Frame Aggregation Research Articles

Performance Analysis of IEEE 802.11ac Very High Throughput at MAC and PHY Layers with Frame Aggregation

In this paper, we present the Very High Throughput (VHT) introduced for the first time by the standard IEEE 802.11ac. We show that we can find an optimized set of parameters which leads to the best performance. We analyze the performance of the standard, while taking into account several features of the PHY and the MAC layers in a MIMO channel, and we compute the throughput using an analytical model verified by simulation of the performance of different aggregation schemes, different modulation and coding schemes and various channel widths. We prove that a carefully chosen set of parameters can increase the throughput remarkably with the hybrid aggregation scheme A-MPDU of A-MSDU providing the best results for the chosen scenario.

Burst Transmission and Frame Aggregation for VANET Communications

In vehicular ad hoc networks (VANETs), due to highly mobile and frequently changing topology, available resources and transmission opportunities are restricted. To address this, we propose a burst transmission and frame aggregation (FAB) scheme to enhance transmission opportunity (TXOP) efficiency of IEEE 802.11p. Aggregation and TXOP techniques are useful for improving transmission performance. FAB aggregates frames in the relay node and utilizes the TXOP to transmit these frames to the next hop with a burst transmission. Simulation results show that the proposed FAB scheme can significantly improve the performance of inter-vehicle communications.

Performance analysis and throughput optimization of the 802.11N EDCA for video traffic

One of the promising candidate access technology for wireless communication in present and the future scenario is based on IEEE 802.11 Wireless LAN (WLAN) standard. The popularity of WLAN is further driven by the ability to use portable mobile hand-held devices that support applications with increasing multimedia content.This study presented on analysis of throughput performance and average delay of video traf fic over wireless EDCA WLAN networks by aggregation effect using the simulation methodology. In this study, the effect of frame aggregation (FA) mechanism for H.264/SVC video traffic on throughput and average delay of IEEE802.11n have been investigated. Simulation results validate the efficiency of the suggested MAC aggregation mechanism and aggregation sizes are adapted to achieve throughput optimization. Result shows significant improvement between measurement defined by the draft of IEEE802.11n and the proposed methodology.

T-SIMn: A trace collection and simulation framework for 802.11n networks

In this paper, we describe the design, implementation and evaluation of a new framework for the trace-based evaluation of 802.11n networks, which we call T-SIMn. In order to accurately estimate the fate of frames that could have been sent at any rate, traces collected for use in trace-based simulators, like T-SIMn, require a sufficiently large number of samples to be collected using each different rate in a relatively short period of time. In this paper, we devise two novel techniques for collecting and processing traces for 802.11n networks that incorporate Frame Aggregation (FA). The first technique, called direct measurement, samples all rates while aggregating the maximum number of possible frames for each sample. This approach is attractive because frame error rates (FERs) may vary with the position of the frame within the aggregated frame and this techniques directly captures the fate of each subframe. However, the length of the aggregated frames limits this approach to smaller numbers of rates, making it unusable for devices with 3 antennas (e.g., 96 rates). As a result, we also devise second technique that collects traces with frame aggregation turned off, permitting a larger number of rates to be sampled within the same period of time. This approach, called inferred measurement, infers the FER of each subframe using models derived from calibration traces combined with a new measure of changing channel conditions we call the channel dynamic indicator (CDI). Using the direct measurement methodology, we evaluate the T-SIMn framework by collecting traces using an iPhone, which is representative of a wide variety of one antenna devices. We show that our framework can be used to accurately simulate several scenarios and demonstrate the fidelity of SIMn by uncovering problems with our initial evaluation methodology. We then demonstrate that our inferred measurement technique permits us to collect traces that sample all 96 rates in a 3x3:3 802.11n MIMO systems. These traces are then used to accurately simulate transmissions in environments with highly variable channel conditions that include mobility and multiple sources of interference.We expect that the T-SIMn framework will be suitable for easily and fairly comparing algorithms that must be optimized for different and varying 802.11n channel conditions, which are challenging to evaluate experimentally. These include rate adaptation, frame aggregation and channel bandwidth adaptation algorithms.

