## 5 Indirect Cooperation via a Third-Party Entity
### Adjustment of LTE and Wi-Fi Transmission Based on Requirements and History  
In a more sophisticated approach than the technique described in the previous section, the CCE adjusts both LTE and Wi-Fi transmission timeslots based on their requirements, as well as the channel activity history. In order to control the duration and the frequency of LTE bursts, we assume variable transmission duration, followed by a variable mute period, in an event-based way similarly to the previous technique. Furthermore, both LTE and Wi-Fi networks must perform a CCA before a transmission in order to be compliant with the regional regulations and respect potential transmissions from other networks that do not participate in the cooperation scheme. In a similar way to the previous section, when a new Wi-Fi or LTE network is activated, the AP or the eNB collects and sends the network requirements to the CCE. Then, the AP or the eNB keeps collecting requirements periodically. This period can be in terms of tens of milliseconds up to a few seconds and can vary between different networks. The new requirements are compared to the previous state reported to the CCE. If the variation exceeds a defined threshold, then they are sent to the CCE. The Wi-Fi requirements are the ones that have been described in Section 5.2. Similarly, the LTE eNB informs the CCE about the transmission load of the LTE network. When the coordinator receives the requirements, then it decides about the LTE transmission duration and mute period based on the current requirements (e.g., summarized bit rate per second) and the history of transmissions. The history of transmissions represents a moving time window that tracks the average channel utilization for each participating network. The decision can be made, taking into account different weights of the history and the current requirements. To this end, the values of \(p\) and \(1-p\), where \(0\leq p\leq 1\), are used to express the weights of the current requirements and history that will be used respectively. Initially, history records are not available. Hence, only the current requirements are taken into consideration. The weights of the current requirements and history will be used by the scheduler of CCE to compute the new duration of the LTE transmission and the new duration of the LTE mute period. Hence, when a network must transmit mainly delay-sensitive traffic, then the weight of the current requirements will be higher than the weight of history, as in this case, the traffic must be delivered on time. In a similar way, when best-effort traffic has to be transmitted, then the history of the channel utilization may have a higher weight in the final decision. If a change to the transmission behavior of LTE is needed, then the CCE triggers an event and informs LTE about the new configuration of transmission. The next LTE transmission will be done according to the new configuration. Again, in case of multiple eNBs, the transmission duration and mute period should be synchronized. Figure 13 presents the aforementioned cooperation technique. Figure 13: Adjustment of LTE and Wi-Fi transmission based on requirements and history. The flowchart of the proposed cooperation method is shown in Figure 14. When needed, the eNB and the AP inform the coordinator about their new requirements. When the coordinator receives the requirements, it evaluates them and decides if modifications to the LTE transmission duration and mute period are required, as described above. Then, the coordinator informs the participating networks about its decision and updates its database. Based on the coordinator's decision, the LTE adjusts its transmission duration and the mute duration for the next time frame giving the necessary slots to Wi-Fi. In this technique, synchronization between Wi-Fi and LTE is not critical, as there is no need for synchronized access to the medium between the wireless technologies that participate in the cooperation scheme.