Index-Based Peer Discovery in Wireless Networks
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Solution Overview
Problem
In wireless communications systems, peer-to-peer discovery signals can interfere with wide area network base stations and consume excessive power, particularly when peer-to-peer frequency bands overlap with WAN frequency bands, leading to increased load on base stations and limited battery life in mobile devices.
Innovation Solution
The method involves using a WAN base station to assist in communicating peer discovery information by transmitting an index corresponding to a peer discovery expression, where the index is conveyed with a small number of bits and the expression is conveyed with a larger number of bits, allowing for efficient power usage and reduced interference, with the index being transmitted at a lower power level than the expression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If peer to peer discovery signals are transmitted at high power to ensure reliable discovery communication, then discovery reliability is improved, but interference to base station communications increases and power consumption increases
Solution Approach 1:
The discovery signal is segmented into two parts: a short index (3 bits or less) transmitted by the peer device, and a longer expression (64 bits or more) transmitted by the base station. This segmentation allows the peer device to transmit only the compact index at lower power, reducing interference while maintaining discovery reliability through the base station's higher power expression transmission.
Solution Approach 2:
The base station acts as an intermediary that receives the index from the peer device and transmits the corresponding expression. This intermediary role allows the system to achieve reliable discovery communication through the base station's high-power transmission while the peer device consumes less power and causes less interference.
2Reliability
If peer to peer discovery signals are transmitted at high power to ensure reliable discovery communication, then discovery reliability is improved, but power consumption increases
Solution Approach 1:
The discovery signal is segmented into a short index (3 bits or less) and a longer expression (64 bits or more). The peer device only transmits the compact index at lower power, significantly reducing its power consumption compared to transmitting the full expression, while the base station transmits the expression to ensure reliable discovery communication.
Solution Approach 2:
The base station serves as an intermediary that transmits the discovery expression on behalf of the peer device. This allows the peer device to achieve reliable discovery communication without consuming excessive power, as the base station handles the high-power transmission of the expression.
3Use of energy by moving object
If the index is transmitted with fewer bits to reduce power consumption, then power efficiency is improved, but information content is reduced
Solution Approach 1:
The discovery information is segmented into a compact index (3 bits or less) that the peer device transmits efficiently, and a comprehensive expression (64 bits or more) that the base station transmits. This segmentation allows the peer device to maintain power efficiency while the full information content is preserved in the base station's expression transmission.
Solution Approach 2:
The base station creates and transmits a copy of the discovery expression based on the index received from the peer device. This copying mechanism allows the peer device to transmit only the compact index while the full information content is available through the base station's expression transmission.
Data Source
AI summary
Base station assisted peer to peer discovery methods are described. A wireless terminal communicates peer discovery expression information to a base station and information identifying a peer discovery resource that it intends to use but which may also be used by other devices. The base station associates the peer discovery expression and peer discovery resource with an index value to be communicated on the peer discovery resource. The base station transmits the peer discovery expression and information associating the peer discovery expression with the peer discovery resource and the index value. The wireless terminal transmits the index value on the peer discovery resource. A wireless terminal receiving the index value determines the peer discovery expression being communicated using information from the base station. Use of different indexes allows multiple devices to use the same discovery resource.