<p>The third generation, 3G, mobile telephone systems are designed for multimedia communication and will offer us similar services as in our stationary computers. This will involve large traffic loads, especially in the downlink direction, i.e. from base station to terminal. To improve the downlink capacity for packet data services a new concept is included in evolved 3G networks. The concept is called High Speed Data Packet Access, HSDPA, and provides peak bit rates of 14 Mbps. HSDPA uses a so-called best effort channel, i.e. it is developed for services that do not require guaranteed bit rates. The channel is divided in time between the users and a scheduling algorithm is used to allocate the channel among them. </p><p>Streaming is a common technology for video transmission over the Internet and with 3G it is supposed to become popular also in our mobiles. Streaming generates lots of data traffic in the downlink direction and it would thus be satisfying to make use of the high bit rates HSDPA provides. The problem is that streaming requires reasonable stable bit rates, which is not guaranteed using HSDPA. The aim of this study is to modify the scheduling algorithms to prioritise streaming over web users and provide streaming Quality of Service, QoS. QoS is the ability to guarantee certain transmission characteristics. </p><p>The results of the study show that it is hard to improve the streaming capacity by modifications of the scheduling. Of course, a consequence is that the web user throughput is decreased and to avoid this, new users have to be rejected by the admission control.The solution is to prioritise the streaming users both in the scheduling algorithm and in the admission control, i.e. when the system is nearly full new web users are rejected. By doing so the results are significantly improved.</p>

<p>The increasing use of data services and the importance of IP basedservices in third generation mobile communication system (3G), requires the transmission from the cell phone to the base station, i.e. uplink, to manage high speed data rates. In the air interface for 3G in Europe, WCDMA, a concept for enhancing the transmission from the cell phone to the base station, called Enhanced Uplink, is being standardized. The overall goal is to provide high speed data access for the uplink. One of the requirements is that the enhanced uplink channels must be able to coexist with already existing WCDMA releases. For example, the enhanced uplink must not impact seriously on real time services, such as speech, carried on current WCDMA channels.</p><p>The purpose of this work is to study how the quality, coverage and capacity of real time services carried on previous WCDMA releases is affected when introducing the Enhanced Uplink in a WCDMA network. The main focus of the study is thus to demonstrate the trade-off between voice and best effort performances.</p><p>Theoretical assessments and simulations show that the Enhanced Uplink has many advantages over previous WCDMA releases. For example the Enhanced Uplink yields a larger system throughput for all voice loads. The noise rise, i.e. the ratio of total received power to the background noise power is being considered as the resource. It is shown that user traffic carried on the Enhanced Uplink is able to operate under a higher noise rise level as well as to get a higher throughput per noise rise. The resource is hence more efficiently utilized.</p>

<p>The demand for wireless communications is increasing every year, but the available resources are not increasing at the same rate. It is very important that the radio resources are used in an efficient way allowing the networks to support as many users as possible. The three types of networks studied in this thesis are frequency hopping GSM networks, ad hoc multi-hop networks and WCDMA networks.</p><p>One type of network with a promising future is ad hoc multi-hop networks. The users in this kind of networks communicate with each other without base stations. Instead the signal can be sent directly between two users, or relayed over one or several other users before the final destination is reached. Resources are shared by letting the users transmit in time slots. The problem studied is to minimize the number of time slots used, when the users broadcast. Two different optimization models are developed for assigning time slots to the users. A reduction of the number of time slots means a shorter delay for a user to transmit next time.</p><p>The rapid growth of the number of subscribers in cellular networks requires efficient cell planning methods. The trend of smaller cell sizes in urban areas for higher capacity raise the need for more efficient spectrum usage. Since the infrastructure of a second generation cellular system, such as GSM, already exists, and the available bandwidth of an operator is limited, frequency planning methods are of utmost importance. Because of the limited bandwidth in a GSM network, the frequencies must be reused. When planning a GSM network the frequencies can not be reused too tightly due to interference. The frequency planning problem in a GSM network is a very complex task. In this thesis an optimization model for frequency assignment in a frequency hopping GSM network is developed. The problem is to assign frequencies to the cells in the network, while keeping the interference to a minimum. Different meta heuristic methods such as tabu search and simulated annealing are used to solve the problem. The results show that the interference levels can be reduced to allow a capacity increase.</p><p>The demand for sending more information over the wireless communication systems requires more bandwidth. Voice communication was handled well by the second generation cellular systems. The third generation of mobile telecommunication systems will handle data transmissions in a greater extent. The last type of network considered in the thesis is a WCDMA cellular network. The aim is to schedule the transmission of packet data from the base station to the users. Scheduling models that maximize the utility are developed for both the downlink shared channel and the high speed downlink shared channel.</p>

