Flying ad hoc networks (FANETs) are crucial for future UAV swarm applications, yet their evaluation is hindered by the complexity of multi-hop wireless communication, UAV dynamics, and protocol interactions. This paper presents a simulation framework for Wi-Fi–based FANETs that integrates: (i) analytical modeling of multi-hop links based on experimental data, (ii) Dronekit-SITL for MAVLink-based UAV behavior emulation, and (iii) custom Python modules for simulation control and real-time UAV interaction. Results are partially validated using NS-3. This hybrid approach enables reproducible, flexible, and cost-effective FANET studies under realistic conditions, bridging the gap between analytical models and field testing.

Beyond 5G networks will not only present an evolution of the current 5G standards, but they will also provision a path for increased convergence with other Radio Access Technologies (RATs). The Wi-Fi Alliance and 3GPP through their standards releases have presented a lucrative inter-working opportunity for the same. Such a convergence will help to enhance the Quality of Experience (QoE) for the users. However, one of the most important challenge towards a more converged scenario is the provision of uniform Quality of Service (QoS) across cellular and Wi-Fi RATs. Hence in this paper, to the best of our knowledge, we propose the first attempt in literature to homogenize Wi-Fi and 5G QoS. Specifically, a method is presented to map Wi-Fi QoS parameters to 5G QoS Identifiers (5QI). The presented results, which show a clear possibility of the 5G and Wi-Fi QoS harmonization, have been obtained via a real testbed setup.

3GPP standards organization is performing an impressive effort trying to reach sub-millisecond latencies for 5G. However, such efforts may become fruitless if exogenously generated delays at transport layer are not considered. Nowadays, Radio Access Networks (RANs) are deployed with large buffers to achieve full utilization and avoid squandering wireless resources. Unfortunately, and since the data path’s bottleneck resides on the radio link, RAN’s buffers are bloated by TCP’s congestion control algorithm. Thus, a flow with low-latency requirements that encounters a bloated buffer, suffers from inevitable large sojourn times associated with the buffer depletion time, severely downgrading its Quality of Service (QoS). This paper presents different solutions for efficiently multiplexing distinct traffic patterns that share buffers on the 5G stack. Bufferbloat is extensively studied within the actual 5G QoS scenario, which presents multiple challenges inherited from the dynamic radio link nature and the presence of multiple queues at different entities. We propose and extensively emulate different algorithms in order to avoid the exogenous delay caused by the bufferbloat phenomena. We use real cellular network traces with realistic delay-sensitive and background traffic patterns in different scenarios. The outcome presents valuable insights in the algorithms that will enable low-latency services to be delivered through the 5G network stack satisfying restrictive envisioned constraints.

IEEE 802.11ah is an Internet of Things enabling technology, where the efficient management of thousands of devices is a key function. To this aim, IEEE 802.11ah provides the restricted access window (RAW) mechanism, which reduces contention by enabling transmissions for small groups of stations. Optimal grouping of RAW stations requires an evaluation of many possible configurations. In this paper, we propose an analytical model (named e-model) that provides an evaluation of the RAW configuration performance, allowing a fast adaptation of RAW grouping policies, in accordance to varying channel conditions. We base the e-model in known saturation models, which we adapted to include the IEEE 802.11ah's PHY and MAC layer modifications and to support different bitrates and packet sizes. As a proof of concept, we use the proposed model to compare the performance of different grouping strategies, showing that the e-model is a useful analysis tool in RAW-enabled scenarios. We validate the model with existing IEEE 802.11ah implementation for NS-3.

