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Milanovic J.,Croatian Post and Electronic Communication Agency
Elektronika ir Elektrotechnika | Year: 2014

In this paper, a coded M-ary pulse position modulation (PPM) scheme for transmitted reference ultrawideband (TR-UWB) systems is proposed. In conventional Mary PPM TR-UWB scheme, modulation level M is defined only with a number of possible pulse positions Z. So, Z radio frequency (RF) wideband delay lines are required in order to map data bits into the proper pulse position, which makes such system very impractical to implement when the current CMOS technology is used. In the proposed scheme the number of required delay lines is reduced by mapping data bits in both, pulse position and K different orthogonal codes on frame level of the signal, producing a modulation level of M = KZ. To evaluate the performances of the proposed coded M-ary PPM scheme, the analytical model for realistic IEEE standard UWB channel models is developed. The performances of the proposed scheme are compared with these of the conventional M-ary PPM scheme for the same modulation level M. The results show that the proposed coded M-ary PPM scheme achieves approximately the same bit error probability (BEP), higher data rate and higher bandwidth efficiency, while the hardware complexity is lower in terms of number of required RF delay lines. However, by increasing the number of used orthogonal codes the minimum number of frames per one information symbol rises and consequently the maximum achievable data rate is limited. Thus the trade-off between the number of orthogonal codes and target data rate should be made.

Milanovic J.,Croatian Post and Electronic Communication Agency | Herceg M.,Josip Juraj Strossmayer University of Osijek | Vranjes M.,Josip Juraj Strossmayer University of Osijek | Job J.,Josip Juraj Strossmayer University of Osijek
Wireless Personal Communications | Year: 2015

One of the main drawbacks of conventional transmitted reference (TR) ultra-wideband systems is the fact that time delay between the reference and the data pulse has to be at least equal to channel delay spread, in order to avoid inter-pulse interference (IPI). This requirement drastically limits the achievable data rate of conventional TR systems based on M-ary pulse position modulation (PPM). In this paper, the new method for M-ary TR PPM scheme bandwidth efficiency increasing is proposed. In the proposed method the orthogonal codes are used such that only the pulses which can cause IPI are coded. Usage of such type of coding allows the reduction of time delay between the reference and the data pulse, whereas IPI is avoided. The proposed method achieves higher bandwidth efficiency than the conventional TR PPM method for the similar BEP performance level. Furthermore, the results show that an additional increase in bandwidth efficiency can be achieved by using higher modulation levels. Additionally, the analysis on tradeoffs between the BEP performance, bandwidth reduction and system costs is given in this paper. © 2015, Springer Science+Business Media New York.

Milanovic J.,Croatian Post and Electronic Communication Agency | Rimac-Drlje S.,Josip Juraj Strossmayer University of Osijek | Majerski I.,Croatian Post and Electronic Communication Agency
Tehnicki Vjesnik | Year: 2010

This paper provides a survey of the basic mechanisms which influence the propagation of electromagnetic waves at most. It also deals with features of empirical models often used in a process of fixed wireless access network planning and implementation. Four empirical models, SUI, COST 231-Hata, Macro and Ericsson, which are most suitable for path loss prediction for such a system, are presented. By using these propagation models the receiving signal levels are predicted for different types of environment for aWiMAX (Worldwide Interoperability for Microwave Access) system installed in the city Osijek, Croatia. Measurement results of receivingWiMAXpower at 3,5GHzare also presented and compared with the results predicted by using the propagation models.

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