## Abstract

In this work, we consider a CDMA cell with multiple terminals transmitting video signals. We adapt the system parameters to minimize the sum of compression powers and transmitter powers of all users while guaranteeing the received video quality at each terminal. The adjustable parameters at user i include the transmitter power P_{t,i,} the video coding bit rate R_{s,i}, and video encoder parameters that control the complexity and hence power consumption of the video coder (referred simply as complexity β_{i}). Instead of determining P_{t,i} directly, we first determine the desired signal to interference-noise ratio (SINK) γ_{i}. Based on the optimal γ_{i} and R _{s,i}, we then determine P_{t,i}i, Our analysis shows that the product of R_{s,i} and γ_{i} is an important quantity. Given the complexity β_{i} (i.e., given the compression power) and quality constraint, in order to reduce the transmission power, one should choose R_{s,i} and γ_{i} to minimize their product. When only the total transmission power is concerned, the optimal operating points can be determined at individual users separately: each user should run the encoder to minimize the product of R_{s,i} and γ_{i}. When the objective is to minimize the sum of compression and transmission powers of all users, the optimal solution can be found in two steps. The first step searches the optimal R_{s,i} and γ_{i} that minimize R _{s,i} × γ_{i} for each video category and each possible β_{i} while satisfying the quality constraint at user i. The second step searches the optima] {β_{i}}_{i=1,...,N} for all users jointly, that minimizes the sum of transmission and compression powers of all users. The first step can be completed offline in advance, only the second step needs to be computed in real time based on channel conditions of the users. Our results indicate that for the same class of video users, the one who is closer to the base station compresses at a lower complexity. Simulation results show that significant power savings are obtained by our adaptive algorithms over nonadaptive approaches, where {R_{s,i}, β_{i}, γ_{i}} are fixed regardless the channel conditions.

Original language | English (US) |
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Pages (from-to) | 674-685 |

Number of pages | 12 |

Journal | IEEE Transactions on Circuits and Systems for Video Technology |

Volume | 17 |

Issue number | 6 |

DOIs | |

State | Published - Jun 2007 |

## Keywords

- Cdma network
- Power control
- Video coding
- Wireless communication

## ASJC Scopus subject areas

- Media Technology
- Electrical and Electronic Engineering