A Reconfigurable Baseband Transmitter for Adaptive Image Coding

The growth in the volume of information transmission and transaction over the internet has necessitated the development and enhancement of measures and techniques required to ensure the safety of critical information during transmission. with developments in mobile technologies and the adoption and diffusion of android mobile devices, research must therefore continue to explore more secured media in which information can be hidden. One of such medium is the use of image carriers referred to as steganography. In tis paper, we provide insughts into the development of an android-based Image Steganography System for concealing data and information using adaptive image steganography. The Least Significant Bit (LSB) algorithm was employed as the algorithmic sequence for the development. Preliminary results from implementation and testing showed promising results Keywords: Android, image steganography, data, information, transmission, images, security

The evolution of cellular networks from one generation to another has led to the deployment of multiple radio access technologies (such as 2G/2.5G/3G/4G) in the same geographical area. This scenario is termed heterogeneous cellular networks. In heterogeneous cellular networks, radio resources can be jointly or independently managed. When radio resources are jointly managed, joint call admission control algorithms are needed for making radio access technology selection decisions. This chapter gives an overview of joint call admission control in heterogeneous cellular networks. It then presents a model of load-based joint call admission control algorithm. Four different scenarios of call admission control in heterogeneous cellular networks are analyzed and compared. Simulations results are given to show the effectiveness of call admission control in the different scenarios. The coexistence of different cellular networks in the same geographical area necessitates joint radio resource management (JRRM) for enhanced QoS provisioning and efficient radio resource utilization. The concept of JRRM arises in order to efficiently manage the common pool of radio resources that are available in each of the existing radio access technologies (RATs) (Perez-Romero et al, 2005). In heterogeneous cellular networks, the radio resource pool consists of resources that are available in a set of cells, typically under the control of a radio network controller or a base station controller. There are a number of motivations for heterogeneous wireless networks. These motivations are (1) limitation of a single radio access technology (RAT), (2) users’ demand for advanced services and complementary features of different RATs, and (3) evolution of wireless technology. Every RAT is limited in one or more of the following: data rate, coverage, security-level, type of services, and quality of service it can provide, etc. (Vidales et al, 2005). A motivation for heterogeneous cellular networks arises from the fact that no single RAT can provide ubiquitous coverage and continuous high QoS levels across multiple smart spaces, e.g. home, office, public smart spaces, etc. Moreover, increasing users’ demand for advanced services that consume a lot of network resources has made network researchers developed more and more spectrally efficient multiple access and modulation schemes to support these services. Consequently, wireless networks have evolved from one generation to another. However, due to huge investment in existing RATs, operators do not readily discard their existing RATs when they acquire new ones. This situation has led to coexistence of multiple RATs in the same geographical area.

Considering multiple radio access technologies (RATs) environment for the future wireless access networks, effective RAT discovery and selection are important tasks. They enable discovery of various RATs and let the user select appropriate RAT considering users' preferences and other parameters. The wireless network operator may also take advantage of RAT selection in order to distribute loads among two or more RATs. This paper introduces our pilot design of smart radio research platform (SRRP), on which performance of RAT discovery and selection algorithms are tested. Designing SRRP, we stressed on compliance with existing technical standard specifications, e.g. IEEE P1900.4 and 802.21, efficient RAT discovery, and reasonable RAT selection performance. In regard to RAT discovery algorithm we focused on short discovery time in order to reduce battery consumption and minimize possible quality of service (QoS) degradation. Objective of RAT selection is two folded; one is to choose a satisfactory radio connection and the other one is to maintain the connection reliably. Besides RAT discovery and selection algorithms we incorporated spectrum aggregation capability into SRRP to support user's QoS requirement by allocating an extra spectrum block to a base station (BS) where the existing spectrum block is congested.