The new medium access method of IEEE 802.11ah, called restricted access window (RAW), divides stations into different groups, and only allows stations in the same group to access the channel simultaneously, in order to reduce collisions and thus achieve better performance (e.g., throughput). However, the existing station grouping strategies only support homogeneous scenarios where all stations use the same modulation and coding scheme (MCS) and packet size. A surrogate model is an efficient mathematical model that represents the behavior of a complex system, trained with a limited set of labeled input-output data samples. In this article, we present a surrogate model that can accurately predict RAW performance under a given RAW configuration in heterogeneous networks. Different from the homogeneous scenario, heterogeneous networks are defined by a large number of parameters, leading to an enormous design space, i.e., the order of 10(17) possible data points. This is too big to achieve feasible training convergence. In this article, we present a novel training methodology that leads to a new design space with highly reduced size, i.e., the order of 10(5) data points. The surrogate model converges when less than 6000 labeled data points are used for training, which is only a tiny portion of the whole design space. The results show that, the relative error between model prediction and simulation results is less than 0.1 for 95% of the data points, in the areas of the design space studied. Its low complexity and high precision make the proposed model a valuable tool to develop real-time RAW optimization algorithms for heterogeneous IEEE 802.11ah networks.

5G is coming with a promise to provide ubiquitous coverage with high data rate availability. To do so, densification of access points to enhance the system capacity is anticipated. For managing such densely populated network, 5G will be employing Centralized Radio Access Network (CRAN), where most of the Radio Access Network (RAN) functionalities are centralized in a central processing unit. This centralization reduces operational costs and eases implementation of advanced technologies, such as, Cooperative multipoint (CoMP) and enhanced inter-cell interference coordination (eICIC), in a cost efficient way. However, CRAN imposes stringent requirements on the fronthaul, i.e. the link connecting access points to the central unit, in terms of capacity and latency. Furthermore, future fronthaul networks are expected to rely on wireless technologies, since wired options are costly, not scalable and not always suitable for all scenarios. Therefore, meeting the expected requirements of fronthaul network utilizing capacity-limited wireless technologies may become an inescapable bottleneck. In this paper, we study different functional splits at the PHY layer in terms of data rate requirements and operational cost, and discuss the combination of different splits aimed at minimizing the overall cost and maximizing the centralization gains, while keeping the capacity requirements below the limit of the fronthaul.

Mobility management is a critical component for any new wireless standard to be ubiquitous. While 4G-LTE and prior wireless standards utilized vendor specific hardware and software on which mobility management (MM) functionality was implemented, recent 5G architecture releases by 3GPP indicate a complete departure from the same. 3GPP in release 14 and the upcoming release 15 has stressed upon the utilization of Software Defined Networking (SDN) and Network Function Virtualization (NFV) as the drivers of 5G technology. Consequently, new challenges related to MM and specifically handover management will be encountered owing to the inter-working setup between the 5G Next-Gen Core (NGC) and the Evolved Packet System (EPS) core. In this paper, we exploit the SDN to enhance the signaling of the HO methods proposed by 3GPP. Although the proposed approach can be applied to any HO method, in this paper we specifically evaluate the scenario wherein a dedicated interface between the Mobility Management Entity (MME) in the EPC and the Access and Mobility management Function (AMF) in the 5G NGC, i.e., N26 as specified by 3GPP, is non-existent. Such a scenario is reasonable during the initial deployment phases of 5G networks. We show that the proposed mechanism is efficient as compared to the 3GPP handover strategy in terms of latency, transmission and processing costs.

The future wireless networks are expected to be extremely dense and heterogeneous, with the users experiencing multi-connectivity through the multiple available radio access technologies (RATs). These prevalent characteristics, along with the strict QoS requirements, renders the handover (HO) process optimization as a critical objective for future networks. Along side the evolving network characteristics and methodologies, an evolving network architecture needs to be considered as well. Such evolution should not only facilitate HO process enhancement, i.e., reduction in HO delay and signaling, but it should also allow for a smooth transition from current to future wireless networks. Hence, in this work we firstly present an evolutionary core network entity called the Integrated MME-SDN Controller and the associated network architecture. The proposed architecture provides a migratory path for the existing 3GPP cellular architectures towards the 5G networks. Next, we discuss the benefits and challenges of such an architectural approach, with one of the benefits being a manageable CAPEX for the network operators through its transitional nature. Subsequently, utilizing the aforementioned proposed architecture, we present the handover process enhancement for the current 3GPP defined HO processes. We quantify the improvements achieved in terms of latency, transmission and processing cost for the different 3GPP HO processes. We also show that the proposed HO mechanism leads to a significant reduction in latency and signaling for certain types of HOs which, as a consequence, will critically benefit any dense and heterogeneous wireless system, such as 5G.

