# Modem API Source: [https://docs.qualcomm.com/doc/80-PK177-134/topic/modem.html](https://docs.qualcomm.com/doc/80-PK177-134/topic/modem.html) - **[Link capacity estimation (smart data link)](https://docs.qualcomm.com/doc/80-PK177-134/topic/latency_capacity_estimation.html)** Link capacity esitmation (LCE) provides uplink and downlink capacity estimations. It provides estimated capacity that can be available based on the current used data rate. These APIs are part of smart data link. - **[Link latency manager (smart data flow)](https://docs.qualcomm.com/doc/80-PK177-134/topic/llm.html)** The link latency manager (LLM) subsystem provides the client with APIs, which allow the client to optimize the latency levels. Application vendors can set the LLM level within a given range of L1 to L6 levels for uplink and downlink. For more information, see [level](https://docs.qualcomm.com/doc/80-PK177-134/topic/level.html). Setting a lower latency level can help in latency-sensitive network use cases. These APIs are part of Smart Data Flow. - **[Data path priority (smart data flow)](https://docs.qualcomm.com/doc/80-PK177-134/topic/data_path_priority.html)** The data path priority subsystem provides clients with APIs to control specific flow priority. These APIs are part of Smart Data Flow. - **[Link latency estimation (smart data link)](https://docs.qualcomm.com/doc/80-PK177-134/topic/link_latency_estimation.html)** The linkLatencyEstimate subsystem provides the client with APIs, to get link latency estimations for uplink and downlink. These APIs are part of smart data link. - **[Link layer interruption (smart data link)](https://docs.qualcomm.com/doc/80-PK177-134/topic/link_layer_interruption.html)** The LinkInterrupt subsystem provides the client with APIs to subscribe to link interrupt events. Application vendors can subscribe for link interruption events happening around handoff. These APIs are part of smart data link. Last Published: Nov 14, 2024 [Previous Topic qesdk\_freeFunctionHandle](https://docs.qualcomm.com/bundle/publicresource/80-PK177-134/topics/native_free_function_handle.md) [Next Topic Link capacity estimation (smart data link)](https://docs.qualcomm.com/bundle/publicresource/80-PK177-134/topics/latency_capacity_estimation.md)