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3G networks penetration is increasing in China, particularly on mobile devices, but little is known about the performance in the country. In this paper, the WCDMA and CDMA's uplink broadband performance was measured in Nanjing. Content of the measuring include throughput, packet loss, delay and receiving interval. Through testing, we can identify the relationship between uplink packet loss, delay...
Data usage is surging in wireless networks and operators are quickly moving from second generation/third generation (2G/3G) networks towards 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) which is expected to provide significant data capacity and latency improvements. In this paper, we examine the benefits of a complete transition from mixed 2G/3G/LTE networks to an all- LTE network...
In this paper we study unslotted ALOHA optical code division multiple access (CDMA) packet switching local area network (LAN). The system uses on-off keying (OOK) and M-ary overlapping pulse position modulation (OPPM) as signaling schemes. Generalized and strict optical orthogonal codes (OOC) are used to implement CDMA concept. The generated packets are assumed to have variable length. The impact...
The IEEE 802.15.6 standard for wireless body area network (WBAN) defines two contention-based channel access schemes: slotted ALOHA and carrier sense multiple access with collision avoidance (CSMA/CA) using an alternative binary exponential backoff procedure. The standard supports quality of service (QoS) differentiation through user priorities and access phases. In this study, we develop an analytical...
Many wireless systems have leveraged the cooperation of nodes to improve network capacity. However, these approaches have left uncertainty over the performance gain of spatial diversity either with protocol overheads or unrealistic assumptions. Also more practical relay selection algorithm is required to be simple and totally distributed. In this paper, a CSMA-liked queue length based algorithm is...
Due to rapidly increasing of elderly population all over the world and quickly developing of entertainment devices, wireless body area network (WBAN) attracts attention. For both medical and non-medical applications, a reliability, high energy-efficiency and high throughput of WBAN communication are requested. The well-known cluster-based is proposed to obtain the high energy-efficiency, however the...
With the advances in technology, Underwater Acoustic Sensor Networks (UW-ASNs) will make it possible to explore and observe the ocean, which covers two-thirds of the Earth's surface. Unlike terrestrial sensor networks, UW-ASNs use acoustic links to explore natural undersea resources and gather scientific data in collaborative monitoring missions. By using the acoustic wave as a means of communication,...
This paper presents a method for optimizing OFDMA upstream scheduling in event monitoring applications related to IEEE 802.22 wireless regional area networks (WRANs). Upstream scheduling optimization is a trade-off between management transmission and data transmission in a frame. We provide analytical models to derive an optimum upstream schedule that maximizes the network performance in terms of...
Random spatial network models have been recently utilized in the performance analysis and system design for multi-cell networks. Such an approach has been mainly adopted to investigate the outage based system performance, such as the outage probability and outage throughput. However, these performance metrics are defined with a fixed-rate transmission, and cannot characterize the performance of data...
In WLAN systems, distributed coordination function (DCF) is used to avoid transmission collision. When an error occurs, the transmitter extends its contention window for the next retransmission to avoid more errors. But this may cause an unfairness problem; in noisy conditions MTs may find it difficult to get transmission opportunities, especially in a heterogeneous network with a large number of...
In this paper, the multi-channel performance of large scale deployment of Long Term Evolution (LTE) in Unlicensed (LTE-U) band and WiFi using stochastic geometry is studied. LTE-U and WiFi cell placement is modeled as a Poisson Point Process (PPP), while transmission activity is modeled as hardcore simple sequential inhibition (SSI) point processes, which have been shown to accurately model Carrier...
Multi-User Coordinated Multi-Point (MU-CoMP) transmission mode is considered as one of the key technologies which offer a good quality of service to low capacity users while maintaining a high spectral efficiency in the system. However, MU-CoMP networks have to determine the total number of users supported by CoMP operation as well as the size of the SDMA (Spatial Division Multiple Access) users'...
There are advantages to retrieve information from the Wireless Sensor Network (WSN) for UAVs (Unmanned Aerial Vehicles). However, the UAV-WSN system has some differences with conventional WSN system. So it is important to design an appropriate scheme to control the transmission in a UAV-WSN system. In this paper we proposed a protocol called A-OAloha (Adaptive-Opportunistic Aloha) for UAV-UAV-WSN...
Wireless body area networks (WBANs) is an emerging technology which consists of a network composed by miniaturized and intelligent sensor nodes in order to monitor a variety of applications. Due to the lack of overall, wireless technology, the special challenges of WBANs, the IEEE 802.15.6 was proposed to solve these issues in this emerging area and to satisfy the requirements for a monitoring system...
Wireless sensor networks (WSNs) may lead to high traffic in network when nodes detect an event and become active to send the data to the sink. Therefore, traffic adaptive medium access control (MAC) protocol for WSNs, with a more strict collision avoidance technique, can help in resolving the issue of collision by allowing less number of sensor nodes to send the data on the shared wireless channel...
In cognitive radio networks with primary users implementing CSMA/CA, such as 802.11 technologies, when all the primary users are in backoff states, the secondary users may detect primary users as inactive and try to access the channel, which will prolong primary users backoff procedure. This phenomenon is called hidden collision. In this paper, we first demonstrate how primary users' performance is...
CSMA/CA protocol shows poor performance for multi-hop transmission due to intra-flow interference (IFI) caused by hidden terminal (HT) problem. We propose an IFI-cancelling (IFIC) multi-hop transmission scheme which can efficiently relay packets under high traffic load and fading environment by using a Known interference cancellation technique. It employs the least mean square (LMS) equalization process...
We propose a novel method to maximise the aggregate throughput of an enhanced IEEE 802.15.4 gateway. By exploiting the gateway's beamforming antenna array and successive interference cancellation (SIC) we simultaneously increase range and maximise throughput. Our algorithm organises nodes into clusters, with each cluster assigned a unique spreading code and target gateway receive power. Within a cluster,...
The IEEE 802.11 specification for Wireless Local Area Networks (WLANs) supports 20 MHz channels utilizing bandwidths up to 160 MHz. However, the support of devices simultaneously transmitting over different, non-overlapping channels, is not specifically addressed. Recently, there has been interest in developing a 802.11 specification for Carrier Grade Wi-Fi which has led to the requirement for solutions...
This paper examines the efficiency of employing energy detectors in a multi-user network, whose nodes are spatially distributed in a geographic area and employ a CSMA MAC protocol to access the channel. It has been observed that explicit expressions for the analysis of imperfect physical carrier-sensing MAC protocols using energy detection are non-existent in the literature. We, therefore, present...
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