A joint OFDM PAPR reduction and data decoding scheme with no SI estimation

The need for side information (SI) estimation poses a major challenge when selected mapping (SLM) is implemented to reduce peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. Recent studies on pilot-assisted SI estimation procedures suggest that it is possible to determine the SI without the need for SI transmission. However, SI estimation adds to computational complexity and implementation challenges of practical SLM-OFDM receivers. To address these technical issues, this paper presents the use of a pilot-assisted cluster-based phase modulation and demodulation procedure called embedded coded modulation (ECM). The ECM technique uses a slightly modified SLM approach to reduce PAPR and to enable data recovery with no SI transmission and no SI estimation. In the presence of some non-linear amplifier distortion, it is shown that the ECM method achieves similar data decoding performance as conventional SLM-OFDM receiver that assumed a perfectly known SI and when the SI is estimated using a frequency-domain correlation approach. However, when the number of OFDM subcarriers is small and due to the clustering in ECM, the modified SLM produces a smaller PAPR reduction gain compared with conventional SLM

A low complexity SI sequence estimator for pilot-aided SLM–OFDM systems

Selected mapping (SLM) is a well-known method for reducing peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. However, as a consequence of implementing SLM, OFDM receivers often require estimation of some side information (SI) in order to achieve successful data recovery. Existing SI estimation schemes have very high computational complexities that put additional constraints on limited resources and increase system complexity. To address this problem, an alternative SLM approach that facilitates estimation of SI in the form of phase detection is presented. Simulations show that this modified SLM approach produces similar PAPR reduction performance when compared to conventional SLM. With no amplifier distortion and in the presence of non-linear power amplifier distortion, the proposed SI estimation approach achieves similar data recovery performance as both standard SLM–OFDM (with perfect SI estimation) and also when SI estimation is implemented through the use of an existing frequency-domain correlation (FDC) decision metric. In addition, the proposed method significantly reduces computational complexity compared with the FDC scheme and an ML estimation scheme

A selective control information detection scheme for OFDM receivers

In wireless communications, both control information and payload (user-data) are concurrently transmitted and required to be successfully recovered. This paper focuses on block-level detection, which is applicable for detecting transmitted control information, particularly when this information is selected or chosen from a finite set of information that are known at both transmitting and receiving devices. Using an orthogonal frequency division multiplexing architecture, this paper investigates and evaluates the performance of a time-domain decision criterion in comparison with a form of Maximum Likelihood (ML) estimation method. Unlike the ML method, the proposed time-domain detection technique requires no channel estimation as it uses the correlation (in the time-domain) that exists between the received and the transmitted selective information as a means of detection. In comparison with the ML method, results show that the proposed method offers improved detection performance, particularly when the control information consists of at least 16. However, the implementation of the proposed method requires a slightly increased number of mathematical computations

Selective Control Information Detection in 5G Frame Transmissions

Control signalling information within wireless communication systems facilitates efficient management of limited wireless resources, plays a key role in improving system performance of 5G systems. This chapter focuses detection of one particular form of control information, namely, selective control information (SCI). Maximum-likelihood (ML) is one of the conventional SCI detection techniques. Unfortunately, it requires channel estimation, which introduces some implementation constraints and practical challenges. This chapter uses generalized frequency division multiplexing (GFDM) to evaluate and demonstrate the detection performance of a new form of SCI detection that uses a time-domain correlation (TDC) technique. Unlike the ML scheme, the TDC technique is a form of blind detection that has the capability to improve detection performance with no need for channel estimation. In comparison with the ML based receiver, results show that the TDC technique achieves improved detection performance. In addition, the detection performance of the TDC technique is improved with GFDM receivers that use the minimum mean square error (MMSE) scheme compared with the zero-forcing (ZF) technique. It is also shown that the use of a raised cosine (RC) shaped GFDM transmit filter improves detection performance comparison with filters that employ root raised cosine (RRC) pulse shape

The analysis of the impact of corporate income tax on investment in Nigeria

The study evaluated the impact of corporate income tax on investment in Nigeria. It also examined the significant relationship corporate income tax and investment in Nigeria. Secondary data were sourced from Central Bank of Nigeria (CBN)Statistical Bulletins (various issues), National Bureau of Statistics. The data covered 25 years period from 1991-2015. Pearson product moment correlation and multiple regressions were employed to examine the relationship between the dependent variable (Investment) and independent variables (Corporate income tax, Import, Exchange rate and Interestrate). Findings reveals that Corporate income tax (CIT) has a negative impacton Investment (β = -.0000104; p ≤ 0.05). Interest rate also has negative significanteffect on Investment in Nigeria (β =-0.48799; p ≤ 0.05) with the adjusted R2 @ 94.2%. In conclusion, corporate income tax has negative and statistical impact on Investment in Nigeria. It is now recommended that Nigeria government should reduce the corporate income tax on companies and work on how interest rate would be minimized in order to accommodate more investment in Nigeria

