Design and implementation of a WLAN/cdma2000 interworking architecture

The combination of 3G and WLAN wireless technologies offers the possibility of achieving anywhere, anytime Internet access, bringing benefits to both end users and service providers. We discuss interworking architectures for providing integrated service capability across widely deployed 3G cdma2000-based and IEEE 802.11-based networks. Specifically, we present two design choices for integration: tightly coupled and loosely coupled, and recommend the latter as a preferred option. We describe in detail the implementation of a loosely coupled integrated network which provides two kinds of roaming services, a SimpleIP service and a Mobile-IP service. We present, in detail, two new components used to build these services: a network element called a WLAN integration gateway deployed in WLAN networks; a client software on the mobile device. For a mobile device with interfaces to both technologies, our system supports seamless handoff in the presence of overlapping radio coverage.     

Efficient authentication and key distribution in wireless IP networks

Emerging broadband access technologies such as 802.11 are enabling the introduction of wireless IP services to an increasing number of users. Market forecasts suggest that a new class of network providers, commonly referred to as wireless Internet service providers, will deploy public wireless networks based on these new technologies. In order to offer uninterrupted IP service combined with ubiquitous seamless mobility, these multiprovider networks need to be integrated with each other, as well as with wide-area wireless technologies such as third-generation cdma2000 and UMTS. Therefore, efficient authentication and dynamic key exchange protocols that support heterogeneous domains as well as networks with roaming agreements across trust boundaries are key to the success of wide-area wireless IP infrastructures. In this article we first describe a simple network model that accounts fro heterogeneity in network service providers, and put forward the requirements any authentication and key exchange protocol that operates in such a model should satisfy, in terms of network efficiency, security, and fraud prevention. We then introduce a new authentication and key exchange protocol, wireless shared key exchange (W-SKE). We characterize properties and limitations of the W-SKE against the requirements discussed earlier. Finally, we contrast W-SKE against other well-known and emerging approaches.     

Efficient data layout, scheduling and playout control in MARS

Large-scale on-demand multimedia servers that can provide independent and interactive access to a vast amount of multimedia information to a large number of concurrent clients will be required for a widespread deployment of exciting multimedia applications. Our project, called Massively-parallel And Real-time Storage (MARS) is aimed at prototype development of such a large-scale server. This paper primarily focuses on the distributed data layout and scheduling techniques developed as a part of this project. These techniques support a high degree of parallelism and concurrency, and efficiently implement various playout control operations, such as fast forward, rewind, pause, resume, frame advance and random access.     

Routing bandwidth guaranteed paths with local restoration in label switched networks

The emerging multiprotocol label switching (MPLS) networks enable network service providers to route bandwidth guaranteed paths between customer sites. This basic label switched path (LSP) routing is often enhanced using restoration routing which sets up alternate LSPs to guarantee uninterrupted connectivity in case network links or nodes along primary path fail. We address the problem of distributed routing of restoration paths, which can be defined as follows: given a request for a bandwidth guaranteed LSP between two nodes, find a primary LSP, and a set of backup LSPs that protect the links along the primary LSP. A routing algorithm that computes these paths must optimize the restoration latency and the amount of bandwidth used. We introduce the concept of "backtracking" to bound the restoration latency. We consider three different cases characterized by a parameter called backtracking distance D: 1) no backtracking (D=0); 2) limited backtracking (D=k); and 3) unlimited backtracking (D=/spl infin/). We use a link cost model that captures bandwidth sharing among links using various types of aggregate link-state information. We first show that joint optimization of primary and backup paths is NP-hard in all cases. We then consider algorithms that compute primary and backup paths in two separate steps. Using link cost metrics that capture bandwidth sharing, we devise heuristics for each case. Our simulation study shows that these algorithms offer a way to tradeoff bandwidth to meet a range of restoration latency requirements.