Method for mobile closed loop power control adapting to user demand of data services

Abstract

A method for uplink closed loop power control in advanced wireless systems which adaptively adjusts target signal-to-interference noise ratio (SINRtarget) in order to achieve the best uplink throughput of data services is disclosed. To derive the desired target SINR, the system collects and evaluates various uplink parameters as inputs: real-time signal-to-interference noise ratio of data physical channel, terminal power headroom, and terminal buffer data status and data service requirements.

Claims

1. A method of Closed loop power control comprising dynamically adjusting a target signal-to-interference and noise ratio (SINR.sub.target) adapting to data rate change of each of a user equipment (UE), comprising the steps of: choosing Uplink channel information including an average signal-to-interference and noise ratio (SINR.sub.average), Power headroom report (PHR), and Buffer status report (BSR) as the inputs for SINR.sub.target determination.

2. The method of claim 1, wherein an average Uplink data rate (THP.sub.avg) is calculated in a predefined periodicity which is equal to UE's PHR periodicity, where THP.sub.avg is determined by the formula: ${\mathrm{THP}}_{\mathrm{avg}}=\frac{\mathrm{Total}\mathrm{Uplink}\mathrm{data}\mathrm{volumes}\mathrm{in}\mathrm{the}\mathrm{recent}\mathrm{PHR}\mathrm{period}}{\mathrm{Time}\mathrm{to}\mathrm{transfer}}$ Where:
Time to transfer=Time of a PHR periodicity.

3. The method of claim 1, wherein UE data services is classified based on Uplink data rate THP.sub.avg, Where ${\mathrm{THP}}_{\mathrm{avg}}=\frac{\mathrm{Total}\mathrm{Uplink}\mathrm{data}\mathrm{volumes}\mathrm{in}\mathrm{the}\mathrm{recent}\mathrm{PHR}\mathrm{period}}{\mathrm{Time}\mathrm{to}\mathrm{transfer}}$ Where:
Time to transfer=Time of a PHR periodicity.

4. The method of claim 3, comprising two types of UE data services: UEs use low data rate service such as web service, over the top (OTT) apps, ping services and some data feedback for Uplink data transfer; and UEs use high data rate service such as video streaming and data Upload.

5. The method of claim 1, wherein SINR.sub.target for each UE Uplink connection is determined by two processes: The first process: SINR.sub.target for UE requiring low data rate SINR.sub.discrete is defined by a formula (2): $\begin{array}{cc}{\mathrm{SINR}}_{\mathrm{disc}rete}={\mathrm{SINR}}_{OLPC}& \left(2\right)\end{array}$ Where: SINR.sub.OLPC is average SINR when Base Station (BS) uses Open loop power control (OLPC), The second process: SINR.sub.target for UE requiring high data rate (SINR.sub.highThp) is defined by the following steps: Step 1: Prepare inputs including PHR, BSR and SINR.sub.average; Step 2: SINR.sub.highThp must be ensured by the equation (3): $\begin{array}{cc}{\mathrm{SINR}}_{\min }\le {\mathrm{SINR}}_{highThp}\left(i\right)\le {\mathrm{SINR}}_{\max }& \left(3\right)\end{array}$ Where: SINR.sub.min is minimum SINR required that Base Station decodes successful Uplink signal, SINR.sub.max is maximum SINR that can be obtained by formula SINR.sub.max=SINR.sub.avg+PHR; Step 3: Calculate SINR.sub.highThp based on the following algorithm:
SINR.sub.highThpinit=SINR.sub.min, Increase SINR.sub.highThp by Δ.sub.SINR step from SINR.sub.min to SINR.sub.max SINR.sub.highThp(i)=SINR.sub.highThp(i−1)+Δ.sub.SINR, Where Δ.sub.SINR is one step to increase efficient channel (AMC algorithm), Using PHR, BSR, SINR.sub.highThp(i) to estimate data rates at each step, Choosing SINR.sub.highThp at the step with the highest data rates.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a mobile wireless communication system using open loop power control and closed loop power control.

(2) FIG. 2 illustrates the flow diagram of the present closed loop power control system of the present invention.

(3) FIG. 3 illustrates the example results for the disclosed closed loop power control system in a LTE base station: SINR.sub.target is dynamically adjusted following Uplink data rates.

DETAILED DESCRIPTION

(4) FIG. 1 shows the general functions of Uplink Power Control system, which comprises: 100: BS broadcasts common network information and configured parameters to UEs. 101: UE collect input parameters by reading BS's information and measuring received signal power. 102: The UE calculates a transmit power based on inputs from 101. 103: UE transmits uplink data. 104: BS receives uplink signal from UEs. 105: BS measures uplink SINR of signals from UE. 106: BS calculates and adjusts SINR.sub.target 107: BS compares UE's uplink SINR with SINR.sub.target 108: BS calculates and sends TPC to UEs. 109: UE gets and accumulates TPC.

(5) The invention concentrates on Outer-loop CLPC which is illustrated in 106 of FIG. 1: The invention proposes a system for determining SINR.sub.target for each UE to meet the following requirement: all data in UE buffer is transmitted with maximum uplink data rates and minimum power correction steps (or minimum number of transmitting TPCs) corresponding to real-time UE power headroom.

