Frame Overhead Research Articles

Spatial pilot-aided fast-adapted framework for stable image transmission over long multi-mode fiber.

Multi-mode fiber (MMF) has emerged as a promising platform for spatial information transmission attributed to its high capacity. However, the scattering characteristic and time-varying nature of MMF pose challenges for long-term stable transmission. In this study, we propose a spatial pilot-aided learning framework for MMF image transmission, which effectively addresses these challenges and maintains accurate performance in practical applications. By inserting a few reference image frames into the transmitting image sequence and leveraging a fast-adapt network training scheme, our framework adaptively accommodates to the physical channel variations and enables online model update for continuous transmission. Experimented on 100 m length unstable MMFs, we demonstrate transmission accuracy exceeding 92% over hours, with pilot frame overhead around 2%. Our fast-adapt learning scheme requires training of less than 2% of network parameters and reduces the computation time by 70% compared to conventional tuning approaches. Additionally, we propose two pilot-insertion strategies and elaborately compare their applicability to a wide range of scenarios including continuous transmission, burst transmission and transmission after fiber re-plugging. The proposed spatial pilot-aided fast-adapt framework opens up the possibility for MMF spatial transmission in practical complicated applications.

Combining Earliest Deadline First Scheduling with Scheduled Traffic Support in Automotive TSN-Based Networks

Recent work on automotive communications based on the Time-Sensitive Networking (TSN) standards proposed an approach to handle all the real-time frames in a uniform way regardless of their arrival pattern. According to such an approach, instead of binding all the frames of the same flow to a traffic class, each periodic or event-driven frame is scheduled based on its absolute deadline according to the Earliest Deadline First (EDF) algorithm. The approach does not impose additional frame overhead and does not require complex offline configurations that would be unsuitable for event-driven traffic. However, EDF scheduling cannot support time-driven communications. To solve this problem, this paper proposes a framework that combines the flexibility of online EDF frame scheduling for both periodic and event-driven traffic with the ability to guarantee temporal isolation to time-driven traffic. The paper describes the design of the proposed approach and the performance obtained using the OMNeT++ simulation environment.

The RAS Scheduling Algorithm Based on 802.11n WIFI Router

In order to solve the frame overhead to the influence of frame transmission performance, improve the throughput, lower hybrid scenario user acces delay, improve user (802.11 n) especially the user experience, this paper aimed at different rate of terminal equipment, designs the RAS algorithm, this algorithm through optimizing scheduling, in does not affect user delay at low speed, reduce the high-speed users send time delay.The algorithm is reasonable configuration of channel resources, make full use of the high speed channel rate, rate of various users (especially in high speed rate of users) to improve the user experience .In the Chariot on Atheros9341 chip using TCP service test 802.11 n AP topology network end-to-end delay and throughput, thus the proposed method was verified. The measured results showed that the proposed method can improve the AP client in a high-density environment effective machine capacity, and increase the throughput, reduce the delay.

VoIPiggy: Analysis and Implementation of a Mechanism to Boost Capacity in IEEE 802.11 WLANs Carrying VoIP Traffic

Handling voice traffic in existing WLANs is extremely inefficient, due to the large overhead of the protocol operation as well as the time spent in contention. In this paper, we propose a simple scheme (VoIPiggy) to improve the efficiency of WLANs with voice traffic. The key idea of the mechanism is to piggyback voice frames onto the MAC layer acknowledgments, which reduces both the frame overhead and the time wasted in contention. To quantify the gains of our proposal, we first study its performance by means of a capacity and delay analysis of a WLAN operating under the VoIPiggy mechanism. Then, we present an implementation of the mechanism using commercial off-the-shelf devices, which involves programming at the driver and firmware levels. The performance of the proposed scheme is evaluated in a large-scale testbed consisting of 30 devices. Our extensive measurements, which are comprised of different network conditions in terms of number of active nodes, traffic load and transmission rates, confirm that the experimental results match the analytical ones, and show a dramatic performance improvement for both “voice only” and “voice and data” scenarios.

Novel user centric, game theory based bandwidth allocation mechanism in WiMAX

AbstractBandwidth allocation plays a crucial role in ensuring overall quality of service in WiMAX. WiMAX supports non-contention based bandwidth allocation mechanism, where the responsibility of bandwidth allocation lies with the base station. In this paper, a novel user- centric, Game Theory-based bandwidth allocation algorithm is proposed. The Users/Mobile Station shall be grouped in pairs and bandwidth allocation is performed alternately between the two users of a group. In any given frame only one user from a pair is allocated bandwidth. The bandwidth thus allocated shall satisfy the requirements of the user/mobile station for two consecutive frames. Since, in any given frame, only one user/MS is allocated the bandwidth, the proposed algorithm reduces the frame overhead, thereby saving precious bandwidth that can be utilized to improve throughput. Simulation results show a 50% decrease in the uplink frame overhead and about 8% improvement in the uplink throughput per user/mobile station.

