An efficient bandwidth demand estimation for delay reduction in IEEE 802.16j MMR WiMAX network

IEEE 802.16j MMR WiMAX networks allow the number of hops between the user and the MMR-BS to be more than two hops. The standard bandwidth request procedure in WiMAX network introduces much delay to the user data and acknowledgement of the TCP packet that affects the performance and throughput of the network. In this paper, we propose a new scheduling scheme to reduce the bandwidth request delay in MMR networks. In this scheme, the MMR-BS allocates bandwidth to its direct subordinate RSs without bandwidth request using Grey prediction algorithm to estimate the required bandwidth of each of its subordinate RS. Using this architecture, the access RS can allocate its subordinate MSs the required bandwidth without notification to the MMR-BS. Our scheduling architecture with efficient bandwidth demand estimation able to reduce delay significantly

Reducing PAPR in PRS-OFDM system using Fraction Time-Selective (FTS) envelope modification

Orthogonal Frequency Division Multiplexing (OFDM) is the most promising technique for next generation broadband wireless communication system. The major setbacks of OFDM signal are intercarrier interference (ICI) and high peakto- average power ratio (PAPR). The purpose of this thesis is to develop mechanisms to reduce ICI and PAPR in OFDM systems. Partial response signaling OFDM (PRS-OFDM) with integer coefficient system has been developed to minimise the ICI. The carrier-to-interference power ratio (CIR) is enhanced by 2.6 dB to 5 dB compared to the normal OFDM. The PAPR has been reduced using Fraction Time-Selective (FTS) Envelope Modification technique. The FTS Envelope Modification PRSOFDM managed to reduce the PAPR by 0.8 dB to 2.8 dB. Efficient bandwidth usage is achieved by manipulating the PRSOFDM signal characteristics, where minimal side information (SI) is required due to restricted envelope modification factor

Software Defined Radio Design for OFDM Based Spectrum Exchange Information Using Arduino UNO and X-Bee

A cost expenditure of software defined radio software has limiting the development of cognitive radio in third countries. Moreover, a complexity of signal processing library in a SDR platform has contributed to the hard implementation in real applications. In this works, the development of SDR platform with low cost expenditure is proposed. Arduino UNO and X Bee uses for the OFDM based spectrum exchange information. In a case of spectrum sensing scenario, the objective of the local spectrum sensing is to detect the PU’s signal detection. The performance of SN ability to sense the PU’s signal is crucial. It was shown that from the previous works as the detected power is quantized into information bit is simulated.  In  order  to  implemented  the  spectrum exchange  information during  sensing,  Arduino  UNO  and  X  Bee  is implemented to sense the presence of PU activity channels of wifi terminals based on the energy of the signals. The detected power (RSSI) of wifi terminals is exchanged into an OFDM subcarrier tone signal such as orthogonal sub-channel that being equally divided from the licensed band.   The results shows that using proposed software defined radio (SDR) based on Arduino and X Bee, the cognitive radio spectrum sensing is applied. The received power from the PU’s channels such as wifi networks can be detected as well. The system could received and exchanged into OFDM-based subcarrier information bits

Orthogonal Frequency-Division Multiplexing-Based Cooperative Spectrum Sensing for Cognitive Radio Networks

The detection of transmitted data collusion among sensing nodes needs to be resolved at data link layer. It takes a lot algorithm calculation effort and time constraint. A new method to sense the performance of cognitive radio (CR) by avoiding interference based on new master node (MN) algorithm. Interference could be reduced significantly by using only PHY (physical) information of the cognitive radio network. It saves a lot computational on above layer and detect the collusion of transmitted data as early as possible. By using a novel MN algorithm at PHY layer, it reduces the cost of computation and time to detect and avoid collusion of transmitted data

Adaptive quantization for spectrum exchange information in mobile cognitive radio networks

