Browse Prior Art Database

Macro to Residential Access Point hand-in as interference mitigation.

IP.com Disclosure Number: IPCOM000199149D
Original Publication Date: 2010-Aug-27
Included in the Prior Art Database: 2010-Aug-27
Document File: 4 page(s) / 249K

Publishing Venue

Motorola

Related People

Freiberg, Lorenz: INVENTOR [+3]

Abstract

The term APC, access point concentrator, is used loosely. Various entities may be involved. The point is that a centralised network entity is responsible, the implementation of which is beyond the scope of this disclosure. UE_m refers to a UE which is attached to the macro, or overlay network RAP is a Residential Access Point, and small base station located in a customers home. 1. Macro-attached UE (UE_m) detects that it is approaching a RAP coverage area. In the presence of interference from RAP CPICH, UE_m triggers a Hand-over request 2. However, since the same RAP scrambling code is used many times within a macro coverage area, the precise RAP cannot be identified without further information: Any RAP experiencing an unusually high level of interference (detected on the UL through Received Total Wideband Power rise) will issue an interference warning to the APC. This warning message is not defined within the 3GPP spec, however, it resides within a proprietary interface: that between the RAP and the APC, contained within the RAP deployment. 3. The APC can match the interference warning with the handover request originating from the macro overlap network. 4. If more than one interference warning exists on the target scrambling code, some ambiguity remains: -- However, the APC can forward the UL scrambling code and relative CPICH timing information to all RAPs issuing an interference warning. The RAP then assigns an additional uplink resource to the UE_m's scrambling code. Specific messages are: 3GPP TS 25.401 - Prepare Handover 3GPP TS 25.413 - Relocation Required Relocation Required uses the concept of a transparent container to convey information to the target RNC (part of the RAP). -- The APC facilitates Handover to the RAP which report UL synchronisation success. The macro overlay network would not need to be informed about any other RAP that had attempted to synchronise to the macro attached UE.

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Macro to Residential Access Point hand-in as interference mitigation.

By Lorenz F

Freiberg

, Richard Heywood, Gerard T Foster

Motorola, Inc.

Home and Networks Mobility

 

ABSTRACT

A Macro-attached UE detects that it is approaching the coverage area of a residential access point. In the presence of interference from the access point pilot signal, the UE triggers a Hand-over request However, since the same access point’s scrambling code is used many times within a macro coverage area, the precise access point cannot be identified without further information: Any residential access point experiencing an unusually high level of will issue a proprietary interference warning to a centralized network entity. The centralized network entity can match the interference warning with the handover request originating from the macro overlap network, thereby identifying the location of the handover request.

PROBLEM

                  In a network of up to a million residential access points (RAPs) there will be in the order of 100 RAPs within the geographical area of a Macro cell.

Only a limited number of entries/measurements (32) are allowed on a neighbour list, say use ~6 to measure RAP neighbours. Therefore RAP layer can reuse 6 assigned SCs throughout it's deployments.

UE/RNC selects a handover candidate based on measurements taken on the 6 neighbours. Therefore the scrambling code can be indentified, but the particular RAP cannot.

Simultaneously, a RAP may be suffering interference from a macro attached UE and would benefit from allowing the RAP to hand in to it's cell. However, it has no may of identifying the UE.

Many solution exist for a RAP user returning to it's home network. This one sided approach only works when the RAP's decision to permit entry into its system can be assumed -- as in the case of a user returning home.

SOLUTION

If handover is not possible, the RAP will experience a large amount of interference from a macro UE if in close proximity to a RAP. This idea uses the very problem experienced by the RAP as a identifier to complete the handover process. A new message is proposed for the RAP for it to indicate to the Residential Access Point Concentrator that it experiencing interference problems.

OPERATION

The term APC, access point concentrator, is used loosely. Various entities may be involved. The point is that a centralised network entity is responsible, the implementation of which is beyond the scope of this discussion. UE_m refers to a UE which is attached to the macro, or overlay network. RAP is a Residential Access Point, and small base station located in a customers home.  The interference mitigation mechanism is as follows:

1. Macro-attached UE (UE_m) detects that it is approaching a RAP coverage area. In the presence of interference from RAP CPICH, UE_m triggers a Hand-over request

2. However, since the same RAP scrambling code is used many times within a macro coverage area, the precise RAP cannot be identified...