Highly Flexible and Efficient Model for QoS Provisioning in WDM EPON

The recent development of new applications and services, primarily multimedia applications, has driven the need for higher bandwidth and a faster access network, but these cannot be fully realized with the conventional single-channel Ethernet passive optical network (EPON). In such circumstances, the realization of WDM EPONs is the best solution for the implementation of converged triple-play networks. In this paper we present a novel algorithm dynamic wavelength priority bandwidth allocation with traffic class hopping for wavelength and bandwidth allocation with quality of service (QoS) support that incorporates both offline and modified online scheduling. In order to implement QoS support, we present an approach in which wavelength assignment takes place per service class and not per optical network unit, as suggested by the common approach in literature. The presented algorithm can guarantee both the priority and fairness of the differentiated traffic classes. Apart from the theoretical analysis, we studied and evaluated the performance of the presented model through detailed simulation experiments. An original network model is developed in MATLAB and incorporates all key parameters of the real network environment, such as queuing, transmission and packet processing delay, round-trip time, and framing overhead. The simulation results confirm the excellent performance of the presented model in terms of average packet delay, jitter, and packet loss.

Energy-Efficient Vertical Handover Mechanism

For integrated WLAN/cellular networks, we propose an energy-efficient vertical handover mechanism that both improves the energy efficiency of the mobile nodes and reduces the WLAN frame overhead.

Design and performance analysis of scheduling algorithms for WDM-PON under SUCCESS-HPON architecture

Results of the design and performance analysis of two new algorithms for efficient and fair scheduling of variable-length frames in a wavelength division multiplexing (WDM)-passive optical network (PON) under the Stanford University aCCESS-Hybrid PON (SUCCESS-HPON) architecture are reported. The WDM-PON under the SUCCESS-HPON architecture has unique features that have direct impacts on the design of scheduling algorithms. First, an optical line terminal (OLT) uses tunable transmitters and receivers that are shared by all the optical network units (ONUs) served by the OLT to reduce the number of expensive dense WDM (DWDM) transceivers. Second, also for cost reduction, ONUs have no local DWDM light sources but use optical modulators to modulate optical continuous wave (CW) bursts provided by the OLT for upstream transmissions. Therefore, the tunable transmitters at the OLT are used for both upstream and downstream transmissions. To provide efficient bidirectional communications between the OLT and the ONUs and guarantee fairness between upstream and downstream traffic, two scheduling algorithms have been designed: 1) batching earliest departure first (BEDF); and 2) sequential scheduling with schedule-time framing (S/sup 3/F). The BEDF is based on the batch scheduling mode where frames arriving at the OLT during a batch period are stored in virtual output queues (VOQs) and scheduled at the end of the batch period. It improves transmission efficiency by selecting the frame with the earliest departure time from a batch of multiple frames, which optimizes the usage of tunable transmitters in scheduling. Considering the high complexity of the optimization process in BEDF, the S/sup 3/F based on the sequential scheduling mode has also been designed as in the original sequential scheduling algorithm proposed earlier. In S/sup 3/F, the authors use VOQs to provide memory space protection among traffic flows and a granting scheme together with schedule-time framing for both upstream and downstream traffic to reduce framing and guard band overhead. Through extensive simulations under various configurations of the tunable transmitters and receivers, it has been demonstrated that both the BEDF and S/sup 3/F substantially improve the throughput and delay performances over the original sequential scheduling algorithm, while guaranteeing better fairness between upstream and downstream traffic.

The impact of mapping wander on the performance of SDH AU-4 and TU-3 uniform pointer processors

Pointer processors in Synchronous Optical Networks (SONET)/Synchronous Digital Hierarchy (SDH) networks may be placed into three categories: fixed threshold, adaptive threshold modulation and uniform. Fixed threshold pointer processors produce gapped pointer sequences during SONET/SDH holdover mode, when one or more node's clock has lost its synchronization reference, as a result of the periodic effects of the SONET/SDH frame overhead bytes. These gapped pointer sequences cause mapping wander in the underlying Plesiochronous Digital Hierarchy (PDH) payloads. Uniform pointer processors can smooth the gapped pointer effects caused by the Synchronous Transport Module (STM), Administrative Unit (AU) and Tributary Unit (TU) overhead bytes. However, uniform pointer processors cannot remove the additional gapped pointer effects caused by the Virtual Container (VC) overhead bytes. Mathematical analysis and simulation results, for fixed threshold pointer processors in SDH networks where VC-3 uses TU-3 to transport an E3-rate PDH payload or VC-4 uses AU-4 to transport an E4-rate PDH payload, illustrate the wander caused by the gapped pointer effects. A proposed uniform pointer processor algorithm shows the residual mapping wander caused by the VC-3 and VC-4 overhead bytes. Finally, a lower bound on the Maximum Time Interval Error (MTIE) that can be achieved with a uniform pointer processor is calculated for these two cases.