Maximum Frame Size Research Articles

Signaling Packet Aggregation and Compression in SIP Network: Modeling and Performance Evaluation

Recent development in communications have increased the demand of internet protocol (IP)-based multimedia conferencing services. Session initiation protocol (SIP) is a signaling protocol used for providing group communication in IP-based next generation network. The conferencing frameworks proposed by Internet Engineering Task Force working groups has limited scalability due to the centralized management of conference control by a single server. In order to overcome this limitation, we propose multiple SIP packet aggregation and compression of common header part of each aggregated packet process. This mechanism increases the bandwidth utilization and processing capability of conference server. A queueing model is developed to describe the process of packet aggregation (PA) and compression at the edge proxy. Using the proposed queueing model, the steady-state probability distribution of the queue length is derived and the average packet transmission delay is obtained. We show the trade-off between the overhead gain and delay. Based on the analytical results, the maximum frame size is optimized for which the average delay of a packet transmission is minimum. A discrete event simulation is performed using network simulator 2 to implement PA and compression mechanism in a SIP network. Further, performance measures are numerically obtained from the simulation results. The simulation results discussed upon the key performance metrics for signaling protocols defined by the International Telecommunication Union (ITU) Telecommunication Standardization Sector (ITU-T E.721).

Updates on RFC 4944: Fragment Forwarding and Recovery

In 2005, IPv6 over Low Power WPAN (6LoWPAN), the first Working Group (WG) on the Internet of Things (IoT), was established in the Internet Engineering Task Force (IETF) to standardize mechanisms to transmit IPv6 datagrams over IEEE 802.15.4 technology. Since IPv6 may contain datagram sizes much larger than the IEEE 802.15.4 maximum frame size, a new adaptation layer was specified by standardizing several documents such RFC 4944, RFC 6282, and RFC 6775 in the 6LoWPAN WG. In 2007, RFC 4944 was published, and it defines the frame format for transmission of IPv6 datagrams. Moreover, it specifies techniques for header compression, fragmentation, and reassembly, and two fragment forwarding modes, mesh and over. In 2012, RFC 6282 was published to update RFC 4944; however, it does not update the fragment forwarding mechanism. Indeed, an IPv6 datagram larger than 1000 bytes could be fragmented to 10 fragments when considering IEEE 802.15.4 technology that comes with a maximum transmission unit of 127 bytes. Furthermore, under the 6LoWPAN route-over mode, the fragmented 6LoWPAN datagram must be reassembled and fragmented again at every hop, which will negatively affect the network reliability and latency. In this article, we first introduce the main operations of RFC 4944, and then we present the potential fragment forwarding issues when the route over mode is employed. We then give an overview of the ongoing proposed works at the IETF to solve the undesired issues of RFC 4944.

MSync: Physical Layer Frame Synchronization without Preamble Symbols

We present a novel physical layer frame format and a corresponding decoding strategy for energy-constraint single-carrier transceivers, often used in sensor networks and cyber-physical systems. The main advantage of our approach is that decoding does not rely on dedicated preamble symbols, which usually introduce considerable overhead in terms of energy consumption and utilization of the wireless channel. We show that omitting the preamble can be achieved by buffering the signal in the receiver and processing the samples twice; first to synchronize and in a second iteration to decode the actual data. To introduce our approach, we provide a theoretical description, including a discussion of the implications of synchronizing on data symbols instead of optimized preamble sequences. The practical feasibility of the algorithm is shown by simulations and experiments using prototype implementations based on software defined radio. We implemented our algorithm for two technologies, a custom ultra low-power BPSK transceiver and the O-QPSK physical layer of the IEEE 802.15.4 standard. Finally, we present an extension of the algorithm that allows us to reduce the buffered data to a small constant number of samples, making our algorithm applicable to physical layers independent from their maximum frame size.

An Advanced Video and Depth Depacking Architecture for 3D Applications

In this paper, a first hardware design for the 2D-compatible format and an architecture for the depth-image-based rendering (DIBR) is proposed. Compared to the format that uses one view plus one depth, the advanced 2D-compatible format reduces the bitrates of both color and depth frames. In order to achieve 3D image generation in real time, a hardware architecture of 2D-compatible format is firstly designed in this paper. In this paper, an edge-based DIBR algorithm is also proposed and implemented in to hardware architecture. The proposed edge-based DIBR algorithm achieves better image quality than the original DIBR algorithm. This paper combines these two architecture in to the advanced video and depth depacking architecture which can reduce the bitrates and increase the image quality of 3D video. Simulation results also show that image quality of the proposed system is better than that of the original DIBR algorithm. For the hardware cost, the proposed system requires 6.34k gates. The operation frequency can reach 100 MHz, which can supports the maximum frame size up to FHD (1920 × 1088) in real time.

