Validation of the ns-3 802.11ax OFDMA implementation (original) (raw)
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Resource Management for OFDMA based Next Generation 802.11ax WLANs
2016
Recently, IEEE 802.11ax Task Group has adapted OFDMA as a new technique for enabling multi-user transmission. It has been also decided that the scheduling duration should be same for all the users in a multi-user OFDMA so that the transmission of the users should end at the same time. In order to realize that condition, the users with insufficient data should transmit null data (i.e. padding) to fill the duration. While this scheme offers strong features such as resilience to Overlapping Basic Service Set (OBSS) interference and ease of synchronization, it also poses major side issues of degraded throughput performance and waste of devices' energy. In this work, for OFDMA based 802.11 WLANs we first propose practical algorithm in which the scheduling duration is fixed and does not change from time to time. In the second algorithm the scheduling duration is dynamically determined in a resource allocation framework by taking into account the padding overhead, airtime fairness and ...
Resource management for OFDMA based next generation 802.11 WLANs
2016 9th IFIP Wireless and Mobile Networking Conference (WMNC), 2016
Recently, IEEE 802.11ax Task Group has adapted OFDMA as a new technique for enabling multiuser transmission. It has been also decided that the scheduling duration should be same for all the users in a multiuser OFDMA so that the transmission of the users should end at the same time. In order to realize that condition, the users with insufficient data should transmit null data (i.e. padding) to fill the duration. While this scheme offers strong features such as resilience to Overlapping Basic Service Set (OBSS) interference and ease of synchronization, it also poses major side issues of degraded throughput performance and waste of devices' energy. In this work, for OFDMA based 802.11 WLANs we first propose practical algorithm in which the scheduling duration is fixed and does not change from time to time. In the second algorithm the scheduling duration is dynamically determined in a resource allocation framework by taking into account the padding overhead, airtime fairness and energy consumption of the users. We analytically investigate our resource allocation problems through Lyapunov optimization techniques and show that our algorithms are arbitrarily close to the optimal performance at the price of reduced convergence rate. We also calculate the overhead of our algorithms in a realistic setup and propose solutions for the implementation issues.
When Is Multiple Access Beneficial? An Analysis of Multi-User Performance in IEEE 802.11ax
Proceedings of the 20th ACM International Symposium on Mobility Management and Wireless Access on 20th ACM International Symposium on Mobility Management and Wireless Access
IEEE 802.11ax introduces OFDMA (Orthogonal Frequency Division Multiple Access), that allows multiple users to transmit or receive frames concurrently. The standard suggests that OFDMA will provide reduced latency and increased throughput in dense scenarios compared to single-user OFDM. This work uses the latest 802.11ax models supplied by the widely used open-source network simulator NS-3 (version 3.34) to investigate the OFDMA performance under various downlink traffic loads and various application settings for both UDP and TCP traffic. Our simulation results show that the actual benefits of OFDMA over OFDM can only be extracted under intermediate traffic loads for UDP and TCP. We observe that in comparison to OFDM, OFDMA provides more consistent performance in the case of video streaming and video conferencing. Further, it provides lesser latency for web-based applications.
The Performance Evaluation of OFDM Based WLAN (IEEE 802.11 a and 802.11 g)
Dipl. insinöörityö. Blekinge Tekniska Högskola, 2009
In the past decade there has been a steady growth in development and implementation of wireless ccess technology in the Local Area Network (LAN) world. Mostly iplexing OFDM has been adopted by IEEE 802.11's standard of WLAN standards. 802.11a and 802.11g n that 802.11a provides high speed throughout the entire coverage area and long term sol demodu ion Multiplexing (OFDM), IEEE 802.11s family, Wireless Local Area Networks and emerged as in the largest sectors of the telecommunication industry. Wireless local area network (WLANs) provides connectivity, mobility, and much higher performance and achievable data rate. WLAN is a new medium of a WLAN applications are used in public sectors such as airports, banks, hotels, offices, city centres because of the flexibility of the people. Orthongonal Frequency Division Mult as a transmission technique for high data rate in WLANs. Now IEEE 802.11 standard has been expanded to a family both are used Orthongonal Frequency Division Multiplexing (OFDM) but operate in different frequency bands. It is show ution however it does not provide better solution in most cases as compared to IEEE 802.11g. Matlab Simulation model based on IEEE 802.11a/g using different modulation and lation techniques such as BPSK, QPSK and QAM to analysis the best performance of IEEE 802.11a/g with implementation of OFDM.
