Device Access Optimization for Virtual Power Plants in Heterogeneous Networks

How many small cell (SC) access points (APs) are required to guarantee a chosen quality of service in a heterogeneous network? In this chapter, we answer this question considering two different network models. The first is the downlink of a finite-area SC network where the locations of APs within the chosen area are uniformly distributed. A key step in obtaining the closed-form expressions is to generalize the well-accepted moment matching approximation for the linear combination of lognormal random variables. For the second model, we focus on a two-layer downlink heterogeneous network with frequency reuse-1 hexagonal macro cells (MCs), and SC APs that are placed at locations that do not meet a chosen quality of service from macro base stations (BSs). An important property of this model is that the SC AP locations are coupled with the MC coverage. Here, simple bounds for the average total interference within an MC makes the formulation possible for the percentage of MC area in outage, as well as the required average number of SCs (per MC) to overcome outage, assuming isolated SCs. Introduction Heterogeneous cellular networks (HCNs) are being considered as an efficient way to improve system capacity as well as effectively enhance network coverage [1, 2]. Comprising multiple layers of access points (APs), HCNs encompass a conventional macro cellular network (first layer) overlaid with a diverse set of small cells (SCs) (higher layers). Cell deployment is an important problem in heterogeneous networks, both in terms of the number and positioning of the SCs. Traditional network models are either impractically simple (such as the Wyner model [3]) or excessively complex (e.g., the general case of random user locations in a hexagonal lattice network [4]) to accurately model SC networks. A useful mathematical model that accounts for the randomness in SC locations and irregularity in the cells uses spatial point processes, such as Poisson point process (PPP), to model the location of SCs in the network [5–10]. The independent placement of SCs from the MC layer, has the advantage of analytical tractability and leads to many useful SINR and/or rate expressions. However, even assuming that wireless providers would deploy SCs to support mobile broadband services, the dominant assumption remains that SCs are deployed randomly and independent of the MC layer [11].

This study aimed to increase the range of the wireless IEEE 802.11 b/g by adding the antenna gain, testing the performance of access point with router access point mode of the wireless IEEE 802.11 b/g, and comparing the performance of access point with router access point mode of the wireless IEEE 802.11 b/g.This research was conducted in Makassar. The method used was by performing direct performance measurement of end to end node, namely: delay time, throughput and Packet Loss. Wireless access point was placed on the SPN tower (Sekolah Tinggi Kepolisian Negara/College of Police of State) of Batua. Wireless clients were placed at 2.7 km, 5.36 km, 8.81 km and 10.82 km.The results showed that wireless IEEE 802.11 b/g can be used for data communications up to 10.82 km by adding 24 dB of antenna gain. Wireless with access point mode and router access point mode experienced 100% of packet loss with 60000 bytes of window size packets’ delivery and can handle only 1000 bytes of window size packets. The performance of wireless with access point mode was better than wireless with access point router mode, as follows: For access point packet: 0% of lost wireless, 8 ms of delay time, and 1 Mbps of throughput; On the other hand, for router access point packet: 30% of lost wireless, 26 ms of delay time, and 0.31 Mbps of throughput. Wireless 802.11 B/G can be used as data communication decive for cost-effective data acquisition and has not impact to carbon emission

The development of internet technology currently has a significant impact on education, so that it can support the learning process in a school. As one of the public schools in Malang district, SD Negeri 01 Jambearjo has utilized the internet network to support the learning process at school. However, the use of the internet network at SD Negeri 01 Jambearjo is currently still not optimized. This study discusses the comparative analysis of the performance of Mikrotik-based Wireless Access Point (WAP) and Virtual Access Point (VAP) at SD Negeri 01 Jambearjo. This research was conducted to find out which system is better to use in SD Negeri 01 Jambearjo. The WAP and VAP network systems are used by Mikrotik RB941-2nD to configure or control access points centrally. In the WAP network, an access point is used that is connected to the Mikrotik using a LAN cable, while the VAP network uses the CAPsMAN mode which combines two Mikrotik RB941-2nD with a LAN cable. The testing process uses parameters based on Quality of Service, including throughput, packet loss, delay, and jitter. In the Quality of Service test, the Wireshark application is used. The test results on the WAP network obtained an average throughput value of 3034 kbps, with packet loss of 3.16%, delay of 2.840 ms, and jitter of 0 ms. While on the VAP network, the average throughput value is 1479 kbps, with packet loss of 9.9%, delay of 4.945 ms, and jitter of 0.0011 ms. Based on the test results, the analysis results show that the WAP network has better quality than the VAP network for use in SD Negeri 01 Jambearjo.

