Mobility: a double-edged sword for HSPA networks

This paper presents an empirical study on the performance of mobile High Speed Packet Access (HSPA, a 3.5G cellular standard) networks in Hong Kong via extensive field tests. Our study, from the viewpoint of end users, covers virtually all possible mobile scenarios in urban areas, including subways, trains, off-shore ferries and city buses. We have confirmed that mobility has largely negative impacts on the performance of HSPA networks, as fast-changing wireless environment causes serious service deterioration or even interruption. Meanwhile our field experiment results have shown unexpected new findings and thereby exposed new features of the mobile HSPA networks, which contradict commonly held views. We surprisingly find out that mobility can improve fairness of bandwidth sharing among users and traffic flows. Also the triggering and final results of handoffs in mobile HSPA networks are unpredictable and often inappropriate, thus calling for fast reacting fallover mechanisms. We have conducted in-depth research to furnish detailed analysis and explanations to what we have observed. We conclude that mobility is a double-edged sword for HSPA networks. To the best of our knowledge, this is the first public report on a large scale empirical study on the performance of commercial mobile HSPA networks

Information Technology

The new millennium has been labeled as the century of the personal communications revolution or more specifically, the digital wireless communications revolution. The introduction of new multimedia services has created higher loads on available radio resources. These services can be presented in different levels of quality of service. Namely, the task of the radio resource manager is to provide these levels. Radio resources are scarce and need to be shared by many users. The sharing has to be carried out in an efficient way avoiding as much as possible any waste of resources. The main contribution focus of this work is on radio resource management in opportunistic systems. In opportunistic communications dynamic rate and power allocation may be performed over the dimensions of time, frequency and space in a wireless system. In this work a number of these allocation schemes are proposed. A downlink scheduler is introduced in this work that controls the activity of the users. The scheduler is a simple integral controller that controls the activity of users, increasing or decreasing it depending on the degree of proximity to a requested quality of service level. The scheduler is designed to be a best effort scheduler; that is, in the event the requested quality of service (QoS) cannot be attained, users are always guaranteed the basic QoS level provided by a proportional fair scheduler. In a proportional fair scheduler, the user with the best rate quality factor is selected. The rate quality here is the instantaneous achievable rate divided by the average throughput Uplink scheduling is more challenging than its downlink counterpart due to signalling restrictions and additional constraints on resource allocations. For instance, in long term evolution systems, single carrier FDMA is to be utilized which requires the frequency domain resource allocation to be done in such a way that a user could only be allocated subsequent bands. We suggest for the uplink a scheduler that follows a heuristic approach in its decision. The scheduler is mainly based on the gradient algorithm that maximizes the gradient of a certain utility. The utility could be a function of any QoS. In addition, an optimal uplink scheduler for the same system is presented. This optimal scheduler is valid in theory only, nevertheless, it provides a considerable benchmark for evaluation of performance for the heuristic scheduler as well as other algorithms of the same system. A study is also made for the feedback information in a multi-carrier system. In a multi-carrier system, reporting the channel state information (CSI) of every subcarrier will result in huge overhead and consequent waste in bandwidth. In this work the subcarriers are grouped into subbands which are in turn grouped into blocks and a study is made to find the minimum amount of information for the adaptive modulation and coding (AMC) of the blocks. The thesis also deals with admission control and proposes an opportunistic admission controller. The controller gradually integrates a new user requesting admission into the system. The system is probed to examine the effect of the new user on existing connections. The user is finally fully admitted if by the end of the probing, the quality of service (QoS) of existing connections did not drop below a certain threshold. It is imperative to mention that the research work of this thesis is mainly focused on non-real time applications.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Analisis handoff pada jaringan high speed downlink access (HSDPA) BERDASARKAN TAHNIK PENJADWALAN

