The financial support of the Cape Peninsula University of Technology and the National Research Foundation for this research is acknowledged. The views expressed in this thesis and the conclusions drawn from it are those of the author and cannot necessarily be attributed to the National Research Foundation.
Introduction
- Distributed Generation
- Interoperability
- Smart grids
- Potential of deploying smart grids within South African power grids
These networks, using the latest 3G, 4G and the prospect of 5G technologies, have the potential to expand and support penetration of DGs in rural areas of the country. The proliferation of GDs and the potential spread of data across the current SA communication network providers will improve the capabilities of future SGs.
Statement of the research problem
Due to its widespread deployment, LTE can be considered as a viable option for communications in SGs (Madueno et al., 2016). For this, the current South African communication infrastructure and communication network topologies will be studied, analyzed and simulated to propose the best possible answers to these questions.
Rational and motivation for the research
20 Smart monitoring is thus expected to play an increasing and crucial role in improving the reliability of power grids as a whole, but more importantly in SGs. To address these problems, it is necessary to transmit fault condition data experienced in SGs ultra-fast, highly secure via communication networks to accurately analyze and transmit the fault condition data to manage and implement measures to minimize and control impact on the electricity network.
The Research Objectives and Aims
The research objective
21 Although DG appears to be the ultimate solution to alleviate the power demand in SA, DG comes with its challenges in terms of how it fits into the overall power infrastructure of SA, how distribution will take place, i.e.
The research aim
Research design and methodology
Research significance
Thesis outline
Here the difference is the variation in mobile traffic and SG traffic, to test the performance of the communication technology in case one of these traffic flows is higher and its overall impact. The synergy of the work performed firstly illustrates the possibilities of using cognitive radio and LTE communication technologies in dealing with a future increase in SG traffic.
Introduction
Communication topologies, advantages, and disadvantages
Evolution from “Conventional Power Grids towards Smarter Power Grids” 26
The authors of (Khan et al., 2015) and (Wang et al., 2011) indicated that the inclusion of these SG technologies can lead to significant improvements in the efficiency, effectiveness, sustainability, reliability, safety and stability of the electric grid. In conclusion, it was recognized that communication infrastructures are essential to the success of the evolving SGs.
Future impact of communication technologies on smart grids
Core network GWs can be base stations (BS) of cellular networks or GWs/access points (AP) of wireless area networks (WLANs). One of the major challenges in SG is handling the massive amount of data in the data center from a large number of SMs (Aiello, 2016).
Transmission of Smart Grid Data via Cellular Communication Networks
Cellular Communication Technologies
This can be a serious problem in the event of a grid emergency (Baimel & Tapuchi, 2016). Global System for Mobile Communications (GSM) is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation (2G) digital cellular networks used by mobile devices such as mobile phones and tablets.
Introduction
- Background to employ Cognitive Radio Networks in Smart Grids
- Cognitive Radio Network Parameters and Smart Grid Data
- Smart Grid Priority Scheme in Cognitive Radio Networks
- Simulation and Results
- Network Parameters
- Proposed Scheme
- Simulation and Results
If a Primary User (PU) wants to access the spectrum, the SU will be buffered with a data call. The job also uses the buffered SU call elapsed time to allow access to the spectrum.
Conclusion
Performance statistics are analyzed with regard to the probability of blocking, the probability of interruptions and the probability of forced termination of SU voice calls. The results indicate that voice call priority significantly reduces the likelihood of voice call blocking and forced termination.
Introduction
There are several schemes given in the literature to reduce the probability of code blocking of mobile networks using OVSF (Adachi et al., 2005). An interference avoidance (IA+CF) scheme is proposed in (Wang et al., 2007) which provides significant improvement of code blocking probability at better QoS.
OVSF, VSF-OFCDM and LTE FUNDAMENTALS
The most common single code assignment schemes are: leftmost code assignment (LCA) and crowded first assignment (CFA), both given in (Tseng & Chao, 2002) and (Adachi et al., 1997), the fixed set partitioning (FSP) ( Atarashi & Ahashi, 2002) and recursive fewer codes blocked (RFCB) scheme proposed in (Rouskas et al., 2005). The schemes proposed in (Saini & Upadhyay, 2009), (Balyan et al., 2010), (Saini & Balyan, 2016) use multiple codes to handle a single call, reducing code blocking and with increased complexity.
