Quality of service and resource management in IP and wireless networks

A common theme in the publications included in this thesis is the quality of service and resource management in IP and wireless networks. This thesis presents novel algorithms and implementations for admission control in IP and IEEE 802.16e networks, active queue management in EGPRS, WCDMA, and IEEE 802.16e networks, and scheduling in IEEE 802.16e networks. The performance of different algorithms and mechanisms is compared with the prior art through extensive ns-2 simulations. We show that similar active queue management mechanisms, such as TTLRED, can be successfully used to reduce the downlink delay (and in some cases even improve the TCP goodput) in different bottlenecks of IP, EGPRS, WCDMA, and IEEE 802.16e access networks. Moreover, almost identical connection admission control algorithms can be applied both in IP access networks and at IEEE 802.16e base stations. In the former case, one just has to first gather the link load information from the IP routers. We also note that DiffServ can be used to avoid costly overprovisioning of the backhaul in IEEE 802.16e networks. We present a simple mapping between IEEE 802.16e data delivery services and DiffServ traffic classes, and we propose that IEEE 802.16e base stations should take the backhaul traffic load into account in their admission control decisions. Moreover, different IEEE 802.16e base station scheduling algorithms and uplink channel access mechanisms are studied. In the former study, we show that proportional fair scheduling offers superior spectral efficiency when compared to deficit round-robin, though in some cases at the cost of increased delay. Additionally, we introduce a variant of deficit round-robin (WDRR), where the quantum value depends on the modulation and coding scheme. We also show that there are several ways to implement ertPS in an efficient manner, so that during the silence periods of a VoIP call no uplink slots are granted. The problem here, however, is how to implement the resumption after the silence period while introducing as little delay as possible

Liikenteen mallintaminen ja simulointi langattomassa ympäristössä

Muutamassa vuodessa kolmannen sukupolven matkaviestinverkot tuovat nopeat Internet-yhteydet myös mobiilipäätelaitteisiin. Tätä tulee kuitenkin edeltämään uusien pakettipohjaisten datapalvelujen, kuten GPRS (General Packet Radio Service), käyttöönotto toisen sukupolven verkoissa. Jotta radiorajapinnan rajalliset resurssit tulisivat parhaiten hyödynnetyiksi, tulee Internet-liikenteen luonnetta tutkia. Suurin osa tästä liikenteestä on HTTP:n (Hypertext Transfer Protocol) aikaansaamaa. Teknillisen korkeakoulun Tietoliikennelaboratoriossa suoritettujen WWW-liikennemittausten pohjalta työssä esitetään ja toteutetaan kaksi Network Simulatorille (ns-2) tehtyä HTTP client-server mallia. Mallien hierarkkinen rakenne on samankaltainen kuin ETSl:n (European Telecommunications Standards Institute) mallissa ei-reaaliaikaisille palveluille. Malleja testataan langattomassa, GPRS:n kaltaisessa simulaatioympäristössä, ja WWW-sivun saapumiseen kuluvaa aikaa sekä IP-pakettien päästä-päähän viivettä eri kuormilla ja käytössä olevien kanavien määrillä vertaillaan toisiinsa. Toinen kiinnostuksen kohde on IP Multicast. Multicast-liikenteen luonnetta tutkitaan, ja tarkoituksena on saada selville, kuinka multicast-liikenne eroaa tavallisesta Internet-liikenteestä

Packet Reservation Multiple Access (PRMA) for Joint Speech and Data Systems

Abstract. Packet Reservation Multiple Access (PRMA) can be viewed as a combination of TDMA and slotted ALOHA protocols. In PRMA, there are speech and data terminals that communicate with a base station. Downlink packets are scheduled by the base station, but for uplink access (first packet of a talkspurt or any data packet), terminals use slotted ALOHA. Speech terminals (and some data terminals, too) can make slot reservations for future frames. PRMA can also be seen as a kind of statistical multiplexing scheme. Statistical multiplexing gain comes from the fact that speech terminals are equipped with speech activity detectors and thus they transmit packets only during talkspurts

Adaptive routing in mobile opportunistic networks

In this paper, we study how to adapt the routing according to dynamic network conditions in wireless ad hoc networks. We present a method that dynamically chooses routing agent between ad hoc on-demand distance vector routing protocol (AODV) with TCP (endto-end transport) and delay-tolerant networking (DTN) routing and bundle protocol (hop-by-hop transport). We use simulations to confirm that DTN routing and the bundle protocol leads to significantly shorter end-to-end delays and higher message delivery ratios than AODV and end-to-end TCP when the wireless node density is low. However, with high node density, DTN routing, especially epidemic routing, suffers from multiple bundle copies and simultaneous transmissions that lead into collisions and retransmissions at the wireless link (MAC) layer. Thus, we propose a simple adaptive scheme that uses only local information to transmit the messages from source to destination using either AODV or DTN routing, depending on current node density, message size, and path length to destination

Measurement and characterization of Internet gaming traffic

Most of the recent computer game releases support multiplayer options over Internet connections. The amount of Internet traffic generated by computer games can be expected to increase fast, especially when the new wave of players enters the Internet with the next generation game consoles that support Internet connections. In order to provide insight into this new but already significant part of Internet traffic, we have conducted a study of a number of popular Internet games. We defined four different classes of games: action games, simulators, real time strategy games, and turn based strategy games. Traffic generated by the representatives of these four different classes was measured and analyzed in terms of packet size distribution and packet interarrival time distribution. One of the main results of this study was that the amount of traffic generated by different games could vary heavily. For example, an action game could generate almost 15 kbps on average, while a turn based strategy game generated less than 1 kbps of traffic. In general, we observed small packets of a few distinct sizes rather than continuous packet size distributions. In most cases, interarrival times could be modeled by multimodal distributions consisting of extreme, normal or exponential distributions