Implementation[ edit ] uIP makes many unusual design choices in order to reduce the resources it requires. It can be called in a timed loop, and the call manages all the retries and other network behavior. The hardware driver is called after uIP is called. It is normal for IP protocol stack software to keep many copies of different IP packets, for transmission, reception and to keep copies in case they need to be resent. First, it uses the packet buffer in a half-duplex way, using it in turn for transmission and reception.
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Background[ edit ] Cellular networks have been designed for licensed spectrum. However, as usage patterns changed from voice-centric to data-centric and data usage surged, operators started looking into unlicensed spectrum opportunities.
Using WLAN does not only allow operators to increase peak data rate and system capacity, but also to offer services for non-cellular devices, such as laptops. All of the above methods of integration assume a certain level of service continuity as well as the terminal devices being always under a licensed spectrum cellular coverage. A terminal device may access either cellular or WLAN access or both.
This procedure may be either network initiated or terminal initiated. When it is network initiated it may be either based on core network signaling eg.
Terminal based initiated procedures are based on either operator policies provided to the terminals eg. These policies may take into account various conditions eg. LWA in depth[ edit ] From the network perspective, there are two options that provide flexibility when looking at deploying LWA - collocated and non-collocated. In order to perform efficient scheduling and to assign packets to LTE and WLAN links in the most efficient manner, the eNB can receive radio information about both links, including flow control indication.
This is a tradeoff between fully network controlled mobility and fully UE controlled mobility. Generally, the design tries to balance between LTE technology which is traditionally network-controlled and WLAN technology, which normally allows a lot of freedom for the terminal e.
With LWA design, the high level decision e. LWA activation is performed by the network, but there is sufficient level of UE freedom and flexibility within the limits set by the network. The first LWA version defined in Release supported downlink aggregation only.
uIP (micro IP)