Performance analysis of IEEE 802.11n network under unsaturated conditions

Frame aggregation is the most important medium access control (MAC) enhancement of IEEE 802.11n. In frame aggregation, multiple frames are encapsulated into a single frame. In the analysis of 802.11n performance, the existing researches assumed that each station always had a packet for transmission. But actually, sometimes stations may have no packet to transmit. In this paper, we develop an analytical model for IEEE 802.11n in unsaturated conditions. Therefore, the transmission of the station is assumed to be a bulk service queue system. Bulk size is aggregation size. According to the 802.11n standard, when the number of packets in the buffer is smaller than the aggregation size, we can also transmit all the packets in the buffer using A-MPDU. Therefore, bulk size is variable. The throughput and mean access delay are achieved. Numerical results show that the proposed algorithm can effectively increase the throughput and lower the access delay.

SmartLA: Reinforcement learning-based link adaptation for high throughput wireless access networks

High throughput wireless standards based on IEEE 802.11n and IEEE 802.11ac have been developed and released within the last few years as new amendments over the commercially popular IEEE 802.11. IEEE 802.11n and IEEE 802.11ac support a large pool of parameter set such as increased number of spatial streams via multiple input multiple output (MIMO) communications, channel bonding, guard intervals, different modulation and coding schemes, several levels of frame aggregation, block acknowledgement etc. As a consequence, they boost up physical data rate in the order of Gigabits per second. However, all these enhancements have their internal trade-offs with the channel quality, as explored in the existing literature. For example, higher channel bonding levels result in poor performance under high bit error rate. In a free wireless environment, multiple heterogeneous stations share the wireless channel which is again a time-varying system. Consequently, none of these link level parameters provide an optimal performance for all channel quality instances. Therefore, to practically meet the theoretical high throughput, each wireless device should adapt its physical data transmission rate dynamically by an appropriate tuning of different link parameters. Otherwise, high transmission failure may arise. In this paper, we design an adaptive automated on-line learning mechanism, called “Smart Link Adaptation” (SmartLA), for dynamic selection of link parameters, motivated by “State-Action-Reward-State-Action” (SARSA) model, a variant of reinforcement learning. SmartLA can make a wireless station quite intelligent to cope up with various network conditions by exploiting the best suited data rate observed so far for various channel conditions from the past experience as well as by exploring different possible set of parameters. We analyze the performance of SmartLA in both from simulation analysis and over a 26 nodes IEEE 802.11ac testbed (6 access points and 20 client devices). We observe that the proposed link adaptation mechanism performs significantly better compared to other competing mechanisms mentioned in the literature.

Delay analysis of mixed fronthaul and backhaul traffic under strict priority queueing discipline in a 5G packet transport network

AbstractVirtualization of the base station for the purpose of centralization is being actively studied and researched as an implementation option for 5G mobile networks. Proposed as Cloud radio access network, the technology is expected to facilitate easier operation and maintenance than regular radio access networks. However, the base stations traffic has stringent delay requirements. In this paper, we explore the possibility of multiplexing fronthaul traffic and traditional backhaul traffic as it traverses over the metropolitan network while keeping the average fronthaul queueing delay and jitter under control. We analyze and simulate the cases of a single fronthaul flow and multiple fronthaul flows arriving at the packet switch assuming strict priority for the fronthaul queue. We propose a fronthaul frame aggregation strategy to improve the packet transmission efficiency while keeping the average fronthaul queueing delay and jitter constant regardless of the percentage of fronthaul traffic. While the criteria for aggregation is different for the 2 cases, we show that the optimal number of basic frames to aggregate is between 3‐10 frames assuming the Common Public Radio Interface protocol.

Cross-layer selective routing for cost and delay minimization in IEEE 802.11ac wireless mesh network

A Wireless Internet-access Mesh NETwork (WIMNET) provides scalable and reliable internet access through the deployment of multiple access points (APs) and gateways (GWs). In this work, we propose a selective routing algorithm aiming at a hierarchical minimization of the operational cost and the maximal end-to-end delay. In particular, by deploying redundant APs/GWs in the network field, the WIMNET becomes robust to the link or AP/GW failure. However, these redundant APs/GWs increase the operational cost like the power consumption. By using Dijkstra algorithm and 2-opt algorithm, the proposed algorithm iteratively deactivates the deployed APs/GWs and performs the routing that reduces the maximal end-to-end delay based on the APs/GWs remaining active. The generated route meets the real-world constraints like fairness criterion. We further propose a cross-layer design to enhance the routing performance by exploiting the MAC-layer frame aggregation technique. The selective routing algorithm is then implemented in the WIMNET simulator proposed by our group. The numerical experiments demonstrate that in both indoor and open space environments, the proposed selective routing greatly reduces the operational cost, i.e., up to \(80\%\) APs/GWs can be deactivated.

