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Network Selection in Heterogeneous Wireless Environment
Published in K. R. Rao, Zoran S. Bojkovic, Bojan M. Bakmaz, Wireless Multimedia Communication Systems, 2017
K. R. Rao, Zoran S. Bojkovic, Bojan M. Bakmaz
Handovers can also be classified as hard and soft, depending on the number of connections involved. In the case of a hard handover, the radio link to the old PoA is released at the same time a radio link to the new base station is established. Here, the data does not have to be duplicated and, therefore, the data overhead is minimized [9]. However, excessive service interruptions can result in an increased demands dropped rate. Hard handovers are used by systems such as GSM and GPRS in which time division multiple access (TDMA) and frequency division multiple access (FDMA) are applied. Hard handover is also the compulsory method to maintain active sessions in the IEEE 802.16-based networks. Contrary to hard handovers, in a soft handover, a mobile node (MN) maintains a connection with no less than two PoAs in an overlapping region and does not release any of the signals until it drops below a specified threshold value. Soft handovers are possible in situations in which the MN is moving between cells operating on the same frequency. They can be used to extend the time needed to take a handover decision without any QoS degradation. However, because the data are transmitted to all links, frequent soft handovers can result in an increased data overhead. The CDMA systems use soft techniques because, in these networks, a MN may communicate with more than one coded channel, which enables it to communicate with more than one PoA [10]. A softer handover is a special case of a soft handover, in which the mobile terminal switches connections over radio links that belong to the same PoA.
Radio Resource Management Schemes for Mobile Terrestrial and Satellite Broadcasting
Published in Borko Furht, Syed Ahson, Handbook of Mobile Broadcasting, 2008
Because the nature of the communication in DVB-H is unidirectional (one to many), the handover procedure will be different, compared to the handover procedure in cellular bidirectional systems. The handover procedure in DVB-H has to be initiated by the user terminal, based on measurements conducted during the periods of inactivity of the home cell broadcasting (due to the time-slicing principle). Because the terminal can monitor both the transmission of the home cell and the transmission of the neighboring cells (the bursts are separated in TDM fashion and are identified by their respective cell_id), it can perform soft handover. The absence of a feedback channel and a dedicated forward channel implies that the terminal has to take the handover decision based on its local measurements and without any interaction with the DVB-H network; this handover is termed passive handover.16
Access Methods
Published in Jerry D. Gibson, The Communications Handbook, 2018
The interference problem that arises at the cell boundaries where mobiles are within range of two or more base stations can be turned into an advantage through the idea of soft handover. On the downlink, all base stations within range can transmit to the mobile, which in turn can combine the received signals to achieve some gain from the antenna diversity. On the uplink, a similar effect can be obtained by selecting the strongest received signal from all base stations that received a user's signal. The base station that receives the strongest signal will also issue power control commands to minimize the transmit power of the mobile. Note, however, that soft handover requires fairly tight synchronization between base stations, and one of the advantages of CDMA over TDMA is lost.
A survey on 3G mobile network traffic performance and analysis in Ethiopia
Published in Cogent Engineering, 2022
Fanuel Melak Asmare, Fekadu Mihret Geremew, Lijaddis Getnet Ayalew
The result has established a good starting point for further study of the performance of 3G network traffic. It has shown that the throughput is too low which indicates the number of users of 3G service is few and this should be dealt with considering the impact that data services alone could increase the gross domestic product (GDP) of one country, as separate studies had revealed. Even though the call drop rate and the soft handover success rate are in good condition, this might be connected to fewer subscribers. Increasing the number of 3G users might be the main issue for ET, but the current very low call setup success rate may be an obstacle. The CSSR is as low as 75% from the threshold value of 98% success rate, which results from an unacceptable amount of call trials for customers.
Neighborhood optimization of intelligent wireless mobile network based on big data technology
Published in International Journal of Computers and Applications, 2021
Three different types of KPIs in mobile communication network are predicted and analyzed by using time series prediction method based on the large data platform. The predicted results are shown in Figure 5. Figure 5(a) shows the result of one day predicted by the initial data of 30 days for RRC setting success rate, Figure 5(b) shows the result of one day predicted by the initial data of 30 days for ARM soft handover rate, and Figure 5(c) shows the result of one day predicted by the initial data of 30 days for RRC dropping rate. It can be seen from the graph that the time series prediction method based on large data platform has good prediction results for different types of KPI prediction, and the prediction results have great coincidence with the real values.