Analysis methodology for flow-level evaluation of a hybrid mobile-sensor network

Our society uses a large diversity of co-existing wired and wireless networks in order to satisfy its communication needs. A cooper- ation between these networks can benefit performance, service availabil- ity and deployment ease, and leads to the emergence of hybrid networks. This position paper focuses on a hybrid mobile-sensor network identify- ing potential advantages and challenges of its use and defining feasible applications. The main value of the paper, however, is in the proposed analysis approach to evaluate the performance at the mobile network side given the mixed mobile-sensor traffic. The approach combines packet- level analysis with modelling of flow-level behaviour and can be applied for the study of various application scenarios. In this paper we consider two applications with distinct traffic models namely multimedia traffic and best-effort traffic

Uplink packet scheduling in cellular networks with relaying—comparative study

Deployment of intermediate relay nodes in cellular networks, e.g. UMTS/ HSPA, has been proposed for service enhancement, which is of particular importance for uplink users at the cell edge suffering from low power capacity and relatively poor channel conditions. In this paper, we propose and investigate a number of uplink packet scheduling schemes deploying the relay functionality in different ways. Using a combined packet and flow level analysis capturing the specifics of the scheduling schemes and the random behavior of the users (initiation and completion of flow transfers), the performance of the various schemes is evaluated and compared to a reference scenario where relaying is not used. The main performance measures considered in our study are realized data rates and mean flow transfer times. Interestingly, considering flow transfer times, it is found that the use of relay nodes is not only particularly beneficial for users at the cell edge but also has a strong, positive effect on the performance of users at other locations not transmitting via a relay node

Analysis of packet scheduling for UMTS EUL - design decisions and performance evaluation

The UMTS Enhanced Uplink (EUL) provides higher capacity, increased data rates and smaller latency on the communication link from users towards the network. In this paper we present a performance comparison of three distinct EUL scheduling schemes (one-by-one, partial parallel and full parallel) taking into account both the packet level characteristics and the flow level dynamics due to the (random) user behaviour.\ud Using a very efficient hybrid analytical and simulation approach we analyse the three schemes with respect to performance measures such as mean file transfer time and fairness. In UMTS, a significant part of the system capacity will be used to support non-elastic voice traffic. Hence, part of our investigation is dedicated to the effects that the volume of voice traffic has on the performance of the elastic traffic supported by the EUL. Finally, we evaluate the impact that implementation specifics of a full parallel scheduler has on these measures.\ud \ud Our main conclusion is that our partial parallel scheduler, which is a hybrid between the one-by-one and full parallel, outperforms the other two schedulers in terms of mean flow transfer time, and is less sensitive to volume and nature of voice traffic. However, under certain circumstances, the partial parallel scheduler exhibits a somewhat lower fairness than the alternatives

Impact of inter-cell interference on flow level performance of scheduling schemes for the UMTS EUL

The UMTS Enhanced Uplink (EUL) is expected to provide higher capacity, increased data rates, and smaller latency on the communication link from users towards the network. A key mechanism in EUL traffic handling is the packet scheduler, for which a number of basic schemes can be identified (one-by- one, partial parallel, and full parallel). In this paper we analyze the interaction between the EUL scheduling scheme deployed in the network and the inter-cell interference. On the one hand, different scheduling schemes cause different inter-cell interference patterns on neighbouring cells. On the other hand, the different schemes are affected by inter-cell interference in different ways. The scheduling schemes are evaluated and compared under different approaches for reserving part of the allowed noise rise at the base station for inter-cell interference. For our analysis, we have developed a hybrid analytical/simulation approach allowing for fast evaluation of performance measures such as the mean flow transfer time and fairness expressing how the performance depends on the user’s location. This approach takes into account both the packet-level characteristics and the flow-level dynamics due to the random user behaviour

Scheduling strategies for LTE uplink with flow behaviour analysis

Long Term Evolution (LTE) is a cellular technology developed to support\ud diversity of data traffic at potentially high rates. It is foreseen to extend the capacity and improve the performance of current 3G cellular networks. A key\ud mechanism in the LTE traffic handling is the packet scheduler, which is in charge of allocating resources to active flows in both the frequency and time dimension. In this paper we present a performance comparison of two distinct scheduling schemes for LTE uplink (fair fixed assignment and fair work-conserving) taking into account both packet level characteristics and flow level dynamics due to the random user behaviour. For that purpose, we apply a combined analytical/simulation approach which enables fast evaluation of performance measures such as mean flow transfer times manifesting the impact of resource allocation strategies. The results show that the resource allocation strategy has a crucial impact on performance and that some trends are observed only if flow level dynamics are considered

Performance Analysis of Uplink Packet Schedulers in Cellular Networks with Relaying

Deployment of intermediate relay nodes in cellular networks, e,g, UMTS/ HSPA, has been proposed for service enhancement, which is of particular importance for uplink users at the cell edge suffering from low power capacity and relatively poor channel conditions. In this paper, we propose and investigate a number of uplink packet scheduling schemes deploying the relay functionality in different ways. Using a combined packet and flow level analysis capturing the specifics of the scheduling schemes and the random behavior of the users (initiation and completion of flow transfers), the performance of the various schemes is evaluated and compared to a reference scenario where relaying is not used. The main performance measures considered in our study are the instantaneous data rate, the energy consumption and the mean flow transfer time. Interestingly, considering flow transfer times, it is found that the use of relay nodes is not only particularly beneficial for users at the cell edge but also has a strongly positive effect on the performance of users at locations close to the base station

