The advent of new wireless technologies in recent years has created a tremendous increase in the demand for wireless connectivity. The estimated number of mobile device connections exceeds eight billion globally, more than the population of the world, and the growth trend is rapidly increasing as the developing world penetration rate is still in its infancy. With the Internet-of-Things (IoT), it is expected that the total number of connections will reach over fifty billion in the next few years. In conjunction with wireless connectivity technology, the need for location awareness is paramount.

This two-part special issue covers relevant aspects of network localization and navigation: theoretical foundations, localization technologies, positioning algorithms, and network operation.

Reliable and accurate position information is of great importance for many mass-market and emerging applications. Network localization and navigation (NLN) is a promising paradigm to provide such information ubiquitously, where a network of nodes is used to aid in localizing its members. This paper explores various network operation strategies, which play an essential role in NLN as they determine the network lifetime and localization accuracy. Efficient network operation requires several functionalities, including node prioritization, node activation, and node deployment. The roles of these functionalities are described and different techniques for implementing respective functionalities via algorithmic modules are introduced. Some important concepts such as cooperative operation, robustness guarantee, and distributed design in the development of the network operation strategies are also introduced. Finally, numerical results are provided to demonstrate the localization performance improvement attributed to the optimized network operation strategies.

The focus of this paper is to derive the symbol error probability (SEP) of a Rake receiver with a limited number of fingers that track the strongest multipath components in a frequency-selective Rayleigh fading channel. We develop an analytical framework that allows the computation of the SEP for nonuniform power dispersion profiles (PDPs) and spreading bandwidth. By transforming the physical Rake receiver with correlated ordered paths into the domain of a 'virtual Rake" receiver with conditionally independent virtual paths, analytical expressions for the SEP are derived in terms of the spreading bandwidth, the channel profile, and the number of combined paths. We show how our analytical results can be used to predict the performance of various Rake architectures in environments with nonuniform PDPs using for example, the channel models defined for the next generation wireless standards. Furthermore, we validate our methodology by comparison to data obtained from channel measurements, showing good agreement with our analytically derived results.

We use a virtual-branch technique to derive higher order statistics of the output signal-to-noise ratio (SNR) of antenna subset diversity in a multipath fading environment. In particular, closed-form expressions of the cumulants, central moments, skewness, and kurtosis for various antenna subset diversity schemes are derived. These measures characterize the statistical behavior of the output SNR distribution.

We develop an analytical framework to quantify the effects of the spreading bandwidth on spread spectrum systems operating in multipath environments with arbitrary power delay profile. The focus of the paper is to characterize the symbol error probability (SEP) performance of a RAKE receiver tracking the L strongest multipath components in frequency-selective Rayleigh fading. By transforming the physical RAKE receiver with correlated ordered paths into the domain of a "virtual RAKE" receiver with conditionally independent virtual paths, analytical expressions for the SEP are derived in terms of the spreading bandwidth, multipath spread of the channel and the number of combined paths.

We use a virtual branch technique to derive higher order statistics of the output signal-to-noise ratio (SNR) of hybrid selection/maximal-ratio combining (H-S/MRC) in a multipath fading environment. In particular, the cumulants, central moments, skewness and kurtosis are derived. We consider the case of independent Rayleigh fading with equal receive SNR averaged over the fading on each diversity branch.

We develop an analytical framework to quantify the effects of the spreading bandwidth (BW) on spread spectrum systems operating in dense multipath environments in terms of the receiver performance, the receiver complexity, and the multipath channel parameters. The focus of the paper is to characterize the symbol error probability (SEP) performance of a RAKE receiver tracking the L strongest multipath components in wide-sense stationary uncorrelated scattering (WSSUS) Gaussian channels with frequency-selective fading. Analytical SEP expressions of the RAKE receiver are derived in terms of the number of combined paths, the spreading BW and the multipath spread of the channel. The proposed problem is made analytically tractable by transforming the physical RAKE paths, which are correlated and ordered, into the domain of a "virtual RAKE" receiver with independent virtual paths. This results in a simple derivation of the SEP for a given spreading BW and an arbitrary number of combined paths.

We develop an analytical framework to quantify the effects of the spreading bandwidth on spread spectrum systems operating in dense multipath environments. The focus of the paper is to characterize the symbol error probability (SEP) performance of a RAKE receiver tracking the L strongest multipath components in frequency-selective fading. By transforming the physical RAKE receiver with correlated ordered paths into the domain of a "virtual RAKE" receiver with independent virtual paths, analytical expressions for the SEP are derived in terms of the spreading bandwidth, multipath spread of the channel and the number of combined paths.

Hybrid selection/maximal-ratio combining (H-S/MRC) is a reduced-complexity diversity combining scheme, where L out of N diversity branches (with the largest signal-to-noise ratio (SNR) at each instant) are selected and combined using maximal-ratio combining (MRC). We derive closed-form expressions for the symbol error probability (SEP) of a H-S/MRC diversity system with arbitrary L and N. We consider coherent detection of M-ary phase-shift keying (MPSK) for the case of independent Rayleigh fading with equal SNR averaged over the fading.

This paper derives the symbol error probability of a 16-QAM modulation scheme that undergoes nonlinear distortion as a result of power amplification. The performance degradation is computed when the receiver does not compensate for the amplitude saturation effects and a relatively simple method that does not resort to complex processing and equalization is proposed and analyzed to compensate for the nonlinear distortion. The exact symbol error probability is derived analytically and it is shown that the compensated system is a viable technique for non-constant envelope higher order modulation schemes.