ABSTRAKSI: 3G/UMTS (3rd Generation/Universal Mobile Telecommunications System), didedikasikan tidak hanya untuk memberikan layanan voice ataupun data, tetapi juga mampu mengalokasikan pada kebutuhan user akan video dan gambar (multimedia). Namun, kecepatan pengiriman data (bit rate) yang masih kurang memadai dianggap sebagai kendala utama. Berbagai solusi berusaha dimunculkan untuk mengatasi masalah bit rate yang minimum, seperti W-CDMA (Wideband Code Division Multiple Access). Sistem W-CDMA ini mampu mengakomodasikan bit rate hingga 384 kbps (kilo bit per second).Terobosan terbaru yang dikeluarkan oleh forum UMTS pada awal tahun 2005 adalah disetujuinya penggunaan HSPA (High Speed Packet Access) berdasarkan standard 3GPP (3rd Generation Partnership Project). HSPA tersebut digolongkan menjadi dua link, yaitu HSDPA (High Speed Downlink Packet Access) dan HSUPA (High Speed Uplink Packet Access). Kedua jenis sistem ini bekerja pada core network yang sama dengan jaringan 3G/UMTS. Kelebihan dari sistem HSDPA adalah bit rate yang tinggi (hingga 14.4 Mbps) serta kemampuan untuk diakses oleh lebih banyak user. Hal ini tak lain karena digunakannya berbagai teknik tambahan pada node-B, seperti Adaptive Modulation and Coding (AMC), penjadwalan trafik, serta kanal HSDSCH. Kondisi pada saat user bergerak dari satu sel dan masuk ke sel yang baru disebut peristiwa handoff.Tugas Akhir ini mensimulasikan pengaruh dari tiga macam teknik penjadwalan, diantaranya Mobility supported low dropping probability, Maximum signal interference ratio, dan Proportional Fairness pada jaringan HSDPA, menggunakan Matlab 7.0. Dan membandingkan hasilnya berdasarkan parameter Downlink_troughput, delay antrian, dan Persentasehandoff_dropping. Dari hasil simulasi yang didapat, penjadwalan Max-SIR memiliki Downlink_throughput yang terkecil dibandingkan dengan penjadwalan LDROP ataupun Proportional Fair. Namun dengan trade-off pada parameter delay antrian dan Persentasehandoff_dropping yang lebih tinggi. Sedangkan Proportional Fair adalah penjadwalan yang memiliki nilai parameter Downlink_throughput, delay antrian, dan Persentasehandoff_dropping berada diantara LDROP dan max-SIR.Kata Kunci : HSDPA, penjadwalan trafik,handoff,downlink_ throughput, delay antrian, persentase handoff_dropping.ABSTRACT: 3G/UMTS (3rd Generation/Universal Mobile Telecommunications System), dedicated not only to give voice and data service, but also able to allocate user needs of video and picture (multimedia). But, less adequate bit rate is still considered as main constraint. Many solutions have been introduced to solve that minimum bit rate, such as W-CDMA (Wideband Code Division Multiple Access). This W-CDMA system is able to accommodate bit rate until 384 kbps (kilo bit per second).New improvement that had been released by UMTS forum in the early year of 2005 was the HSPA (High Speed Packet Access) impementation based on 3GPP (3rd Generation Partnership Project) standard. HSPA can be classified into two link, there are HSDPA (High Speed Downlink Packet Access) and HSUPA (High Speed Uplink Packet Access). Both of them work with the same core network as 3G/UMTS. The excess of this HSDPA system is a high bit rate (until 14.4 Mbps) also ability to be accessed by many user. It is because of use of several additional techniques, such as Adaptive Modulation and Coding (AMC), traffic scheduling, and HS-DSCH. Handoff is a condition where user is moving from a previous base station to cuurent base station.This final project simulated the effect of three kind of traffic scheduling, there are Mobility supported low dropping probability, Maximum signal interference ratio, and Proportional Fairness on HSDPA network using Mathlab 7.0. And comparing result based some parameters, e.g. Downlink_throughput, queue delay, and Pecentagehandoff_dropping. From the result of simulation, obtained that Max-SIR scheduling give smaller Downlink_throughput than LDROP or Proportional Fair scheduling. But with trade off on queue delay and Percentagehandoff_dropping which is highest of all. While Proportional Fair give average value of downlink_throughput, queue delay and Percentagehandoff_dropping among LDROP and Max-SIR.Keyword: HSDPA, traffic schedulling. Throughput, queue delay, fairness

Optimization and Performance Analysis of High Speed Mobile Access Networks

The end-to-end performance evaluation of high speed broadband mobile access networks is the main focus of this work. Novel transport network adaptive flow control and enhanced congestion control algorithms are proposed, implemented, tested and validated using a comprehensive High speed packet Access (HSPA) system simulator. The simulation analysis confirms that the aforementioned algorithms are able to provide reliable and guaranteed services for both network operators and end users cost-effectively. Further, two novel analytical models one for congestion control and the other for the combined flow control and congestion control which are based on Markov chains are designed and developed to perform the aforementioned analysis efficiently compared to time consuming detailed system simulations. In addition, the effects of the Long Term Evolution (LTE) transport network (S1and X2 interfaces) on the end user performance are investigated and analysed by introducing a novel comprehensive MAC scheduling scheme and a novel transport service differentiation model