(6) The details of proposed SINR.sub.target determining system is shown in FIG. 2: 201 This module collects UE uplink information from 104 module to provide inputs for 204 module. This inputs includes 3 parameters: SINR.sub.average, Power headroom report (PHR) and Buffer status report (BSR). SINR.sub.average, PHR and BSR are calculated as below: SINR.sub.average: SINR of UE Uplink signals, which is accumulated from the initiation of the uplink connection to the calculated time, the formula is:

(7) $\begin{array}{cc}{\mathrm{SINR}}_{avg}\left(t\right)=\propto *{\mathrm{SINR}}_{avg}\left(t-1\right)+\left(1-\propto \right)*{\mathrm{SINR}}_{inst}\left(t\right)& \left(1\right)\end{array}$ Where: SINR.sub.avg(t): average SINR at “t” time SINR.sub.avg(t−1): average SINR at “t−1” time SINR.sub.inst(t): SINR is measured at “t” time ∝: an adjustable coefficient.

(8) Power headroom report (PHR) is periodically sent by the UE to the BS to indicates how much transmission power left for a UE to use in addition to the power being used by current transmission BSR: indicates how much data in UE buffer to be sent out. The module 202 calculates the average uplink data rate (THP.sub.avg) in a predefined periodicity, which is selected to be equal to UE's PHR periodicity. The THP.sub.avg is calculated by the following equation:

(9) ${\mathrm{THP}}_{avg}=\frac{\mathrm{Total}\mathrm{Uplink}\mathrm{data}\mathrm{volumes}\mathrm{in}\mathrm{the}\mathrm{recent}\mathrm{PHR}\mathrm{pediod}}{\mathrm{Time}\mathrm{to}\mathrm{tranfer}}$ Where: Time to transfer=PHR periodicity collected from FIG. 1_104. THP.sub.avg calculated from 202 will be the input to 203. The module 203 classifies user data services based on THP.sub.avg from 202. BS differentiates between UEs which are having the demand to increase uplink throughput and the UEs which only need to maintain connections. By doing this, not all the UEs have to increase transmitted power to the high level so it can avoid interference to UEs in adjacent BSs and decrease noise floor.

(10) The output of this module comprises two types of UE data services: UEs use low data rate services (such as web service, over the top (OTT) apps, ping services and discrete uplink feedbacks for the downlink services . . . ) UEs use high data rate services (such as video streaming, data Upload . . . )

(11) The following module is the most important module of the invention: module 204 determines SINR.sub.target for each UE Uplink connection based on output from 203. The module has two processes, including: The first process: calculating SINR.sub.target for UE requiring low data rate (SINR.sub.discrete). SINR.sub.discrete is defined by a formula (2):

(12) $\begin{array}{cc}{\mathrm{SINR}}_{\mathrm{disc}rete}={\mathrm{SINR}}_{OLPC}& \left(2\right)\end{array}$

(13) Where:

(14) SINR.sub.OLPC is the average SINR when BS uses Open loop power control (OLPC). By using average SINR.sub.OLPC as the SINR target, BSs still ensures the required SINR for decoding UE uplink signals while minimize the number of transmitted TPCs. The second process: calculating SINR.sub.target for UE requiring high data rate (SINR.sub.highThp). The steps to calculate SINR.sub.highThp are: Step 1: Collects input parameters: PHR, BSR and SINR.sub.avg from 201. Step 2: Ensures SINR.sub.highThp to satisfy the disequations (3):

(15) $\begin{array}{cc}{\mathrm{SINR}}_{\min }\le {\mathrm{SINR}}_{highThp}\left(i\right)\le {\mathrm{SINR}}_{\max }& \left(3\right)\end{array}$

(16) Where:

(17) SINR.sub.min is minimum required SINR for BS to successfully decode UE Uplink signal.

(18) SINR.sub.max is maximum SINR that can be obtained by formula SINR.sub.max=SINR.sub.avg+PHR. Step 3: Calculate SINR.sub.highThp based on the following algorithm:
SINR.sub.highThpinit=SINR.sub.min Increase SINR.sub.highThp by Δ.sub.SINR step from SINR.sub.min to SINR.sub.max.
SINR.sub.highThp(i)=SINR.sub.highThp(i−1)+Δ.sub.SINR.

(19) Where Δ.sub.SINR is one SINR step to increase a step of spectral efficiency (depending on AMC algorithm). Using PHR, bsr, SINR.sub.highThp(i) to estimate data rates at each step. Finally the algorithm will choose SINR.sub.highThp at the step with the highest data rates.

(20) Furthermore, to evaluate the efficiency of the invention, FIG. 3 illustrates an example of results from the proposed Closed loop power control system implemented in a LTE base station: SINR.sub.target is dynamically adjusted following Uplink data rates. The SINR.sub.target and UE Uplink data rates are sampled and averaged by monitoring over a long-time duration. The results illustrates on the graph: in the same radio condition SINR.sub.target is dynamically changed adapting to Uplink data rates; the more increasing SINR.sub.target the more increasing Uplink data rates and vice versa.