16,480 research outputs found
Fronthaul evolution: From CPRI to Ethernet
It is proposed that using Ethernet in the fronthaul, between base station baseband unit (BBU) pools and remote radio heads (RRHs), can bring a number of advantages, from use of lower-cost equipment, shared use of infrastructure with fixed access networks, to obtaining statistical multiplexing and optimised performance through probe-based monitoring and software-defined networking. However, a number of challenges exist: ultra-high-bit-rate requirements from the transport of increased bandwidth radio streams for multiple antennas in future mobile networks, and low latency and jitter to meet delay requirements and the demands of joint processing. A new fronthaul functional division is proposed which can alleviate the most demanding bit-rate requirements by transport of baseband signals instead of sampled radio waveforms, and enable statistical multiplexing gains. Delay and synchronisation issues remain to be solved
Performance Prediction of Nonbinary Forward Error Correction in Optical Transmission Experiments
In this paper, we compare different metrics to predict the error rate of
optical systems based on nonbinary forward error correction (FEC). It is shown
that the correct metric to predict the performance of coded modulation based on
nonbinary FEC is the mutual information. The accuracy of the prediction is
verified in a detailed example with multiple constellation formats, FEC
overheads in both simulations and optical transmission experiments over a
recirculating loop. It is shown that the employed FEC codes must be universal
if performance prediction based on thresholds is used. A tutorial introduction
into the computation of the threshold from optical transmission measurements is
also given.Comment: submitted to IEEE/OSA Journal of Lightwave Technolog
An Analytical Model for Wireless Mesh Networks with Collision-Free TDMA and Finite Queues
Wireless mesh networks are a promising technology for connecting sensors and
actuators with high flexibility and low investment costs. In industrial
applications, however, reliability is essential. Therefore, two time-slotted
medium access methods, DSME and TSCH, were added to the IEEE 802.15.4 standard.
They allow collision-free communication in multi-hop networks and provide
channel hopping for mitigating external interferences. The slot schedule used
in these networks is of high importance for the network performance. This paper
supports the development of efficient schedules by providing an analytical
model for the assessment of such schedules, focused on TSCH. A Markov chain
model for the finite queue on every node is introduced that takes the slot
distribution into account. The models of all nodes are interconnected to
calculate network metrics such as packet delivery ratio, end-to-end delay and
throughput. An evaluation compares the model with a simulation of the Orchestra
schedule. The model is applied to Orchestra as well as to two simple
distributed scheduling algorithms to demonstrate the importance of
traffic-awareness for achieving high throughput.Comment: 17 pages, 14 figure
Downlink Coverage and Rate Analysis of Low Earth Orbit Satellite Constellations Using Stochastic Geometry
As low Earth orbit (LEO) satellite communication systems are gaining
increasing popularity, new theoretical methodologies are required to
investigate such networks' performance at large. This is because deterministic
and location-based models that have previously been applied to analyze
satellite systems are typically restricted to support simulations only. In this
paper, we derive analytical expressions for the downlink coverage probability
and average data rate of generic LEO networks, regardless of the actual
satellites' locality and their service area geometry. Our solution stems from
stochastic geometry, which abstracts the generic networks into uniform binomial
point processes. Applying the proposed model, we then study the performance of
the networks as a function of key constellation design parameters. Finally, to
fit the theoretical modeling more precisely to real deterministic
constellations, we introduce the effective number of satellites as a parameter
to compensate for the practical uneven distribution of satellites on different
latitudes. In addition to deriving exact network performance metrics, the study
reveals several guidelines for selecting the design parameters for future
massive LEO constellations, e.g., the number of frequency channels and
altitude.Comment: Accepted for publication in the IEEE Transactions on Communications
in April 202
- âŠ