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Enhancements in Second Generation Systems
Published in Jerry D. Gibson, The Communications Handbook, 2018
A concentric cell coverage is implemented by splitting the available traffic carriers in two groups. One group transmits at full power required to cover the complete cell and the other group transmits at a lower level thus providing the coverage of an inner zone concentric with the original cell. The pilot carrier is transmitted at full power. The localized transmission in the inner zone creates a lower level of interference for other cells. Hence, a smaller cluster size can be used for the frequencies of the inner zone leading to traffic capacity enhancement. Call admission control is designed to keep the MSs near the BS on the carriers of inner zone. Simple intracell handover mechanisms are used to ensure call continuity for the MSs moving across the boundary of the inner zone. Analysis and simulations have shown that optimized capacity enhancement is achieved if the inner zone is limited to 40% of the total cell area. Field trials of concentric cell networks have demonstrated 35% higher spectrum efficiency as compared to single cell networks.
ATM Signaling and Traffic Control
Published in P. S. Neelakanta, ATM Telecommunications, 2018
The call admission control discussed earlier is not sufficient to prevent congestion. The main reason is that users may not stay within the connection parameters negotiated at the call setup phase. This is because: ✓ Users may not be aware of and/or they might have inadvertently underestimated the connection requirements✓ User equipment may be malfunctioning✓ User may be deliberately underestimating their bandwidth requirements in order, for example, to pay less tariff✓ Users may be purposely trying to crash the network.
Convergent Network Management and Control Plane
Published in Iannone Eugenio, Telecommunication Networks, 2017
A call may embody any number of underlying connections, including zero. The call and connection control separation makes also sense for restoration after faults. In such a case, the call can be maintained (i.e., it is not released) while restoration procedures are underway. The call control must support coordination of connections in a multiconnection call and the coordination of parties in a multiparty call. It is responsible for negotiation of endtoend sessions, call admission control, and maintenance of the call state. The connection control is responsible for the overall control of individual connections, including setup and release procedures and the maintenance of the state of the connections.
Throughput and Power Efficiency Analysis Considering Traffic Loads in FFR with Movable Boundary
Published in IETE Journal of Research, 2018
Mustafa H. Mohsini, Seung-Yeon Kim, Choong-Ho Cho
In FFR, each cell is divided into two areas; cell inner area (CIA) and COA. In addition, the whole frequency band of the cell is also divided into cell inner band and cell outer band. The resource is frequently reused so that to improve spectrum efficiency in order to support the higher data rate. Figure 1 shows one of FFR scheme example. From the figure, the same physical resource block (PRB) from frequency band is assigned to the different UEs in the target base station (BS) and the neighbouring BS. However, when resources are highly utilized, the sharing of resources becomes exhausted, and this leads to a high call blocking probability. This makes users in the COA, cell outer users (COUs) suffer more than users in the CIA, cell inner users (CIUs). Therefore, depending on the size of the COA and traffic loads in it, the availability of the spectrum resources for CIA can be determined. Thus, in designing our FFR based on the size of the COA, it is crucial to characterize a trade-off between the call blocking in the CIA and improved COA performance. Accordingly, our paper investigates this trade-off by proposing a simple cross layer call admission control (CAC) in FFR in order to maximize system total throughput and energy efficiency while keeping some constraints of the quality of service (QoS).
QoS in WiMAX hybrid schedulers for heterogeneous traffic and their performance comparison
Published in International Journal of Electronics, 2020
Anju Lata Yadav, Prakash Vyavahare, Prashant Bansod
It may be concluded that there is a need to design a channel-aware scheduler that considers the channel conditions while making scheduling decisions. Wireless channels have scarce bandwidth and are highly variable; therefore, providing guaranteed service to subscribers is a vital task. The optimal integration of schedulers with Call Admission Control (CAC) schemes and Congestion Control schemes could be a matter of future investigation.