Analyzing the impact of relay station characteristics on uplink performance in cellular network

Uplink users in cellular networks, such as UMTS/ HSPA, located at the edge of the cell generally suffer from poor channel conditions. Deploying intermediate relay nodes is seen as a promising approach towards extending cell coverage. This paper focuses on the role of packet scheduling in cellular networks with relay nodes. In particular, two uplink scheduling schemes deploying the relay functionality in different ways are compared in performance to a reference scenario where relaying is not used. We derive expressions which characterize for each of the two relay-enabled schedulers the service area of a relay station as a function of the relay location and transmit power. The results show that the service area is significantly influenced by the type of scheduling. Examining for both schedulers the impact on the effective data rates of mobile stations shows that there is an optimal combination of relay's position and transmit power which maximizes the service provided to all mobiles

Analysing uplink scheduling in mobile networks - a flow-level perspective

The main purpose of mobile networks is to enable customers that are located at arbitrary geographical locations to communicate with each other without the need of a physical connection. Within only two centuries mobile technology has evolved from analogue networks providing telephony services towards digital networks supporting larger variety of mobile services, enhanced coverage and higher data rates. A key element of providing wireless connectivity is the management of the radio spectrum to be shared by the mobile users. The challenge in the spectrum management is to nd a trade-o between eciently using the network and at the same time providing the quality of service (QoS) requested by the users. In this task operators are strongly assisted by the radio resource management (RRM) mechanisms and scheduling in particular. Scheduling is responsible for the distribution of the available radio resource over the users that have requested service. This thesis focuses on the performance of uplink scheduling schemes in mobile networks. We have dedicated special attention to the impact of ow-level dynamics, i.e. the random user behaviour regarding the initiation and completion of data ow transfers. Additionally, we investigate the possibilities to adopt relaying as a technique to boost performance and how it interacts with the scheduling mechanism. In order to evaluate the impact of the ow-level dynamics on the scheduling performance we propose a novel hybrid analysis approach, which we consider to be an overall contribution of this thesis. The approach is a combination of analytical methods and simulation. Packet level details, playing on a small time scale, are captured by analytical methods, while the ow-level behaviour, playing on a larger time scale, is simulated. This combination enables fast evaluation and comparison of the performance of dierent schedulers expressed in terms of ow throughputs and mean ow transfer times. Our general conclusion is that ow dynamics can have signicant impact on performance. For example, we show that some changes (benets) in performance exhibit only during the interaction of ow transfers. Therefore, analysis of the system at ow level should be included in the analysis of mobile systems. The proposed hybrid analytical/simulation approach, which captures both packetand ow-level behaviour, is very exible and can be easily adapted to reect changes in factors such as environmental conditions or technological specications. These features make the approach very appropriate for application in other studies as well. In our studies we have investigated the impact of various factors, e.g. intercell interference and individual user channel conditions, on the scheduling scheme. Based on our ndings we conclude that a scheduling scheme should be carefully designed to consider, among others, requirements towards utilisation eciency, user's QoS demands and the wireless environment. Furthermore, we also show that relaying leads to improved service provided, not only to users that directly make use of a relay station but also to users that communicate directly to the network

Impact of relaying on inter-cell interference in mobile cellular networks

Incorporating relay nodes in cellular networks, e.g. UMTS/ HSPA, is beneficial for extending coverage as well as for service enhancement. In this paper we study the inter-cell interference generated by a relay-enabled cell and how this influences the performance of mobile users. The performance measures of interest are the inter-cell interference distribution, realized rates and flow throughput. Our investigations show that not only relaying reduces interference but as result of this decrease all users experience an additional performance improvement, independently whether they use a relay or not. The effect is even stronger when flow throughputs are evaluated. The consideration of flow dynamics is a strong and distinctive aspect of our analysis methodology. We show that the evaluation on flow level contributes significantly to better understanding of the effects of relaying. Special attention is also given to the applied scheduling scheme

Scheduler dependent modeling of inter-cell interference in UMTS EUL

In this paper we analyze the performance of the UMTS Enhanced Uplink (EUL) in a network scenario, under various packet scheduling schemes. Besides the impact of the intrinsic differences of the scheduling schemes on EUL performance (which we studied in a previous paper for a single cell scenario), we are particularly interested in how the different scheduling schemes influence EUL performance through their impact on the characteristics of the intercell interference. For our analysis we use a hybrid analytical/simulation approach, originally developed for the single cell situation, and extend it to our multi cell scenario. We show that the mutual influence between neighbouring cells due to inter-cell interference is largely determined by only one or two power iteration steps, which considerably speeds up computations. Our approach takes into account both the packet-level characteristics and the flow-level dynamics due to the random user behaviour. For the considered schedulers we evaluate and compare performance measures such as the mean flow transfer time and throughput. © 2009 IEEE