Abstract-Cloud Radio Access Network (C-RAN) is a novel mobile network architecture which can address a number of challenges the operators face while trying to support growing end-user's needs. The main idea behind C-RAN is to pool the Baseband Units (BBUs) from multiple base stations into centralized BBU Pool for statistical multiplexing gain, while shifting the burden to the high-speed wireline transmission of In-phase and Quadrature (IQ) data. C-RAN enables energy efficient network operation and possible cost savings on baseband resources. Furthermore, it improves network capacity by performing load balancing and cooperative processing of signals originating from several base stations. This article surveys the state-of-the-art literature on C-RAN. It can serve as a starting point for anyone willing to understand C-RAN architecture and advance the research on C-RAN.
A new magnetic separation idea utilizing several ideas from microfabrication and nanomagnetics is presented. The basic idea comes from our earlier work using asymmetry in obstacles and Brownian motion to effect separation of objetcs [10] by moving them in streams whose angle to the hydrodynamic average velocity is a function of the diffusion coefficient of the object. The device we propose here is not technically a Brownian ratchet device but uses the idea of force which acts at angle to the hydrodynamic flow. In our case, the force is generated by a magnetic field gradient which comes from an array of magnetized wires which lie at an angle 0 to a hydrodynamic field flow. The sum of the hydrodynamic force and the magnetic force create a new vector which as in the case of the Brownian ratchet moves the cell out of the main stream direction.
The placement of the complete baseband processing in a centralized pool results in high data rate requirement and inflexibility of the fronthaul network, which challenges the energy and cost effectiveness of the Cloud Radio Access Network (C-RAN). Recently, redesign of the C-RAN through functional split in the baseband processing chain has been proposed to overcome these challenges. This paper evaluates, by mathematical and simulation methods, different splits with respect to network level energy and cost efficiency having in the mind the expected quality of service.The proposed mathematical model quantifies the multiplexing gains and the trade-offs between centralization and decentralization concerning the cost of the pool, fronthaul network capacity and resource utilization. The event-based simulation captures the influence of the traffic load dynamics and traffic type variation on designing an efficient fronthaul network.Based on the obtained results, we derive a principle for fronthaul dimensioning based on the traffic profile. This principle allows for efficient radio access network with respect to multiplexing gains while achieving the expected users' quality of service.Index Terms: C-RAN; functional split; multiplexing gain; energy efficiency.c This is the author's version of an article that has been published in this journal. Changes were made to this version by the publisher prior to publication.The final version of record is available at http://dx.
Abstract-Buffered crossbars with Virtual Output Queuing are considered an alternative to bufferless crossbars mainly because the latter requires a complex global scheduling algorithm that matches input with output. Buffered crossbars require only simple schedulers that operate independently for each output crosspoint queue column and independently for each port card. In this paper, fluid-model techniques will be utilized to show that the necessary and sufficient speedup for a NxN buffered crossbar with 1-cell crosspoint buffers is 2-1/N to deliver 100% throughput. Round robin scheduling is assumed, both among Virtual Output Queues in port cards and among crosspoint buffers in output columns.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.