Service Data Unit Research Articles

Demonstration of mobile backhaul uplink jitter reduction with optical-wireless cooperative control for multiple traffic flows

We experimentally demonstrate the performance of mobile backhaul (MBH) uplink jitter reduction techniques with optical-wireless cooperative control under multiple traffic flow conditions. Mobile systems beyond the 5th generation (5G) and 6th generation (6G) will require low jitter in addition to low latency, but current new radio (NR) mobile systems cause packet jitter in uplink traffic because of the radio transmission schemes used, such as downlink/uplink separation in time division duplexing (TDD) and medium access control (MAC) service data unit (SDU) concatenation to compose transport blocks. Our proposed uplink jitter reduction techniques perform traffic shaping at a router in the MBH network to reduce uplink jitter. The shaping rate is calculated with mobile scheduling information forwarded from a next generation node B (gNB) via an extended cooperative transport interface (eCTI). The eCTI is an interface between gNBs and network equipment for realizing optical-wireless cooperative control. We developed a shaper prototype that implements functions for receiving mobile scheduling information as eCTI frames, calculating the shaping rate, and executing shaping. eCTI frame formats are also defined by specifying where the mobile scheduling information is stored in an Ethernet frame. Using a shaper prototype, we experimentally evaluated the end-to-end (E2E) jitter performance for a single traffic flow, multiple gNB traffic flows, and multiple user equipment (UE) traffic flows. The results show that the uplink jitter reduction techniques reduce jitter from more than 1 ms to less than 300 µs, which meets the future jitter requirement of less than 1 ms.

Smart all-time vision: The battery-free video communication for urban administration and law enforcement

The Chinese government is dedicated to enhancing the level of informatization in administrative law enforcement to ensure fairness and increase credibility. Currently, law enforcement has exposed such problems as insufficient force, difficulties in collecting evidence, and low evidential power. These problems contradict the principles of rule of law and standardization. Many local governments have implemented advanced information technologies for urban administration and law enforcement, including big data, artificial intelligence, and IoT. Among these technologies, IoT is the core communication infrastructure for innovative law enforcement platforms. However, traditional video communications rely on batteries or dedicated power sources, leading to maintenance challenges and high power consumption. In this paper, we propose AT-Eye, a new video communication paradigm for all-time law enforcement video monitoring, which is battery-free and high-throughput. The key enabler of AT-Eye is ambient backscatter technology, which enables energy harvesting and video communication simultaneously. Unlike previous methods, our proposal introduces a novel CCK-based modulation for tag cameras and achieves 4-way concurrency. The modulation is simple because it uses phase difference and it is energy-efficient because generating square waves is adequate. Moreover, to ensure full compatibility with COTS WiFi, we modulate the physical service data unit. Therefore, data recovery is possible using only commercial NICs. We conduct comprehensive experiments to examine our proposal and experiment results show that AT-Eye achieves a throughput of 10.8 Mbps with COTS radios. We also simulate a 16-way battery-free tag camera system, demonstrating AT-Eye's feasibility of high-definition video communication.

PERFORMANCE EVALUATION OF DATA TRANSPORT OVER DIFFERENT-NODE DENSITY OF ZIGBEE SENSOR NETWORK – AN OPNET SIMULATION STUDY

In this paper, we analyze the performance of different node density of Wireless Sensor Network (WSN) operating under the IEEE Standard 802.15.4 in the beacon-enabled mode. The motivation for evaluating the beacon-enabled mode is due to its flexibility for WSN applications as compared to the non-beacon enabled mode. The analysis is based on an accurate OPNET simulation model which supports slotted Carrier Sense Multiple Access Mechanism with Collision Avoidance (CSMA/CA) mechanism and Guaranteed Time Slot (GTS). The performance of the slotted CSMA/CA sensor network is evaluated and analyzed for different network settings to understand the impact of the protocol attributes, including super-frame order (SO), beacon order (BO), data packet size and maximum back-off number. Through the simulation results, high SO provides better network throughput, otherwise results in lower average latency. We also found that the MAC overheads on small MAC Service Data Unit (MSDU) are more significant than the overheads on large MSDU. And the back-off mechanism results in longer delays when the network traffic is heavy.