Stringent demands for a continuous evolution of cellular networks push today academic and industrial researchers to re-think backhaul solutions for 5G. In one hand, wireless backhaul solutions are cost effective and easy to deploy but suffer from limited capacity. On the other hand, wired solutions have the potential to meet bandwidth requirements but usually involve higher costs. Thus, adoption of heterogeneous technologies will be necessary. Moreover, in 5G, access and backhaul networks will work closely, and therefore, total separation of their resources may not be possible anymore; rather, cooperation between the two portions of the cellular network is desirable. Subsequently, cooperative access-backhaul mechanisms become necessary to ensure the best use of the scarce resources, i.e. bandwidth. Hence, in this paper we present the idea of spectrum sharing among different links from a cooperative access-backhaul mechanism point of view. We present simulation results for different approaches of such sharing from a common spectrum pool. The results show that traffic-aware approaches show increased fairness thus reinforcing the idea of cooperative access-backhaul mechanisms as essential strategies in current and future networks.

The popularity and wider acceptance of IEEE 802.11 based WLANs has resulted in their dense deployments in diverse environments. While this massive deployment can potentially increase capacity and coverage, the current physical carrier sensing of IEEE 802.11 cannot limit the overall interference induced and also cannot insure high concurrency among transmissions. Recently, the IEEE 802.11 working group has continued efforts on developing WLAN technology through the creation of the TGax, which aims to improve efficiency of densely deployed IEEE 802.11 networks. In this paper, we propose a Dynamic Sensitivity Control for Access Point (DSC-AP) algorithm for IEEE 802.11ax. This algorithm dynamically adjusts the Carrier Sensing Threshold (CST) of an AP based on received signal strength from its associated stations and interfering APs. We show that the aggregate throughput of a dense network (under asymmetric traffic conditions) utilizing DSC (both at the stations and AP) is considerably improved (i.e. up to 32%) when compared with legacy IEEE 802.11.

The need for higher data rates and improved coverage has led to massive and uncoordinated deployments of IEEE 802.11 based WLAN Access Points in geographically limited areas that has resulted in increased interference with reduced area throughput. Recently, the IEEE 802.11 working group has continued efforts to cater the aforementioned problems by creating the IEEE 802.11ax Task Group, TGax (which aims to improve performance in dense environments). TGax has been actively involved in the design of Clear Channel Access (CCA) modification schemes, where Dynamic Sensitivity Control (DSC) algorithm has been proposed as one of the key innovative technologies to increase the spectral reuse. However, DSC scheme has drawbacks: increase in frame collisions as well as hidden node count. In this paper, we propose the combined usage of DSC along with an intelligent mechanism to enable RTS/CTS on selected stations within densely deployed WLAN network. We present methods to select stations for 4-way handshake and indicate considerable gains (up to 60%) when a network utilizing the aforementioned method is compared with legacy IEEE 802.11 operation.

The explosive growth in the usage of IEEE 802.11 network has resulted in dense deployments in diverse environments. Most recently, the IEEE working group has triggered the IEEE 802.11ax project, which aims to amend the current IEEE 802.11 standard to improve efficiency of dense WLANs. In this paper, we evaluate the Dynamic Sensitivity Control (DSC) Algorithm proposed for IEEE 802.11ax. This algorithm dynamically adjusts the Carrier Sense Threshold (CST) based on the average received signal strength. We show that the aggregate throughput of a dense network utilizing DSC is considerably improved (i.e. up to 20%) when compared with the IEEE 802.11 legacy network.

Abstract Since the advent of the first IEEE 802.11 standard for WLANs, several papers have been presented that evaluate the IEEE 802.11 DCF access method. In realistic WLAN environments frame errors usually occur due to non‐ideal channel conditions; in this way, papers including adverse transmission conditions in the evaluation have been published later in the literature. In this paper, we review existent analytical models that include the influence of transmission errors in IEEE 802.11 DCF performance. We modify current models and provide a more accurate analysis, thus allowing the evaluation in single rate and multi‐rate scenarios with stations subject to different link error conditions. Moreover, this paper exposes the unfairness problem that arises in IEEE 802.11 DCF networks with stations subject to different transmission conditions through analytical and simulation results. Stations are not able to distinguish collisions from failed transmissions due to link errors; both result in a missing ACK and, consequently, the transmitting stations apply the exponential backoff algorithm. This fact leads to a lower performance for stations in worse transmission conditions. Copyright © 2010 John Wiley & Sons, Ltd.

