Enhanced Channel Access

TX Parameters of a Conventional Channel with Enhanced Channel Access circled red.

Enhanced Channel Access (ECA) is a Motorola Solutions proprietary feature that improves the reliability of transmissions by minimizing over the air collisions when two or more radios attempt to initiate a call simultaneously.

It is a channel access procedure where a call-initiating radio transmits a channel access request and then listens on the channel to determine the request's status. The radio proceeds with the call transmission only after it obtains access to the channel. ECA provides the ability to reserve a channel for one of the call-initiating radios, granting exclusive access for a short duration.

Enhanced Channel Access works by performing a high-speed handshake with the repeater, which takes approximately 120 milliseconds to complete. This handshake helps to reduce the number of collisions between radios transmitting data.

To enable it, the Admit Criteria setting in the channel or personality needs to be set to either Channel Free or Color Code Free and Enhanced Channel Access. If set to Always, the procedure is not applied.

Data and CSBK calls are always considered polite transmissions, regardless of the configured Admit Criteria, so ECA is applied during their transmission if enabled. However, enabling ECA can slightly increase system/voice access times for voice calls and latency for data/CSBK calls. It also minimizes the impact of voice transmissions colliding with Over-The-Air Programming (OTAP) data, making it advisable to enable ECA on all radios in the system if OTAP is used.

Applicability and Limitations

Enhanced Channel Access is available in Single Site Conventional mode IP Site Connect mode. Enhanced Channel Access is not required in Capacity Plus Single Site or Capacity Plus Multi Site modes because their call setup processes implicitly include ECA. In these modes, ECA is built into the Capacity Plus Trunked Channels and is not user-configurable. Also, for Capacity Plus Data Revert Channels, ECA is supported by the repeater when enabled in the radio, but not on Enhanced GPS channels.

A repeater supports ECA on conventional digital channels and IPSC Local Area Channels (LACs)/Wide Area Channels (WACs) when enabled in the radio. However, the repeater does not support ECA on Enhanced GPS and Dual Capacity Direct Mode channels.

When the Enhanced GPS feature is enabled on a channel, ECA is disabled and not required because each radio transmits during an assigned time window. ECA is also supported in Extended Range Direct Mode to minimize transmission collisions. For phone calls across all system configurations, ECA is enabled by default to achieve optimal performance. It is recommended to enable ECA on all radios accessing the channel for maximum benefit. For correct and reliable operation, it is strongly recommended to upgrade the repeater firmware version to R01.08.00 or later before initiating calls with ECA enabled on the radio. If ECA is enabled on a Capacity Plus Data List, members of the list cannot have Enhanced GNSS activated, as this configuration would be invalid.

See Also

• TX Admit Criteria