taken by a data packet to travel from its source to its destination. Latency is particularly important in some network services such as voice and video streaming, where transmission delays can seriously reduce the quality of service to the end user. Line-of-Sight (LOS): Line-of-sight refers to an unobstructed line between transmitting and receiving stations. Line-of-sight is required for any wire- less link for frequencies above ca. 11 GHz. When setting up long distance wireless links, a line-of-sight survey can be used to assess whether one aerial can be "seen" by another. Glossary Link Margin: The excess available power, over and above that required by the link budget, to achieve a desired received signal strength and SNR at the receiver. Local Area Network (LAN): A network used to link computers and other devices such as printers over short distances, typically tens of metres to a few hundred metres. The most common LAN technologies are 100 BaseT Ethernet for wired and 802.11b/g or Wi-Fi for wireless networks. Low Density Parity Check Codes: LDPC codes are error correction codes that are computationally efficient and perform close to the theoreti- cal limit in enabling error recovery in noisy communication channels. A check code is computed from a data block by sparsely sampling bits in the block using a random sampling matrix. For example, the first bit in the check code may be defined as y1 = X1 + X3 + 8 + 9 + 10, where the sum is modulus 2. The check code enables lost bits in the received data block to be recovered with high efficiency. MAC Service Access Point (MAC SAP): The MAC SAP is the logical point at the "top" of the MAC layer, where the MAC interfaces with the Network layer and higher layers in the OSI model. The MAC SAP is taken as a reference point when specifying the effective data rate of a network, as distinct from the data rate transmitted at the PHY layer. Manchester Coding: Manchester code is a data encoding method in which each bit or chip of data is represented by a transition between two 