Easing the Transition from Inspiration to Implementation: A Rapid Prototyping Platform for Wireless Medium Access Control Protocols

Packet broadcast networks are in widespread use in modern wireless communication systems. Medium access control is a key functionality within such technologies. A substantial research effort has been and continues to be invested into the study of existing protocols and the development of new and specialised ones. Academic researchers are restricted in their studies by an absence of suitable wireless MAC protocol development methods. This thesis describes an environment which allows rapid prototyping and evaluation of wireless medium access control protocols. The proposed design flow allows specification of the protocol using the specification and description language (SDL) formal description technique. A tool is presented to convert the SDL protocol description into a C++ model suitable for integration into both simulation and implementation environments. Simulations at various levels of abstraction are shown to be relevant at different stages of protocol design. Environments based on the Cinderella SDL simulator and the ns-2 network simulator have been developed which allow early functional verification, along with detailed and accurate performance analysis of protocols under development. A hardware platform is presented which allows implementation of protocols with flexibility in the hardware/software trade-off. Measurement facilities are integral to the hardware framework, and provide a means for accurate real-world feedback on protocol performance

Novel algorithms for fair bandwidth sharing on counter rotating rings

Rings are often preferred technology for networks as ring networks can virtually create fully connected mesh networks efficiently and they are also easy to manage. However, providing fair service to all the stations on the ring is not always easy to achieve. In order to capitalize on the advantages of ring networks, new buffer insertion techniques, such as Spatial Reuse Protocol (SRP), were introduced in early 2000s. As a result, a new standard known as IEEE 802.17 Resilient Packet Ring was defined in 2004 by the IEEE Resilient Packet Ring (RPR) Working Group. Since then two addenda have been introduced; namely, IEEE 802.17a and IEEE 802.17b in 2006 and 2010, respectively. During this standardization process, weighted fairness and queue management schemes were proposed to be used in the standard. As shown in this dissertation, these schemes can be applied to solve the fairness issues noted widely in the research community as radical changes are not practical to introduce within the context of a standard. In this dissertation, the weighted fairness aspects of IEEE 802.17 RPR (in the aggressive mode of operation) are studied; various properties are demonstrated and observed via network simulations, and additional improvements are suggested. These aspects have not been well studied until now, and can be used to alleviate some of the issues observed in the fairness algorithm under some scenarios. Also, this dissertation focuses on the RPR Medium Access Control (MAC) Client implementation of the IEEE 802.17 RPR MAC in the aggressive mode of operation and introduces a new active queue management scheme for ring networks that achieves higher overall utilization of the ring bandwidth with simpler and less expensive implementation than the generic implementation provided in the standard. The two schemes introduced in this dissertation provide performance comparable to the per destination queuing implementation, which yields the best achievable performance at the expense of the cost of implementation. In addition, till now the requirements for sizing secondary transit queue of IEEE 802.17 RPR stations (in the aggressive mode of operation) have not been properly investigated. The analysis and suggested improvements presented in this dissertation are then supported by performance evaluation results and theoretical calculations. Last, but not least, the impact of using different capacity links on the same ring has not been investigated before from the ring utilization and fairness points of view. This dissertation also investigates utilizing different capacity links in RPR and proposes a mechanism to support the same

Adaptive Telemetry for Software-Defined Mobile Networks

The forthcoming set of 5G standards will bring programmability and flexibility to levels never seen before. This has required introducing changes in the architecture of mobile networks, enabling different features such as the split of control and data planes, as required to support the rapid programming of heterogeneous data planes. Software Defined Networking (SDN) has emerged as a basic toolset for operators to manage their infrastructure, as it opens up the possibility of running a multitude of intelligent and advanced applications for network optimization purposes in a centralized network controller. However, the very basic nature that makes possible this efficient management and operation in a flexible way-the logical centralization-poses important challenges due to the lack of proper monitoring tools, suited for SDN-based architectures. In order to take timely and right decisions while operat-ing a network, centralized intelligence applications need to be fed with a continuous stream of up-to-date network statistics. However, this is not feasible with current SDN solutions due to scalability and accuracy issues. This article first analyzes the monitoring issues in current SDN solutions and then proposes a telemetry frame-work for software defined mobile networks capable of adapting to the various 5G services. Finally, it presents an experimental validation that shows the benefits of the proposed solution at alleviating the load on the control and data planes, improv-ing the reactiveness to network events, and providing better accuracy for network measurements.This work has been partially funded by the H2020 Framework Programme Europe/Taiwan joint action 5G-DIVE Project (Grant No. 859881), by the H2020 Framework Programme EU 5G-Transformer Project (Grant No. 761586), and by the H2020 Framework Programme EU 5Growth Project (Grant No. 856709)

