# Cross-Layer Methods for Ad Hoc Networks--Review and Classification
## 3 Cross-Layer Method Publications Review
### Multiple Layers
#### 3.2.2 Independent Layers and Information Sharing
[107] propose a cross-layer approach that controls the transmission power, signal constellation size and channel access time depending on packet transmission rate, QoS requirements, power constraints and channel state. The authors' technique helps to deal with the divergence problem of the traditional power control and facilitate the execution of scheduling in a distributed manner; a power control algorithm with adaptive SINR was adopted. The authors simplified the scheduling by automatically implementing it in the power control phase after solving the \"transmit-receive collision\". [PERSON] et al. [108] consider a cross-layer approach using virtual MISO. In virtual MISO, multiple nodes jointly form a virtual antenna system for transmission and transmit information to a single node. For this purpose, nodes in visibility of each other are used. When one of the nodes in the group of virtual MISO receives a packet, the node distributes the packet to the nodes in the group and then the nodes in the group send the packet to the next recipient. Sending to the group may cause more interference, but the gains from the virtual antenna system can be greater. Authors state that throughput can be increased by a factor of 1.5, delivery delay can be reduced by up to 75 percent, and the number of attempts to find new routes after breaking links can be reduced by up to 60 percent. The cross-layer approach consists of several things. In the case of the network layer, routes are first searched using the usual routing protocol; then the found route is checked if there are MISO links and if the route nodes are part of MISO groups, the route is rebuilt using this information with potentially fewer hops and more stable links due to the spatial separation of MISO. The physical layer receives information from the channel layer that the transmitter is part of the virtual antenna system. [PERSON] et al. [109] propose a joint optimization of the selection of the data flow rate at the transport layer and the probability of sending a packet at the channel layer--the channel layer chooses whether or not to transmit a packet with some probability depending on the channel load. [PERSON] et al. [13] optimize the UAV network parameters depending on the height and angle of the drones. UAVs can alternately use an omnidirectional antenna and a narrow directional antenna. The use of a narrow directional antenna is necessary when the UAV is at high altitude and the line budget does not allow the use of wide directional antennas. Each UAV has two directional antennas with main lobe rotation (one for communication in the down direction (in a geometrical sense), another for communication in the up direction) and two omnidirectional antennas. The UAVs also use GPS and an inertial navigation system to orient the antennas. The UAVs transmit their coordinates and orientations in space to each other based on the coordinates and orientation, and the antennas can be properly pointed toward the receivers. The authors use the OLSR routing protocol for omnidirectional antennas and a modification of the OLSR protocol for directional antennas. In this modification, the routing protocol learns the properties of directional antennas and the coordinates and orientations of the nodes. [PERSON] et al. [110] propose the optimization of link delay and power consumption through joint congestion control at the transport layer, channel layer queuing control, transmission speed control, and power control at the physical layer. The control is performed at different time scales. Very often at the physical layer, since signal fading can change rapidly, the average frequency for the channel layer is determined at time intervals proportional to the length of the channel packet, and the transport layer controls congestion at time intervals in seconds. Routing is not considered in the paper. [PERSON] et al.