IEEE 802.15.4 Frame Aggregation Enhancement to Provide High Performance in Life-Critical Patient Monitoring Systems.

In wireless body area sensor networks (WBASNs), Quality of Service (QoS) provision for patient monitoring systems in terms of time-critical deadlines, high throughput and energy efficiency is a challenging task. The periodic data from these systems generates a large number of small packets in a short time period which needs an efficient channel access mechanism. The IEEE 802.15.4 standard is recommended for low power devices and widely used for many wireless sensor networks applications. It provides a hybrid channel access mechanism at the Media Access Control (MAC) layer which plays a key role in overall successful transmission in WBASNs. There are many WBASN’s MAC protocols that use this hybrid channel access mechanism in variety of sensor applications. However, these protocols are less efficient for patient monitoring systems where life critical data requires limited delay, high throughput and energy efficient communication simultaneously. To address these issues, this paper proposes a frame aggregation scheme by using the aggregated-MAC protocol data unit (A-MPDU) which works with the IEEE 802.15.4 MAC layer. To implement the scheme accurately, we develop a traffic patterns analysis mechanism to understand the requirements of the sensor nodes in patient monitoring systems, then model the channel access to find the performance gap on the basis of obtained requirements, finally propose the design based on the needs of patient monitoring systems. The mechanism is initially verified using numerical modelling and then simulation is conducted using NS2.29, Castalia 3.2 and OMNeT++. The proposed scheme provides the optimal performance considering the required QoS.

Throughput and Range Characterization of IEEE 802.11ah

The most essential part of Internet of Things (IoT) infrastructure is the wireless communication system that acts as a bridge for the delivery of data and control messages. However, the existing wireless technologies lack the ability to support a huge amount of data exchange from many battery driven devices spread over a wide area. In order to support the IoT paradigm, the IEEE 802.11 standard committee is in process of introducing a new standard, called IEEE 802.11ah. This is one of the most promising and appealing standards, which aims to bridge the gap between traditional mobile networks and the demands of the IoT. In this paper, we first discuss the main PHY and MAC layer amendments proposed for IEEE 802.11ah. Furthermore, we investigate the operability of IEEE 802.11ah as a backhaul link to connect devices over a long range. Additionally, we compare the aforementioned standard with previous notable IEEE 802.11 amendments (i.e. IEEE 802.11n and IEEE 802.11ac) in terms of throughput (with and without frame aggregation) by utilizing the most robust modulation schemes. The results show an improved performance of IEEE 802.11ah (in terms of power received at long range while experiencing different packet error rates) as compared to previous IEEE 802.11 standards.

Impact of IEEE 802.11n/ac PHY/MAC High Throughput Enhancements on Transport and Application Protocols—A Survey

Since the inception of IEEE 802.11 wireless local area networks (WLANs) in 1997, wireless networking technologies have tremendously grown in the last few decades. The fundamental IEEE 802.11 physical (PHY) and medium access control (MAC) protocols have continuously been enriched with new technologies to provide the last mile wireless broadband connectivity to end users. Consequently, several new amendments of the basic IEEE 802.11 gradually came up in the forms of IEEE 802.11a, IEEE 802.11b, and IEEE 802.11g. More recently, IEEE 802.11n, IEEE 802.11ac, and IEEE 802.11ad are introduced with enhanced PHY and MAC layers that boost up physical data rates to the order of Gigabit per second. So, these amendments are generally known as high throughput WLANs (HT-WLANs). In HT-WLANs, PHY layer is enhanced with multiple-input multiple-output antenna technologies, channel bonding, short guard intervals, enhanced modulation and coding schemes. The MAC sublayer overhead is reduced by introducing frame aggregation and block acknowledgement technologies. However, several existing studies reveal that, many a time, the aforesaid PHY and MAC enhancements yield negative impact on various upper layer protocols, that is end-to-end transport and application layer protocols. As a consequence, a large number of researchers have focused on improving the coordination among PHY/MAC and upper layer protocols. In this survey, we discuss impact of HT-WLAN PHY and MAC layer enhancements on various transport and application layer protocols. This paper also summarizes several research works that use aforesaid enhancements effectively to boost up data rate of end-to-end protocols. We also point out limitations of the existing researches and list down different open challenges that can be meaningfully explored for the development of the next generation HT-WLAN technologies.

