The Multi-connection Tactile Internet Protocol (MTIP) is a transport protocol for the remote control of Tactile Internet applications. This repository presents models, applications and evaluation results of the protocol. Each folder has its own README.md with additional information. Below, we give an overview of the protocol and API documentation.
MTIP creates a link between two endpoints (typically a remote device and a controller) that consists of several sublinks. Current implementation of MTIP offers a C/C++ API described as follows.
This section presents the API functions in a typical order of usage.
int mtip_socket(int options)
- @param options: OPT_NOT_FULLMESH (Disable connection fullmesh), OPT_NOT_MONITOR (Disable MTICP), OPT_FULL_DEBUG (Disable debug information).
int mtip_bind(int sd, char *addr, int port)
int mtip_link(int sd, uint8_t mode, char *addr, int port)
- @param mode: Controller (to connect), Device (to listen).
int mtip_preferences(int sd, char *prefs)
- @param prefs: Go to Context Information section.
mtip_receive(int sd, void (*callback)(char *, double))
- @param char *: message data.
- @param double: timestamp information.
int mtip_finished(int sd, void (*callback)())
int mtip_send(int sd, char *message, int flag)
- @param flag: FLAG_DATAPRIO (Data with priority), 0 (Normal data).
int mtip_feedback(int sd, char *&feedback, int type)
- @param feedback: Go to Context Information section.
- @param type: GENERAL (Characterization of each sublink).
int mtip_close(int sd)
Context information refers to the communication preferences that can be set in mtip_preferences and the feedback information that can be retrieved from mtip_feedback.
The application can set the following communication preferences:
| Communication preference | Description | Accepted values in current implementation | Default value in current implementation |
|---|---|---|---|
| Algorithm mode (AM) | It selects the algorithm that is going to be used for the selection of sublinks. The sublinks might be selected by the application (fixed selection) or dynamically by the protocol. | 0: Use all sublinks (fixed selection) 1: Use one sublink (fixed selection) 2: Use best (N) sublinks (dynamic selection) 3: Use the MTIP Algorithm (dynamic selection) | 0 |
| Number of sublinks (N) | It selects the sublink that is in use (in the case of AM 1) or the number of sublinks that should be in use (in the case of AM 2). | 0 to the maximum number of sublinks available | 0 |
| Maximum latency (deadline) | It defines the maximum end-to-end latency of the packets, namely the deadline | 0 to 1e9 nanoseconds | 1e7 nanoseconds |
| Duplicate threshold (DT) | It defines the maximum percentage of duplicate packets that the MTIP algorithm considers reasonable (only used in AM 3). | 0 to 100 % | 50 |
| Loss-late threshold (LT) | It defines the maximum percentage of loss or late packets that the MTIP algorithm considers reasonable(only used in AM 3). | 0 to 100 % | 10 |
| Latency weight (LW) | It defines how the sublink ranking must be calculated, using just reliability measurements (LW 0), using only latency measurements (LW 100), or using a weighted mean of both measurements (LW from 0 to 100). | 0 to 100 % | 100 |
The application can obtain the following feedback information:
| Feedback | Description | Values in current implementation |
|---|---|---|
| Sublink | It indicates the network information on the available sublinks. | Sublink ID, IP addresses and ports |
| Latency (ingress) | It indicates the measured latency (ingress) in each sublink. | Latency in nanoseconds |
| Latency (egress) | It indicates the measured latency (egress) in each sublink. | Latency in nanoseconds |
| Reliability (ingress) | It indicates the measured reliability (ingress) in each sublink | Reliability in the percentage of packets sucessfully forwarded to the application |
| Reliability (egress) | It indicates the measured reliability (ingress) in each sublink | Reliability in the percentage of packets sucessfully forwarded to the application |
To showcase an example of the use of MTIP API, Applications/ presents a remote control application and a controlled device application.