Traffic load balancing and radio resource management is key to harness the dense and increasingly heterogeneous deployment of next generation “5G” wireless infrastructure. Strategies for aggregating user traffic from across multiple radio access technologies (RATs) and/or access points (APs) would be crucial in such heterogeneous networks (HetNets), but are not well investigated. In this paper, we develop a low complexity solution for maximizing an α-optimal network utility leveraging the multi-link aggregation (simultaneous connectivity to multiple RATs/APs) capability of users in the network. The network utility maximization formulation has maximization of sum rate (α = 0), maximization of minimum rate (α → ∞), and proportional fair (α = 1) as its special cases. A closed form is also developed for the special case where a user aggregates traffic from at most two APs/RATs, and hence can be applied to practical scenarios like LTE-WLAN aggregation (LWA) and LTE dual-connectivity solutions. It is shown that the required objective may also be realized through a decentralized implementation requiring a series of message exchanges between the users and network. Using comprehensive system level simulations, it is shown that optimal leveraging of multi-link aggregation leads to substantial throughput gains over single RAT/AP selection techniques.

This paper demonstrates hosting IoT gadgets on the wireless AP(Access Point) at home. For this, the process and profile of the IoT gadgets need to be virtualized into JavaScript-based objects. Then, to execute and control the instances of the virtualized IoT objects on the wireless AP, a novel instance management method is required. The demonstration shows the IoT gadget registration, monitoring, and control on the wireless AP. In addition, generating mash-up instances by connecting multiple gadgets and controlling them together is performed.

Analysis and performance evaluation of scalable video coding over heterogeneous cellular networks

This paper studies how to maximize the per-user-based throughput in an M-tier heterogeneous wireless network (HetNet) by optimally managing traffic flows among the access points (APs) in the HetNet. The APs in the first M - 1 tiers can use the licensed spectrum at the same time whereas they share the unlicensed spectrum with the APs in the Mth tier by the proposed opportunistic CSMA/CA protocol. The APs that access the licensed and unlicensed spectra simultaneously are able to integrate their spectrum resources by the carrier aggregation technique. For an AP in each tier, the tight bounds on its mean spectrum efficiencies in the licensed and unlicensed spectra are derived in a low-complexity form for general random channel gain and AP association weight models, and they can provide some insights into how channel gains, AP association weights and void AP probabilities affect the mean spectrum efficiencies of APs. The per-user throughput based on the mean spectrum efficiencies in the licensed and unlicensed spectra is found and maximized by the proposed decentralized traffic management scheme. Numerical results show that the mean spectrum efficiencies and the per-user throughput can be significantly improved by the proposed decentralized traffic management scheme.

The placement of the access points (APs) has a significant impact on the wireless system performance, especially for irregular heterogeneous networks with hierarchical APs such as macro/micro base-stations, pico-stations, and femto-stations. Traditional system modeling and optimization are based on the regular 2D hexagonal cellular topology and a set of predefined large-scale propagation models, which is highly abstract and may be inaccurate. This paper considers the AP placement optimization problem in realistic deployment environments, where radio-wave propagation characteristics are accurately modeled using ray-tracing techniques. Toward this end, this paper proposes a novel concept of area proportional fairness utility for the entire network under a given user geographic distribution, and proposes an iterative method to optimize the placement of the APs for utility improvement while taking into account the mutual interference between the APs. The significant benefit of the placement optimization is shown in a numerical experiment conducted in a realistic Chicago downtown topology, where placement optimization is shown to improve the sum rate by up to 40%.

Wireless fidelity (WiFi) networks are deployed in several varied environments all around the World. Usually, the wireless fidelity access points are always on in houses and other small companies. In buildings of large companies and public organizations and in university campuses the number of access points is elevated; they are powered using power over the ethernet and are always on. Consequently, they consume a considerable amount of electric energy. The last versions of the International Electric and Electronic Engineers 802.11 standardized procedures to save energy in a wireless fidelity terminal but not in the access point. We designed a formal method to show when energy can be saved in wireless fidelity access points considering different power supplies for the access point: an electric energy battery and a standard voltage supply. We use an external battery that stores electric energy during an interval of time from a standard voltage supply (Charge period). After that interval (Discharge period), the energy supply for the access point is the external battery. Those intervals of time are repeated sequentially (Charge and Discharge cycles). We verified our formal model implementing a hardware circuit that controls the power supply for the access point. The amount of energy saving for a large number of of access points during a long period of time is considerably high.

