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Carrier aggregation (CA) has been proposed to aggregate two or more component carriers (CCs) to support a much wider transmission bandwidth for LTE-Advanced systems. With carrier aggregation, it is possible to schedule a user equipment (UE) on multiple component carriers simultaneously. In this paper, we evaluate the performance of uplink CA in LTE-Advanced systems with different CC allocation schemes...
The next generation of wireless networks (e.g., Long Term Evolution (LTE)and WiMAX) use multiple techniques to improve channel spectral efficiencies. In this paper we focus on one such technique, namely Coordinated Beam Switching (CBS). With CBS, each sector determines a sequence of beams (possibly with repetitions) over which it continuously cycles. Each sector independently determines its beam pattern...
Re-farming of 900 MHz band into HSPA has been started and is likely to happen later with LTE. Typically operators have less than 10 MHz block of 900 MHz spectrum and therefore co-existence of two systems in that band is causing challenges. One of the major issues is the high GSM voice traffic that will remain in the GSM network. How to cope the same traffic with significantly less bandwidth for GSM?...
WANETs is a recent network architecture where the nodes are spread all over the world but behave exactly as if they are part of a single-hop or multi-hop wireless networks at the PHY and MAC layers. Without distinguishing data packets and noise, the Software Defined Access Point (SoDA) samples the wireless channel for the uplink and multicasts the sampled data via Internet to other SoDAs. This leads...
We focus on the problem of efficient dissemination of available gateways information throughout a Vehicular Ad-hoc Network (VANET). Contrary to previous works, we also consider how the gateway discovery protocol affects user data flows that are routed to the infrastructure network. The cases of both delay-tolerant and delay-constrained user traffic are studied. We propose two schemes targeted at reliable,...
In this paper, sensitivity of the first three standardized moments of both unencumbered call interruption time and cell dwell time on teletraffic performance metrics of wireless cellular networks is investigated. Mathematical analysis for obtaining system-level performance metrics is developed considering that cell dwell time and unencumbered call interruption time are phase-type distributed random...
CBTC (Communication Based Train Control) will be based on mobile communication, which the key problem is how to support reliability of control data transmission to improve track utilization and enhance train safety. This paper proposed a kind of real-time transmission model for high speed train end-to-end control data operation, which based on circuit switched data service by traditional wireless...
This paper analyzes the performance of Proportional Fair (PF) scheduling in Orthogonal Frequency Division Multiple Access (OFDMA) wireless systems. OFDMA represents a promising multiple access scheme for high-data-rate transmission over wireless channels as it combines the Orthogonal Frequency Division Multiplexing (OFDM) modulation and subcarrier allocation. On the other hand, the PF scheduling is...
The concept of small cells such as femtocells has been regarded as a promising solution to overcome the indoor coverage problem and deal with the growth of traffic within macrocells. However, the unpredictable deployment pattern of such cells makes centralized network planning impractical and requires more efficient interference management and distributed spectrum planning schemes to realize the benefit...
Traditional wireless sensor networks (WSNs) working in the license-free spectrum suffer from uncontrolled interference as the license-free spectrum becomes increasingly crowded. A WSN based on cognitive radios can potentially provide data transmissions with quality of service, while avoiding the high cost for accessing the licensed spectrum and uncontrolled interference in the license-free spectrum...
In this paper, we consider a DTN/WLAN integrated network where nomadic nodes with high mobility comprise a delay tolerant network (DTN) while local nodes with low mobility reside in the coverage area of wireless local area networks (WLANs). A message dissemination service is considered, where data traffic is generated by a server in the Internet and destined to a group of nomadic nodes. In order to...
Through sensing and utilizing available network resources, cognitive network can obviously increase network performance. In this paper, a distributed on-demand routing protocol with traffic awareness (TACR) is proposed for cognitive wireless network. This routing protocol establishes the path based on the cognition and reasoning of traffic loads in a network and it also meet quality of service (QoS)...
This paper proposes a novel method for detecting traffic congestions, qualifying and quantifying congestion levels using mobile phones as traffic probes. The system provides a robust mechanism for granularly comparing the seriousness of different congested areas. Congested areas are detected in a detailed manner by which exact congested positions are reported. Moreover, congestions can be detected...
We define and evaluate the downlink flow-level capacity of a fractionally loaded OFDMA network utilizing round robin (RR) or proportional fair (PF) scheduling. The flow-level capacity is the maximum traffic intensity that can be supported by a sector while satisfying a minimum flow throughput requirement for bursty, elastic traffic. We obtain a simple, insightful capacity expression for RR scheduling;...
In a loaded 1-reuse cellular network as e.g. 3GPP Long Term Evolution (LTE) the inter-cell interference limits the user bitrate for link adaptive packet data access. The cell isolation together with the link performance defines the spectrum efficiency and the achievable gain of higher order modulation or other link improving features. In this paper the cell isolation is measured as geometry factor...
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