To reduce the detection failure of the exchanging signal power onto the OFDM subcarrier signal at uniform quantization, dynamic subcarrier mapping is applied. Moreover, to addressing low SNR’s wall-less than pre-determine threshold, non-uniform quantization or adaptive quantization for the signal quantization size parameter is proposed. μ-law is adopted for adaptive quantization subcarrier mapping which is deployed in mobility environment, such as Doppler Effect and Rayleigh Fading propagation. In this works, sensing node received signal power then sampled into a different polarity positive and negative in μ-law quantization and divided into several segmentation levels. Each segmentation levels are divided into several sub-segment has representing one tone signal subcarrier number OFDM which has the number of quantization level and the width power. The results show that by using both methods, a significant difference is obtained around 8 dB compared to those not using the adaptive method

CRLB analysis for cognitive IR-UWB with imperfect sensing

Cognitive ultra wideband (UWB) technology has ability to sense the environment, and offers an adaptive system with low transmission power and high throughput for wireless communications. Impulse radio UWB (IR-UWB) supports flexible modulations, with short mono-pulses, in which channel estimation has a critical role. However, imperfect sensing in cognitive IR-UWB introduces the channel estimation errors associated to the interfering primary users. Two main schemes of channel parameters identification are known as pilot-aided and blind methods. In this paper, the effect of primary user interference is considered for channel estimation based on maximum-likelihood (ML) criterion. Cramer-Rao lower band (CRLB) analysis is derived, and performance analysis is simulated to compare both pilot-aided and blind methods in cognitive IR-UWB system. The results verify the better performance of the pilot-aided estimation, and also show the negative effect of increasing the number of primary users and paths on the performance. At SNR=10 dB, for pilot-aided method with 10 users and 3 paths, the CRLB square root of gain is and that of delay is less than blind method. Besides, when the number of primary users is 20, and the paths are 7, this gap is for gain, and for dela

Biologcally-inspired optimal video streaming over unpredictable wireless channel

Recently there has been an alarming increase in demand for wireless video streaming and the need to provide the required quality of service (QoS) to support video applications is very crucial. It is obvious that supporting multimedia applications and services over wireless is very challenging task due to network heterogeneity and different QoS requirements. This requires low complexity and highly efficient optimization scheme to cope with the unpredictable channel condition. This paper is aimed at developing a biologically-inspired scheme using particle swarm optimization (PSO) to achieve optimal video streaming. The optimal parameters configuration selected provide the best settings to enhance the video streaming quality over wireless LAN. The scenario has been simulated in NS-2 environment, it clearly shows that the video quality has been improve by selecting best configuration to ultimately support video application. The PSO-based approach outperforms other techniques used to compare the performance of the develop scheme in terms of perceived video quality by more than 0.5dB. The experimental simulation has been used to verify the efficiency and potential application of the PSO in wireless multimedia networks

Biological inspired autonomously secure mechanism for wireless sensor networks

Wireless communication plays an important role in these days in the sector of telecommunication and has huge importance for future research. There has been an exponential growth in wireless communication due to the development of different devices and applications. In addition, there is an explosive increase in integration and convergence of different heterogonous wireless networks to ensure effective and efficient communication. These technologies primarily includes Wireless Wide Area Networks (WWANs), Wireless Local Area Networks (WLANs), Wireless Personal Area Net-works (WPANs), and the Internet. The cellular networks can be classified under the WWAN, Blue-tooth, and Ultrawide Bands classified as WPANs, and finally the WLANs and High-Performance Radio Local Area Networks (HiperLANs) belongs to the WLAN class

MPEG-4 video transmission using distributed TDMA MAC protocol over IEEE 802.15.4 wireless technology

The issues of green technology nowadays give an inspiration to the researcher to make all the future design to be energy efficient. Medium Access Control (MAC) layer is the most effective layer to provide energy efficient due to its ability to control the physical radio directly. One of the important applications in the future is a video transmission that can be transmitted with low-cost and low power consumption. MPEG-4 is one of the international standards for moving video. MPEG-4 provide better compression and primarily design at low bit rate communication. In order to achieve good quality for video application, the design at MAC layer must be strong. Therefore, to increase the performance of the MPEG-4 in IEEE 802.15.4, in this paper we propose a cross layer design between MAC layer and Application layer. A priority queue will be implemented at MAC scheduling depends on the level of frame important in MPEG-4 format frame. A distributed Time division Multiple Access (TDMA) will be used for MAC protocol to provide reliable data transmission for high priority frame