This thesis addresses handoff issues in a WCDMA system with space-time block coded transmit antenna diversity. Soft handoff has traditionally been used in CDMA systems because of its ability to provide an improved link performance due to the inherent macro diversity. Next generation systems will incorporate transmit diversity schemes employing several transmit antennas at the base station. These schemes have been shown to improve downlink transmission performance especially capacity and quality. This research investigates the possibility that the diversity obtained through soft handoff can be compensated for by the diversity obtained in a transmit diversity system with hard handoff. We analyze the system for two performance measures, namely, the probability of bit error and the outage probability, in order to determine whether the improvement in link performance, as a result of transmit diversity in a system with hard handoffs obviates the need for soft handoffs.

The demand for wireless communications is increasing every year, but the available resources are not increasing at the same rate. It is very important that the radio resources are used in an efficient way allowing the networks to support as many users as possible. The three types of networks studied in this thesis are frequency hopping GSM networks, ad hoc multi-hop networks and WCDMA networks. One type of network with a promising future is ad hoc multi-hop networks. The users in this kind of networks communicate with each other without base stations. Instead the signal can be sent directly between two users, or relayed over one or several other users before the final destination is reached. Resources are shared by letting the users transmit in time slots. The problem studied is to minimize the number of time slots used, when the users broadcast. Two different optimization models are developed for assigning time slots to the users. A reduction of the number of time slots means a shorter delay for a user to transmit next time. The rapid growth of the number of subscribers in cellular networks requires efficient cell planning methods. The trend of smaller cell sizes in urban areas for higher capacity raise the need for more efficient spectrum usage. Since the infrastructure of a second generation cellular system, such as GSM, already exists, and the available bandwidth of an operator is limited, frequency planning methods are of utmost importance. Because of the limited bandwidth in a GSM network, the frequencies must be reused. When planning a GSM network the frequencies can not be reused too tightly due to interference. The frequency planning problem in a GSM network is a very complex task. In this thesis an optimization model for frequency assignment in a frequency hopping GSM network is developed. The problem is to assign frequencies to the cells in the network, while keeping the interference to a minimum. Different meta heuristic methods such as tabu search and simulated annealing are used to solve the problem. The results show that the interference levels can be reduced to allow a capacity increase. The demand for sending more information over the wireless communication systems requires more bandwidth. Voice communication was handled well by the second generation cellular systems. The third generation of mobile telecommunication systems will handle data transmissions in a greater extent. The last type of network considered in the thesis is a WCDMA cellular network. The aim is to schedule the transmission of packet data from the base station to the users. Scheduling models that maximize the utility are developed for both the downlink shared channel and the high speed downlink shared channel.

The increasing use of data services and the importance of IP basedservices in third generation mobile communication system (3G), requires the transmission from the cell phone to the base station, i.e. uplink, to manage high speed data rates. In the air interface for 3G in Europe, WCDMA, a concept for enhancing the transmission from the cell phone to the base station, called Enhanced Uplink, is being standardized. The overall goal is to provide high speed data access for the uplink. One of the requirements is that the enhanced uplink channels must be able to coexist with already existing WCDMA releases. For example, the enhanced uplink must not impact seriously on real time services, such as speech, carried on current WCDMA channels. The purpose of this work is to study how the quality, coverage and capacity of real time services carried on previous WCDMA releases is affected when introducing the Enhanced Uplink in a WCDMA network. The main focus of the study is thus to demonstrate the trade-off between voice and best effort performances. Theoretical assessments and simulations show that the Enhanced Uplink has many advantages over previous WCDMA releases. For example the Enhanced Uplink yields a larger system throughput for all voice loads. The noise rise, i.e. the ratio of total received power to the background noise power is being considered as the resource. It is shown that user traffic carried on the Enhanced Uplink is able to operate under a higher noise rise level as well as to get a higher throughput per noise rise. The resource is hence more efficiently utilized.

This thesis studies the Message Queue Telemetry Transport protocol (MQTT) as an application layer protocol in geographical location sharing applications using third generation cellular communication (3G). The MQTT protocol is compared in terms of energy efficiency and amount of data generated with the Hypertext Transfer Protocol (HTTP), which is currently used in typical location sharing applications. In order to compare the communication energy efficiency of both protocols a location sharing application prototype was developed for the Android platform. The application allows the use of HTTP and MQTT and was used to perform a number of experiments. The evaluation experiments show that MQTT is a good candidate as a protocol for location sharing. At comparable bandwidth and energy expenses MQTT offers better quality of user experience, since the subscribers are notified at once when the location of clients of interest has changed. The MQTT protocol is more energy-efficient than the HTTP protocol when the number of other uses with whom the client shares location is low and the location updates are frequent. The experiments also indicate that MQTT protocol is more energy-efficient than HTTP protocol in idle state, when there are no location information updates due to inactivity of all the clients, for example, if they are stationary. This is because MQTT client does not spend energy to poll the server for information updates.