Single User MAC Level Throughput Comparision: IEEE 802.11ax vs. IEEE 802.11ac

With the ever-increasing range of video and audio applications in portable handheld devices, demand for high throughput in Wi-Fi networks is escalating. In this paper we introduce several novel features defined in next generation WLAN, termed as IEEE 802.11ax standard, and compare between the maximum throughputs received in IEEE 802.11ax and IEEE 802.11ac in a scenario where the AP continuously transmits to one station in the Single User mode. The comparison is done as a function of the modulation/coding schemes in use. In IEEE 802.11ax we consider two levels of frame aggregation. IEEE 802.11ax outperforms IEEE 802.11ac by about 29% and 48% in reliable and unreliable channels respectively.

Comprehensive Spectrum Management for Heterogeneous Networks in LTE-U

Recent interesting activities in spectrum analysis have introduced an additional band, the 5 GHz unlicensed spectrum, which has been primarily used for Wi-Fi. There are many challenges related to the coexistence of two different networks, a Wi-Fi network and an LTE network, sharing unlicensed bands but causing interference with each other. In this article, to solve the coexistence challenges, we propose a new protocol for carrier sensing and interference avoidance for heterogeneous networks: carrier sense LTE unlicensed access (CASLUA). The key idea of this protocol is that it listens to the channel by using a Wi-Fi air interface, but actually transmits data via an LTE air interface. This is achieved by using a proposed dual frame aggregation scheme where two frames (an L-frame and a U-frame) are allocated to licensed and unlicensed bands, respectively. Two implementations of CASLUA are carried out, one based on standalone operation (S-CASLUA)and the other operating with assistance from a software-defined network controller (SDN-CASLUA). SDN assistance lies in the monitoring of multiple network parameters, which are then used to make a decision on effective spectrum allocation with awareness of interference and capacity demands. Simulation results show that the CASLUA protocol helps to avoid interference and increases the average throughput by up to 40 percent for both Wi-Fi and LTE users in LTE-Unlicensed.

Performance Analysis of IEEE802.11ac DCF Enhancement for VHT with Frame Aggregation

<strong>IEEE 802.11ac standard has brought several significant improvements compared to its predecessor IEEE 802.11n. It managed to break the Gigabits barrier with a combination of both refining older techniques and presenting new ones. The new enhancements such as channel bonding, beamforming, frames aggregation and finer modulation allow Wireless Local Area Networks (WLAN) the use of Very High Throughput (VHT). The physical layer (PHY) data rates are in the range of Gbps in the 5 GHz band. But the variety of releases and options available for this standard has left many ambiguities regarding its real capabilities. The Medium Access Control layer (MAC) throughput is influenced by several factors, causing the MAC efficiency to decrease. In this paper we present a performance analysis in the VHT with frame aggregation for different access mechanisms, different channels and different modulation schemes.</strong>

An accurate two dimensional Markov chain model for IEEE 802.11n DCF

According to the amendment 5 of the IEEE 802.11 standard, 802.11n still uses the distributed coordination function (DCF) access method as mandatory function in access points and wireless stations (essentially to assure compatibility with previous 802.11 versions). This article provides an accurate two dimensional Markov chain model to investigate the throughput performance of IEEE 802.11n networks when frame aggregation and block acknowledgements (Block-ACK) schemes are adopted. Our proposed model considered packet loss either from collisions or channel errors. Further, it took anomalous slots and the freezing of backoff counter into account. The contribution of this work was the analysis of the DCF performance under error-prone channels considering both 802.11n MAC schemes and the anomalous slot in the backoff process. To validate the accuracy of our proposed model, we compared its mathematical simulation results with those obtained using the 802.11n DCF in the network simulator (NS-2) and with other analytical models investigating the performance of 802.11n DCF. Simulation results proved the accuracy of our model.

Adaptive A-MPDU retransmission scheme with two-level frame aggregation compensation for IEEE 802.11n/ac/ad WLANs

The aggregate MAC protocol data unit (A-MPDU) is one of the significant frame aggregation schemes to improve the performance for high-rate IEEE 802.11n/ac/ad wireless local area networks (WLANs). However, the performance of the A-MPDU scheme does not meet the user expectations because the frame length of the retransmitted A-MPDU will be inevitably and sharply reduced due to the effect of the lost subframe on the number of the aggregatable subframes (i.e., the aggregation level). To overcome this problem, an adaptive A-MPDU retransmission scheme with the two-level frame aggregation compensation is proposed. In this scheme, when the aggregation level of the retransmitted A-MPDU frame dramatically decreases, one of the appropriate two-level aggregation strategies is adaptively employed to compensate the length of the retransmitted A-MPDU frames according to the theoretical analysis of the throughput performance for the conventional A-MPDU scheme and two strategies of the two-level aggregate frame respectively. Simulations using ns-3 platform are performed and the results demonstrate that the proposed adaptive A-MPDU retransmission scheme can achieve higher throughput and medium access control (MAC) layer efficiency.

