We consider a set of secondary transmitter-receiver pairs in a cognitive radio setting. Based on channel sensing and access performances, we consider the problem of assigning channels orthogonally to secondary users through distributed coordination and cooperation algorithms. Two economic models are applied for this purpose: matching markets and competitive markets. In the matching market model, secondary users and channels build two agent sets. We implement a stable matching algorithm in which each secondary user, based on his achievable rate, proposes to the coordinator to be matched with desirable channels. The coordinator accepts or rejects the proposals based on the channel preferences which depend on interference from the secondary user. The coordination algorithm is of low complexity and can adapt to network dynamics. In the competitive market model, channels are associated with prices and secondary users are endowed with monetary budget. Each secondary user, based on his utility function and current channel prices, demands a set of channels. A Walrasian equilibrium maximizes the sum utility and equates the channel demand to their supply. We prove the existence of Walrasian equilibrium and propose a cooperative mechanism to reach it. The performance and complexity of the proposed solutions are illustrated by numerical simulations
The fourth industrial revolution, also referred to as Industrie 4.0, has triggered a number of research projects to improve communication systems for industrial environments. Wireless technologies for mission-critical machine-to-machine communication are expected to enable very efficient and highly flexible production processes. It is especially challenging for wireless interfaces to fulfill the required end-to-end latency and the reliability constraints of the automation industry. In order to design novel PHY and MAC schemes for ultra low delay, ultra reliable and deterministic transmission of data, e.g., through optimized pulse shaping, we study the indoor radio propagation in a representative factory automation cell where industrial robots are to be controlled. We performed channel measurements using a broadband channel sounder at 5.85 GHz carrier frequency. During the measurements, the robots were in motion and executed a typical pick-and-place process. From the recorded data we evaluate the channel characteristics and calculate relevant delay statistics. We distinguish two measurement series that differ in the scattering environment and present the derived parameters. Finally, we discuss the impact of our results on the design of new 5G waveforms for industrial radio systems
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