Modem link-property advertisements

Devices and associated applications are increasingly connected to a variety of smart modems that have dynamically varying link characteristics. For example, incoming and outgoing link rates can be varied over time with adaptive coding and modulation to suit the channel characteristics. In addition, those links may go up and down due to a variety of factors. The link rate and conditions offered by the modem to connected devices and associated applications therefore vary. In order to autonomously condition traffic and allow the network to get the most out of the modem´s link capacity, the upstream devices and applications need to be informed of the modem´s link conditions. This becomes a form of cognitive networking. This paper will discuss the problem and present a simple protocol that can be used to provide upstream devices and applications with downstream link conditions. While the protocol in this document is described in the context of modem radio-frequency link properties, it can also be broadly applied to other scenarios such as cryptographic devices.