This article presents discussion behind emerging need for the Unified Traffic Steering (UTS) approach in the evolving mobile networks to efficiently handle multitude of 3GPP radio access schemes and technologies. Considering the approaching 5G networks which will introduce yet another Radio Access Technology (RAT) to the equation, we need to think of tight radio level integration of all available RATs with the available spectrum resources and spectrum access schemes. That is a must to allow efficient radio resources utilization in mobile networks to cope with the booming mobile data demand in evolving mobile broadband use cases. For that purpose, analysis of traffic steering functionalities was performed based on the 3GPP standards, which lead to the formulation of UTS framework. UTS framework is considered as the enabler for unified 5G architecture, where UTS-logic plays as central entity, serving as engine to coordinate traffic steering mechanisms with respect to scenarios, feature groups, operator strategies and load conditions taking into account mobile demand and SON decisions.

Ubiquitous access to information anywhere, anytime and anyhow is a main feature of the upcoming 4G mobile communication networks, which will interconnect existing and future networks via common IP core. 4G networks are termed, therefore, as All-IP and are expected to provide higher bandwidth than currently obtained from 3G networks at lower costs. One of the main challenges arising while deploying these networks is the guarantee of fast and smooth mobility support for customers so that seamless functionality for ongoing applications can be guaranteed. As the mobility in heterogeneous network environments is becoming more complex to be handled by Mobile Nodes (MNs), network-based mobility management solutions are of major interest. Such solutions are currently being developed by the IETF working group NETLMM. The basic idea is to develop a new modular mobility management architecture that better accommodates any changes in technologies while reducing the complexity of the MN's stack software. The well-known proposal of the NETLMM working group is Proxy MIPv6 (PMIPv6), which tries to support mobility without involving MNs. This paper analyzes this proposal and evaluates it compared to the well-known Fast MIPv6 (FMIPv6) protocol in different radio access technologies. The comparison has been achieved with respect to the experienced handoff latency, resulting handoff interruption time and expected number of dropped packets per handoff. This analysis takes the dropping of control messages into account and has been done using mathematical models developed for both protocols. The obtained results show that the best performance can be seen by FMIPv6 in predictive mode. Access technology affects significantly the handoff interruption time. PMIPv6 performs almost comparable to FMIPv6 in reactive mode using a fast radio access technology. However, for slower radio access technologies, PMIPv6 performs better than FMIPv6 in reactive mode. PMIPv6 shows more robustness against control messages dropping than FMIPv6. Similar results are noticed with respect to the expected number of dropped packets per handoff. A main property of PMIPv6 is that there is no remarkable impact of radio access technologies on the number of dropped packets per handoff for downlink traffic.

Different node types in smart grid (SG) system have different communication necessities. Different type of information such as power grid status and demand requests and responses are established between control station (CS) and different SG node types. Assigning the certain percentage of the nodes traffic to the radio access technologies (RATs) with respect to their cost functions (CFs) value can help to achieve this goal by defining the highest fitness degree between SG node type communication requirements and RATs communication characteristics to have an efficient load balance. In this study, the key performance indicators (KPIs) for CFs are the SG node communication requirements which are defined as data rate, delay, reliability, and security. The value of the work can be seen in node assigning method based on the CFs as a function of different RAT communication characteristics and node type communication requirements. The highest fitness degree between node communication needs and RAT characteristics are achieved in an efficient way which causes to make an efficient heterogeneous network. The work impact of using a certain RAT which has the best efficiency in sense of communication aspects by using a well-defined CF is the innovation of this study as well.

