About
Since the publication of the ALOHA MAC protocol in 1970 the scientific community has proposed a large number of wireless medium access control (MAC) protocols. This results in two issues. Firstly, name collisions: Most of the single-letter abbreviations like L MAC, M MAC, O MAC and so on are already used multiple times, some up to five times. Even two-letter abbreviations like AS MAC are used three times. This makes it harder than necessary to distinguish different protocols purely based on their name. Secondly, it is very likely that some of these publications are (unintentional) reinventions of previous protocols.
Surveys are usually limited to a small subset of protocols due to time constraints and their target medium, printed journals, which limits the page count. They are static in two ways: Once published they cannot be modified or updated. And secondly printed surveys cannot provide interactivity like feature-based filtering and searching. Additionally their results are not reusable and extendable since they are not machine-readable.
The comprehensive MAC taxonomy database (comatose), aims to fix these problems. It lists most known scientific MAC protocol proposals including their short and long name, a description and refererences the publication it originated from. Its code is public and open source and thus can be updated whenever new research appears. The database is machine-readable and searchable by humans through a browser interface. It also assigns tags or features to each protocol to aid finding protocols with specific properties. These features are grouped into 13 categories. For some categories features are mutually exclusive.
Channel access
Basic method for channel access, that is how sender and/or receiver decide who is allowed to access the medium.
- Polling
- Base or master station polls slaves, granting them acces to the medium. This is also called receiver-initiated (RI) access.
- Random
- Stations access the medium in a random, uncoordinated fashion.
- Dynamic reservation
- Stations request transmission resources
- Static schedule
- Scheduled access to the medium.
- Token-passing
- Permission to speak is granted by the node who previously held it (the “token”) with no fixed master involved.
Applications
Target applications the protocol was designed for or explored with.
- Serial console
- Industrial
- Underwater
- Vehicular mobile ad hoc network
- Wireless Sensor Network
Channel usage
- Multi
- Multiple radio channels are used.
- Single
- Only a single radio channel is used.
Deployment
How and when stations or the whole network is deployed.
- Ad-hoc
- Supports joining and leaving of stations in an ad-hoc fashion. Stations may move around.
- Static
- The network is mostly static. Stations are deployed at fixed posititons.
Transmission initiation
- Receiver
- Sender
Other features
- Quality of Service
Powersave mechanisms
- Duty-cycling
- Low-power listening/preamble sampling
Radio
Features of the radio hardware.
- Carrier sense
Real-time
- Guaranteed
- Worst-case latency is bounded.
- Probabilistic
- Protocol was designed with latency in mind and tries to reduce it, but an upper bound cannot be guaranteed.
Reliability
Mechanisms employed that increase transmission reliability.
- Channel hopping
- Radio channels are switched frequently in pseudorandom fashion, avoiding collisions and jamming.
- Error correcting codes
- Telegrams contain redundant information allowing recovery of (some) corrupted bits.
- Retransmission
- Packets will be acked/nacked by the receiver and retransmitted in case of an error.
Routing
- Broadcast
- Multicast
- Unicast
Time model
- Continuous
- Continuous time without synchronization.
- Discrete
- Discrete time, which usually requires some form of time synchronization.
Topology
The network’s topology.
- Centralized
- Star topology with a single, central gateway.
- Clustered
- Multi-Hop
- MAC transports data through multiple hops.
- Single-Hop
- MAC relies on upper layers to transmit packet to out-of-range stations.
Implementation
Comatose uses two separate databases. The first one contains basic information about a protocol, like name, description and features, in a YAML file. This file format is human and machine-readable at the same time and thus easy to maintain. Additional software like an SQL database server is not required. The second database is a standard BibTeX file. Since TeX is used for a lot of scientific publications these records usually exist already and can be copied, as well as reused for new publications. Therefore, both databases should provide value beyond the scope of this project.
Contributing
As mentioned earlier, this database is not an exhaustive list of MAC protocols as long as new protocols are invented. Due to the large number of protocols listed some of them are still lacking descriptions and tags. If you want to help send an email with your suggestions or clone the repository from GitHub, edit the database and create a pull request.
Acknowledgements
This work has been partly funded by the German Federal Ministry of Education and Research (BMBF) within the project “TreuFunk” (grant number 16KIS0236).
If you want to cite this work use either the URL of this document https://6xq.net/comatose/ or doi:10.4119/unibi/2918509.
References
- Wireless medium access control protocols, , 2000
- A survey, classification and comparative analysis of medium access control protocols for ad hoc networks, , 2004
- MAC protocols for wireless sensor networks: a survey, , 2006
- Comparison of Multichannel MAC Protocols, , 2008
- The MAC Alphabet Soup, , 2010
- MAC Essentials for Wireless Sensor Networks, , 2010
- Analyzing MAC Protocols for Low Data-rate Applications, , 2010
- A Survey of MAC Protocols for Mission-Critical Applications in Wireless Sensor Networks, , 2012
- A Survey and Projection on Medium Access Control Protocols for Wireless Sensor Networks, , 2012
- Survey on Latency Issues of Asynchronous MAC Protocols in Delay-Sensitive Wireless Sensor Networks, , 2013
- An Industrial Perspective on Wireless Sensor Networks – A Survey of Requirements, Protocols, and Challenges, , 2014