CSG-based Home Zone Indication

Transcription

1 CSG-based Home Zone Indication Contents 1 Executive Summary 3 2 Introduction 3 3 CSG Names and Identifiers for HZI 3 4 CSG-based HZI Use Cases Use Case 1: Automatic Search Use Case 2: Manual Search 5 5 References 7

2 1 Executive Summary This paper illustrates CSG-based Home Zone Indication method. 2 Introduction CSG (Closed Subscriber Group) concept is being introduced to EUTRAN and UTRAN Rel8 onwards. Its motivation is to enforce closed access mode for Femto cell (a.k.a. Home (e) NodeB or Femto Access Point). There is a good lesson to learn from pre-rel8 UMTS system that the support of closed access control and HZI were not sufficiently considered during the initial UMTS design and standardisation. Thus, keeping in mind the criticality of HZI (Home Zone Indication) feature for closed Femto cell service for e.g. tariff suggestion purpose, CSG designers specified in 3GPP standards [1~4] several powerful and flexible HZI indicators and functions for CSG cells, which will be elaborated as follows. 3 CSG Names and Identifiers for HZI In total four CSG identifiers have been defined: H(e)NB equipment identity, CSG identity, HNB name and CSG Type. H(e)NB equipment identity is associated with H(e)NB physical entity and only for administrative purpose. It is not known to UE and will not be displayed to user; therefore, it is not useable by UE to identify a H(e)NB. Except H(e)NB equipment identity, all other three can be used for HZI purpose. CSG identity is 27bits in length (as defined in [5] sec and [6] sec ), and is mandatory for CSG cell to broadcast to UE over air interface. A CSG identity is unique within a PLMN. In the UE a CSG ID, together with a PLMN ID, identifies a CSG globally uniquely. CSG identity is used for automatic and manual CSG selection and access control to CSG cells. CSG identity is displayed to user only when HNB name is not available. The purpose of HNB name is to display a friendly name to the user during manual selection. Its length shall not exceed 48x8 bits, which allows at least 12 characters (a range of 12~48) in UTF-8 encoding for a HNB name in any language. It is optional for a CSG cell or a hybrid cell to broadcast its HNB name in free text format. When it is available in UE (i.e. stored in USIM, or via broadcast, or stored in ME), it shall be displayed to user during the manual CSG selection procedure for ease of use ; whereas its display is optional during UE normal operation. HNB name may be stored in either UE s USIM or ME, and USIM entry takes precedence over broadcast and ME. A HNB name needs to be associated with a CSG identity in the UE. CSG Type is used for additional information (on e.g. billing mode) to the user when camping on a CSG cell (i.e. after CSG has been selected and UE stays in normal operation mode). The CSG Type shall be stored in text and/or graphical format. When the CSG Type has a text component,

3 the CSG Type text length shall not exceed 12 characters in any language. The CSG Type is provided by initial UE configuration, OTA and device management to UEs. The association between a CSG Type and a CSG identity needs to be done by operator. Only when the CSG Identity of the camping CSG cell is in UE s Allowed CSG List will the associated CSG Type be displayed to users. If the CSG Type for a CSG identity has not been configured in the UE, the UE may provide the HNB Name instead. And the UE s USIM entry of CSG Type takes precedence over ME. 4 CSG-based HZI Use Cases Depending the availability of different CSG names and different CSG search modes (automatic, manual), there are several CSG-based home zone indication scenarios. 4.1 Use Case 1: Automatic Search Zoe is stepping into a celebrity club to attend a cocktail party for her next movie: Avatar II. Her iphone 3GS+ performs periodical automatic search, detecting a CSG cell being active onsite. After reading the CSG identity and checking it against the stored Allowed CSG List, her smart iphone readily knows it is ok to camp on to this club CSG cell. Therefore, without any user intervene or awareness, Zoe s iphone smoothly reselects and log onto the club private cell. The club cell s CSG Identity is associated with CSG Type of Free Cell, which will be displayed on the iphone s screen (see Fig. 1). Figure 1: CSG-based HZI display for automatic search use case 4.2 Use Case 2: Manual Search

4 Figure 2: CSG-based HZI display for manual search use case Zoe is visiting her friend Susan in Cambridge. Before Zoe comes, Susan already notified the operator to add Zoe s iphone into her home cell s Allowed UE list for one week of her stay. Susan welcomes Zoe into the sitting room, where Susan tells Zoe that her iphone can register and use Susan s home cell. Zoe then navigates the iphone menu to instruct it to enter Manual Search mode. After several seconds, iphone displays a list of all its detected CSG cells nearby, including Susan s home cell (HNB name: Susan s Home Cell ). Zoe swiftly chooses Susan s home cell to camp on. After the selection is made, Zoe s iphone shows CSG Type of Flat rate CSG cell.

5 5 References [1] 3GPP TS Architecture aspects of Home Node B (HNB) / Home enhanced Node B (HeNB) [2] 3GPP TS Service requirements for Home Node B (HNB) and Home enode B (HeNB) [3] 3GPP TS Service accessibility [4] 3GPP TS Mobility procedures for Home Node B (HNB); Overall description; Stage 2 [5] 3GPP TS UTRAN Iu interface Radio Access Network Application Part (RANAP) signalling [6] 3GPP TS Evolved Universal Terrestrial Radio Access (E-UTRA); S1 Application Protocol (S1AP)