Franco Mazzenga

On the coexistence of power-controlled ultrawide-band systems with UMTS, GPS, DCS1800, and fixed wireless systems

Ultrawide bandwidth (UWB) wireless technology will play a key role in short-range wireless connectivity supporting very high bit rates availability, low power consumption, and location capabilities. UWB can be conveniently deployed in the design of wireless local and personal area networks, providing advanced integrated multimedia services to nomadic users within hot-spot areas. The very large bandwidth required by the UWB signals cannot be exclusively allocated; thus, UWB band overlaps with the bands allocated to many other narrow-band systems. Therefore, the assessment of the interference caused by UWB devices on already-existing systems is of primary importance to ensure coexistence and, therefore, to guarantee acceptance of UWB technology worldwide. We study the coexistence issues between an UWB-based system and universal mobile telecommunication systems, global positioning systems, DCS1800, and fixed wireless access systems and point-to-point (PP) links terminals. UWB interference is evaluated accounting for the UWB signal model, a realistic UWB master/slave system architecture with power-controlled terminals. Furthermore, we analyze the dependence of the UWB interference from the UWB signal parameters and demonstrate through computer simulation that, in all practical cases, a UWB system can coexist with the selected victim terminals without causing any dangerous interference.

Exponential effective SINR approximations for OFDM/OFDMA-based cellular system planning

Classical single carrier cell planning is extended to multi-carrier systems operating over frequency selective channels. Extension is achieved by expressing the link outage probability in terms of the statistics of the effective SINR. Two approximations for the link outage probability are obtained by considering log-normal and Gaussian assumptions for the derivation of the statistics of the exponential effective SINR. A simplified planning procedure is presented and applied to the calculation of the network parameters for the typical two cells interference scenario. Results having accuracy within one dB are obtained for a number of sub-carriers greater than six and for an outage target of 5%.

Performance Evaluation of Detect and Avoid Procedures for Improving UWB Coexistence with UMTS and WiMAX systems

Detect and avoid procedures (DAA) aim at improving ultra-wideband (UWB) coexistence with existing narrowband-wideband systems operating at the same time and in the same area. We assess the interference caused by UWB devices implementing DAA on UMTS, as well as on WiMAX systems, by estimating the time percentage where UWBs interferer with these systems. Both UMTS and WiMAX are supposed to provide primary services with respect to UWB. As a consequence, UWB is not allowed to influence their operations, i.e. no cooperation is assumed between UWB and UMTS, WiMAX devices. In this paper we present and discuss the performances of two DAA techniques, analyzing their dependence on some key UWB transmission parameters, such as the bit rate and emitted power. The proposed DAA procedures are simple to be implemented and their parameters can be selected so to arbitrarily reduce the average percentage of time the UWB interferes with the two considered victim systems

Algorithms for dynamic frequency selection for femto-cells of different operators

The self-installation nature of femtocells sharing the same frequency band can lead to harmful femto-to-femto interference levels. The possibility for operators to share its licensed spectrum allows femtocells of one operator to exploit the frequency resources of other operators. In this paper we propose and analyze the performance of two dynamic frequency selection algorithms that permit to the generic femtocell the smart selection of its operating band, among those available from every operator, starting from the measurements of local interference. The performance of the proposed techniques are analyzed by simulation in terms of outage probability and the achievable Signal-to-Interference Ratio (SIR). It is observed that, in a multi-operator scenario this approach offers significant improvement in terms of achievable network capacity and quality of service to customers.

