Overcoming the Challenges of Wireless Networking

Wireless networking poses unique challenges when compared to traditional networking. Two issues in particular are at the heart of these difficulties: every act of communication involves broadcasting and packet loss is much more frequent and dynamic. The broadcasting nature of wireless networks means that the medium of communication, air, is precious, as it must be shared by everyone. Also, it is very difficult for nodes to know whether or not adjacent nodes are available for communication, since an adjacent node may be busy communicating with a third node that the first node can't detect. Lastly, the packet loss characteristics of wireless communication in combination with TCP can lead to uneven resource availability and even full starvation, especially with multi-hop communication.

That said, researchers have applied their creative intellects to making the best of a fairly harsh networking environment. For instance, one paper proposed a change to a core multi-hop network to cause nodes in a network to work together to enforce fairness constraints at each hop of the network. While the algorithm could slightly reduce overall bandwidth utilization, it significantly reduced resource starvation and uneven resource usage between nodes. In another paper a group of researchers proposed that multiple packets be encoded together at once by XOR-encoding packets together. This method requires nodes to remember recent packets they have heard, as well as track other neighbor state, but could result in as much as 4x improvements in bandwidth usage. Lastly, we learned of a proposed technique to allow nodes to cooperate with another in sending a packet across a multi-hop network. When a node fires a batch of packets, all capable listeners are enabled to assist those packets in traversing the network, so that even if the original next-hop destination failed to hear some packets nearby neighbors could pass on the packets for it.

These innovative solutions showed me both just how difficult improving wireless networking and extending its use cases can be. At the same time, it showed me that difficult problems can provide fertile ground for creative thinkers to apply themselves.