# Location-Based Deferred Broadcast for Ad-Hoc Named Data Networking
## 2 Related Work
### Existing Work to Mitigate Broadcast Storm in Ad-Hoc NDN  
Selective Broadcast: Protocols typically pre-select eligible forwarders so that the total number of forwarders can be reduced, lead to the reduction of the overall transmission overhead. A direction-selective forwarding strategy [18] is proposed to reduce overhead generated by interest packet forwarding process. Each node chooses the farthest neighbor in each direction to be the next forwarder. The scheme can reduce broadcast overhead significantly. However, it could decrease the hit ratio. Additional control packets are also needed to exchange neighbor information. The latter brings more overhead. [PERSON] et al. proposed Navigo [4], a location based packet forwarding mechanism for Vehicular Named Data Networking (V-NDN) [3]. The scheme guides interests packets towards data producers using a specialized shortest path over the road topology by mapping data names to data locations and forwarding interest packets along the best path. Special selection of forwarders at the intersections allows the interest to cover a large area with the smallest number of hops. [PERSON] et al. proposed a forwarding strategy to unicast instead of broadcast by selecting forwarder based on neighboring forwarding information [19]. [PERSON] and [PERSON] proposed a similar strategy [20]. [PERSON] and [PERSON] proposed a broadcast scheme combining two strategies: a mobility-based forward node selection algorithm selecting less mobile nodes as the forwarders and an available link capacity-based forwarding scheme selecting nodes with larger available link capacities [21]. Probabilistic Broadcast: Each node will have a certain probability to determine whether to be a forwarder. As such, not all the nodes will participate in broadcast. For example, the protocol \"Neighborhood-Aware Interest Forwarding (NAIF)\" achieves a lower bandwidth usage [22] by adjusting the percentage of interest package to be forwarded (forwarding rate) dynamically. It calculates the estimated missed rate based on the overheard forwarding packets. If the missed rate is low or zero, the relay node will continue to decrease forwarding rate. Otherwise, it will increase forwarding rate. In this way, each node reduces forwarding overhead by sharing workload with its neighbors. In another work of [PERSON] [23], each packet is forwarded by considering a counter-based suppression mechanism to reduce the collision probability and limit the broadcast storm. It requires each node, be it a consumer or a forwarder, to keep track of reachable content providers and the distance to them. Deferred Broadcast: In this category, each node will wait on a timer before rebroadcasting an interest. The one with higher forwarding priority will have a shorter waiting timer. While waiting, if a node overhears an incoming interest/data packet that has the same data name as its already scheduled transmission, it cancels its own scheduled transmission because the same interest has been forwarded by another node that has a higher forwarding priority. As a result, only a part of nodes that have higher forwarding priorities actually forward the interest. Thus, the deferred broadcast (or timer-based rebroadcast) mechanism reduces the probabilities of packet collisions and lowers the bandwidth usage. Listen First Broadcast Later (LFBL) [24] is a scheme adopted by some wireless NDN forwarding strategies to address physical mobility of nodes and logical mobility of data for highly dynamic wireless networks. In LFBL, only the nodes closer to a packet destination than the previous sender are eligible to be the forwarders. Eligible forwarders set up waiting timers before forwarding [25], which serves two purposes: collision avoidance and forwarding prioritization. In LFBL, the value of the timer is determined by the distance on the best path to the destination plus a random value. Thus, a receiver closer to the best path will have a shorter waiting timer.