A wireless mesh network is a mesh network implemented over a wireless network system such as wireless LANs. Wireless Mesh Networks(WMNs) are promising for numerous applications such as broadband home networking, enterprise networking, transportation systems, health and medical systems, security surveillance systems, etc. Therefore, it has received considerable attention from both industrial and academic researchers. This dissertation explores schemes for resource management and optimization in WMNs by means of network routing and network coding. In this dissertation, we propose three optimization schemes. (1) First, a triple-tier optimization scheme is proposed for load balancing objective. The first tier mechanism achieves long-term routing optimization, and the second tier mechanism, using the optimization results obtained from the first tier mechanism, performs the short-term adaptation to deal with the impact of dynamic channel conditions. A greedy sub-channel allocation algorithm is developed as the third tier optimization scheme to further reduce the congestion level in the network. We conduct thorough theoretical analysis to show the correctness of our design and give the properties of our scheme. (2) Then, a Relay-Aided Network Coding scheme called RANC is proposed to improve the performance gain of network coding by exploiting the physical layer multi-rate capability in WMNs. We conduct rigorous analysis to find the design principles and study the tradeoff in the performance gain of RANC. Based on the analytical results, we provide a practical solution by decomposing the original design problem into two sub-problems, flow partition problem and scheduling problem. (3) Lastly, a joint optimization scheme of the routing in the network layer and network coding-aware scheduling in the MAC layer is introduced. We formulate the network optimization problem and exploit the structure of the problem via dual decomposition. We find that the original problem is composed of two problems, routing problem in the network layer and scheduling problem in the MAC layer. These two sub-problems are coupled through the link capacities. We solve the routing problem by two different adaptive routing algorithms. We then provide a distributed coding-aware scheduling algorithm. According to corresponding experiment results, the proposed schemes can significantly improve network performance.

As an increasing position of the world’s communication moves towards the cloud and wireless solutions the requirement for good throughput and low delay increases. One step towards meeting higher requirements is the move from 4G Long Term Evolution (LTE) to 5G New Radio (NR). In order to utilize the potential of 5G NR, software needs to be improved. With the goal to lower the delay for delay critical applications and services when using 5G NR this thesis studies a new scheduler inspired by Earliest Deadline First (EDF) as a soft real-time system scheduler. This new scheduler called Real-Time Inspired Hybrid Scheduler (RTIHS) is proposed where two different schedulers are used depending on if the network traffic is delay critical or not. Delay critical traffic is served by the new Deadline Inspired Scheduler (DIS) scheduler and other traffic by a traditional Round Robin (RR) scheduler. The transmissions that are delay critical are prioritized differently with the use of a constant that has two functions. To determine if the transmission is in time or not, and how close the transmission is to the fixed deadline. Up until the deadline the priority of that transmission is increased with a factor that is affected by how close the current time is to the deadline. If the deadline has been missed the priority is, however, decreased with respect to how much it missed the deadline.RTIHS is implemented and tested in a state-of-the-art system simulator where services such as;Cloud Gaming (CG), Video on Demand (VoD), and web browsing are evaluated. An already existing technology named Low Latency Low Loss Scalable Throughput (L4S) is included in the evaluations to investigate how RTIHS scales. The performance of RTIHS is then compared to a Delay Scheduler(DS) and a RR scheduler that act as the baseline. The results show that RTIHS performs better for CG in terms of delay and nominal rate than the baseline, especially when the network is under high load. Using RTIHS compared to a DS shows an average increase of nominal rate by roughly 6 % and an average decrease of delay by 16 % for the average users. At the same time RTIHS does show higher delay and lower throughput for services such as VoD and web browsing, making its performance for those service worse than the baseline, especially when the network load is high. With the same comparison as before, RTIHS shows an average 17 % higher delay for web browsing and 1 % lower requested video rate than the DS for the average users. This is due to how the evaluated services are prioritized with the limited resources available. Since RTIHS prioritizes CG more, less resources remain for the other services. The baseline is not as biased towards CG and therefore has a lower nominal rate and higher delay for said service but better for the other services in comparison. Activating L4S mitigates the underwhelming performance of RTIHS for VoD and web browsing further improves the performance for CG. This is also true for the baseline which increases performance for CG and further increases the performance for other services with a small amount. With L4S activated the average increase of nominal rate in CG for RTIHS compared to the DS is 13 % for the average users and the average delay decrease is 9 %. Meanwhile the average requested video rate for RTIHS is less than 1 % lower than that of the DS for the average users and the delay for web browsing is 10 % higher than the DS for the average users.

Ethernet Switches are widely used in real-time distributed systems as a solution to guarantee the real-time behavior in communication. In this solution there are still some limitations which are the important obstacles obtaining timeliness in the network. These limitations are the limited number of priority levels as well as the possibility of memory overruns with consequent messages. The mentioned limitations can be eliminated using a master/slave technique along with FTT paradigm. The FTT-SE protocol which is a technique based on the master/slave and FTT methods was proposed to overcome the mentioned limitations. However, the FTT-SE protocol has been investigated for a small network architecture with a single switch and master node. Extension of this solution to larger networks is still an open issue. Three different architectures were suggested to scale the FTT-SE to large scale network. In this thesis we propose a solution that extends the FTT-SEprotocol while keeping the real-time behavior of the network. In this solution, we divided the network into a set of sub-networks, each contains one switch, set of slave nodes and one master node that connected to the associated switch in the network. Moreover, the switches are connected together directly without gateways and form a tree topology network. The solution includes both synchronous and asynchronous traffic in the network. We also show that the timeliness of the traffic can still be enforced. Moreover, to validate the solution we have designed and implemented a simulator based on the Matlab/Simulink which is a tool to evaluate different network architecture using Simulink blocks. All transmission can be visualized by the ordinary Scope block in the Simulink. Moreover, the end-to-end delay for all messages is calculated after the simulation running to show the response time of the network. Furthermore, the response time analysis is done for both synchronous and asynchronous messages in this thesis according to the proposed solution. The results from simulation and the analysis are compared together to validate the investigations.

Networks-on-Chip (NoC) have been proposed to meet many challenges of modern Systems-on-Chip (SoC) design and manufacturing. At the architectural level, a clean separation of computation and communication helps integration and verification. Networking abstraction of the communication infrastructure also promotes reuse and fast development. But the benefit is most visible when it comes to circuit and physical design. Networks can be made sparse and regular and thus facilitate placement and route. It is also much easier to reach timing and power closure as NoC shield communication details away from complicating analysis. Last but not the least, networks are flexible at the design stage and adaptable post-silicon. Many techniques of tackling process variation and interconnect failure can be built upon NoC. However, when interconnects are time multiplexed in a NoC, the network’s performance will deteriorate if it is not scheduled properly. For a wide range of applications, the traffic on the network can be determined before run-time and offline scheduling offers guaranteed performance and enables simple design. We propose a synthesis flow that takes the data flow graph of the application and a network topology as inputs; and outputs an offline schedule that can be deployed directly to the NoC. We analyze the complexity of combinatorial problems that arise from this context and provide efficient heuristics when polynomial time algorithms are not available assuming P [not equal to] NP. Results on LDPC decoding and FFT designs are compared with previous ones. We further apply our findings to parallel shared memories (PSM) and formalize the PSM architecture and its scheduling problem. An efficient heuristic is derived from our algorithm for unbuffered networks. Another application exemplifies how the NoC can be reprogrammed after silicon is back from fab in order to avoid failed interconnects due to process variation. A simple statistical model is studied and the simulation result is rather interesting. We find out that high performance and yield are not always at conflict if we are able to change the network schedule based on silicon diagnosis. / text