Johannes Lessmann

Learn More
Cloud radio access networks promise considerable benefits compared to decentralized network architectures, but they also put challenging requirements on the fronthaul and backhaul network. Flexible centralization can relax these requirements by adaptively assigning different parts of the processing chain to either the centralized baseband processors or the(More)
For the evaluation of wireless network protocols, simulation has established itself as a good compromise between cost and complexity, on the one hand, and accuracy of results, on the other hand. Most established network simulators, however, were originally developed for wired networks and only later extended to the wireless domain. Some simulators like(More)
Existing mobile network infrastructures, for example the Evolved Packet Core (EPC), are based on mission specific, specialized network nodes/entities that are interconnect via standardized interfaces in a static manner, each providing a specific service/function. One common practice adopted by many Mobile Network Operators (MNOs) in order to cater to(More)
The task of a MAC protocol is to manage the access to the (wireless) medium so that it can be shared by multiple nodes. TDMA MACs achieve this by providing non-overlapping access schedules. Typically, such schedules are dictated by a set of master nodes or negotiated between the nodes in a preliminary phase by exchanging messages. This has to be(More)
IP based design comprises two main steps. First, a suitable IP has to be found. Second, the IP has to undergo further processing before it can be included in existing designs. Since IP providers use different formats and design tools require different parts of the IP for their services it is hard to find an IP format that satisfies and is exchangeable(More)
For the evaluation of wireless network protocols, simulation has established itself as a good compromise between cost and complexity, on the one hand, and accuracy of results, on the other hand. In order to assess and debug the simulated protocols, visualization both in the form of textual console messages and graphical representations can be of great help.(More)
This work presents Xhaul: the 5G Integrated Fronthaul/Backhaul. Xhaul aims at developing an adaptive, sharable, cost-efficient 5G transport network solution integrating the fronthaul and backhaul segments of the network. This transport network will flexibly interconnect distributed 5G radio access and core network functions, hosted on in-network cloud(More)
In order to evaluate the behavior and performance of protocols for wireless networks, simulations are a good compromise between cost and complexity, on the one hand, and accuracy of the results, on the other hand. Since there are many simulators for wireless networks, it is often difficult to decide which simulator to choose. To help shed light on this(More)
The IEEE 802.21 standard facilitates media independent handovers by providing higher layer mobility management functions with common service primitives for all technologies, thus hiding the technology specifics of the lower layers. Right after the base specification was published, several voices rose up in the working group advocating to broaden the scope(More)