Fractional Frequency Reuse Planning for WiMAX over Frequency Selective Channels

Fourth generation broadband wireless access systems based on OFDMA/OFDM techniques operate in point-to-multipoint (PMP) configuration so that conventional cellular planning methods can be used for network design. As an alternative planning method fractional frequency reuse (FFR) strategy has been recently proposed for OFDMA/OFDM cellular systems such as WiMAX. For what concerns the determination of the system outage prediction, planning procedures for multi-carrier systems are usually based on bit error rate curves as a function of the average signal-to-interference plus noise ratio (SINR). Such curves are obtained after simulating the entire transmitter-receiver chain including multipath channel. However these approaches do not explicitly evidence the role of the number of M sub-carriers allocated to each user and are computationally intensive. In order to avoid such inconveniences we express the outage probability as a function of the effective SINR which is a function of the M SINRs (one for each sub-carrier). Such function already includes the decoding effects thus avoiding the re-simulation of the decoder behavior. Furthermore, this approach allows to explicitly evidence the role on planning of the number of sub- carriers allocated for one user. For evaluation purposes we apply the procedure in a simple two cell FFR interference scenario. It is shown that the number of sub-carriers can play a significant role in the entire planning process i.e. the reuse distance can be lowered at the expense of an increased number of sub-carriers to be allocated per block.

Evaluation of packet loss probability in Bluetooth networks

We provide a closed-form expression for the packet loss probability in Bluetooth networks accounting for capture effects due to propagation losses. The effectiveness of the proposed approach is assessed comparing the analytical results with those obtained from Monte Carlo simulations. By considering different scenarios, we show the dependence of results on the geometry and on the characteristics of the environment. It is observed that packet loss probability can significantly change with the position of the reference receiver in the area, as well as with the extension of the served area as compared with the coverage area of the receiver.

Adaptive cell sectorization for UMTS third generation CDMA systems

Cell sectorization is commonly used to increase system capacity in cellular systems and is easily implemented. We propose a technique to improve system capacity based on adaptive sectorization. Sectors are rotated and/or resized adaptively in order to equalize the uplink C/I or the total downlink transmitted power in each sector The performance of the proposed procedure is analyzed for both uplink and downlink transmissions. Noticeable performance improvements are obtained when traffic is not uniformly distributed both spatially and in terms of data rate.

Blind least-squares estimation of carrier phase, Doppler shift, and Doppler rate for m-PSK burst transmission

A novel blind algorithm is proposed for joint carrier phase/Doppler shift least-squares (LS) estimation for burst transmission of m-PSK modulated data. The algorithm can be extended to include Doppler rate estimation. The performance of the algorithm is contrasted against that of known algorithms, and it is shown to be advantageous particularly for short bursts and large frequency offsets. The signal-to-noise ratio penalty with respect to the ideal estimation case is shown to be below 1 dB for a frequency error as large as 0.1 of the symbol rate and bursts as short as 20 symbols.

Consumed power analysis for mobile radio system dimensioning

Cellular mobile radio networks are expected to increase the energy requirements due to their massive deployment. Then, it is required to improve their energy efficiency in order to favor the eco-sustainability and not to obstacle their economic impact. In this paper we study the impact of the power consumption in the design of mobile networks. The evaluation has been performed for GSM and LTE systems. The main aim is the analytical evaluation of the optimal cell radius accounting for the network sustainability and for both coverage and traffic constraints. Overall power consumption is expressed as the sum of static and dynamic terms. The former is due to BSs switch on and signaling, the latter is function of the traffic in the cell. The beneficial effects of power control on energy consumption are evaluated and compared with the non-power controlled case. Finally, reduction in power consumption for LTE respect to GSM is analyzed.

On the UWB coexistence with UMTS terminals

Ultra wide bandwidth (UWB) spread-spectrum techniques will play a key role in short range wireless connectivity providing high bit rates, low power consumption and location capabilities. UWB can be used in the design of advanced wireless local and personal area networks providing integrated multimedia services to nomadic users within hot-spot areas. Due to the very large UWB signal bandwidth, the assessment of the possible interference caused by UWB devices on already existing narrowband systems is important to ensure not conflicting coexistence and, therefore, to guarantee acceptance of UWB technology worldwide. This paper investigates on the coexistence between an UWB-based system and WCDMA-UMTS terminals. UWB interference on the UMTS terminal is evaluated accounting for the UWB signals characteristics and the UWB network architecture. The dependence of the interference from the UWB signal parameters is analyzed through computer simulation and demonstrates that, in all practical cases, UWB system can coexist with UMTS terminals without causing any dangerous interference.