Computational geometry : theory and applications.

This paper proposes a novel scheme for the design of topology-transparent scheduling (TTS) in mobile ad hoc networks (MANETs), based on the Chinese remainder theorem (CRT). TTS can provide each node with guaranteed success in each schedule without any detailed topology information and yields a guaranteed upper bound on the transmission delay of each packet at every node in a MANET. In general, TTS requires two global constraints on the number of nodes in the MANET and the maximum nodal degree of the graph representing connectivity of the MANET. Due to the inherent mobility of MANETs, the maximum nodal degree, however, cannot be available or easily estimated. To eliminate the requirement for the maximum nodal degree, this paper proposes TTS via the CRT. By the redundancy property of the Chinese remainder representation, the proposed CRT-based scheme not only preserves the advantages of providing guaranteed success in each schedule with only the global constraint on the number of nodes in the MANET, but also offers flexibility in constructing TTS. To have a better transmission delay bound for a node with lower interference, this paper also introduces two threaded counterparts of the proposed CRT-based scheme. This paper provides performance analyses for the proposed CRT-based scheme and its threaded counterparts. Numerical results demonstrate that TTS via the CRT can outperform existing schemes, especially in scenarios with harsh interference, and is a versatile approach for the design of TTS.

Topology-transparent scheduling via the Chinese remainder theorem

Broadcasting is a key function in mobile ad hoc networks. Topology-dependent scheduling algorithms depend on the detailed network connectivity information and cannot adapt to dynamic topological changes in mobile networks. To overcome this limitation, topology-transparent broadcast scheduling algorithms have been proposed. Due to the large overhead of implement- ing the acknowledgement mechanism in broadcast communica- tions and to guarantee that there is at least one collision-free transmission in each frame, most existing topology-transparent broadcast scheduling algorithms require a node to transmit the same packet repeatedly at multiple slots during one frame. This is very inefficient. In this paper, we propose an efficient topology- transparent broadcast scheduling algorithm. First, instead of transmitting the same packet repeatedly during one frame, each node collects transmission codes of its two-hop neighbors and transmits several different packets during one frame. Second, noting that many unassigned slots are not utilized, we propose several methods to utilize the unassigned slots efficiently in a collision-free and traffic-adaptive manner. Thus, our algorithm provides a guaranteed throughput and achieves a much better average throughput. The analytical and simulation results show that our proposed algorithm outperforms other existing topology- transparent broadcast algorithms dramatically.

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Performance Improvement of Topology-Transparent Broadcast Scheduling in Mobile Ad Hoc Networks

We present a novel geographical routing scheme for spontaneous wireless mesh networks. Greedy geographical routing has many advantages, but suffers from packet losses occurring at the border of voids. In this paper, we propose a flexible greedy routing scheme that can be adapted to any variant of geographical routing and works for any connectivity graph, not necessarily Unit Disk Graphs. The idea is to reactively detect voids, backtrack packets, and propagate information on blocked sectors to reduce packet loss. We also propose an extrapolating algorithm to reduce the latency of void discovery and to limit route stretch. Performance evaluation via simulation shows that our modified greedy routing avoids most of packet losses.

Efficient Greedy Geographical Non-Planar Routing with Reactive Deflection

The aim of topology-transparent scheduling in multi-hop packet radio networks is to find a schedule for the nodes in such a way that the schedule of the existing nodes need not be recomputed when the network topology changes. It caters to highly dynamic scenarios where topology changes occur faster than the speed at which schedule updates can be orchestrated. Hence, the scheduler is typically expected to use only global network parameters like upper bounds on the number of nodes in the network and on the maximum degree of any node in the network. The problem is non-trivial if there are restrictions on the frame length or the minimum throughput of a node in a frame. Over the years, several innovative solutions have been proposed using a variety of mathematical techniques. We present a lucid tutorial-style survey of the approaches using an integrative taxonomy and a comparative analysis. We also outline a few directions for future research in the field.

A Survey of Topology-Transparent Scheduling Schemes in Multi-Hop Packet Radio Networks

To solve collisions of topology-transparent schedules in multihop ad hoc networks, we propose a topology-transparent schedule with reservation and carrier sense. Our schedule is based on slotted architecture in which each slot is divided into reservation phase and data phase. Each node resolves possible collisions in its assigned slots by reservation and utilizes free ones among its non-assigned slots by carrier sense. By analysis, we derive the optimal parameter for the best performance. Compared results show that our schedule is better than others.

Topology-transparent schedule with reservation and carrier sense for multihop ad hoc networks

The transmission collisions of topology-transparent reservation time division multiple access protocol with MIMO links are solved by dynamically trading off the MIMO link transmission capacity and its anti-interference ability. Through theoretical analysis, we derive the guaranteed throughput and optimal frame length. Results show that the guaranteed throughput will be improved greatly by dynamic allocation of MIMO transmission capacity and its anti-interference ability. Moreover, the protocol is immune to topology change.

Topology-transparent reservation time division multiple access protocol with MIMO links in multihop ad hoc networks

With the development of ad hoc networks, some researchers proposed several geometric routing protocols which depend on the planarization of the network connectivity graph to guarantee the delivery of the packet between any pair of nodes in the network. In this paper, we proposed a new online routing algorithm GLNFR (greedy and local neighbor face routing) for finding paths between the nodes of the ad hoc networks by storing a small amount of local face information at each node. The localized Delaunay triangulation was used to be the backbone of wireless network on which the GLNFR routing algorithm runs. It has the better scalability and adaptability for the change of ad hoc networks. Experiment on NS have been conducted. The results show that the delivery rate of packets and routing protocol message cost under such novel routing protocols performs better than others proposed before.

A novel geographic routing algorithm for ad hoc networks based on localized Delaunay triangulation

This invention discloses a small wave packet multi-carrier amplifying-frequency system based on neural net balancer and its controlling method. The system comprises a transmitting end composed of a quad-rature modulator, a copier, an inverse small wave packet conversion with an amplifying frequency code inserted before; a receiving end composed of multi-radial neural net balance, discrete small wave packet conversion, summer, a maximum likelihood tester and quad-rature modulator; after the conversion, inserting amplifying frequency code WH and sub-belt gain factor. The system owes a control switch to control its dislocation to realize using LMS method to renewing weight of multiradial neural net balancer and the communication of the sender and receiver, including channel balance, amplifying frequency, small wave packet multi-carrier adjusting, modulation and ML testing decision.

Lei Zhou

Papers

Topology-transparent schedule with reservation and carrier sense for multihop ad hoc networks

Topology-transparent reservation time division multiple access protocol with MIMO links in multihop ad hoc networks

A novel geographic routing algorithm for ad hoc networks based on localized Delaunay triangulation

Wavelet packet multi-carrier spread-spectrum system and control method based on neural net equalizer

Topology-transparent reservation time division multiple access in multihop ad hoc networks