We construct a bio-inspired nanomachine network via the quorum sensing (QS) mechanism and analyze that nanonetwork from the perspective of global synchronization time and channel capacity. We propose a realistic (stochastic) approach using birth-death-process-based bacterial growth model and compare it to a conventional ideal (deterministic) approach using exponentially-increased bacterial growth model. For the comparative study, we first define a diffusion-based molecular communication channel between bacterial density and autoinducer (AI) concentration as an approximated Gaussian process, and then analyze the presented QS behavior model numerically as well as theoretically. Increases in the bacterial density augment the diffused AI concentration. When the AI concentration satisfies a specified threshold indicating gene expression, almost all bacteria in that colony represent a collective QS behavior such as biofilm formation. Compared to the ideal approach that is simple but not feasible in real life given the limited resources (e.g., food), the realistic approach is complex but better at representing real and probabilistic QS nature, less sensitive at gene expression, and so more suitable for global synchronization analysis. Via simulation, we evaluate the proposed model in terms of AI concentration versus bacterial density, synchronization time, and information sensing capacity, and demonstrate its superiority over the traditional model.

We present a multiple-input-multiple-output (MIMO) power line communication (PLC) system using coupled indoor differential mode ports, where 2 × 2 and 2 × 4 MIMO configurations are considered. In simulation, MIMO orthogonal frequency-division multiplexing (OFDM) PLC with the two OFDM symbol sequence reordering schemes, namely, Alamouti-scheme-based sequence reordering and circularly-shifted sequence reordering, is compared under the coupled channel conditions. For MIMO coding, we employ a maximum ratio combining scheme that is effective for both MIMO and single-input-single-output over indoor power line conditions. In simulation, we compare space-frequency coding (SFC), space-time coding (STC), and space-time-frequency coding (STFC) over statistical indoor power line channels, including fading, impulse noise, and crosstalk by coupling between ports. STFC and STC are more robust against crosstalk than SFC, and STFC, with some added complexity, outperforms the other coding schemes in terms of bit-error-rate performance. A least squares scheme for power line channel estimation is used, which is simple but has comparable performance to minimum mean square error. A decision-feedback-loop-based crosstalk cancellation scheme that effectively reduces the MIMO channel estimation error due to crosstalk is presented. Simulation results show that STFC is less sensitive to impulse noise than STC or SFC.

In this paper, we presents a MIMO-OFDM based indoor power line communication (PLC) using space-frequency-coding (SFC), space-time-coding (STC), and space-time-frequency-coding (STFC) via low-voltage (LV) indoor power lines. The proposed MIMO-OFDM system model is simulated at the practical PLC fading and impulse noise channels. The used MRC scheme effectively combines both multiple antenna diversity gain and multipath fading diversity gain over 1-phase 3-wire (2×2 MIMO) or 1-phase 2-wire (SISO) power line channels. We analyze and compare SFC, STC, and STFC, with or without crosstalk between antenna paths.

In this paper we present a slotted ALOHA based multi-channel cognitive radio network opportunistically using the unused spectrum of incumbent devices and analyze its throughput and delay. We also evaluate packet capture effect of our proposed system over Rayleigh fading.

We present a coded closed-loop power control scheme with power control command bit error protection for delay-prone burst transmission systems.

The authors present and analyse a predictive closed-loop power control (CLPC) scheme, which employs a comb-type sample arrangement to effectively compensate multiple power control group delays over mobile fading channels. The authors consider both least squares and recursive least squares filters in our CLPC scheme. The effects of channel estimation error, prediction filter error and power control bit transmission error on the performance of the proposed CLPC method along with competing non-predictive and predictive CLPC schemes are thoroughly investigated. The results clearly indicate the superiority of the proposed scheme with its improved robustness under non-ideal conditions. Furthermore, the authors carry out a Monte-Carlo simulation study of a 5×5 square grid cellular network and evaluate the user capacity. Capacity improvements up to 90% are observed for a typical cellular network scenario.

This paper investigates a least square (LS) based multi-step autoregressive prediction filter for the delay compensation over multiple input multiple output (MIMO) channels and presents a robust adaptive MIMO-OFDM system with the filter in mobile fading channels. Computer simulation verifies that data capacity of proposed MIMO- OFDM is 20% greater than that of conventional MIMO-OFDM.

We present the trellis-coded code-division multiple-access (TC-CDMA) system based on a multisequence signaling, called orthogonal plane sequence modulation (OPSM), in correlated Rayleigh fading channels and derive its pairwise error probability with different degrees of channel state information. Numerical results show that the OPSM-based TC-CDMA system outperforms conventional convolutionally coded CDMA or TC-CDMA systems.

Within the context of CDMA, in comparison to the standard single sequence signaling (L=1, L is the number of sequences per symbol), a multi-sequence based trellis-coded-modulation (TCM) (L/spl ges/2) - also called orthogonal plane sequence modulation (OPSM), exhibits both better cross-correlation properties and good distance profiles, especially for data rate R/sub b//spl ges/2 bits/s/Hz. In correlated Rayleigh fading channels, despite the time diversity reduction in TCM, the simulation results show that a trellis-coded CDMA (TC-CDMA) system based on OPSM outperforms standard convolutionally coded CDMA systems. Compared to TC-CDMA with parallel transitions, TC-CDMA without parallel transitions is superior due to its increased time diversity.

We introduce a novel signal set defined over a signal space that consists of L (L/spl ges/2) orthogonal planes, and a quasi-synchronous trellis-coded code-division multiple-access (TC-CDMA) system based on it. The proposed scheme makes efficient use of the available processing gain to improve power and/or bandwidth efficiency for practical multiuser interference environments. Having a multiplanar signal constellation structure, the proposed scheme provides several options for a given required data rate, which makes it better adapted to dynamic channel conditions. Analytical bounds and simulation results indicate that at practical error rates and 2 b/s/Hz the proposed scheme is approximately 1.2 dB better than a TC-CDMA system based on 8-PSK, and 3 dB better at 3 b/s/Hz compared to TC-CDMA using 16-QAM. Additionally, the proposed system is approximately 1 dB better than a multicoded system using two signature sequences per user.

We introduce a novel modulation signal set defined over a signal space that consists of L Euclidean signal planes, and the synchronous trellis-coded CDMA system based on it. Whereas conventional schemes utilize a limited number of orthogonal sequences due to delay and power control error, this scheme fully and efficiently utilizes the N orthogonal signature sequences (i.e. the processing gain N) such that power and/or bandwidth efficiency is improved. The proposed scheme could be highly adaptable to the dynamic channel conditions, because for a single data rate we can choose the best signal constellation from a multi-planar signal space.