IEEE 802.11 Wireless LANs (WLANs) are highly sensitive to Denial of Service (DoS) attacks carried out with jamming devices. In this paper we focus on 2.4GHz wideband constant jammers. The interest in the wideband jammer lies in the fact that it beats all possible channels at the same time, leaving no possible escape following traditional channel-switching defenses. After studying and developing an effective detection mechanism, we propose the implementation of a load balancing technique based on cell breathing for mitigating the harmful effects of the jammer over an IEEE 802.11 WLAN. Cell breathing is achieved by dynamically tuning the transmission power to adjust the size of a WLAN cell.

In atypical deployment of IEEE 802.11 wireless LANs in the infrastructure mode, an access point acts as abridge between the wireless and the wired parts of the network. Under the current IEEE 802.11 Distributed Coordination Function (DCF) access method, which provides equal channel access probability to all devices in a cell, the access point cannot relay all the frames that it receives on the downlink. This causes significant unfairness between upload and download connections, long delays, and frame losses. This unfairness problem comes from the not-so-complex interaction of transport-layer protocols with the MAC-layer access method. The main problem is that the access point requires more transmission attempt probability than wireless stations for correct operation at the transport layer. In this paper, we propose to solve the unfairness problem in a simple elegant way at the MAC layer. We define the operation of an Asymmetric Access Point that benefits from a sufficient transmission capacity with respect to wireless stations so that the overall performance improves. The proposed method of operation is intrinsically adaptive so that when the access point does not need the increased capacity, it is used by wireless stations. We validate the proposed access method by simulation to compare it with other solutions based on IEEE 802.11e. Unlike many papers in this domain, which only validate MAC-layer modifications through simulation or analytical modeling, we provide measurement data gathered on an experimental prototype that uses wireless cards implementing the proposed method.

In this paper, we present an evaluation of chosen wireless LAN access methods involving stations with different bit error rates: n-1 stations in ideal transmission conditions (BER = 0) and 1 station with a given bit error rate (BER ne 0). The simulation results show that the IEEE 802.11 DCF and its modifications (Slow Decrease, AOB) are very sensitive to transmission errors, whereas Idle Sense provides good channel access fairness: the value of the contention window is almost the same regardless of transmission errors, so that the throughput difference between stations subject to different bit error rates corresponds only to the proportion of lost frames.

Since the advent of the first IEEE 802.11 standard, many research efforts have been spent on evaluating different aspects of the specification. In this paper, we present a new method to predict the capacity of a multicell IEEE 802.11 network. The mechanism takes the effect of co-channel and adjacent channel interference into account. In addition, the study of a common rate adaptation algorithm is included. When the effect of rate adaptation is considered within the throughput computation, the results provided by our algorithm are closer to the measurements obtained in a real scenario. To the best of our knowledge, this paper presents the first analytical study of throughput performance including both types of interferences and the effect of bit rate adaptation.

In this paper, we address the issue of evaluating performance of wireless LANs in multicell scenarios. We try to understand the complex behavior of the DCF (distributed coordination function) access method defined in the IEEE 802.11 standard [1] and its modifications proposed for improving performance: slow decrease [2], asymptotically optimal backoff [3], and idle sense [4]. We analyze the influence of overlapping cells and large multicell environments on their performance. Our results show that the IEEE 802.11 DCF and its two modifications (slow decrease and AOB) exhibit important unfairness between stations close to the access point and those near the border of a neighbor cell. Idle Sense performs much better: it provides much better fairness than the IEEE 802.11 DCF and its modifications. It also obtains the highest throughput when stations adapt their bit rate to channel conditions.

