Adaptive and cognitive radios (CR) have been becoming popular for optimizing mobile radio system transmission and reception One of the most important elements of the adaptive radio and CR concepts is the ability to measure, sense, learn about, and be aware of parameters related to the radio channel characteristics, availability of spectrum and power, interference and noise temperature, operational environment of radio, user requirements and applications, available networks and infrastructures, local policies, other operating restrictions, and so on This paper discusses some of the important measurement parameters for enabling adaptive radio and CR systems along with their relationships and impacts on the performance including relevant challenges

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Real-time measurements for adaptive and cognitive radio systems

The cochannel interference for a code division multiple access (CDMA) wireless communication network is considered and analyzed. A new CDMA cellular network architecture has been proposed. An analytic expression for the proposed method is derived. Simulation results show that the proposed method provides better signal-to-noise (S/N) ratio than the existing cochannel interference reduction methods. In the proposed microzoning architecture, a significant reduction of cochannel interference is achieved compared to sectoring and omni-directional architectures.

https://ieeexplore.ieee.org/iel5/9541/30232/01389187.pdf

Reduction of cochannel interference on the forward link CDMA systems

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Environment, channel, and interference awareness for next generation wireless networks

Technical Communication: Reduction of cochannel interference in WCDMA cellular systems

In this thesis, we derive analytical expressions for the interference and estimate the capacity of a CDMA based wireless system for indoor mobiles in 6 groups of high riser buildings occupying 6 building blocks of a typical high density downtown city environment. The analysis compares the performances of a single element panel antenna, a 1-dimensional linear array, and a 3-dimensional vertical planar array. We further consider an appropriate 3-dimensional urban model representative for such an environment, and based upon this model, a more accurate 3-dimensional user distribution is introduced. Our work has shown that, for such an environment, the traditional assumption of uniform user distribution is not valid. It is found that by arranging smart antenna elements in specific 2and 3-dimensional geometries, reduction of sidelobes and significant improvements in the directivity can be achieved with the same number of elements traditionally used in a 1-dimensional linear array. For a more accurate analysis, short dipoles and panel antenna elements are used instead of isotropic point sources. Surface plots for the interference and capacity from the 6 building groups for different vertical and azimuth angles are produced. The capacity with the use of a 3-dimensional smart antenna and the improvement over a linear array are then compared, taken into account of different building materials' and dimensional effects. These performance evaluation results have shown that, as compared to the 1-dimentional linear array employing the same number of antennas, significant capacity improvements are achievable.

Capacity and interference analysis of multicell CDMA systems using 3-dimensional smart antennas

Wideband code-division multiple access (CDMA) systems are interference-limited, and so must utilize some form of interference reduction in order to maintain an acceptable quality of service and capacity. In this paper, co-channel interference for several different CDMA architectures is evaluated. For wideband CDMA systems such as W-CDMA and cdma2000 with carrier stealing, co-channel interference is significantly reduced by the implementation of either microzoning or sectoring. The disadvantage of microzoning is that intra-cell interference is no longer ideally zero on the forward channel, as it is with sectoring and omnidirectional architectures. For wideband CDMA systems such as cdma2000 without carrier stealing, co-channel interference is reduced by both microzoning and sectoring architectures even more than in the case of W-CDMA and cdma2000 with carrier stealing. In this case, since forward channel intra-cell interference remains ideally zero, the significant reduction of co-channel interference by microzoning makes microzoning clearly superior to omnidirectional architectures.

/pdf/co-channel-interference-reduction-on-the-forward-channel-of-nr5d7ok2lw.pdf

Co-channel interference reduction on the forward channel of a wideband CDMA cellular system

One of the major design, considerations in a cellular mobile radio system is the reduction of co-channel interference. A technique known as microzoning can reduce interference while maintaining system capacity and quality of service. Based on the worst-case mobile location at the edge of a microzone, narrowband, frequency-division multiple access cellular systems require seven-cell per cluster architectures in order to maintain a signal-to-noise ratio of 18 dB. This is contrary to the conclusion drawn from previously published work: that three-cell per cluster systems are sufficient. A three-cell per cluster architecture can maintain a signal-to-noise ratio of 15 dB.

/pdf/forward-channel-signal-to-noise-ratio-with-microzoning-for-4he0ezx38h.pdf

T. Mayer

Papers

Co-channel interference reduction on the forward channel of a wideband CDMA cellular system

Forward channel signal-to-noise ratio with microzoning for narrowband, FDMA cellular systems