Power control is one of the technologies used to utilize the radio resources as efficient as possible in WCDMA. The transmission power is adjusted to transmit with the lowest power level possible while the required received signal quality is maintained. Since there are large variation in channel quality over time, the power has to be adjusted to compensate for these variations. During moments of bad channel conditions a high transmission power has to be used which will to a greater extent interfere with other users in the system. To solve this problem a concept called transmission timing was proposed. The basic idea is that the transmitter avoids data transmission during the short periods of bad channel conditions caused by fast fading. Higher bit rates can be used to compensate for this when the channel conditions are good. In this thesis the performance of transmission timing applied to uplink data transmissions is evaluated. This is accomplished through a theoretical analysis as well as simulations of a cellular system using transmission timing. Lowered transmission power is achieved and thus lowered interference is induced. Simulations showed that the transmission power can be lowered by up to 1.6 dB compared to ordinary continuous transmission with equal average data rate. These results are however strongly dependent on the used radio environment. It is also showed that transmission timing provides increased system stability in case of rapid changes in the load situation.

The third generation, 3G, mobile telephone systems are designed for multimedia communication and will offer us similar services as in our stationary computers. This will involve large traffic loads, especially in the downlink direction, i.e. from base station to terminal. To improve the downlink capacity for packet data services a new concept is included in evolved 3G networks. The concept is called High Speed Data Packet Access, HSDPA, and provides peak bit rates of 14 Mbps. HSDPA uses a so-called best effort channel, i.e. it is developed for services that do not require guaranteed bit rates. The channel is divided in time between the users and a scheduling algorithm is used to allocate the channel among them. Streaming is a common technology for video transmission over the Internet and with 3G it is supposed to become popular also in our mobiles. Streaming generates lots of data traffic in the downlink direction and it would thus be satisfying to make use of the high bit rates HSDPA provides. The problem is that streaming requires reasonable stable bit rates, which is not guaranteed using HSDPA. The aim of this study is to modify the scheduling algorithms to prioritise streaming over web users and provide streaming Quality of Service, QoS. QoS is the ability to guarantee certain transmission characteristics. The results of the study show that it is hard to improve the streaming capacity by modifications of the scheduling. Of course, a consequence is that the web user throughput is decreased and to avoid this, new users have to be rejected by the admission control.The solution is to prioritise the streaming users both in the scheduling algorithm and in the admission control, i.e. when the system is nearly full new web users are rejected. By doing so the results are significantly improved.

In the standardized air interface for third generation mobile communication systems, WCDMA release 5, a concept called High Speed Downlink Packet Access (HSDPA) is introduced. HSDPA enables faster transmissions from base stations to mobile users by using a shared, high-capacity channel called the High-Speed Downlink Shared Channel (HS-DSCH) that is designed for best effort services. The HS-DSCH is developed for usage in the frequency band licensed for third generation communication systems. As the use of licensed frequency bands is costly it may be interesting to make use of the unlicensed frequency bands at 2.4 GHz and 5 GHz with higher interference and stricter regulations. Using HS- DSCH in unlicensed frequency bands would lead to smaller costs and a new kind of usage of the HS-DSCH. In order to transmit in unlicensed frequency bands, some requirements set up by the public authorities must be followed. This means that the maximum transmit power used by the HS-DSCH must be decreased and, on the 5 GHz frequency band, that features to avoid disturbing radar systems have to be implemented. The HS- DSCH has a bandwidth of 5 MHz. To use the available frequency spectra more efficiently, multiple carriers could be used. Wireless Local Area Networks (WLANs) are the most common way to transfer data in unlicensed frequency bands today. Assessments and simulations of WLAN and the HS-DSCH in unlicensed frequency bands show that WLAN can provide higher bitrates than the HS-DSCH for low loads. HS-DSCH can however provide a larger coverage per base station, and is more bandwidth effective than WLAN. Using a larger bandwidth is necessary for HS-DSCH to compete with WLAN, which uses a bandwidth approximately four times as large as the HS-DSCH bandwidth. The usage of the HS-DSCH in unlicensed frequency bands also has the advantage that the services provided by the third generation communication systems can be accessed easily.