Читать книгу Wireless Connectivity - Petar Popovski - Страница 32

1 State machine for a TDMA system. Describe a possible state machine through which the devices and the base station implement the protocol from Figure 1.7.

2 An even more practical state machine. Extend the state machine from the previous model in order to make the protocol practical, such as introduction of timeout mechanisms, dealing with device mobility, etc.

3 More than one rendezvous channel. Assume that there are different rendezvous channels. Two nodes can establish a link only if one of them sends and the other one receives on the same channel. At a given time, a device can use only one channel. Devise a strategy for establishing a link between two devices and try to compare its performance to the case when there is a single rendezvous channel. When and why would it be useful to have channels for rendezvous?

4 Unequal slots. Consider a generalization of a frame, which consists of a header, followed by communication resources. However, now assume that the communication resources are not organized into equal slots and instead the frame can contain slots with different lengths. Discuss how does this affect the type and amount of signaling bits used in the header.

5 Reservation with variable number of data slots. The analysis in Section 1.4.3 is done for the case in which the number of data slots following the reservation slots is fixed. Let us now consider the case in which is variable and adapted to the actual number of resources required in the reservation slots. Assume that each of the devices can request up to resources through the reservation packets.Find the number of bits that are required in the reservation packets and the allocation packet.Using the assumptions for bit duration from Section 1.4.3, find the maximal throughput that can be offered in a given frame. NB: the maximal throughput depends on the amount of resources requested by the devices.In practical systems, the allocation packet A may not be received by some of the devices due to errors caused by noise or interference. When is the impact of not receiving A worse, when is fixed or when is variable? How do you suggest to design the system to be more robust to this type of error?