The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Nowadays, receivers can separate multiple transmitted packets simultaneously through the use of advanced signal processing techniques. This capability is called multi-packet reception (MPR). Currently, several proposals have been made to modify the operation of 802.11 and take advantage of the MPR capability. However, under multi-rate transmissions, these techniques suffer from the phenomenon known...
With the exponential growth of wireless data demand and the increasing scarcity of licensed spectrum, mobile network operators are considering extending the use of Long Term Evolution (LTE) into the unlicensed spectrum to offload their traffic. In the future, it is very likely that LTE will coexist with WiFi on the same unlicensed bands, such as the Industrial, Scientific and Medical (ISM) bands....
Wireless local area networks (WLANs) are becoming denser and thus interference-limited due to heavy traffic from a number of adjacent access points (APs) and stations (STAs). We propose a novel interference management technique for overlapping basic service sets (OBSSs) in such WLANs, which intelligently applies an opportunistic interference alignment (OIA) concept to WLANs. Each BSS has an AP and...
Ad-hoc network usually employs IEEE 802.11 based wireless LAN with a single channel as wireless links. A multi-hop communication and a single channel interference would cause a transmission performance degradation. The multichannel technique is effective to improve the transmission performance. This paper proposes the cross-layer design associated with the new multi-channel MAC protocol and the routing...
This paper proposes a new backoff algorithm for IEEE 802.15.4 MAC protocol in high-density wireless sensor networks, which is based on two-level channel information mined by nodes locally, namely channel busyness rate and packet collision rate. According to the two-level periodical renewing information, each node can achieve real-time and comprehensive network traffic load status, and then the node...
Analysing the performance of WLANs in non-ideal channel conditions is a fundamental consideration in practical situations since wireless channels are error-prone. This paper presents a closed form analytical solution for the non-saturated throughput of a QoS differentiated p-persistent CSMA protocol that takes into account the capture effect in a Rayleigh multipath fading environment. The results...
Dense carrier sensing wireless networks are important scenarios to enable ubiquitous mobile Internet access. In this work, we study user experience from the end-to-end performance of dense p-persistent CSMA networks that suffers from operation interference among many non-coordinated APs. Results show that in dense networks, the effective coverage of APs shrinks and most STAs don't receive satisfactory...
Due to the high expected increase in mobile data traffic and the scarcity of licensed spectrum for cellular networks, 3GPP has started preliminary work for standardizing LTE operation in the 5 GHz unlicensed band (LTE-U). However, LTE-U would interfere with other legacy technologies operating in the unlicensed band, the most important being contention-based Wi-Fi, which would be blocked by conventional...
Rapid increases in mobile data demand and inherently limited RF spectrum motivate the use of dynamic spectrum sharing between different radio technologies such as WiFi and LTE, most notably in small cell (HetNet) scenarios. This paper provides a analytical framework for interference characterization of WiFi and LTE for dense deployment scenarios with spatially overlapping coverage. The first model...
It has recently been shown that distributed queue-based adaptation of CSMA's contention aggressiveness can provably optimize network utility. However, such an approach is fragile, in that it suffers high performance degradation under conditions of asymmetric channels, heterogeneous traffic, and packet collisions. In this work, we address the main sources of performance degradation in optimal CSMA...
Filter Bank MultiCarrier modulation (FBMC) is a promising waveform technology envisaged for future mobile communication networks. For many transmission scenarios, the combination of multiple non-contiguous spectrum bands is foreseen. Because of coexistence issues, very low Adjacent Channel Leakage is required making FBMC waveforms of particular interest. However the fair frequency localization of...
The aim of this paper is to present a model for the throughput of the 1-persistent CSMA protocol in underwater networks, where the typically large propagation delay with respect to the packet transmission time requires to take into account the spatial distribution of the nodes. Our model is developed based on the analysis carried out in [1] for the non-persistent CSMA protocol. Our results show that...
We address the problem of downlink throughput improvement for IEEE 802.11a/g systems by using a modified access point (AP) equipped with multiple antennas. The main restriction is that standard terminals should not be modified in any way. An alternating time-offset space division multiple access (SDMA) solution is proposed to overcome restrictions imposed by the legacy terminals requirement. In this...
In this work, we significantly increase the peak rate of the wideband CDMA spatio-temporal array-receiver (STAR) by enabling its operation with high-order modulations (HOM) up to 256QAM (i.e., peak rate of 768 Kb/s per spreading code with 32 spreading factor and 1/2 coding rate in 5 MHz). In order to allow an effective rate control for adaptive modulation and maximize throughput with the resulting...
The token passing multiple access (TPMA) scheme is a common adopted scheme for wireless network-on-chip (WiNoC) in chip multi-processors (CMPs). The drawback of TPMA is the channel access delay due to TPMA passing the token in a round-robin manner no matter the node has packets to send. In this paper, we study the performance of the slotted p-persistent carrier sense multiple access (CSMA) scheme...
Machine to machine communication (M2M) or machine type communication (MTC) facilitates communication without any human intervention. These applications will support an enormous number of stations (STAs). To mitigate degradation of the throughput and delay performance in wireless local area networks (WLAN) that employ carrier sense multiple access collision avoidance (CSMA/CA) protocol with request...
Recent work has shown that adaptive CSMA algorithms can achieve throughput optimality. However, these adaptive CSMA algorithms assume a rather simplistic model for the wireless medium. Specifically, the interference is typically modelled by a conflict graph, and the channels are assumed to be static. In this work, we propose a distributed and adaptive CSMA algorithm under a more realistic signal-to-interference...
Wireless body area network collects information from medical devices that monitor the physiological parameters of a human body. Energy constraints of medical devices and bounded latencies of medical applications are the chief QoS requirements of WBANs. With the standardization of the WBAN network, viz. 802.15.6 standard, mechanisms for medium access have been specified which can be skillfully manipulated...
In a wireless network the network throughput is extremely significant factor. Before it achieve by CSMA/CA, except its throughput is little. Though the number of nodes in a WLAN increase speedily, cruel collision to a great extent degrade system routine. In CSMA /CA cruel collisions in the uplink, (ii) head-of-line problem cause by evaporation out the downlink, and (iii) stern injury connecting uplink...
Cognitive radio networks are an emerging paradigm for intelligent networks to resolve the spectrum under-utilization problem, as they allow cognitive users to utilize frequency bands assigned to primary users. In this paper, we consider the transmit power control of a secondary transmitter when a primary user accesses a wireless channel through a carrier sense multiple access (CSMA) mechanism. In...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.