Proposed Scheme
Find a suitable UMTS code using TD (Balyan & Saini, 2013) and update 𝑠𝑈𝑈𝑑𝑑𝑆𝑆𝑈𝑈𝑇𝑇𝑆𝑆+𝑘𝑘𝑅𝑅. a) Find the speed, direction of movement and location of BS. B). Assign a new call to the UMTS interface and assign codes using the TD multicode approach (Balyan & Saini, 2013), and update 𝑆𝑠𝑠𝑈𝑈𝑑𝑑𝑆𝑆𝑈𝑈𝑇𝑇𝑆𝑆 +𝑘𝑘𝑅 𝑅. Other than 𝐶𝐶𝑆𝑆𝑠𝑠𝑈𝑈𝑑𝑑𝐿𝐿𝑇𝑇𝐸𝐸 > 𝐶𝐶𝑇𝑇ℎ𝐿𝐿𝑇𝑇𝐸𝐸 and 𝐶 Block the call .
Simulations and Results
The probability of TSD code blocking is lowest due to the use of multicode and LTE interfaces. Code blocking probability comparison of (a) quantized arrival rates and (b) quantized rates and non-quantized rates both [R-16R].
Conclusion
Introduction
65 To improve the quality of service (QoS) of the UMTS interface, orthogonal variable spreading factor (OVSF) codes using OFCDM are spread in two dimensions, time and frequency (Yiqing Zhou, Tung-Sang Ng, Jiangzhou Wang, 2008), (Kuo et al., 2008). In (Wang et al., 2007) a time slicing scheme is proposed, which does two-dimensional propagation in the frequency and time code.
Motivation of the work
The HLU scheme assigns the RB or number of codes depending on the current location and direction of movement of a new calling user. The allocated resources increase or decrease when the distance of the user increases or decreases from the BS respectively.
Network Architecture and Parameters
For LTE using OFDMA, one MS will be allocated at least one RB and in the same subframe duration different MSs can use the number of RBs assigned to them by the eNodeB. For LTE using OFDMA, one MS will be allocated at least one RB and in the same subframe duration different MSs can use the number of RBs assigned to them by the eNodeB.
Calculation of utilization of LTE interface and UMTS interface
68 The transmission unit for an MS is defined by the resource block (RB) within a subframe (for time) and a subchannel (for frequency) for the LTE interface. The transmission unit for an MS is defined by the resource block (RB) within a subframe (for time) and a subchannel (for frequency) for the LTE interface.
Proposed Handoff LTE-UMTS Scheme
𝑁𝑁𝑅𝑅𝐵𝐵𝐵𝐵𝑓𝑓𝐵𝐵𝑡𝑡𝑙𝑙 − 𝑁𝑁𝑅𝝑𝑵𝐵 𝑙𝑖𝑖𝑈𝑈𝑈𝑈𝑈𝑑𝑑 𝑅𝑅𝐵𝐵𝑅𝑅𝑈𝑈𝑅 𝑚𝑝𝑝 (5.8) The number of RB or UMTS codes required by the call depends on its position in the cell. The number of RB or UMTS code required by the data call at rate 2𝑖𝑖−1𝑅𝑅 depends on its position in the cell.
Proposed UMTS ANC Scheme
74 To illustrate the ANC multiple code assignment scheme, consider the arrival of a call at rate 8R at a QPSK location moving toward 16-QAM. Note the status of the OVSF code tree in Figure 5.1 (b), when the second 8R call arrives with BPSK location, it will request 8 R rate codes.
Results and Simulations
The reason is the fragmentation of empty code in the code tree due to the random behavior of call arrivals and departures. The ANC scheme ensures the minimum probability of code blocking by searching the entire code tree if there is no single code with the required rate and using fragmented capacity in the code tree.
