The emergence of Wireless Sensor Networks (WSN) as one of the dominant technology trends in the coming decades has posed numerous challenges for researchers. These networks are likely to be comprised of hundreds, and potentially thousands of tiny sensor nodes, functioning autonomously, and in many cases, without access to renewable energy resources. While the set of challenges in sensor networks are diverse, we focus on fundamental networking challenges (routing) in sensor networks. Routing in WSN is very challenging due to the inherent characteristics that distinguish these networks from other wireless networks like mobile ad hoc networks or cellular networks. In this paper we present a routing algorithm used by WSN, Sensor Protocols for Information via Negotiation (SPIN). This algorithm is a multi hop flat routing protocol and is data centric. This protocol motivated the design of many other protocols which follow a similar concept. Advantages and performance issues of the algorithm is also highlighted.
Keywords: Wireless Sensor Networks, Data centric Routing, Sensor Protocols for Information via Negotiation
[...] We refer to the descriptors used in SPIN negotiations as meta-data. In SPIN, nodes poll their resources before data transmission. Each sensor node has its own resource manager that keeps track of resource consumption; applications probe the manager before transmitting or processing data. This allows sensors to cut back on certain activities when energy is low, e.g., by being more prudent in forwarding third-party data. It also allows sensors to take resource tradeoffs into account when making decisions. For example, a SPIN node may decide to send a piece of data unconditionally, without any negotiation, if it believes that the associated costs of sending the data are less than the costs of negotiating for it. [...]
[...] Upon receiving an ADV packet from node node B checks to see whether it possesses all of the advertised data If not, node B sends an REQ message back to listing all of the data that it would like to acquire When node A receives the REQ packet, it retrieves the requested data and sends it back to node B as a DATA message Node in turn, sends ADV messages advertising the new data it received from node A to all of its neighbors It does not send an advertisement back to node because it knows that node A already has the data. These nodes then send advertisements of the new data to all of their neighbors, and the protocol continues. Figure The SPIN-PP Protocol Although this protocol has been designed for lossless networks with symmetric communication links, it can easily be adapted to work in lossy or mobile networks. [...]
[...] If not, it forwards a copy of the data to all of its neighbors and updates the record. This is therefore a straightforward protocol requiring only a small amount of protocol state at any node, and it disseminates data quickly in a network where bandwidth is not scarce and links are not loss-prone. Three deficiencies of this simple approach render it inadequate as a protocol for sensor networks: Implosion: In classic flooding, a node always sends data to its neighbors, regardless of whether or not the neighbor has already received the data from another source. [...]
[...] Maintains only local information about the nearest neighbors. Suitable for mobile sensors since the nodes base their forwarding decisions on local neighborhood information 4.7 DISADVANTAGES It cannot isolate the nodes that do not want to receive information; unnecessary power may be consumed. SPIN's data advertisement mechanism cannot guarantee the delivery of data. Figure SPIN-BC Protocol The disadvantage of such networks is that whenever a node sends out a message, all nodes within transmission range of that node must pay a price for that transmission, in terms of both time and energy. [...]
[...] As a result, when a node sends out a message in a lossless, symmetric broadcast network, it is received by every node within a certain range of the sender, regardless of the message's destination. SPIN-BC improves upon SPIN-PP for broadcast networks by exclusively using cheap, one-to-many communication. This means that all messages are sent to the broadcast address and thus processed by all nodes that are within transmission range of the sender. Like the SPIN-PP protocol, the SPIN-BC protocol has an ADV, REQ, and DATA stage, which serve the same purpose as they do in SPINPP. There are three central differences between SPIN-PP and SPIN-BC. [...]
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