A cross-layer approach to enhance QoS for multimedia applications over satellite

The need for on-demand QoS support for communications over satellite is of primary importance for distributed multimedia applications. This is particularly true for the return link which is often a bottleneck due to the large set of end-users accessing a very limited uplink resource. Facing this need, Demand Assignment Multiple Access (DAMA) is a classical technique that allows satellite operators to offer various types of services, while managing the resources of the satellite system efficiently. Tackling the quality degradation and delay accumulation issues that can result from the use of these techniques, this paper proposes an instantiation of the Application Layer Framing (ALF) approach, using a cross-layer interpreter(xQoS-Interpreter). The information provided by this interpreter is used to manage the resource provided to a terminal by the satellite system in order to improve the quality of multimedia presentations from the end users point of view. Several experiments are carried out for different loads on the return link. Their impact on QoS is measured through different application as well as network level metrics

Design of a High Capacity, Scalable, and Green Wireless Communication System Leveraging the Unlicensed Spectrum

The stunning demand for mobile wireless data that has been recently growing at an exponential rate requires a several fold increase in spectrum. The use of unlicensed spectrum is thus critically needed to aid the existing licensed spectrum to meet such a huge mobile wireless data traffic growth demand in a cost effective manner. The deployment of Long Term Evolution (LTE) in the unlicensed spectrum (LTE-U) has recently been gaining significant industry momentum. The lower transmit power regulation of the unlicensed spectrum makes LTE deployment in the unlicensed spectrum suitable only for a small cell. A small cell utilizing LTE-L (LTE in licensed spectrum), and LTE-U (LTE in unlicensed spectrum) will therefore significantly reduce the total cost of ownership (TCO) of a small cell, while providing the additional mobile wireless data offload capacity from Macro Cell to small cell in LTE Heterogeneous Networks (HetNet), to meet such an increase in wireless data demand. The U.S. 5 GHz Unlicensed National Information Infrastructure (U-NII) bands that are currently under consideration for LTE deployment in the unlicensed spectrum contain only a limited number of 20 MHZ channels. Thus in a dense multi-operator deployment scenario, one or more LTE-U small cells have to co-exist and share the same 20 MHz unlicensed channel with each other and with the incumbent Wi-Fi. This dissertation presents a proactive small cell interference mitigation strategy for improving the spectral efficiency of LTE networks in the unlicensed spectrum. It describes the scenario and demonstrate via simulation results, that in the absence of an explicit interference mitigation mechanism, there will be a significant degradation in the overall LTE-U system performance for LTE-U co-channel co-existence in countries such as U.S. that do not mandate Listen-Before-Talk (LBT) regulations. An unlicensed spectrum Inter Cell Interference Coordination (usICIC) mechanism is then presented as a time-domain multiplexing technique for interference mitigation for the sharing of an unlicensed channel by multi-operator LTE-U small cells. Through extensive simulation results, it is demonstrated that the proposed usICIC mechanism will result in 40% or more improvement in the overall LTE-U system performance (throughput) leading to increased wireless communication system capacity. The ever increasing demand for mobile wireless data is also resulting in a dramatic expansion of wireless network infrastructure by all service providers resulting in significant escalation in energy consumption by the wireless networks. This not only has an impact on the recurring operational expanse (OPEX) for the service providers, but importantly the resulting increase in greenhouse gas emission is not good for the environment. Energy efficiency has thus become one of the critical tenets in the design and deployment of Green wireless communication systems. Consequently the market trend for next-generation communication systems has been towards miniaturization to meet this stunning ever increasing demand for mobile wireless data, leading towards the need for scalable distributed and parallel processing system architecture that is energy efficient, and high capacity. Reducing cost and size while increasing capacity, ensuring scalability, and achieving energy efficiency requires several design paradigm shifts. This dissertation presents the design for a next generation wireless communication system that employs new energy efficient distributed and parallel processing system architecture to achieve these goals while leveraging the unlicensed spectrum to significantly increase (by a factor of two) the capacity of the wireless communication system. This design not only significantly reduces the upfront CAPEX, but also the recurring OPEX for the service providers to maintain their next generation wireless communication networks

