5,047 research outputs found
Strong fairness and ultra metrics
AbstractWe answer an open question of Costa and Hennessy and present a characterization of the infinite fair computations in finite labeled transition systems—without any structure of the states—as cluster points in metric spaces. This technique is applied to reduce the logical complexity of several known fairness concepts from Π03 to Π02 and from Σ11 to Π03, respectively
Quasi-Dynamic Frame Coordination For Ultra- Reliability and Low-Latency in 5G TDD Systems
The fifth generation (5G) mobile technology features the ultra-reliable and
low-latency communications (URLLC) as a major service class. URLLC applications
demand a tight radio latency with extreme link reliability. In 5G dynamic time
division duplexing (TDD) systems, URLLC requirements become further challenging
to achieve due to the severe and fast-varying cross link interference (CLI) and
the switching time of the radio frame configurations (RFCs). In this work, we
propose a quasi-dynamic inter-cell frame coordination algorithm using hybrid
frame design and a cyclic-offset-based RFC code-book. The proposed solution
adaptively updates the RFCs in time such that both the average CLI and the
user-centric radio latency are minimized. Compared to state-of-the-art dynamic
TDD studies, the proposed scheme shows a significant improvement in the URLLC
outage latency, i.e., 92% reduction gain, while boosting the cell-edge capacity
by 189% and with a greatly reduced coordination overhead space, limited to
B-bit
Adaptive Beam-Frequency Allocation Algorithm with Position Uncertainty for Millimeter-Wave MIMO Systems
Envisioned for fifth generation (5G) systems, millimeter-wave (mmWave)
communications are under very active research worldwide. Although pencil beams
with accurate beamtracking may boost the throughput of mmWave systems, this
poses great challenges in the design of radio resource allocation for highly
mobile users. In this paper, we propose a joint adaptive beam-frequency
allocation algorithm that takes into account the position uncertainty inherent
to high mobility and/or unstable users as, e.g., Unmanned Aerial Vehicles
(UAV), for whom this is a major problem. Our proposed method provides an
optimized beamwidth selection under quality of service (QoS) requirements for
maximizing system proportional fairness, under user position uncertainty. The
rationale of our scheme is to adapt the beamwidth such that the best trade-off
among system performance (narrower beam) and robustness to uncertainty (wider
beam) is achieved. Simulation results show that the proposed method largely
enhances the system performance compared to reference algorithms, by an
appropriate adaptation of the mmWave beamwidths, even under severe
uncertainties and imperfect channel state information (CSIs).Comment: 5 pages, 6 figures, 1 table, 1 algorith
Energy-efficiency for MISO-OFDMA based user-relay assisted cellular networks
The concept of improving energy-efficiency (EE) without sacrificing the service quality has become important nowadays. The combination of orthogonal frequency-division multiple-access (OFDMA) multi-antenna transmission technology and relaying is one of the key technologies to deliver the promise of reliable and high-data-rate coverage in the most cost-effective manner. In this paper, EE is studied for the downlink multiple-input single-output (MISO)-OFDMA based user-relay assisted cellular networks. EE maximization is formulated for decode and forward (DF) relaying scheme with the consideration of both transmit and circuit power consumption as well as the data rate requirements for the mobile users. The quality of-service (QoS)-constrained EE maximization, which is defined for multi-carrier, multi-user, multi-relay and multi-antenna networks, is a non-convex and combinatorial problem so it is hard to tackle. To solve this difficult problem, a radio resource management (RRM) algorithm that solves the subcarrier allocation, mode selection and power allocation separately is proposed. The efficiency of the proposed algorithm is demonstrated by numerical results for different system parameter
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