How the Power Save Operation performs in LTE?

Question

As we know the data rates in LTE is 50 times than 3G but the UE's battery size is still same. So how LTE is taking care of this?

Answer 1

the major of UE battery power consuming comes from transmitting on Uplink direction, the following points may be the answer of your question:

1- SC-FDMA technique has high spectral effciency compared to CDMA, so higher throughputs can be achieved.

2- In LTE, Discontinuous Reception (DRX) has been introduced as one of the key solutions to conserve battery power in mobile terminal, this is an advantages of Packet switching over Circuit switching that in packet switching Radio resources assigned only when IP layer has a packet ready to be sent, these is accomplished on RRC Layer which has two modes (RRC_CONNECTED and RRC_IDLE).

3- in addition, eNodeB use Power control which can reduce UE transmission power.

Answer 2

Hi,
Lets cut to the chase..
by being always connected but only on the Core side, the radio resources are being torn down when there is an inactivity (no down/up traffic) detected.
Then the UE only listens to a "common channel" in case there is a Downlink Data Notifiaction for this subsc.

This is probably one out of many, but as I always say, I'm not radio person.

Answer 3

Though it is always connected in LTE but to save the power it can turn off the radio for the possible time. The modem can be turned off most of the time while the mobile device stays connected to the network with reduced throughput. The receiver is turned on at specific times for updates. Devices can quickly transition to full power mode for full performance and Some of the changes is required in Hardware, UE system architecture and few has been taken care by the protocol. I hope this is how we can save the Power.

Answer 4

My take on this query -
While designing the LTE specs planner has picked SC-FDMA for uplink to save the battery usage as sleek phone and low power was one of the critaria of LTE design. OFDMA has high PAPR i.e. higher power consumption so was avoided for uplink (for the downlink energy was consumed at eNodeB for uplink at the handset).

Answer 5

Connected Mode DRX (also called C-DRX) is implemented in LTE to save battery life in connected mode in addition to idle mode DRX conventionally used in other systems like WCDMA.