Throughput Maximization Based on Optimized Frame-Aggregation Levels for IEEE 802.11 WLANs

To improve the throughput via frame aggregation (FA), the number of aggregate medium access control service data unit (A-MSDU) and protocol data unit (A-MPDU) subframes must be set appropriately under the IEEE 802.11 standards. In this letter, we construct an optimization problem that maximizes theoretical throughput considering bit error in A-MSDU under the IEEE 802.11ac standard based on the detailed structure of FA. Further, we propose a scheme to determine the optimal subframe sets through an exhaustive search for not only A-MPDU but also A-MSDU. The proposed scheme is validated through numerical calculations and Monte Carlo computer simulations. Although the computational complexity of the proposed scheme is larger than that of the conventional scheme, it leads to a significant throughput improvement.

A Priority-Based Synchronous Phasor Transmission Protocol Extension Method for the Active Distribution Network

With the advancement of active distribution network construction, to solve the shortcomings of the existing distribution network technology in distribution network perception and control, the relevant technologies of the Wide Area Measurement System (WAMS) in the transmission network have attracted more attention in terms of their usage in the distribution network. Micro Multifunction Phasor Measurement Unit (μMPMU), as an example, is being gradually utilized in the distribution network. However, the existing synchronous phasor transmission protocol is mainly designed for the transmission network, which requires an extension to meet the communication requirements to be directly used in the distribution network. In this work, the requirements of active distribution network communication are analyzed, and trade-offs between National Standard of the People’s Republic of China/Recommended (GB/T) 26865.2-2011 and International Electro technical Commission (IEC) 60870-5-101/104 protocol are compared. An extension method of the communication protocol is proposed, with the benefits of the prioritized transmission of important data, expanded remote control function of μMPMU, increased types of offline files, and reduced amount of network communication and data storage. The method is built upon the existing GB/T 26865.2-2011 protocol, and refers to the Application Service Data Unit (ASDU) of IEC 60870-5-101/104 to add an application extension frame. Application extension frames are used to transmit telemetry data, telesignalization, partial commands, and partial offline files. Finally, an experimental environment is set up, which includes a phasor measurement unit (PMU) Emulator, distribution network phasor data concentrator (PDC), and main station emulator to implement the standard GB/T 26865.2-2011 protocol and extension protocol. The feasibility and effectiveness of the method are confirmed by the superior performance of the extended protocol compared with the standard protocol.

Exploiting frame aggregation and weighted round robin with beamforming smart antennas for directional MAC in MANET environments

The development of Directional Medium Access Control (DMAC) strategies that allow to enhance the limitations due to the use of omnidirectional antennas in Mobile ad Hoc Networks (MANET), introduces several issues that need to be properly addressed such as the Deafness problem. The use of Smart Antenna Systems (SAS) along with Directional Request To Send (DRTS) and Directional Clear To Send (DCTS) could be not sufficient to mitigate the Deafness. In this regard, a sectorized antenna approach together with a frame scheduling mechanism can improve the overall MAC performance while limiting the Deafness; however, the employment of scheduling algorithms without priority such as the Round Robin could limit the network performance especially in terms of Packet Delivery Ratio (PDR) and fairness. For this reason, we propose two approaches: the A-MSDU (Aggregation MAC Service Data Unit) MAC and a WRR (Weighted Round Robin) MAC that could allow to overcome the limitations of the Round Robin scheme applied at MAC layer in order to have an high efficiency in the overall resource allocation. More specifically, obtained results show that, through the use of frame aggregation, it is possible to considerably reduce issues implied by Round Robin such as time slice and network overhead; WRR approach, instead, is able to enhance the overall network fairness by reducing the number of collisions provided by a directional MAC based on Round Robin scheduling; this aspect translates into higher PDR performance compared to Round Robin approach.

