the VMI model [86]. One of the undisputed critical elements related to the functioning of online sales, from the perspective of logistics processes, is precisely an adequate warehouse management system [7]. The adaptation of LSPs to current trends related to digitalisation is also an important element in multi-channel. Digitalisation is changing the market environment in which companies are moving, most notably in terms of changing working environments, customer experiences, and entirebusiness models [6]. This is also the case for multi-channel logistics operators. They have to adapt their operations to current trends and to the requirements of their internal customers, which is consequently considered to be an adaptation of the operators' business models to contemporary market requirements. In addition, issues such as, for example, the operation of click-and-mortar shops, i.e., shops where orders can be placed electronically or in person by traditional means, require increased logistics integration. This integration should allow customers to order online and pick up their purchases from the nearest shop or return those products at the most convenient location [5]. One of the logistical issues in cross-channel is the delivery from warehouses adapted to the collection process for small shipments. Warehouses adapted to the pick-up process can be linked to existing warehouses. In the cross-channel area, further distribution channels are usually differentiated in the area of last-mile logistics [80]. LSPs in such a situation should pay special attention to the reverse flow of products [74]. Some authors assign logistics related to delivery and product picking and return a high score in estimating the risks that occur in cross-channels [87]. Such risks can be mitigated by outsourcing logistics operations to logistics operators. The main challenge for LSPs in the omni-channel era is managing the increasing number of small shipments, fulfilling more frequent orders, shorter lead times, a higher number of SKUs, and synchronising distribution processes across channels [1]. The literature notes that logistics service providers should develop their skills and infrastructure towards enhancing their capabilities in automating consignment sorting processes in the area of warehouse management [74]. Concepts such as fully automated warehouses, carbon-neutral buildings, hybrid or all-electric trucks, robotics, drones, and voice- or optically-guided warehouse operations are increasingly being used by LSPs [1]. LSPs should also invest in software and IT platforms to automate transport planning tasks in terms of considering fleet location, road congestion, and capacity [74]. Some researchers note the possibility of combining technological solutions from, among others, the Internet of Things used at the manufacturer with LSP operations [88]. LSPs should tailor logistics services for specific modes of receipt and also demonstrate the ability to integrate their solutions with customer-friendly solutions such as QR codes [78]. Among the main challenges of LSPs is that they need to satisfy customers with different needs in a variety of channels [2]. The literature also indicates in their research that most LSPs create additional customer value in omni-channel systems [89]. Using dedicated applications and personalised IT systems, LSPs aim to increase the transparency of distribution channel flows, create a customer base with their needs, and increase customer satisfaction by improving the quality of logistics services tailored to specific customers. An IT platform can serve as an application, providing seamless digital communication between companies throughout the supply chain [90].