Infrastructure‐less networks connect communication devices end‐to‐end by managing links and routes independent of fixed networking facilities, relying on dedicated protocols running on end‐user devices. The large variety of infrastructure‐less concepts and related aspects can be confusing both for beginning Ph.D. students as well as experienced researchers who wish to get an overview of neighbouring areas to their own research foci. Frequently discussed topics such as different types of sensor‐, vehicular‐, or opportunistic networks are covered. The authors describe different networking concepts by looking at aspects such as the main properties, common applications, and ongoing research. Furthermore, the concepts by common characteristics such as node mobility, network density, or power consumption are compared. The authors also discuss network performance evaluation by describing commonly used metrics, different evaluation techniques, and software tools for simulation‐based evaluation. The references given in each section help obtain in‐depth information about the presented topics and give hints about open research questions, which can be a starting point for own investigations.
Communication has been crucial since the beginning of space exploration. Control information and telemetry data of the space vessels as well as voice and video communication of the crew with the ground control have to be maintained. This paper is a survey for readers new to the topic to get an overview about the current status of space communication in national agencies and standardization bodies and ongoing research in the field. It also gives a short overview about the historical development and finally summarizes the authors’ thoughts about future challenges in space communication.
This paper initially, describes the NOMAD test-bed being set up at ComNets for network integration to integrate various bearer technologies (GSM, GPRS, WLAN, Ethernet). It is based on different Mobile IP versions (IPv4 and IPv6) and software for ad-hoc networking using the AODV (Ad-hoc On Demand Vector routing) protocol. The second section describes the Mobile IP implementations and the improvements achieved in the area of handoff delays. The paper also details the results obtained from the ad-hoc network, to determine the performance of AODV when new nodes are added, and explains future research.
In this paper, transmit power control algorithms are discussed to support the spectrum management required by the wireless LAN standard IEEE 802.11h. A centralised algorithm for the infrastructure mode and an algorithm working on a link-by-link basis for ad-hoc networks are discussed. The performance of the algorithms, in particular the reduction of the transmit power and the enhancements of the QoS parameters delay and throughput are considered. It is shown that both algorithms significantly reduce the transmit power and improve the quality-of-service characteristics of wireless networks
In this paper, a cross-layer scheduler for wireless LAN access points is introduced which includes a MAC and a PHY layer stage. For the MAC scheduler, both a simple round-robin scheme and an adaptive scheme which considers both the queue length and the packet lifetimes of each flow are considered. The MAC scheduler hands over a list with the most important packets to the PHY scheduler, which selects one or more packets according to the channel capacity available for the respective destination stations. It is shown that the combination of the MAC and the PHY layer scheduler increases the throughput while the delay is reduced. Fairness is supported in the way that the performance is enhanced not only for the entire system, but also for the individual flows.