Energy efficiency analysis of aggregation mechanisms in IEEE 802.11n radio-over-fiber-based distributed antenna systems

It is known that distributed antenna systems (DAS) using radio-over-fiber (RoF) links are able to increase coverage and to improve energy efficiency compared to traditional wireless access networks. In this paper, we focus on the energy efficiency of 802.11n RoF DAS architectures and we provide a methodology based on ns-3 to evaluate and optimize energy consumption in those environments. Our results confirm that there exists an optimal number of distributed antennas for a given scenario. Furthermore, we show that aggregation mechanisms included in IEEE 802.11n enable to further improve the energy efficiency in RoF DAS. Finally, we demonstrate that media access control protocol data unit aggregation techniques outperform media access control service data unit aggregation schemes in providing higher end-to-end throughput and a better energy efficiency in IEEE 802.11n RoF DAS.

IEEE 802.11n의 2-레벨 집적 방식에서 최소 MPDU 시작 간격을 이용하는 새로운 재전송 방법

IEEE 802.11n 23456789:%; ?@AB @(MAC) CD6A-MSDU(Aggregate-MAC Service Data Unit)EA-MPDU(Aggregate-MAC Protocol Data Unit)FG%HIJ. KLM(, A-MPDU&3G*+;NO$%;P A-MSDUQJ56789RNQ#HIJ. STUA-MPDUV3G*+;NO$WXYA-MPDU Z[MPDU\;V MPDU !\;QJ 6MPDU]^&_>(dummy) MPDU.`ab(delimiter)cV(.d*+efghP 789i%jk#lm%noJ. pXk; qrs%;<%=A-MPDU Z[MPDU\;V MPDU !\;QJ 6]^A-MPDU Z[MPDUV`ab(Ftu2- , ;{*+, 6e|A-MPDU}r~*+€%HI~  ‚%&*+, &*+ƒ#„\;V MPDU !\;QJ 6]^- MSDU†‡*+MSDU†ˆ‰%=*+€dJ. pX ‚d*+, #;{*+, QJ_Š6789RNV‹J.AbstractIn IEEE 802.11n WLANs(Wireless Local Area Networks), to support high throughput, MAC(Media Access Control) layer adopts A-MSDU(Aggregate-MAC Service Data Unit) and A-MPDU(Aggregate-MAC Protocol Data Unit). Generally, as the A-MPDU uses a selective retransmission capability, A-MPDU provides higher throughput than A-MSDU. However, although A-MPDU uses the selective re-transmission capability, if the size of MPDU within A-MPDU is smaller than the size of minimum MPDU starting spacing, A-MPDU can reduce throughput because of the overhead of retransmission owing to the addition of delimiter, that is a dummy MPDU. Therefore, to overcome the above problem, two-level Aggregation method, where the small MPDU within A-MPDU is replaced by not delimiter but A-MSDU, has been introduced. In the two-level Aggregation method, the existing re-transmission scheme retransmits only A-MPDU, but if the size of retransmission data is smaller than the size of the minimum MPDU starting spacing, the proposed retransmission scheme retransmits the aggregated retransmission data and MSDUs. Therefore, we know that the proposed retransmission scheme have better throughput that the existing retransmission scheme.Keywords: IEEE 802.11n, A-MPDU, A-MSDU, Retransmission, Two-level Aggregation, ThroughputŒ (Regular Paper) 20 2, 20153(JBE Vol. 20, No. 2, March 2015)http://dx.doi.org/10.5909/JBE.2015.20.2.300ISSN 2287-9137 (Online) ISSN 1226-7953 (Print)

Throughput Characteristics of WiMAX Video Surveillance Systems

This paper presents the throughput characteristics for an All-WiMAX (AW) and a Hybrid Wi-Fi –WiMAX (HWW) video surveillance system with varying number of nodes, frame rate and MAC Service Data Unit (MSDU) size. An AW video surveillance system consists of WiMAX IP cameras connected directly to the Base stations while the HWW system consists of Wi-Fi IP cameras linked to the Customer Premises Equipment (CPE) which is equally linked to the base station. Local viewing PCs are connected at the CPE while remote viewing can be done via the internet. WiMAX and Wi-Fi IP cameras capture the video images; convert them to an appropriate digital signal and transmit them via Ethernet cables or wireless interface links. The investigation of the performance of the AW and HWW systems has been done by simulation of the systems using the OPNET modeler.Results show that, under similar conditions, the HWW video surveillance system outperforms the AW system in terms of throughput by a factor of 1.75. The results further show that throughput increases with increase in MSDU size and/or video resolutions, frame rate, number of nodes and decrease with increase in frame time, the reverse being true as well.