Group improved enhanced dynamic frame slotted ALOHA anti-collision algorithm

With the development of information technology and declining in the cost of tags, radio frequency identification (RFID) system has become more and more popular, which has been widely used in a lot of areas, such as logistics tracking, animals identification, medicine, electronic toll collection, inventory, asset management, manufacturing, etc. However, when we use RFID technology to identify the objects, tag collision is one of the important factors to influence the identification efficiency. Currently, Aloha-based algorithm is one of the popular anti-collision algorithms which performs well when the number of tags is small. But it is not very efficient for cases with large number of tags and some areas which tags' number can be estimated, such as warehouse, supermarket, the production lines of smart factory and so on. So in this paper, we proposed a new anti-collision algorithm called group improved enhanced dynamic frame slotted ALOHA (GroupIEDFSA) by estimating the number of unread tags first, comparing the maximum frame size and dividing tags into groups when the number of tags which are activated is large. What is more, compared with enhanced dynamic frame slotted ALOHA (EDFSA) algorithm in the process of identification, GroupIEDFSA algorithm will combine new group based on the unread tags' number. Simulation results show that the efficiency of GroupIEDFSA algorithm system improves by 20 % in time and over 50 % in rounds than EDFSA algorithm in the standard mode, and increases by 1 % in time when we used fast mode.

Delay-Constrained Optimized Packet Aggregation in High-Speed Wireless Networks

High-speed wireless networks such as IEEE 802.11n have been introduced based on IEEE 802.11 to meet the growing demand for high-throughput and multimedia applications. It is known that the medium access control (MAC) efficiency of IEEE 802.11 decreases with increasing the physical rate. To improve efficiency, few solutions have been proposed such as Aggregation to concatenate a number of packets into a larger frame and send it at once to reduce the protocol overhead. Since transmitting larger frames eventuates to dramatic delay and jitter increase in other nodes, bounding the maximum aggregated frame size is important to satisfy delay requirements of especially multimedia applications. In this paper, we propose a scheme called Optimized Packet Aggregation (OPA) which models the network by constrained convex optimization to obtain the optimal aggregation size of each node regarding to delay constraints of other nodes. OPA attains proportionally fair sharing of the channel while satisfying delay constrains. Furthermore, reaching the optimal point is guaranteed in OPA with low complexity. Simulation results show that OPA can successfully bound delay and meet the requirements of nodes with only an insignificant throughput penalty due to limiting the aggregation size even in dynamic conditions.

Maximum Frame Size Control Based on Predicted BER in Wireless Networks

This letter discusses the prediction of the time-varying bit error rate (BER) for a transmitting channel using recent transmissions and retransmissions. Depending on the predicted BER, we propose a maximum frame size control to improve the goodput in wireless networks. It is shown, using simulation, that when the maximum frame size is controlled relative to the time-varying BER the goodput of the network is improved.

Performance modeling of the IrDA protocol for infrared wireless communications

This article presents a performance analysis of the IrDA protocol used for short-range IR data communication using an analytical mathematical model. The IrDA protocol specifies a protocol stack for reliable short-range infrared wireless data communication between devices with the data link layer (IrLAP) being an HDLC derivative. The mathematical model is based on unidirectional data transfer and uses the concept of the virtual transmission time, which provides the average end-to-end transmission time of a packet, incorporating the time for retransmissions if packet errors occur or other enforced delays. Analytical results are produced for throughput against packet size, BER and minimum turnaround time. They indicate certain limitations of the protocol for efficient throughput at high data speeds, and indicate that the maximum frame size and window size should be increased and the minimum turnaround time minimized for improved results.

Updating of speech transmission parameters obtained from nonuniform analysis segments in a linear predictive speech compression system

A linear predictive speech compression system based on stationary autocorrelation formulation is described. This system employs pitch synchronous analysis of 4-kHz bandlimited input speech sampled at 10-kHz rate. An all-pole speech production model has been assumed and a 10th-order linear predicter is used. Quantization properties of k parameters [Markel and Gray, “On Autocorrelation Equations as Applied to Speech Analysis,” IEEE Trans. Audio Electroacoust. (April 1973)], pitch and energy from a large speech data base, and phonetically balanced (PB) words and sentences are discussed. This paper emphasizes the updating of speech transmission parameters based on relative changes in normalized energy between two consecutive analysis intervals. The transmission rate is assumed to be constant but the frame size, for which the transmission parameters are used, is time variant. Thresholds have been defined for relative changes in normalized energy and changes in analysis interval size between two consecutive analysis intervals. Before compression, parameters are extracted every pitch period for voiced speech and every 8.5 msec for unvoiced speech. However, the parameters are used for transmission purpose if and only if the above-mentioned thresholds are exceeded. The parameters are forcefully updated when frame size becomes equal to maximum frame size, a preset value, even though the threshold criteria are satisfied. The transmitted parameters are pitch synchronously interpolated at the receiver end. Results of synthesized PB sentences at different bit rates are reported.