Proceedings of 1995 IEEE International Symposium on Information Theory, 2000
Constructions for families of cyclic constant weight codes are presented to be used in fiber opti... more Constructions for families of cyclic constant weight codes are presented to be used in fiber optic CDMA networks for multirate transmission. It is shown that the code families discussed satisfy the requirements for successful transmission of different data rates using the CDMA technique
Proceedings of 6th International Symposium on Personal, Indoor and Mobile Radio Communications, 1995
We address the problem of efficiently using the resources in the digital European cordless teleph... more We address the problem of efficiently using the resources in the digital European cordless telephone (DECT) system in multi-rate situations. We consider two type of users: high rate data traffic which needs more that one time slot per time frame and low rate voice traffic needing one time slot per time frame. The physical layer of the DECT system is
IEEE Second International Symposium on Spread Spectrum Techniques and Applications, 1992
In this paper we discuss the influence of vehicular traffic, in particular trucks and busses, on ... more In this paper we discuss the influence of vehicular traffic, in particular trucks and busses, on hand-held terminals in a microcell CDMA system. General differences between vehicle and pedestrian traffic are outlined and it is shown that although the pedestrians do not cross cell boundaries as often as vehicles, handoffs are necessary in order to compensate for the loss in signal strength caused by the presence of trucks in the traffic. Cell planning issues for the microcell environment are reviewed. Interference to the hand-held terminals both by parked and passing trucks is obtained by measuring the signal strength at the receiver. The measurements are compared with measurements performed when the line-of sight (LOS) is lost due to turning around a street comer. Differences in the measurements are examined in order to determine handoff necessity and suggest possible handoff algorithms. It is shown that any hand-held handoff algorithm must take into consideration the possible causes of the signal strength loss in order to prevent unnecessary handofs.
1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333), 1998
ABSTRACT We investigate the capacity of an OOK FH CDMA channel. We assume random FH codes and tha... more ABSTRACT We investigate the capacity of an OOK FH CDMA channel. We assume random FH codes and that the i-th receiver is only interested in the message transmitted by the i-th transmitter. The degradation of the AWGN and non-selective Rayleigh fading environments on the FH system are also investigated. We then give an algebraic construction of a new family of FH codes. The construction is based on the property of cyclic groups in finite fields; it is shown that for each field GF(pm) there exists a large number of codes of length pm. The codes are also shown to possess the best possible two-dimensional auto- and cross-correlation properties
The problem of constructing frequency hopping patterns for use in time division multiple access-f... more The problem of constructing frequency hopping patterns for use in time division multiple access-frequency division multiple access (TDMA-FDMA) cellular systems that employ frequency diversity to minimize bursty errors occurring due to the fading channel is discussed. Conditions under which two frequency and time channels fade independently in a mobile fading channel are reviewed. The construction of a family of effective
We address the possibility of applying a new type of a frequency hopping system in order to deliv... more We address the possibility of applying a new type of a frequency hopping system in order to deliver information from roadside beacons to passing vehicles. The system is based on being able to divide the FH addresses into two parts and use one of them as a group address and the other as individual address. Families of FH codes suitable for this application are given. The information class CDMA in the context of FH is also explained and some examples given
Proceedings of IEEE International Symposium on Information Theory, 1997
Costas (1984) and sonar sequences are those patterns for which you send out exactly one signal at... more Costas (1984) and sonar sequences are those patterns for which you send out exactly one signal at every time slot, and with the special property that even if only two signals return you can reconstruct the whole pattern. This last point means that there is no ambiguity. This is also referred in the literature as having perfect or one hit
ICC 91 International Conference on Communications Conference Record, 1991
... results presented by WC Kwong et al. [3]. * This work was supported in part by a grant from S... more ... results presented by WC Kwong et al. [3]. * This work was supported in part by a grant from SDIO/IST and managed by the Office of Naval Research under contract N00014-86-K-0511 The use of fiber optics communication media ...