Conclusion
Introduction
Work in Literature
The OCA scheme assigns incoming call requests to a free code that leads to minimal future code blocking while maintaining the QoS of ongoing and new calls. Time domain tree numbers with Cl An optimal code is defined as the code that leads to minimal code blocking, minimal reassignment and recombination in the future with channel loading of the time domain code within the threshold and this scheme as an optimal code assignment (OCA). The Cl for an 8 layer tree is calculated for a different number of busy calls from different layers and is given in Table 6.2 with variable time domain code. For the quantized call rate request 𝛾𝛾𝑄𝑄𝑅𝑅, 𝛾𝛾𝑄𝑄𝑅𝑅{𝛾𝛾𝑄𝑄= 2𝑙𝑙−1} free layer code 𝑙𝑙𝛾𝛾𝑄 𝛾𝛾𝑄𝑄𝑅𝑅{𝛾𝛾𝑄𝑄= 2𝑙𝑙−1} = (𝑙𝑙𝑓𝑓𝑐𝑐 2𝛾𝛾𝑄𝑄+ 1�= 𝐼𝐼: 𝑖𝑖𝑛𝑛𝑛𝑡𝑡𝑐𝑐𝑐 𝑐𝑐𝑐𝑖𝑖 is assigned, leading to overall code capacity utilization. blocking of future calls, as the unused capacity of already blocked codes will be used. This also reduces code blocking by using unused capacity of higher and lower layer codes. Combine the fractions so that 𝑐𝑐𝑓𝑓 =∑𝑛𝑛𝑖𝑖=1𝑓𝑓 𝑠𝑠𝑖𝑖 provided 𝑙𝑙𝑐𝑐𝑛𝑓 𝑐2𝑐𝑐𝑓𝑓+ 1) and (2) In Figure 6.4, the arrival of non-quantized rate leads to an increase in code blocking probability of all the schemes. The LCA and RM calculation time or a number of code searches is minimum, with a higher code blocking probability. Also, the calculation time is higher for IA+CF, which is most comparable to OCA, searching for the same codes again in case of a tie. The chapter focuses on the use of LTE-UMTS resources for communication or calls within SGs to transfer measurement information or other data required. The proposed scheme aims to reduce the loading of the LTE-UMTS interface at the base station (BS) to increase call capacity. The number of subchannels depends on the bandwidth spectrum, e.g. for a 3MHz spectrum, the number of subchannels is 15. For LTE using OFDMA, an MS will be allocated at least one RB and in the same subframe time duration, different MSs can use the number of RBs allocated to them by eNodeB. Consider that an 8R rate call arrives, the number of RBs (𝑛𝑛𝑅𝑅𝐵𝐵) required by it depends on its location in the cell. The system can assign the requested RBs however it is preferable to set a maximum limit on the number of RBs that can be assigned denoted by 𝑛𝑛𝑅𝑅𝐵𝐵𝑚𝑚𝑡𝑡𝑚𝑚=4. SGT Request The result in Figure 7.1 compares the blocking probability when the RT arrival is higher and the SGT is lower, LTE-UMTS provides the minimum blocking probability by discarding the periodic messages and saving the measurement information in the MS and workstation, which are sent together as one data call. For the result in Figure 7.2, RT arrival is low and SGT is higher, LTE-UMTS provides a blocking probability comparable to LAA and RADA, the network only handles SGT calls comprising higher frequency periodic messages. Conclusion The 3G interface is used for data calls in mobile communication when no RB or LTE interface is available. For a larger amount of data, LTE interface is used, this results in lower call blocking. In our case, smart grid nodes are usually stationary and can easily use the 3G interface to transmit small to moderate data. LTE communication is used to process calls, data requests, etc. coming from networks. Cognitive Radio Network for the Smart Grid: Experimental System Architecture, Control Algorithms, Security and Microgrid Testbed.System Model
Single Code Assignment Approach
Call Request: Quantized
Call Request: Non-Quantized
Simulations and Results
Conclusion
INTRODUCTION
System Model and Parameters
Proposed Scheme
RT Request
Results and Simulations
Conclusion
Recommendations
Future work