Mobile communication plays an important role in the future of communication systems. To meet personalized and intelligent requirements, mobile communication has evolved from single wireless cellular network to heterogeneous mobile communication network, including wireless cellular network, wireless local network, and wireless personal network. In the heterogeneous communication system, to entirely fulfill the spectrum resource complementary advantages of such a heterogeneous wireless network, the spectrum resource trade algorithm has attracted tremendous research efforts. In this paper, the advantages and disadvantages of dynamic spectrum allocation and load balancing are discussed and spectrum auction takes the place of spectrum allocation to maximize the operation revenue. The authors design a joint spectrum auction and load balancing algorithm (SALB) based on heterogeneous network environment to develop a more flexible and efficient spectrum management. The simulation result shows that SALB increases the operation profit significantly.

We explore the use of clock skew of a wireless local area network access point (AP) as its fingerprint to detect unauthorized APs quickly and accurately. The main goal behind using clock skews is to overcome one of the major limitations of existing solutions - the inability to effectively detect Medium Access Control (MAC) address spoofing. We calculate the clock skew of an AP from the IEEE 802.11 Time Synchronization Function (TSF) time stamps sent out in the beacon/probe response frames. We use two different methods for this purpose - one based on linear programming and the other based on least-square fit. We supplement these methods with a heuristic for differentiating original packets from those sent by the fake APs. We collect TSF time stamp data from several APs in three different residential settings. Using our measurement data as well as data obtained from a large conference setting, we find that clock skews remain consistent over time for the same AP but vary significantly across APs. Furthermore, we improve the resolution of received time stamp of the frames and show that with this enhancement, our methodology can find clock skews very quickly, using 50-100 packets in most of the cases. We also discuss and quantify the impact of various external factors including temperature variation, virtualization, clock source selection, and NTP synchronization on clock skews. Our results indicate that the use of clock skews appears to be an efficient and robust method for detecting fake APs in wireless local area networks.

In very dense or ultra-dense scenarios wherein Wi-Fi alone may not be enough to accommodate the needs of all stations, LiFi (Light Fidelity) access points can help alleviate the strain on the Wi-Fi by offloading some Wi-Fi traffic to LiFi. We study the issue of associating stations in a Wi-Fi/LiFi heterogeneous network composed of a Wi-Fi access point and multiples LiFi access points. We propose a conceptually simple and easy to implement solution to search and find an efficient mapping for the associations between stations and access points using analytical performance models for the individual throughput of each station and for the overall network energy consumption. Using two realistic deployments of heterogeneous networks for offices, we have evaluated the effectiveness of our solution at discovering better trade-offs than baseline strategies. Our numerical results show that significant gains can be obtained in terms of the throughput of the stations as well as overall energy consumption.

There has been an increasing interest on designing a single-radio client for time-division access to multiple Access Points (APs) on different radio-channels. These works have focused mainly on different scheduling policies at the client-side to allocate the percentage of time to each AP. However the performance of these systems is limited by 1) the overhead to switch between APs on different radio-channels, 2) the jitter in the switching procedure, that modifies the expected percentage of time assigned by schedulers and 3) the packet losses caused by the switching. In this paper, we introduce WiSwitcher, a client able to connect to multiple APs that i) reduces the cost of switching down to the hardware switching time and ii) increases the stability of the percentage of time assigned by schedulers, even if the station transmits in saturation mode. We implement WiSwitcher over commodity hardware and show that it achieves high aggregate throughput over the connecting APs and seamlessly transmits TCP traffic under controlled scenarios. Finally, we characterize the dependency between the switching frequency at the WiSwitcher client and the packet losses in off-the-shelf APs.

As integration of heterogeneous networks has become one of the most important characters for next-generation networks, it becomes a very challenging issue to ensure effective handoff when mobile node moves between different heterogeneous networks. In this paper we propose an effective handoff mechanism based on location information. By processing geographical data (consisting of information about mobile node movement and the coverage area of each point of attachment) acquired through GPS, mobile node's next position will be predicted. The identification of the MN's next access point in advance enables all the required parameters on the MN to be configured ahead of time, and this will reduce the handoff delay. The effective handoff mechanism proposed can improve handoff performance significantly.

Small cell base stations deployment is a promising approach to offload traffic from macrocell, and improve the network capacity and coverage. However, interference management and providing seamless hand offs between access points (APs) for user equipments (UEs) remain main technical challenges especially in dense heterogeneous wireless networks. In this paper, a novel context-aware resource allocation (CARE) mechanism is proposed based on an adaptive space-time beamforming (ASTB) scheme, where different beam-widths (in time and space domains) are allocated to UEs according to their performance preferences with respect to delay tolerance, throughput, energy consumption and link robustness to the potential hand-off failure. We formulate CARE as a two-step matching game consisting of two many-to-one sub-matching games with externality for access and backhaul networks. We introduce two-step stable matching and Nash stability concepts as solutions of CARE. Our numerical results show that CARE with space-time beamforming provides at least two times higher capacity for UEs in comparison to space beamforming while the average delay and complexity are significantly decreased.