International Conference on Acoustics, Speech, and Signal Processing, 1990
The cross-ambiguity properties of Costas-array frequency-hop coded signals for use in wideband mu... more The cross-ambiguity properties of Costas-array frequency-hop coded signals for use in wideband multiuser sonar systems are established. In order to prevent system crosstalk, cross-ambiguity function for the signals should be minimized. The conditions under which Costas arrays achieve the minimum value of their cross-ambiguity functions are provided. The upper bound on the maximum number of hits in the cross-ambiguity function
1st International Conference on Universal Personal Communications - ICUPC '92 Proceedings, 1992
The demand for cellular service will increase dramatically in the near future. One way of increas... more The demand for cellular service will increase dramatically in the near future. One way of increasing the cellular system capacity is by reducing the cell size. The authors discuss the problems associated with the new microcell environment. The propagation characteristics of the system are discussed and various types of microcell coverages introduced. In order to solve the cell planning problem,
IEEE International Symposium on Information Theory, 2003. Proceedings., 2003
ABSTRACT In this work we present an explicit construction of perfect difference sets divisible by... more ABSTRACT In this work we present an explicit construction of perfect difference sets divisible by four. In addition, we also consider distinct difference sets which are a generalization of perfect difference sets. Finally, we relax our constructions in order to obtain others which are not optimal but do not have any divisibility requirements.
The authors discuss the problem of designing a frequency hop-multilevel frequency shift keying (F... more The authors discuss the problem of designing a frequency hop-multilevel frequency shift keying (FH-MFSK) code division multiple access (CDMA) system for applications in mobile radio. The need for such system is explained, and a system is proposed. The system is shown have the capability of servicing an increased number of users in the same available frequency bandwidth with a higher spectral efficiency than previously proposed FH-MFSK systems. Families of frequency hop codes are reviewed, and it is shown that codes based on the number theoretic concept of linear congruences achieve the best performance in the system. The operation of the decoder at the receiver is explained, and the error probability calculated in both the synchronous and asynchronous case
Proceedings IEEE International Symposium on Information Theory,, 2002
ABSTRACT Costas sequences were introduced by John Costas in 1975, and a theory of Costas sequence... more ABSTRACT Costas sequences were introduced by John Costas in 1975, and a theory of Costas sequences was introduced by Golomb and Taylor in 1984. In this paper we similarly develop a theory of Costas sequences for multiple targets.
The frequency hopping code division multiple access (FH-CDMA) systems are discussed from the stan... more The frequency hopping code division multiple access (FH-CDMA) systems are discussed from the stand point of the Shannon and Fourier bandwidth. We show that using a new definition for spread spectrum (SS) signals forming a slow FH-CDMA system are indeed SS signals, however, fast FH-CDMA systems reveal an interesting fact-that a signal being an SS one actually depends on the receiver's knowledge of transmitters FH codes. The concept of the processing gain is connected with the new SS definition and also extended to TDMA systems
Proceedings of 1995 IEEE International Symposium on Information Theory, 2000
Constructions for families of cyclic constant weight codes are presented to be used in fiber opti... more Constructions for families of cyclic constant weight codes are presented to be used in fiber optic CDMA networks for multirate transmission. It is shown that the code families discussed satisfy the requirements for successful transmission of different data rates using the CDMA technique
Proceedings of 6th International Symposium on Personal, Indoor and Mobile Radio Communications, 1995
We address the problem of efficiently using the resources in the digital European cordless teleph... more We address the problem of efficiently using the resources in the digital European cordless telephone (DECT) system in multi-rate situations. We consider two type of users: high rate data traffic which needs more that one time slot per time frame and low rate voice traffic needing one time slot per time frame. The physical layer of the DECT system is
IEEE Second International Symposium on Spread Spectrum Techniques and Applications, 1992
In this paper we discuss the influence of vehicular traffic, in particular trucks and busses, on ... more In this paper we discuss the influence of vehicular traffic, in particular trucks and busses, on hand-held terminals in a microcell CDMA system. General differences between vehicle and pedestrian traffic are outlined and it is shown that although the pedestrians do not cross cell boundaries as often as vehicles, handoffs are necessary in order to compensate for the loss in signal strength caused by the presence of trucks in the traffic. Cell planning issues for the microcell environment are reviewed. Interference to the hand-held terminals both by parked and passing trucks is obtained by measuring the signal strength at the receiver. The measurements are compared with measurements performed when the line-of sight (LOS) is lost due to turning around a street comer. Differences in the measurements are examined in order to determine handoff necessity and suggest possible handoff algorithms. It is shown that any hand-held handoff algorithm must take into consideration the possible causes of the signal strength loss in order to prevent unnecessary handofs.
