This paper presents corresponding results and compares them with those of a new, polling-based class of protocols, called adaptive intervals. Hence, an important question is, how good the so-called realtime performance, a set of measures taking reliability and timeliness into account, of the PPOFIBUS protocol over wireless links is. On the other hand, wireless links are error-prone and show time-variable behavior. The PPOFIBUS is used for its abil- ities in matching realtime requirements even under harsh environmental conditions. Hence, the question comes up, how this technology can be used in the creation of a wireless PPOFIBUS. In the area of wireless local area networks (WLANs) clearly the IEEE 802.11 stan- dard is the leading technology. A natural approach in creating such a system is to re-use as much existing technology as possible. I.įor the PPOFIBUS, a standardized and wellknown fieldbus system, it is attractive to use wireless media. Index Terms-Deterministic processes, digital wireless channels, enhanced general packet radio service (EGPRS) systems, error models, hard and soft generative models.
The validity of the suggested DPBGMs is further confirmed by the excellent match of the simulated frame-error rates and residual bit-error rates of coded EGPRS systems obtained from the target and generated error sequences.
Simulation results indicate that the proposed DPBGMs enable us to approximate very closely all the interested burst-error statistics of the target hard and soft error sequences. The target hard and soft error sequences are provided by computer simulations of uncoded enhanced general packet radio service (EGPRS) systems with typical urban and rural area channels. The proposed deterministic-process-based generative models (DP-BGMs) are all based on a properly parameterized and sampled deterministic process followed by a threshold detector and two parallel mappers. In this paper, deterministic processes are used to derive a new class of hard and soft generative models for simulation of digital wireless channels with hard and soft decision outputs, respectively.
FIWI LINKS MAC
Our simula-tion results indicate that VMP achieves significant improvements in throughput-delay performance for all three traffic types as well as reductions in the playback starvation probability for video traffic compared to existing state-of-the-art MAC mechanisms.Ībstract-Accurate and efficient generative models are significant for the design and performance evaluation of wireless communication protocols as well as error-control schemes. VMP consists of three main novel components: (i) frame fragmentation in conjunction with hierarchical frame aggregation for efficient MAC frame transport over the integrated optical and wireless network segments, (ii) multi-polling medium access control for upstream voice and data packets and acknowledgements for downstream video packets, and (iii) prefetching of video frames over the optical and wireless network segments in conjunction with hybrid reservation/contention-based medium access. In this paper, we introduce and evaluate a comprehensive video MAC protocol (VMP) to efficiently deliver prerecorded video downstream to wireless consumers over a FiWi network in the presence of voice and data upstream and downstream traffic.
In triple-play (voice, video, and data) service scenarios for such FiWi access networks, video traffic will likely dominate due to the widely predicted increase in video network services and the high traffic volume of compressed video compared to voice and data services. Abstract-Optical and wireless network technologies are ex-pected to converge in the near to midterm, giving rise to bimodal fiber-wireless (FiWi) broadband access networks.
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