Rate Allocation in Multi-User Communication Systems
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Solution Overview
Problem
In multi-user shared-frequency communication systems, such as CDMA and OFDM, maximizing data transmission rates while maintaining signal quality is challenging due to interference between users, leading to unfair allocation of system bandwidth and compromised throughput.
Innovation Solution
A communication system that allocates user transmission rates fairly by ensuring a minimum quality of service for each user, incrementally adjusting rates based on signal power and unfairness, using a system-level selection criteria to maximize achievable rates while preventing disproportionate bandwidth allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data transmission rate is increased to maximize throughput, then system productivity improves, but signal quality deteriorates due to increased interference and noise
Solution Approach 1:
The patent dynamically adjusts transmission parameters including data rate, power level, and modulation scheme based on channel conditions and interference levels. By changing these parameters adaptively, the system can operate at higher rates when conditions permit while maintaining signal quality through power control and error correction mechanisms.
2Productivity
If transmission rate of one user is increased to maximize individual throughput, then that user's productivity improves, but unfairness in bandwidth allocation increases and other users' performance deteriorates
Solution Approach 1:
The patent implements feedback mechanisms where the base station monitors channel conditions, interference levels, and quality of service metrics for all users. Based on this feedback, the system dynamically adjusts power allocation and data rate assignments to maintain fairness while maximizing overall throughput. The feedback loop ensures that no single user can monopolize resources at the expense of others.
3Productivity
If power allocation is adjusted to maximize system throughput, then overall productivity improves, but signal quality for individual users may deteriorate due to power constraints
Solution Approach 1:
The patent applies local quality by allocating power and resources differently to different users based on their specific channel conditions, quality of service requirements, and current system state. Users with poor channel conditions or higher QoS requirements receive preferential power allocation, while users with good channels can tolerate lower power levels. This localized approach maintains individual signal quality while optimizing overall system throughput.
Data Source
AI summary
According to example embodiments for use in a communication system that is adapted to permit the users to transmit data simultaneously via shared frequency and spatial resources, an allocation of user transmission rates involves setting and maintaining the transmission rates of the users to at least a minimum user transmission rate to provide an expected minimum quality of communication for each of the users. These rates of the users are incrementally adjusted by iteratively changing the transmission rate of each user as a function of a resulting vector of transmit powers ensuing from the increased transmission rate, a degree of transmission-rate-allocation unfairness relative to the transmission rates of all the users, and a power-based selection criteria. With such an approach, the rates are fairly allocated without a disproportionate allocation of system bandwidth. Various embodiments are applicable to a variety of communication applications including OFDM or CDMA communication systems.