You can find an extensive evaluation of this implementation in our paper [*Orchestra: Robust Mesh Networks Through Autonomously Scheduled TSCH*](http://www.simonduquennoy.net/papers/duquennoy15orchestra.pdf), ACM SenSys'15.
## Features
This implementation includes:
* Standard IEEE 802.15.4e-2012 frame version 2
* Standard TSCH joining procedure with Enhanced Beacons with the following Information Elements:
/* TSCH uses explicit keys to identify k1 and k2 */
#undef LLSEC802154_CONF_USES_EXPLICIT_KEYS
#define LLSEC802154_CONF_USES_EXPLICIT_KEYS 1
/* TSCH uses the ASN rather than frame counter to construct the Nonce */
#undef LLSEC802154_CONF_USES_FRAME_COUNTER
#define LLSEC802154_CONF_USES_FRAME_COUNTER 0
```
The keys can be configured in `net/mac/tsch/tsch-security.h`.
Nodes handle security level and keys dynamically, i.e. as specified by the incoming frame header rather that compile-time defined.
By default, when including security, the PAN coordinator will transmit secured EBs.
Use `tsch_set_pan_secured` to explicitly ask the coordinator to secure EBs or not.
When associating, nodes with security included can join both secured or non-secured networks.
Set `TSCH_CONF_JOIN_SECURED_ONLY` to force joining secured networks only.
Likewise, set `TSCH_JOIN_MY_PANID_ONLY` to force joining networks with a specific PANID only.
## TSCH Scheduling
By default (see `TSCH_SCHEDULE_WITH_6TISCH_MINIMAL`), our implementation runs a 6TiSCH minimal schedule, which emulates an always-on link on top of TSCH.
The schedule consists in a single shared slot for all transmissions and receptions, in a slotframe of length `TSCH_SCHEDULE_DEFAULT_LENGTH`.
As an alternative, we provide Orchestra (under `apps/orchestra`), an autonomous scheduling solution for TSCH where nodes maintain their own schedule locally, solely based on their local RPL state.
Orchestra can be simply enabled and should work out-of-the-box with its default settings as long as RPL is also enabled.
See `apps/orchestra/README.md` for more information.
Finally, one can also implement his own scheduler, centralized or distributed, based on the scheduling API provides in `core/net/mac/tsch/tsch-schedule.h`.
## Porting TSCH to a new platform
Porting TSCH to a new platform requires a few new features in the radio driver, a number of timing-related configuration paramters.
The easiest is probably to start from one of the existing port: `jn516x`, `sky`, `z1`.
### Radio features required for TSCH
The main new feature required for TSCH is the so-called *poll mode*, a new Rx mode for Contiki radio drivers.
In poll mode, radio interrupts are disabled, and the radio driver never calls upper layers.
Instead, TSCH will poll the driver for incoming packets, from interrupt, exactly when it expects one.
TSCH will check when initializing (in `tsch_init`) that the radio driver supports all required features, namely:
* get and set Rx mode (`RADIO_PARAM_RX_MODE`) as follows:
* enable address filtering with `RADIO_RX_MODE_ADDRESS_FILTER`
* disable auto-ack with `RADIO_RX_MODE_AUTOACK`
* enable poll mode with `RADIO_RX_MODE_POLL_MODE`
* get and set Tx mode (`RADIO_PARAM_TX_MODE`) as follows:
* disable CCA-before-sending with `RADIO_TX_MODE_SEND_ON_CCA`
* set radio channel with `RADIO_PARAM_CHANNEL`
* get last packet timestamp with `RADIO_PARAM_LAST_PACKET_TIMESTAMP`
* optionally: get last packet RSSI with `RADIO_PARAM_LAST_RSSI`
* optionally: get last packet LQI with `RADIO_PARAM_LAST_LQI`
### Timing macros required for TSCH
The following macros must be provided:
*`US_TO_RTIMERTICKS(US)`: converts micro-seconds to rtimer ticks
*`RTIMERTICKS_TO_US(T)`: converts rtimer ticks to micro-seconds
*`RADIO_DELAY_BEFORE_TX`: the delay between radio Tx request and SFD sent, in rtimer ticks
*`RADIO_DELAY_BEFORE_RX`: the delay between radio Rx request and start listening, in rtimer ticks
* optionally, `TSCH_CONF_DEFAULT_TIMESLOT_LENGTH`: the default TSCH timeslot length, useful i.e. for platforms
