In 5G and 6G, a user device is expected to perform an arduous blind search in each downlink control space to detect its DCI (downlink control information) messages. To save energy and complexity, especially for reduced-capability IoT applications, low-complexity procedures are disclosed that enable each user to request a custom search-space comprising one or more specific times and frequencies. Each downlink control or data message then starts in the custom search-space. The data or control messages may include the user's ID code, in plain text (as opposed to complex encoding) and/or the length of the message, so that the user can readily identify its messages. The user device may thereby readily separate its messages from the stream of incoming data. Result: saved time and energy, fewer dropped messages, and generally improved network performance, especially for simpler processors and devices.