Virtual Groups for Femto-Cell Hand-In Identification
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Solution Overview
Problem
In wireless communication systems, the increasing number of femto-cells within a macro-cell's coverage area leads to ambiguity in identifying target femto-cells during hand-in processes due to the limited number of available pseudorandom noise (PN) codes, potentially causing dropped calls and difficulties in accommodating a large number of femto-cell access points without modifying existing air interface specifications.
Innovation Solution
Implementing a virtual group mechanism where femto-cells sharing the same PN code are grouped together, allowing the macro-cell base station to control and manage these groups to determine which femto-cell is within communication range of a wireless device, and assigning different communication codes for macro-cells and femto-cells to reduce ambiguity and facilitate hand-in requests without altering existing air interface specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of femto-cells within a macro-cell's coverage area is increased, then network capacity and coverage are improved, but ambiguity in identifying target femto-cells during hand-in processes occurs due to limited PN codes
Solution Approach 1:
The patent segments the limited set of PN codes into multiple groups, where each group is assigned to a specific macro-cell. This segmentation allows multiple femto-cells within the same macro-cell to share the same PN code without causing ambiguity, as the macro-cell context provides additional identification information. The segmentation resolves the contradiction by organizing resources to support more femto-cells while maintaining reliable identification.
Solution Approach 2:
The patent introduces an intermediary identification mechanism that combines the PN code with macro-cell specific information. When a hand-in request occurs, the system uses both the PN code and the associated macro-cell identifier to uniquely identify the target femto-cell. This intermediary approach allows multiple femto-cells to share PN codes while maintaining unambiguous identification, thus resolving the contradiction between increasing femto-cell quantity and maintaining identification reliability.
2Adaptability or versatility
If existing air interface specifications are not modified, then system compatibility is maintained, but the ability to accommodate a large number of femto-cells is limited
Solution Approach 1:
The patent makes the existing PN code structure multi-functional by using it for both traditional cell identification and for identifying femto-cells within macro-cells. By assigning PN code groups to macro-cells and allowing multiple femto-cells to share codes within those groups, the system achieves universality without requiring new identification mechanisms. This resolves the contradiction by enabling support for more femto-cells while maintaining compatibility with existing air interface specifications.
Solution Approach 2:
The patent implements preliminary assignment of PN code groups to macro-cells during network configuration. This pre-organization of resources allows the system to accommodate multiple femto-cells without requiring real-time complex allocation decisions. The preliminary structuring reduces operational complexity while enabling enhanced adaptability, resolving the contradiction between supporting more femto-cells and maintaining system simplicity.
3Productivity
If PN codes are reused across multiple femto-cells, then code resource efficiency is improved, but ambiguity in target femto-cell identification occurs
Solution Approach 1:
The patent segments the PN code usage by associating each PN code group with a specific macro-cell. While PN codes are reused across multiple femto-cells, the segmentation through macro-cell association ensures that the combination of PN code and macro-cell identifier provides unique identification. This resolves the contradiction by enabling code reuse for efficiency while maintaining identification precision through the segmented organizational structure.
Solution Approach 2:
The patent adds another dimension to PN code identification by incorporating macro-cell context. Instead of relying solely on the PN code (one dimension), the system uses the PN code combined with macro-cell identifier (two dimensions). This dimensional expansion allows PN code reuse across multiple femto-cells while maintaining unambiguous identification, resolving the contradiction between code utilization efficiency and identification accuracy.
Data Source
AI summary
Techniques, apparatuses, and systems for handling femto-cell hand-in requests can include operating a macro-cell base station to provide wireless service to wireless devices in a geographical coverage area; receiving, from a wireless device, a message indicative of the wireless device's reception of a base station radio signal, the message including a base station identifier; controlling multiple femto-cell base stations that are assigned to the base station identifier to communicate with the wireless device and to report a reception of a radio signal from the wireless device; and transferring the wireless device from the macro-cell base station to a femto-cell base station of the multiple femto-cell base stations that reports a reception of the radio signal from the wireless device. The multiple femto-cell base stations can provide wireless service in different nonadjacent portions of the geographical coverage area.