Actually, Wireless Local Area Networks (WLAN) are being extensively deployed in many places to provide easy access to Internet. Moreover, networks that span large buildings or campuses must comprise multiple cells. Surprisingly, multicell environments that correspond to realistic situations in highly deployed areas have received little attention in the literature.If we compare the system performance in a multicell scenario with its behavior in an isolated single cell, we can observe an important performance decrease that becomes higher with the growth of the transmission data rate employed and due to co-channel interference.In this paper, we propose some power control mechanisms to operate in IEEE 802.11 cellular networks. With the employment of such methods we aim at reducing the interference influence on network performance and at homogenizing the behavior of the stations placed at different spatial positions with respect to their access point. Results exposed show that the employment of such power control mechanisms leads to an important reduction in the interference level.

Up to the present, several studies have been performed in order to provide prioritization of stations or classes of service for WLAN IEEE 802.11. The IEEE 802.11e draft specification aims to extend the original IEEE 802.11 MAC protocol to support QoS. One of the mechanisms for prioritizing traffic is the assignment of different AIFS times to each priority level. Nevertheless, the AIFSs employed are separated by values that are multiples of the slot time. Therefore, due to the fact that the backoff time counter is slotted, the different priority levels can attempt for transmission simultaneously. In this paper, we evaluate the performance of the IEEE 802.11e when its working procedure is desynchronized: we avoid that stations belonging to different priority levels attempt for transmission at the same time. We assign AIFS times that are separated by values that are not multiples of the slot time, in order to avoid collisions between the different priority levels. We present a mathematical model and simulation results for analyzing the performance of the differentiation mechanism proposed. The results show that it solves the strangulation of low priority traffic, fact that occurs in IEEE 802.11e EDCA. Moreover, this proposal leads to a significant increase in the performance of the system as a whole

Most studies about the performance of IEEE 802.11 consider scenarios of ad-hoc topology and networks where all stations have the same traffic load (symmetric traffic conditions). This paper presents a study of performance parameters of more realistic networks. We focus the attention on WLAN with infrastructure networks, where the traffic distribution is asymmetric. In this case, the traffic load at the access point is much heavier than that at user stations. These studies are more realistic because most nowadays installed WLAN are infrastructure topology type, due to the fact that they are used as access networks. In this case, the access point has to retransmit all incoming traffic to the basic service set and therefore its traffic load is higher. Finally, the paper presents the tuning of the contention window, taken from IEEE 802.11e, used to increase the system performance under asymmetric traffic conditions, and the proposal of an adaptive algorithm to adapt the MAC layer settings to the system traffic load

Most studies about the performance of IEEE 802.11 are limited to a single cell environment. Nevertheless, the idea of designing an outdoor cellular network based on WLAN IEEE 802.11 is very attractive, due to the several advantages that this technology presents: the low cost of the equipment, its operation in unlicensed spectrum and its higher data rates. In this paper, we study the possibility of designing an outdoor cellular network based on the IEEE 802.11g standard. We present its performance under different load conditions and compare this behavior with the results obtained in an isolated single cell environment, without co-channel interference. Finally, going a step further, this paper explores the IEEE 802.11g cellular network performance for different cluster sizes, as a method to reduce the interference influence on network's performance.

This paper is focused on the study of WLAN performance in IEEE 802.11 networks that are in a situation of asymmetric traffic, where the access point (AP) transmits much more than the user stations (US). This situation is very different from the symmetric one, wherein all the stations have the same traffic load. The paper also presents a discussion of the different mechanisms in order to increase AP priority under the asymmetric traffic situation.

Most studies of the performance of IEEE 802.11 consider scenarios of ad-hoc topology networks and do not contemplate the network broadcast information contained in beacon frames. The paper presents a study of the performance of a WLAN whose infrastructure's topology is such that the access point is in charge of broadcasting the beacon frames. Thus, it is more realistic than previous studies, because beacon frames are usually transmitted in order to announce control information and network identity. Furthermore, in the coverage area, user stations are likely to be working at different data rates, depending on their signal quality. Because beacon frames must be received by all stations, they are transmitted at the lowest data rate operating in the coverage area. The article introduces a mathematical method to calculate the influence of beacon frames on the total throughput, collision probability and delays of the IEEE 802.11g protocol. The model is validated by simulation analysis.