System throughput improvement by optimizing timeout for wireless network coding and frame aggregation on CSMA/CA bidirectional two‐hop relaying prototype

This paper reports an outdoor experiment to optimize the timeout of wireless network coding (WNC) and frame aggregation (FA), which are implemented to carrier sense multiple access with collision avoidance (CSMA/CA)‐based wireless two‐hop relay prototype. The system throughput is improved. In the prototype, FA is implemented at the terminal nodes. Timeout function for WNC is available at the relay node and that for FA is available at the terminal nodes. Our outdoor experiment shows that optimizing the timeout values of WNC and FA can improve system throughput by 2.04‐fold compared to the conventional relay without WNC or FA. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Less Transmissions, More Throughput: Bringing Carpool to Public WLANs

A typical scenario for public WLANs is large audience environment where Wi-Fi hotspots serve scores of mobile devices. The performance of those Wi-Fi hotspots is extremely poor in terms of low goodput and severe delay due to heavy contention and MAC inefficiency. After carefully investigating the traffic patterns in public WLANs, we propose Carpool , a practical design that facilitates transmission sharing among multiple receivers, to tackle this problem. The key idea is to reduce contention by feeding frames for multiple destinations into one transmission at physical layer (PHY). As such, each downlink transmission carries payloads for multiple receivers, which reduces contention overhead and enables in-time response to concurrent requests from multiple users. To achieve efficient and reliable transmission in Carpool, we propose i) a lightweight frame structure to support multiple receivers, and ii) a real-time channel estimation scheme to continuously calibrate channel estimation during the transmission of a Carpool frame. We have implemented the entire PHY of Carpool on the GNURadio/USRP platform and tested it in various indoor environments. Furthermore, our trace-driven MAC evaluation shows that Carpool achieves up to $3.2 \times$ goodput gain and reduces up to $75$ percent delay compared to the IEEE 802.11n MAC frame aggregation scheme.

Alleviating Hidden and Exposed Nodes in High-Throughput Wireless Mesh Networks

This paper proposes an opportunistic approach to mitigating the hidden and exposed node problem in a high-throughput mesh network, by exploiting the frame aggregation and block acknowledgment (BACK) capabilities of IEEE 802.11n/ac wireless networking standard. Hidden nodes significantly drop down the throughput of a wireless mesh network by increasing data loss due to collision, whereas exposed nodes cause under-utilization of the achievable network capacity. The problem becomes worse in IEEE 802.11n/ac supported high-throughput mesh networks, due to the large physical layer frame size and prolonged channel reservation from frame aggregation. The proposed approach uses the standard carrier sense multiple access (CSMA) technology along with an opportunistic collision avoidance (OCA) method that blocks the communication for hidden nodes and opportunistically allows exposed nodes to communicate with the peers. The performance of the proposed CSMA/OCA mechanism for high throughput mesh networks is studied using the results from an IEEE 802.11n+s wireless mesh networking testbed, and the scalability of the scheme has been analyzed using simulation results.

Improving Energy Efficiency in Idle Listening of IEEE 802.11 WLANs

This paper aims to improve energy efficiency of IEEE 802.11 wireless local area networks (WLANs) by effectively dealing with idle listening (IL), which is required for channel sensing and is unavoidable in a contention-based channel access mechanism. Firstly, we show that IL is a dominant source of energy drain in WLANs and it cannot be effectively alleviated by the power saving mechanism proposed in the IEEE 802.11 standard. To solve this problem, we propose an energy-efficient mechanism that combines three schemes in a systematic way: downclocking, frame aggregation, and contention window adjustment. The downclocking scheme lets a station remain in a semisleep state when overhearing frames destined to neighbor stations, whereby the station consumes the minimal energy without impairing channel access capability. As well as decreasing the channel access overhead, the frame aggregation scheme prolongs the period of semisleep time. Moreover, by controlling the size of contention window based on the number of stations, the proposed mechanism decreases unnecessary IL time due to collision and retransmission. By deriving an analysis model and performing extensive simulations, we confirm that the proposed mechanism significantly improves the energy efficiency and throughput, by up to 2.8 and 1.8 times, respectively, compared to the conventional power saving mechanisms.