Design of Orthogonal Variable Spreading Factor (OVSF) Performance Simulation Program in Multipath Fading Channels

The characteristics of wireless channel are determined by multipath propagation. The transmitted signal will be scattered so that it produces fading. Fading influenced by multipath component will cause delay spread which damages the signal. Thus, spread spectrum technology is used by using a bandwidth that is greater than the original signal. The objective of this study was to determine the effect of the number of multipath components on orthogonal variable spreading factor (OVSF) codes on multipath fading channels viewed from values and Bit Error Rate (BER) graphs versus Energy Bits per Noise (Eb/No). This study would compare the performance of OVSF code communication system on multipath channels by varying multipath components of 4, 8, 12, 16 and the length of OVSF codes used of 16, 8 and 4. The simulation results showed an increase in BER values when the number of multipath components was added. The more the number of multipath components used, the more the number of reflected signals that will interfere with the desired signal in the receiver. The length of the OVSF code influences the performance of the OVSF code on the multipath fading channel, because each code has a different processing gain value that is affected by the length of the code used

Service Time-Based Region Division in OVSF-Based Wireless Networks with Adaptive LTE-M Network for Machine to Machine Communications

The 3GPP standards have presented the LTE-M as one of the main technologies to provide services to Internet of Things (IoT). The IoT applications are usually short-lived applications like smart sensing, surveillance systems for home or businesses, and data uploading applications like metering. In this paper, the proposed architecture of the base station has a LTE interface which assigns resource blocks (RBs) and another 3G interface which is equipped with orthogonal variable spreading factor (OVSF) codes. The IoT devices deployed ubiquitously leads to massive machine type communication, which leads to burst traffic on current cellular services. The IoT devices when assigned large resources will reduce the radio efficiency. The work in this paper assigns OVSF codes available on 3G interface to the IoT devices. The LTE resources are used for IoT devices in case of emergency or when resources of 3G interface are 100% utilized. This will solve the problem of both small data transfer and connectivity requirement of IoT devices. The IoT applications are event-driven and time-bound also, and the resources are also reserved for these applications in the proposed work. The simulations and results show that proposed work increases both network efficiency and capacity.