Wireless Multicast with Multi-User Diversity

Abstract — Efficient wireless packet data access is possible by exploiting multi-user diversity. This is done by using an opportunistic multiple access system that allocates system resources to one user at a time while using adaptive modulation and coding. A scheduling algorithm provides resource allocation in such a system, and its proper design is crucial in ensuring satisfactory system performance. Multicasting is a spectrally efficient method of supporting group communication by allowing transmission of packets to multiple destinations using fewer resources. When the wireless opportunistic multiple access system provides a multitude of services, at least one of which is a multicast service, the scheduler needs to incorporate the service type as well as the time-varying wireless channel states and the individual observed user latencies for proper resource allocation. This paper presents a number of efficient scheduling algorithms that enable such an operation. Extensive, detailed simulations are performed to show the feasibility of the multicast service provisioning in the opportunistic multiple access system. I

Rf energy harvesting and transfer for spectrum sharing cellular iot communications in 5g systems

Due to copyright restrictions, the access to the full text of this article is only available via subscription.This paper proposes an energy and spectrum efficient IoT network for 5G systems where spectrum is shared with the cellular system for spectrum efficiency and energy harvesting and energy transfer are utilized for energy efficiency. The IoT network, which consists of sensor nodes and a cluster head with a reliable energy source, reuses part of the cellular band whenever the cellular network does not utilize it. The cluster head performs spectrum sensing, random scheduling of the sensor nodes, and schedules some idle time for energy transfer. The sensor nodes harvest RF energy from the cellular traffic and the transferred energy from the cluster head. Provided the sensor nodes have sufficient energy, they transmit collected sensory data when scheduled. The inter-play between the cellular and IoT network introduces trade-offs between the spectrum availability, energy availability, information and energy transfer. This paper shows that for the same cellular traffic level, as the number of sensor nodes in the network increases, the IoT network utilization increases resulting in a multi-user gain thanks to the broadcast nature of the energy transfer. The results offer insights into different operational regimes and exposes what type of IoT applications may be feasible with such networks

GEZGIN: A case study of a real-time image processing subsystem for micro-satellites

GEZGIN is a real-time image processing subsystem, developed as an R&D payload for BILSAT-1, the first earth observing micro-satellite of Turkey. The main functionality of GEZGIN is to compress in real-time multi-spectral images coming concurrently from the 4-band multi-spectral imager on BILSAT-1, using JPEG2000 Image Compression algorithm. The mission definition of BILSAT-1 imposes a 5.5 seconds interval constraint between two consecutive multi-spectral images with 20% overlap. GEZGIN fullfills this mission requirement by exploiting the parallelism among image processing units and assigning compute intensive tasks to dedicated hardware. The architecture of GEZGIN is highly integrated and fully reconfigurable allowing for the upgrade of all processing units in orbit. Hence it maintains flexibility and robustness against failures which are crucial properties for space applications. GEZGIN is built at low cost using completely "commercial-off-the-sheff" (COTS) components and having performed well in all the flight readiness tests, has been succesfully integrated on BILSAT-1. It is currently undergoing orbital tests