OFDMA Resource Allocation for Real-Time Applications in IEEE 802.11ax Networks
2019 IEEE International Black Sea Conference on Communications and Networking (BlackSeaCom)
Support of real-time applications that impose strict requirements on packet loss ratio and latency is an essential feature of the next generation Wi-Fi networks. Initially introduced in the 802.11ax amendment to the Wi-Fi standard, uplink OFDMA seems to be a promising solution for supported lowlatency data transmission from the numerous stations to an access point. In this paper, we study how to allocate OFDMA resources in an 802.11ax network and propose an algorithm aimed at providing the delay less than one millisecond and reliability up to 99.999% as required by numerous real-time applications. We design a resource allocation algorithm and with extensive simulation, show that it decreases delays for real-time traffic by orders of magnitude, while the throughput for non-real-time traffic is reduced insignificantly.
Sensors (Basel, Switzerland), 2021
IEEE 802.11ax uplink orthogonal frequency division multiple access (OFDMA)-based random access (UORA) is a new feature for random channel access in wireless local area networks (WLANs). Similar to the legacy random access scheme in WLANs, UORA performs the OFDMA backoff (OBO) procedure to access the channel and decides on a random OBO counter within the OFDMA contention window (OCW) value. An access point (AP) can determine the OCW range and inform each station (STA) of it. However, how to determine a reasonable OCW range is beyond the scope of the IEEE 802.11ax standard. The OCW range is crucial to the UORA performance, and it primarily depends on the number of contending STAs, but it is challenging for the AP to accurately and quickly estimate or keep track of the number of contending STAs without the aid of a specific signaling mechanism. In addition, the one for this purpose incurs an additional delay and overhead in the channel access procedure. Therefore, the performance of a ...
OFDMA-Based Medium Access Control for Next-Generation WLANs
EURASIP Journal on Wireless Communications and Networking, 2009
Existing medium access control (MAC) schemes for wireless local area networks (WLANs) have been shown to lack scalability in crowded networks and can suffer from widely varying delays rendering them unsuited to delay sensitive applications, such as voice and video communications. These deficiencies are mainly due to the use of random multiple access techniques in the MAC layer. The design of these techniques is highly linked to the choice of the underlying physical (PHY) layer technology. The advent of new PHY schemes that are based on orthogonal frequency division multiple access (OFDMA) provides new opportunities for devising more efficient MAC protocols. We propose a new adaptive MAC design based on OFDMA technology. The design uses OFDMA to reduce collision during transmission request phases and makes channel access more predictable. To improve throughput, we combine the OFDMA access with a carrier sense multiple access (CSMA) scheme. Data transmission opportunities are assigned through an access point that can schedule traffic streams in both time and frequency (subchannels) domains. We demonstrate the effectiveness of the proposed MAC and compare it to existing mechanisms through simulation and by deriving an analytical model for the operation of the MAC in saturation mode.
Resource Allocation with Padding Overhead in OFDMA based Next Generation 802.11 WLANs
2016
Recently, IEEE 802.11ax Task Group has proposed new guidelines for the use of OFDMA-based medium access control. In this new framework, it has been decided that the transmission for all the users in an multi-user OFDMA should end end at the same time, and the users with insufficient data should transmit null data (i.e. padding) to fill the duration. While this scheme offers strong features such as resilience to Overlapping Basic Service Set (OBSS) interference and ease of synchronization, it also poses major side issues of degraded throughput performance and waste of devices' energy. We investigate resource allocation problems where the scheduling duration (i.e., time) is optimized through Lyapunov optimization techniques by taking into account the padding overhead, airtime fairness and energy consumption of the users. Also, being aware of the complexity of the existing OFDMA solutions, we propose lightweight and agile algorithms with the consideration of their overhead and impl...
Implementation of IEEE802.11 (Wi-Fi) in NS-3
Journal of Communication and Computer, 2016
Computer networks technology is subject to constant change and innovation. New ideas and concepts regarding the usage of internet networks demand new network protocol and technologies. Due to its complexity many challenges arise from developing, implementing, testing and understanding these technologies. This is where simulation comes into play. Network Simulator is used to evaluate the performance of different wired and wireless networks and their topologies without real world implementation. Network Simulators are widely used by the research community to evaluate new theories and hypothesis. NS-3(network simulator 3) has a number of helper objects that assist in execution and analysis of simulation. The main focus of this paper is to study the Wi-Fi (wireless fidelity) performance when implemented on NS-3. This paper is offering a closer look on network simulation by describing NS-3, its core functionality and Wi-Fi implementation in NS-3.