SERVICE ADVERTISEMENT, DISCOVERY, AND ASSOCIATION (ADA) AND WIRELESS BILLBOARD CHANNELS (WBCS)

Advertisement, discovery and association (ADA) of access networks’ communications services and teleservices are key aspects of the future 4G wireless communication world as mobile users/ terminals need to discover all services available/deployed at a given area/location. Several different service discovery protocols have been proposed in the past with two basic modes of operation: pull mode and push model. In the pull mode, clients query the environment about given services and dedicated servers express interest with a reply. In the push mode, servers periodically advertise their services while the clients listen for these advertisements.

With the potential for access network services in UCWW being sold to users on a consumer basis, transaction by transaction, rather than through a long-term subscriber contract as at present, wireless access networks competing for consumer business will seek new dynamic ways to advertise their services to potential customers. We believe that the future consumer-centric wireless communication environment should behave according to the push mode in which a network infrastructure (e.g., access network provider, ANP) or a source of data (teleservice provider, TSP) takes care of preparing connections and services, and proposes them to the mobile user. In this proactive mode of operation, the only user intervention is to choose the ‘best’ possible connection for each needed ‘best’ service.

Wireless Billboard Channels (WBC), is a novel ‘push’ advertising concept, and new business opportunity, to cater for this need. For mobile users, as consumers, WBCs will be an effective means to discover who is offering what services; with what QoS options; at what price/tariff schedules; how to gain access to these services; etc. WBCs will have broad attraction for other Internet businesses and teleservice providers seeking to increase consumers’ usage of their wireless networks and service offerings. WBCs will be:

• Broadcast, narrowband, and unidirectional channels;
• Local, regional, national, and international in their coverage regimes;
• Owned by WBC service providers (WBC-SPs), independent of wireless ANPs (for reasons of fairness); The existing digital TV and radio broadcasters are prime candidates for WBC-SPs;
• Typically hosted on suitable existing broadcast services’ physical infrastructures, e.g., as an additional service. New potential broadcast platforms include but are not limited to Digital Radio Mondiale (DRM), Digital Audio Broadcasting (DAB), Digital Video Broadcasting - Handheld (DVB-H), Digital Multimedia Broadcasting (DMB), and Multimedia Broadcast Multicast Service (MBMS).

To broadcast datasets over narrowband and unidirectional WBC channels, the service advertisements represented by service descriptions (SDs) should be specified in a structured, efficient, and compact formal language. The typical SD structure consists of a set of attributes, such as ServiceType, ScopeList, Length, Composite Capabilities/Preferences Profile (CC/PP), QoS, and AttrList. 

The Service Type is used to group together all SDs performing the same function. Each ServiceType needs a corresponding ServiceTeplate to specify the SD attributes. The ScopeList, CC/PP, and QoS act as filters for SDs (together with the user profiles) and thus facilitating the blocking or receiving of SDs by the user mobile terminal. Since using as little bandwidth as possible is one of the WBC desired properties, in order to reduce the SD size the abstract syntax notation's packet encoding rules (ASN.1-PER) are used to format SDs. A set of pre-defined basic and constructed types, such as INTEGER, IA5String, BIT STRING, LIST, SEQUENCE, CHOICE etc, are used to describe the complex SD data structure. 

In addition, with PER, the final data stream of SDs is smaller comparing with other formal languages, such as document type definition - extensible mark-up language (DTD-XML) and augmented Backus-Naur form (ABNF). Thus, the ASN.1-PER was selected to describe data structures in WBC. To integrate the ASN. 1-PER scheme into a platform-independent environment, all SD templates were compiled to JAVA classes with an ASN. 1 Java compiler. The ASN. 1-PER encoder/decoder (Figure 1) depends on the Java classes used for the encoding a SD Java object to PER octets and decoding of PER octets to a SD Java object.

Figure 1: The ASN.1-PER encoder /decoder 

 

Considering the trend that the future mobile terminals will integrate IP-based transmission techniques, the WBCs should employ an IP data-casting (IPDC) such as that proposed. To simplify the design and achieve compatibility with this technique, the WBCs are designed with a three-layer protocol architectural model containing the following layers:

1. Service layer, which describes the service discovery model, and data collection, clustering, scheduling, indexing, broadcasting, discovery, and association schemes;
2. Link layer concerned with the frame processing issues, such as addressing, forward error control, etc.;
3. Physical layer, which realizes the transmitter (in the WBC-SP node) and receiver (in the user mobile terminal).

The WBC link layer and physical layer are hardware-dependent layers and thus have different structures depending on the carrier technology used. The service layer is the main WBC layer for research, design and development. It is a pure software layer, independent of the carrier technology. It must ensure smooth IPDC processing with different types of WBC link layer and physical layer, i.e., different carrier technologies.