PHY-Supported Frame Aggregation for Wireless Local Area Networks

An aggregate medium access control (MAC) service data unit (A-MSDU) contains multiple subframes with a single sequence number. Hence, it has a major drawback in environments with high error rates because if any subframes are corrupted, then the entire A-MSDU will be lost. In addition, performance of the A-MSDU depends strongly on the choice of parameters, such as frame size, modulation level, coding rate, and spatial mode. In this paper, a novel link-adaptation mechanism, dubbed physical (PHY)-supported frame aggregation (PSFA), is proposed over IEEE 802.11 networks, and its performance is analyzed. The proposed PSFA technique is based on a cross-layer interaction that enables joint optimization of various parameters between the PHY and MAC layers. This paper derives a new packet error rate (PER) expression for convolutionally coded multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems as an example. Then, this PER expression is used to efficiently estimate the link quality, given the channel conditions and system parameters, and most importantly, it is able to facilitate a parametric study of the cross-layer interaction. In the proposed PSFA algorithm, we present a rule for selecting the parameters so that MAC throughput is maximized. It is shown analytically and verified using Monte Carlo simulations that this choice of parameters can improve throughput performance significantly and also ensure quality of service (QoS) requirements compared to existing conventional algorithms.

A Bi-Scheduler Algorithm for Frame Aggregation In IEEE 802.11N

IEEE 802.11n mainly aims to provide high throughput, reliability and good security over its other previous standards. The performance of 802.11n is very effective on the saturated traffic through the use of frame aggregation. But this frame aggregation will not effectively function in all scenarios. The main objective of this paper is to improve the throughput of the wireless LAN through effective frame aggregation using scheduler mechanism. The Bi-Scheduler algorithm proposed in this article aims to segregate frames based on their access categories. The outer scheduler separates delay sensitive applications from the incoming burst of multi-part data and also decides whether to apply Aggregated - MAC Service Data Unit (AMSDU) aggregation technique or to send the data without any aggregation. The inner scheduler schedules the remaining (delay-insensitive, background and best-effort) packets using Aggregated-MAC Protocol Data unit (A-MPDU) aggregation technique.

End-to-End QoS Improvement using IPv6 Header Reduction over MPLS

standards, PHS suppresses redundant parts of payload header in MAC service data unit. This paper proposes Label Switched Path-Payload Header Suppression (LSP- PHS), in which an MPLS-enabled backbone route compresses packets over an MPLS LSP without compression or decompression cycles at each router. It has two main contributions for MPLS-IPv6 header compression. First, LSP- PHS adds a new facility (MPLS/PHS) to the existing MPLS facilities. Second, it provides an analysis of the effect of implementing LSP-PHS on real-time and non-real-time IPv6 traffic in terms of QoS metrics. The implementation results using NS 2.34 show QoS improvement for real-time and non- real-time traffic.

New adaptive frame aggregation call admission control (AFA‐CAC) for high throughput WLANs