현재 이동통신망에서 요구되는 많은 통신량을 수용하기 위해서 새로운 주파수 대역을 사용하는 5G New RAT(: Radio Access Technology) 에 대한 연구가 활발히 진행되고 있다. 하지만, 이러한 새로운 New RAT 기술이 이동통신에 적용되었을 때에 이를 유선 이동통신망에서 수용할 수 있을지에 대해서는 제대로 연구된 바가 없다. 따라서, 본 연구에서는 이러한 New RAT 기술을 RoF(: Radio over Fiber) 기술로 이동통신망의 Fronthaul에서 수용이 가능한지에 대한 연구를 진행하였다. 본 연구에서는 New RAT 의 기술로 밀리미터파 통신기술, 테라헤르츠파 통신기술, 무선 광통신 기술 등을 고려하고, 이들 각각에 대한 RoF 기술의 응용 가능성을 연구하였다. 연구의 결론을 요약하면, 10 년 이내의 범위에서 세 가지 New RAT 기술 중에 밀리미터파 통신기술에 대해서만 RoF 수용성을 고려하면 되는 것으로 판단되며, 빔포밍을 사용하는 경우에는 밀리미터파 통신기술의 요구 전송 대역폭이 너무 많아 Fronthaul 에서 RoF 기술로도 수용이 쉽지 않은 것으로 결론이 내려졌다. 5G New Radio Access Technology(: RAT) is studied by many researchers because the current radio frequency is insufficient to accommodate the increased mobile communication data traffic. However, there are few researches to study on the issue whether the wired mobile network can accommodate the new RAT. Therefore, in the paper, the study on the issue whether the Radio over Fiber(: RoF) system can accommodate the new RATs such as millimeter wave communication, terahertz communication, and optical wireless communication. As a result of the study, only millimeter wave communication deserve to be considered in ten years and even RoF system may not support the increased bandwidth of the millimeter wave communication when beamforming is used.

The increasing demand for broadband service, especially in some hot spot areas, requires the network operator integrate different kind of radio access technology (RAT). In order to provide seamless service among the RATs, a vertical handover algorithm is needed. In this paper, we present a cooperative vertical handover algorithm which considers not only the QoS factors but also the signaling cost and the load balance. The QoS information is gathered by the mobile terminal and the grey relational coefficient (GRC) of the QoS part is calculated. After receiving the information from the mobile terminal, the network side estimates the velocity of the mobile terminal and checks the load of different RATs. Finally, handover decision is made according to the GRC of the different RATs.

Next generation wireless networks (NGWN) will be heterogeneous, comprising a number of radio access technologies (RATs) coexisting in the same geographical area. In NGWN, a joint call admission control (JCAC) algorithm is needed to select the most appropriate RAT for each incoming call. The JCAC algorithm must be user-centric (i.e., consider user preferences in making RAT selection decisions) in order to enhance userspsila satisfaction. This paper investigates a user-centric JCAC (UJCAC) algorithm for heterogeneous wireless networks. The UJCAC algorithm uses Fuzzy multiple-attribute decision-making technique to select the most appropriate RAT for each incoming call. We develop a Markov model for the UJCAC algorithm to evaluate the overall call blocking probability and handoff call dropping probability in heterogeneous wireless networks. Performance of the UJCAC algorithm is evaluated using a three-RAT heterogeneous network. Simulation results show that a UJCAC algorithm can lead to highly unbalanced network load, and high call blocking/dropping probability. Therefore, a flexible UJCAC algorithm is more suitable for NGWN. In flexible UJCAC, if the mostly preferred RAT for incoming call is fully loaded, the next preferred RAT will be selected for the call. The call will be blocked only if none of the available RATs can accommodate the call. Therefore, call blocking/dropping probability will be reduced.

There is an increasing demand for high bandwidth-consuming services such as real-time video and video streaming over wireless access networks. A single radio access technology (RAT) in a heterogeneous wireless network may not always have enough radio resource to admit high bandwidth-consuming calls, such as video calls. Existing joint call admission control (JCAC) algorithms designed for heterogeneous wireless networks block/drop an incoming call when none of the available individual RATs in the network has enough bandwidth to admit the incoming call. Consequently, video calls experience high call blocking/dropping probability in the network. However, some calls such as multi-layer coded (scalable) video can be transmitted/received over one or multiple RATs. This article proposes a JCAC algorithm that selects a single or multiple RATs for scalable video calls in heterogeneous wireless networks, depending on availability of radio resources in available RATs. Non scalable calls are always admitted into a single RAT by the algorithm. The aim of the proposed algorithm is to reduce call blocking/dropping probability for both scalable and non-scalable calls. An analytical model is developed for the proposed JCAC algorithm, and its performance is evaluated. Simulation results show that the proposed algorithm reduces call blocking/dropping probability in heterogeneous wireless networks.