Service composition based on SIP peer-to-peer networks

Today the telecommunication market is faced with the situation that customers are requesting for new telecommunication services, especially value added services. The concept of Next Generation Networks (NGN) seems to be a solution for this, so this concept finds its way into the telecommunication area. These customer expectations have emerged in the context of NGN and the associated migration of the telecommunication networks from traditional circuit-switched towards packet-switched networks. One fundamental aspect of the NGN concept is to outsource the intelligence of services from the switching plane onto separated Service Delivery Platforms using SIP (Session Initiation Protocol) to provide the required signalling functionality. Caused by this migration process towards NGN SIP has appeared as the major signalling protocol for IP (Internet Protocol) based NGN. This will lead in contrast to ISDN (Integrated Services Digital Network) and IN (Intelligent Network) to significantly lower dependences among the network and services and enables to implement new services much easier and faster. In addition, further concepts from the IT (Information Technology) namely SOA (Service-Oriented Architecture) have largely influenced the telecommunication sector forced by amalgamation of IT and telecommunications. The benefit of applying SOA in telecommunication services is the acceleration of service creation and delivery. Main features of the SOA are that services are reusable, discoverable combinable and independently accessible from any location. Integration of those features offers a broader flexibility and efficiency for varying demands on services. This thesis proposes a novel framework for service provisioning and composition in SIP-based peer-to-peer networks applying the principles of SOA. One key contribution of the framework is the approach to enable the provisioning and composition of services which is performed by applying SIP. Based on this, the framework provides a flexible and fast way to request the creation for composite services. Furthermore the framework enables to request and combine multimodal value-added services, which means that they are no longer limited regarding media types such as audio, video and text. The proposed framework has been validated by a prototype implementation

Muistikeskeisen radioverkon vaikutus tietopääsyjen suoritusnopeuteen

Future 5G-based mobile networks will be largely defined by virtualized network functions (VNF). The related computing is being moved to cloud where a set of servers is provided to run all the software components of the VNFs. Such software component can be run on any server in the mobile network cloud infrastructure. The servers conventionally communicate via TCP/IP -network. To realize planned low-latency use cases in 5G, some servers are placed to data centers near the end users (edge clouds). Many of these use cases involve data accesses from one VNF to another, or to other network elements. The accesses are desired to take as little time as possible to stay within the stringent latency requirements of the new use cases. As a possible approach for reaching this, a novel memory-centric platform was studied. The main ideas of the memory-centric platform are to collapse the hierarchy between volatile and persistent memory by utilizing non-volatile memory (NVM) and use memory-semantic communication between computer components. In this work, a surrogate memory-centric platform was set up as a storage for VNFs and the latency of data accesses from VNF application was measured in different experiments. Measurements against a current platform showed that memory-centric platform was significantly faster to access than the current, TCP/IP using platform. Measurements for accessing RAM with different memory bandwidths within the memory-centric platform showed that the order of latency was roughly independent of the available memory bandwidth. These results mean that memory-centric platform is a promising alternative to be used as a storage system for edge clouds. However, more research is needed to study how other service qualities, such as low latency variation, are fulfilled in memory-centric platform in a VNF environment.Tulevaisuuden 5G:hen perustuvissa mobiiliverkoissa verkkolaitteisto on pääosin virtualisoitu. Tällaisen verkon virtuaaliverkkolaite (VNF) koostuu ohjelmistokomponenteista, joita ajetaan tarkoitukseen määrätyiltä mobiiliverkon pilven palvelimilta. Ohjelmistokomponentti voi olla ajossa millä vain mobiiliverkon näistä pilvi-infrastruktuurin palvelimista. Palvelimet on tavallisesti yhdistetty TCP/IP-verkolla. Jotta suunnitellut alhaisen viiveen käyttötapaukset voisivat toteutua 5G-verkoissa, pilvipalvelimia on sijoitettu niin kutsuttuihin reunadatakeskuksiin lähelle loppukäyttäjiä. Monet näistä käyttötapauksista sisältävät tietopääsyjä virtuaaliverkkolaitteesta toisiin tai muihin verkkoelementteihin. Tietopääsyviiveen halutaan olevan mahdollisimman pieni, jotta käyttötapausten tiukoissa viiverajoissa pysytään. Mahdollisena lähestymistapana tietopääsyviiveen minimoimiseen tutkittiin muistikeskeistä laitteistoalustaa. Tämän laitteistoalustan pääperiaatteita on korvata nykyiset lyhytkestoiset ja pysyvät muistit haihtumattomalla muistilla sekä kommunikoida muistisemanttisilla viesteillä tietokonekomponenttien kesken. Tässä työssä muistikeskeisyyttä hyödyntävää sijaislaitteistoa käytettiin VNF-datan varastona ja ohjelmistokomponenttien tietopääsyviivettä sinne mitattiin erilaisilla kokeilla. Kokeet osoittivat nykyisen, TCP/IP-pohjaisen alustan huomattavasti muistikeskeistä alustaa hitaammaksi. Toiseksi, kokeet osoittivat tietopääsyviiveiden olevan saman suuruisia muistikeskeisen alustan sisällä, riippumatta saatavilla olevasta muistikaistasta. Tulokset merkitsevät, että muistikeskeinen alusta on lupaava vaihtoehto reunadatakeskuksen tietovarastojärjestelmäksi. Lisää tutkimusta alustasta kuitenkin tarvitaan, jotta muiden palvelun laatukriteerien, kuten matalan viivevaihtelun, toteutumisesta saadaan tietoa