AbstractThe major enhancements introduced by the very high throughput wireless local area network, cannot provide quality of service (QoS) satisfaction for real time and multimedia applications. The recent standard IEEE 802.11n introduced new Medium Access Control (MAC) mechanisms based on aggregation scheme to enhance throughput. Besides that, functional modules for QoS provisioning such as call admission control and bandwidth management should be implemented in the access point. Hence, an efficient call admission control (CAC) algorithm is required for 802.11n network to satisfy QoS requirements of strict multimedia services. In this paper, we propose a new model‐based call admission control algorithm, called adaptation of frame aggregation AFA‐CAC to be implemented within the QoS access point in IEEE 802.11n standard in a way to provide QoS satisfaction to real time services. We first propose an accurate analytical model to estimate the achieved QoS metrics of a new flow entering in the network. Then, we detailed the AFA‐CAC algorithm that supports IEEE 802.11n aggregation schemes aggregated MAC service data unit and aggregated MAC protocol data unit and consider the IEEE 802.11e enhanced distributed channel access. AFA‐CAC is based on both predicting the QoS constraints of the already active flows and the new flow, and adjusting the number of aggregated subframes of each flow. Conducted simulations illustrate the performance of our proposed AFA‐CAC in terms of satisfying QoS throughput and end‐to‐end delay requirements of voice and video traffics. Copyright © 2013 John Wiley &amp; Sons, Ltd.

SRA-MSDU: Enhanced A-MSDU frame aggregation with selective retransmission in 802.11n wireless networks

The main goal of the IEEE 802.11n standard is to achieve more than 100Mbps of throughput at the MAC service access point. This high throughput has been achieved via many enhancements in both the physical and MAC layers. One of the MAC enhancements is the frame aggregation in which multiple frames are concatenated into a single large frame before being transmitted. The 802.11n MAC layer defines two types of aggregation, aggregate MAC service data unit (A-MSDU) and aggregate MAC protocol data unit (A-MPDU). The A-MPDU outperforms A-MSDU due to its large aggregation size and the subframes retransmission in erroneous channels. However, in error free channels and under the same aggregation size the A-MSDU performs better than the A-MPDU due to its smaller headers. Thus, adding a selective retransmission capability to the A-MSDU would improve the system performance. In this paper, we have proposed an MSDU frame aggregation scheme that enables selective retransmission at the MSDU level without altering the original MAC header. In this proposed scheme an implicit sequence control mechanism has been introduced in order to keep the frames in sequence and preserve their correct order at the receiver side. The results show that the proposed scheme improves the system performance in terms of throughput and delay even under highly erroneous channels.

FER Performance in the IEEE 802.11 a/g/n Wireless LAN over Fading Channel

This paper explores and compares FER (Frame Error Rate) of a MAC (Medium Access Control) layer in the IEEE 802.11 a/g/n wireless LAN. It is evaluated under the fading wireless channel, using theoretical analysis method. It is analyzed by using the number of stations with both variable payload size and mobile speed on the condition that fading margin and transmission probability are fixed. Especially, in the IEEE 802.11n, A-MSDU (MAC Service Data Unit Aggregation) scheme is considered and the number of subframe is used as the variable parameter. In the IEEE802.11a/g wireless LAN, fixed wireless channel is assumed to be Rayleigh fading channel. Mobile wireless channel is assumed to be flat fading Rayleigh channel with Jake spectrum. The channel is in fading states or inter-fading states by evaluating a certain threshold value of received signal power level. If and only if the whole frame is in inter-fading state, there is the successful frame transmission. If any part of frame is in fading duration, the frame is received in error.

A Reliable A-MSDU Frame Aggregation Scheme in 802.11n Wireless Networks

IEEE 802.11n standard is introduced to enhance the throughput to more than 100Mbps at the MAC service access point. This high throughput is achieved through several enhancements at the physical and MAC layers. Frame aggregation is a key enhancement at the MAC later in which multiple frames are concatenated and then sent in one channel access. In error free channels the 802.11n MAC service data unit aggregation (A-MSDU) performs better than the MAC protocol data unit aggregation (A-MPDU)due to its smaller headers. However, the performance of A-MSDU at erroneous channels is poor due to lack of sub-frames integrity check. In this paper, we proposed an A-MSDU frame aggregation with sub-frame integrity check and retransmission at the MSDU level without altering the original MAC frames header structure. The results show that the proposed scheme improves the system performance in terms of throughput and delay even under highly erroneous channels.