The concept of wireless heterogeneous networks is based on the coexistence and interoperability of different types of radio access technologies in a unified wireless heterogeneous platform. A key process in the wireless heterogeneous networks is the initiation and execution of vertical handovers. Variety of mechanisms are proposed in the literature that are tailored to optimize the choice of radio access network in the process of vertical handover initialization. This paper proposes a novel mechanism for radio access technology (RAT) selection, the Hopfield neural network Rat selection Mechanism (HRM), that utilizes the Hopfield neural networks as a powerful decision making tool. The main advantage of the proposed mechanism lays in its ability of Artificial Intelligence (AI) reasoning and the use of multi-parameter decision by exploiting the options of IEEE 802.21 protocol. This approach allows improvements in terms of service retainability, decreased packet loss, jitter, etc. The performance of the novel mechanism is compared with two other types of RAT selection mechanisms (RSS based, and Multi-criteria policy based mechanism) throughout extensive simulations. The results clearly show the benefits of the proposed new mechanism and its justified usage in wireless heterogeneous systems.

5G - A Revolutionary Future of Networking

This paper discusses load balancing architecture among heterogeneous wireless networks (HWNs). Load balancing is an important issue for efficient use of radio resources not only in a single network but among different radio access technologies (RATs) in HWNs. Cooperative management of radio resources among heterogeneous RATs is considered to reduce imbalance of utilization of radio resources and enhance availability of the system. For effective load balancing, we define a ldquocommunityrdquo concept, in which radio resources of various RATs are managed together. Radio resource management functional entities of RATs cooperatively work in the community. We present a load balancing architecture applied to 3GPP LTE, WiBro and WLAN and describe architectural considerations. We also present a straightforward load balancing algorithm that takes account of bandwidth usage and received signal to noise ratio. The load balancing algorithm of community radio resource management enhances utilization of radio resources and reduces call blocking probability of individual RATs in the community and further enhances average performance of the whole community.

Network slicing is an architectural solution that enables the future 5G network to offer a high data traffic capacity and efficient network connectivity. Moreover, software defined network (SDN) and network functions virtualization (NFV) empower this architecture to visualize the physical network resources. The network slicing identified as a multiple logical network, where each network slice dedicates as an end-to-end network and works independently with other slices on a common physical network resources. Most user devices have more than one smart wireless interfaces to connect to different radio access technologies (RATs) such as WiFi and LTE, thereby network operators utilize this facility to offload mobile data traffic. Therefore, it is important to enable a network slicing to manage different RATs on the same logical network as a way to mitigate the spectrum scarcity problem and enables a slice to control its users' mobility across different access networks. In this paper, we propose a mobility management architecture based network slicing where each slice manages its users across heterogeneous radio access technologies such as WiFi, LTE and 5G networks. In this architecture, each slice has a different mobility demands and these demands are governed by a network slice configuration and service characteristics. Therefore, our mobility management architecture follows a modular approach where each slice has individual module to handle the mobility demands and enforce the slice policy for mobility management. The advantages of applying our proposed architecture include: i) Sharing network resources between different network slices; ii) creating logical platform to unify different RATs resources and allowing all slices to share them; iii) satisfying slice mobility demands.

More flexible spectrum access policies that take advantage of the cognitive radio capabilities of small cells are required to improve the suboptimal spectrum utilization at small cells. However, care must be taken to ensure that interference from autonomously deployed small cells is tightly controlled when developing such policies. This paper presents a dynamic spectrum access framework that enables small cells employing a specific Radio Access Technology (RAT) to access the spectrum allocated to other RATs as secondary users without degrading the performance of primary RATs. Secondary small cells opportunistically access unutilized spectrum in their coverage area and the protection of primary RATs is achieved by preventing secondary small cells from accessing spectrum when a potential interference scenario is detected. A system where HSPA and LTE-Advanced are co-deployed is considered. Simulation results show that substantial performance gains for both RATs are achieved by increasing spectrum utilization through secondary access for small cells. Furthermore, gains are achieved without degrading the performance of primary RATs.