Comparative study of physicochemical properties of Tithonia diversifolia and Sunflower seed oils

This study investigates the physico-chemical properties of Tithonia diversifolia seed and oil using standard analytical methods and then compared the results with Sunflower oil. The results showed that Tithonia diversifolia seed contained 5.80% moisture, 18.83% crude protein, 30.40% crude fat, 17.85% crude fibre, 4.30% ash and 22.82% carbohydrate. The content of magnesium, copper, iron, zinc and calcium were 3930, 168, 277, 2091 and 432 mg/kg, respectively. Iodine value for T. diversifolia and Sunflower oils, respectively were 109.00 and 145.67 g iodine/kg; saponification values, 212.61 and 188.63 mg KOH/g; ester values, 184.15 and 206.86 mg KOH/g; peroxide values 4.0 and 5.87 meq peroxide/kg; acid values, 5.76 and 4.48 mg KOH / g; % unsaponifiable matter, 0.83 and 1.22 %; and total phenol content, 118.63 and 108.75 µg/g. Others include, specific gravity, 0.937 and 0.920; surface tension 0.042 and 0.051 N/m; viscosity 42.50 and 30.50 cSt; and smoke point, 215 and 245 0C. The study revealed that Tithonia diversifolia seed oil content and physicochemical parameters are comparable with those of Sunflower oil. Hence the oil could be used as raw materials for industrial processes, biodiesel production and a good source of dietary antioxidant which could complement or replace some conventional oils

Computational efficient SLM–OFDM receiver for time-invariant indoor fading channel

This paper addresses receiver related side information (SI) estimation issues when selected mapping is used to reduce peak-to-average power ratio in orthogonal frequency division multiplexing (OFDM) systems. The SI contains critical information and its accurate estimation is required to enable successful recovery of payload data regardless of the channel condition. However, the need for SI estimation poses some practical issues in the form of high computational complexity and implementation challenges. Through simulations, this paper investigates the performance of an alternative data decoding approach called Embedded Coded Modulation (ECM), which requires no SI estimation. Using a form of block-type OFDM frame structure, results show that the ECM technique produces identical data decoding performance as other methods even in the presence of some non-linear amplifier distortions. In addition, it is shown that the ECM method eliminates SI related computational complexity and implementation problems

A time-domain control signal detection technique for OFDM

Transmission of system-critical control information plays a key role in efficient management of limited wireless network resources and successful reception of payload data information. This paper uses an orthogonal frequency division multiplexing (OFDM) architecture to investigate the detection performance of a time-domain approach used to detect deterministic control signalling information. It considers a type of control information chosen from a finite set of information, which is known at both transmitting and receiving wireless terminals. Unlike the maximum likelihood (ML) estimation method, which is often used, the time-domain detection technique requires no channel estimation and no pilots as it uses a form of time-domain correlation as the means of detection. Results show that when compared with the ML method, the time-domain approach improves detection performance even in the presence of synchronisation error caused by carrier frequency offset

Application of information and communication technology for internationalization of Nigerian small‐ and medium‐sized enterprises

Information and communication technology (ICT) has fundamentally transformed business transactions. While its uses have become ubiquitous in the advanced economies, emerging and developing economies are still struggling with the mode and manner of the deployment of ICT for business. Thus, this study seeks to investigate how small‐ and medium‐sized enterprises (SMEs) utilize ICT in Nigeria for business internationalization. To achieve the goal of the study, a mixed‐method was employed. A questionnaire was administered to 265 people consisting of SMEs staff, managers, and owners. Similarly, interviews were conducted with seven SME decision makers. Findings revealed that Nigerian SMEs used ICT tools, such as websites and social media platforms, for internationalization. The findings also revealed that the challenges of ICT did not affect its application by these SMEs, which contrasts with many previous studies. Furthermore, this study identified privacy concerns, internet problems, cyber insecurity, trust, and system anxiety as new challenges facing the application of ICT tools by SMEs. Similarly, the findings showed that lack of ICT competence and strategic focus of ICT applications are internal problems facing Nigerian SMEs. These findings provide insight for practitioners and academia on the internationalization of Nigeria SMEs and the application of ICT to promote business growth.</p