1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333), 1998
ABSTRACT We investigate the capacity of an OOK FH CDMA channel. We assume random FH codes and tha... more ABSTRACT We investigate the capacity of an OOK FH CDMA channel. We assume random FH codes and that the i-th receiver is only interested in the message transmitted by the i-th transmitter. The degradation of the AWGN and non-selective Rayleigh fading environments on the FH system are also investigated. We then give an algebraic construction of a new family of FH codes. The construction is based on the property of cyclic groups in finite fields; it is shown that for each field GF(pm) there exists a large number of codes of length pm. The codes are also shown to possess the best possible two-dimensional auto- and cross-correlation properties
The problem of constructing frequency hopping patterns for use in time division multiple access-f... more The problem of constructing frequency hopping patterns for use in time division multiple access-frequency division multiple access (TDMA-FDMA) cellular systems that employ frequency diversity to minimize bursty errors occurring due to the fading channel is discussed. Conditions under which two frequency and time channels fade independently in a mobile fading channel are reviewed. The construction of a family of effective
We address the possibility of applying a new type of a frequency hopping system in order to deliv... more We address the possibility of applying a new type of a frequency hopping system in order to deliver information from roadside beacons to passing vehicles. The system is based on being able to divide the FH addresses into two parts and use one of them as a group address and the other as individual address. Families of FH codes suitable for this application are given. The information class CDMA in the context of FH is also explained and some examples given
Proceedings of IEEE International Symposium on Information Theory, 1997
Costas (1984) and sonar sequences are those patterns for which you send out exactly one signal at... more Costas (1984) and sonar sequences are those patterns for which you send out exactly one signal at every time slot, and with the special property that even if only two signals return you can reconstruct the whole pattern. This last point means that there is no ambiguity. This is also referred in the literature as having perfect or one hit
ICC 91 International Conference on Communications Conference Record, 1991
... results presented by WC Kwong et al. [3]. * This work was supported in part by a grant from S... more ... results presented by WC Kwong et al. [3]. * This work was supported in part by a grant from SDIO/IST and managed by the Office of Naval Research under contract N00014-86-K-0511 The use of fiber optics communication media ...
International Conference on Acoustics, Speech, and Signal Processing, 1990
The cross-ambiguity properties of Costas-array frequency-hop coded signals for use in wideband mu... more The cross-ambiguity properties of Costas-array frequency-hop coded signals for use in wideband multiuser sonar systems are established. In order to prevent system crosstalk, cross-ambiguity function for the signals should be minimized. The conditions under which Costas arrays achieve the minimum value of their cross-ambiguity functions are provided. The upper bound on the maximum number of hits in the cross-ambiguity function
1st International Conference on Universal Personal Communications - ICUPC '92 Proceedings, 1992
The demand for cellular service will increase dramatically in the near future. One way of increas... more The demand for cellular service will increase dramatically in the near future. One way of increasing the cellular system capacity is by reducing the cell size. The authors discuss the problems associated with the new microcell environment. The propagation characteristics of the system are discussed and various types of microcell coverages introduced. In order to solve the cell planning problem,
IEEE International Symposium on Information Theory, 2003. Proceedings., 2003
ABSTRACT In this work we present an explicit construction of perfect difference sets divisible by... more ABSTRACT In this work we present an explicit construction of perfect difference sets divisible by four. In addition, we also consider distinct difference sets which are a generalization of perfect difference sets. Finally, we relax our constructions in order to obtain others which are not optimal but do not have any divisibility requirements.
The authors discuss the problem of designing a frequency hop-multilevel frequency shift keying (F... more The authors discuss the problem of designing a frequency hop-multilevel frequency shift keying (FH-MFSK) code division multiple access (CDMA) system for applications in mobile radio. The need for such system is explained, and a system is proposed. The system is shown have the capability of servicing an increased number of users in the same available frequency bandwidth with a higher spectral efficiency than previously proposed FH-MFSK systems. Families of frequency hop codes are reviewed, and it is shown that codes based on the number theoretic concept of linear congruences achieve the best performance in the system. The operation of the decoder at the receiver is explained, and the error probability calculated in both the synchronous and asynchronous case
Proceedings IEEE International Symposium on Information Theory,, 2002
ABSTRACT Costas sequences were introduced by John Costas in 1975, and a theory of Costas sequence... more ABSTRACT Costas sequences were introduced by John Costas in 1975, and a theory of Costas sequences was introduced by Golomb and Taylor in 1984. In this paper we similarly develop a theory of Costas sequences for multiple targets.
The frequency hopping code division multiple access (FH-CDMA) systems are discussed from the stan... more The frequency hopping code division multiple access (FH-CDMA) systems are discussed from the stand point of the Shannon and Fourier bandwidth. We show that using a new definition for spread spectrum (SS) signals forming a slow FH-CDMA system are indeed SS signals, however, fast FH-CDMA systems reveal an interesting fact-that a signal being an SS one actually depends on the receiver's knowledge of transmitters FH codes. The concept of the processing gain is connected with the new SS definition and also extended to TDMA systems
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Papers by Svetislav Maric