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The contribution of this paper is twofold. First, we introduce a new efficient analytical method for uplink performance estimation in multi-service UMTS networks by taking the dynamic behaviour of the user transmission rate into account. Our performance measures are the average user information rate and the blocking probability of new calls. Next, a traffic management technique is applied to UMTS and incorporated into the analytical approach to specify how resources have to be adequately engineered to meet quantitative performance objectives.For this we investigate the joint behaviour of the admission control characteristics, scheduling, threshold and reservation scheme for UMTS Terrestrial Radio Access Network (UTRAN) in terms of their agreement with Grade of Service (GoS) requirements. The performance of the proposed algorithms is evaluated.

Abstract. The goal of this work is first to analyze the feasibility of a peer-to-peer file sharing technique in mobile cellular environments, taking into account key characteristics and peculiarities of the UMTS Radio Access Network (UTRAN). The concept is referred here to as mobile-tomobile (m2m). Next, our research efforts explore the performance benefits of m2m file sharing applications in UMTS networks in terms of releasing overall downlink capacity, which can be used to provide better Quality of Service (QoS) for real-time services. To evaluate the performance of the proposed m2m concept we conducted extensive simulation studies with appropriately modified radio propagation models for low antenna heights for both, transmitter and receiver, as it is typical for m2m. Two alternative scenarios of serving user requests (m2m network mode and conventional UMTS mode) have been constructed and analyzed. The results indicate a dramatic increase in service probability and overall throughput gain of up to 85 % in a UMTS network, supported by the m2m data transmission mode. Furthermore, results show that by a well-designed m2m routing policy and proper utilization of currently not used uplink resources (due to asymmetric uplink/downlink traffic load) substantial reduction of the expected file download time can be achieved.

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Abstract-The goal of this work is to analyze the feasibility of a peer-to-peer file sharing technique in mobile cellular environments, taking into account key characteristics and peculiarities of the UMTS Radio Access Network (UTRAN). The concept is referred here to as mobile-to-mobile (m2m).Our research efforts explore the performance benefits of m2m file sharing applications in UMTS networks in terms of releasing overall downlink capacity. In our concept the users that are interested in downloading a popular file form a mobile cooperative community and using the fact that traffic load of multimedia services is asymmetrically distributed between uplink and downlink, contribute their own currently not used uplink capacity for providing the packets of the content to other users within the group in multicast mode on the uplink carrier frequencies. As a result a major part of the traffic is shifted away from the downlink, making the released downlink capacity available for providing better Quality of Service (QoS) for real-time services.Two alternative scenarios of serving user requests (m2m and conventional UMTS mode) have been analyzed. The results indicate a dramatic increase in service probability and overall throughput gain of up to 85 % in a UMTS network, supported by the m2m data transmission mode. Furthermore, results show that by a well-designed m2m routing policy and proper utilization of uplink resources substantial reduction of the expected file download time can be achieved.

Abstract-This paper is a sequel of previous work, in which we have studied the problem of congestions on the typically overloaded downlink channels in UMTS (Universal Mobile Telecommunication System) networks. Our concept is based on the uplink/downlink traffic imbalance in 3G wireless networks and is realized by organizing seamless cooperation between peerto-peer and cellular networks using a unified radio interface for both systems. The primary goal is to improve the spectral efficiency of cellular networks by enabling direct mobile-tomobile (m2m) communication on temporarily unused uplink channels for the distribution of a large popular content in a non-real time multicast manner.The aim of this work is to further improve the interaction between cellular and peer-to-peer networks by generalizing the traditional scheduling paradigm. A network coding technique is embedded as a solution to the scheduling problem in the distributed dynamic environment of wireless large-scale networks. We investigate the performance of the system in terms of dependability of information distribution among m2m users.Simulations demonstrate the enhanced performance of the file distribution in terms of file download time. Furthermore, the obtained results highlight that network coding based m2m data transfer allows distribution of popular files to a large number of users while placing minimal bandwidth requirements on the central server.

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Abstract. This paper is a sequel of previous work, in which we have studied the traffic management problem in UMTS. The main objective was to improve the spectral efficiency of cellular networks by employing network coding supported direct mobile-to-mobile communication on usually underloaded uplink channels for the distribution of a delay insensitive popular content in multicast manner. Simulations demonstrate the noticeable performance enhancement in terms of file download times and at the same time a substantial reduction of the number of necessary transmissions in both uplink and downlink directions. However, popular content is often too large to be processed with a straightforward realization of network coding; combining the entire file to construct a single encoded block is impractical due to high encoding and decoding costs. To circumvent this problem, a novel concept is proposed in this paper. The scheme is based on processing popular content of virtually arbitrary size by embedding multiple generations into network coding.Key words: improvement in information distribution, direct mobile-tomobile communication, network coding, multiple generations. Related Previous WorkThe aim of the analysis performed in the previous paper [PSGK07] was to improve the interaction between cellular and peer-to-peer networks by generalizing the traditional scheduling paradigm. A network coding technique [ACLY00, FBW05] was embedded as a solution to the scheduling problem in the distributed dynamic environment of wireless large-scale networks. We have investigated the performance of the Universal Mobile Telecommunication System (UMTS) in terms of improvement in information distribution and dependability of information distribution among users by using direct mobile-to-mobile (m2m) data transmission mode. We have shown how, and in which terms network coding can thereby help. We have been especially interested in the distribution of the file download times for m2m users in different states of the download progress.