Towards an optimal transmission of SDUs in IEEE 802.16e WiMAX systems

In this paper we address the mutual influence between the PHY layer budding blocks (FEC blocks) and the MAC level allocations in the Uplink and Downlink of IEEE 802.16e systems, and address methods to increase the overall PHY and MAC combined efficiency. We evaluate the efficiency of several schemes for the transmission of Service Data Unit (SDU) packets through Protocol Data Units (PDUs) in physical Bursts. The optimality criterion is the Goodput. When using the Convolutional Turbo Code, Bursts are composed of FEC blocks that have a direct influence on the probability of bits being received successfully, and thus on the Goodput. In the first scheme, every SDU is transmitted as a stand-alone PDU. In the second scheme, the Burst is first divided into PDUs in a way that maximizes the Goodput, assuming the transmission of a bit stream (and not SDUs). Then the SDUs are mapped into the PDUs with possible Fragmentation/Packing. The optimal size of the PDUs is computed by an O(1) running time algorithm, an important feature because this algorithm is a part of the scheduler in the BS. The results show that when the estimation of the FEC success probability is accurate, SDUs should be mapped into optimal size PDUs in reliable channels. For unreliable channels it is better to transmit each SDU as a separate PDU. When the estimation of the FEC success probability is not accurate, it is always better to transmit SDUs as separate PDUs.

Performance evaluation and optimisation guidelines for the Type II power-saving class of mobile World Interoperability for Microwave Access

In Mobile World Interoperability for Microwave Access (also known as IEEE802.16e), a standard power-saving mechanism (PSM) that alternates between sleep and wake modes is adopted to extend the lifetime of mobile stations (MSs), but it simultaneously induces a medium access control (MAC) service data unit (SDU) response delay. The standard PSM defines three power-saving classes (PSCs), among which Type I is based on a binary-exponential increase in the sleep window, and Type II is based on a constant sleep window. Over the years, most studies have mainly focused on PSC Type I, while only a few have considered Type II. This study derives several analytical models of PSC Type II and evaluates the power consumption and MAC SDU response delay performance. Based on the derived models, an optimised power under delay-bound mechanism (OPDBM) is proposed to find the optimal initial sleep window parameter that minimises the power consumption of an MS while satisfying a given MAC SDU response delay constraint. Both numerical analysis and simulation experiments show that the OPDBM effectively minimises the power consumption of an MS while guaranteeing any imposed/required MAC SDU response delay constraint in a wide variety of environments.

An Optimized A-MSDU Frame Aggregation with Subframe Retransmission in IEEE 802.11n Wireless Networks

The IEEE 802.11n standard is defined to achieve a high throughput at the MAC layer. This high throughput is accomplished via many enhancements in both the physical and MAC layers. A key enhancement introduced in the 802.11n standard is frame aggregation. Two types of aggregation defined by the 802.11n standard, aggregate MAC service data unit (A-MSDU) and aggregate MAC protocol data unit (A-MPDU). Frame aggregation reduces both the headers and timing overheads at the MAC layer by aggregating multiple frames into a single large frame before being transmitted. The aggregation headers themselves still have a negative impact on the network performance especially when aggregating frames of small payload. Moreover, the lack of partial retransmission in the A-MSDU aggregation is behind its poor performance in error-prone channels. In this paper we proposed an optimized header A-MSDU frame aggregation (OHA-MSDU) with subframes retransmission capability at the MSDU level. The simulation results show the significance of the proposed scheme, especially for applications that have a small frame size such as VoIP.

DCF Throughput Analysis of IEEE 802.11a/g/n-based Mobile LAN over Correlated Fading Channel

This paper explores a MAC (Medium Access Control) layer throughput with DCF (Distributed Coordination Function) protocol in the IEEE 802.11a/g/n-based mobile LAN. It is evaluated in Rayleigh fading wireless channel, using theoretical analysis method. The DCF throughput performance is analyzed by using the number of stations with both variable payload size and mobile speed on the condition that fading margin and transmission probability are fixed. In the IEEE 802.11n, A-MSDU (MAC Service Data Unit Aggregation) scheme is considered and number of subframe is used as the variable parameter. It is identified that MAC efficiency of IEEE 802.11n is the best out of four schemes.