Object Organization on a Single Broadcast Channel in the Mobile Computing Environment

Broadcasting dependent data for ordered queries without replication in a multi-channel mobile environment

“…When a mobile user submits a query Q i , the mobile device should wait until the system starts to broadcast the first required data item of Q i (i.e., D q i (1) ). This time interval is called the startup time.…”

“…In this example, data allocation algorithms assuming independent data are not able to effectively optimize the performance of the broadcast programs. This phenomenon attracts a series of studies [1][3] on solving the problem of broadcasting dependent data.…”

An effective broadcast program generation algorithm for dependent data

“…We also assume that the offset between the start time of the m-th broadcast cycle and the moment of the mobile user submits a query is a uniform distribution over (0, L). To simplify the further derivation, we define a series a(j), j = 1, 2, · · · , n(D q i (1) ), to represent the sorted placements of all copies of D q i (1) , and b to represent n(D q i (1) ). Then, we have the following lemma.…”

“…2) The Derivation of Average Waiting Time: To facilitate the derivation of the average waiting time of a query (T W aiting (Q i )), we first define p i (j) to be the probability that the user retrieves the j-th copy of D q i (1) as the first required data item of Q i . Thus, we have the following lemma.…”

“…This phenomenon attracts a series of studies on solving the problem of broadcasting dependent data. Explicitly, the problems of broadcasting dependent data can be categorized by the following three properties: (1) the number of broadcast channels (single [1][10] [14] or multiple channels [5][6]), (2) the constraint of the sequence of the data items (ordered [1][6] [8] or unordered 1 [2][3] [4][7] queries) and (3) the employment of data replication 2 (without replication or with replication).…”