pter 7 4 Elaborate service plan 7 Implement service Crucial for user 5 Identify 6 Implement solutions perception infrastucture Network Figure 7.1 Position of the chapter Understanding Changing Telecommunications - Building a Successful Telecom Business. Edited by A. Olsson © 2004 John Wiley & Sons, Ltd ISBN: 0-470-86851-1 Understanding Changing Telecommunications - Building a Successful Telecom Business still one of the main services, especially when it comes to generating revenue. Also, voice is still a main focus of QoS discussions. A main reason is that voice is an isochronous service, which means that the decoded signal ideally should have the same audio frequency and frequency stability as the sent signal. With the present technology convergence the subject of voice and multimedia in packet networks comes into focus. Against this background a lot of the performance criteria in a packet network are included in this chapter: Packet delay (or delay in general) Jitter (delay variations) Packet loss or bit error rate Bandwidth or throughput Silence encoding, if background noise if suppressed The above criteria are network oriented. Let us call it bearer level QoS. Nowadays the user may also perceive an application-related QoS performance. At least for mobile network terminals, various perceptions occur within the possible terminal capability range, depending on service enablers, application support enablers and service layer middleware. See Figure 7.2. QoS is one of the critical success areas for a telecom actor, since the perceived end-to-end QoS has a major impact on user perception and satisfaction and consequently on churn. Compensation for a poor QoS might be to offer the service in question for free during a limited time period, or at a lower price. However, such solutions might need financial perseverance and are not considered is this chapter. The opposite solution, at least at bearer level, is to over-dimension the network, which would reduce ROCE. Regarding the QoS business model, let us return to the h