1. 21-16-0075-00-0000 IEEE 802.21 MEDIA INDEPENDENT HANDOVER DCN: 21-16-0075-00-0000 Title: Load balancing in heterogeneous network use case Date Submitted: May, 18, 2016 Presented at IEEE 802.21 session #74 in Waikoloa, USA Authors or Source(s): Krzysztof Grochla (IITIS PAN) Abstract: The load balancing between heterogeneous wireless networks using IEEE 802.21 handoff procedures use case is presented, with discussion of required extensions to monitor the load of Points of Access and trigger the handoff in response to network load changes

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3. Load Balancing – motivation for the use case Modern mobile devices often have multiple radio interfaces and are able to use multiple access technologies The coexistence of multi-RAT allows the operators to shift load from one RAT to another when some of the network PoA are overloaded The availability of D2D communication (WiFi Direct, ProSe) allows to offload the traffic to direct communication whenever possible The 802.21 allows to execute the handover procedure, but does not provide the methods to monitor the load of the network to detect when it should be performed In load balancing the handoff procedure is generally network initiated Currently used, client defined preference is not feasible as it requires periodic measurements or user-defined preferences 21-16-0075-00-0000

4. Load Balancing use case The MIS-capable Point of Attachment (PoA) is overloaded and is unable to service all of the clients or is servicing them with limited throughput The 802.21 procedures allow to locate the neighbors which can be candidates for the handover The Serving PoA communicates with other neighboring PoAs to find the candidate which has the resources available to service new clients If there are another PoAs able to service the MN the serving PoA initiates the handoff The network initiated handover procedure is started to switch the user to a less loaded PoA 21-16-0075-00-0000

5. Extensions required to execute the load balancing use case Current MIS_Net_HO_Candidate_Query allows to define only the acceptance status (permit/decline) of the handover request, which is not enough Load status information to be advertised by MIS-capable PoA May be in a simple 3-state information: overloaded (want to decrease the number of clients serviced), full (does not want to accept new clients switched because of the load balancing procedures) and under-utilized (may accept new clients) A more sophisticated measure of load (e.g. number between -127 and +128 or the expected effective throughput offered for the client) is also an option May be added on one of the reference points RP4/RP5 May be added to the MIS_Net_HO_Candidate_Query response of added by a separate message The load balancing algorithm should be outside the scope of the standard 21-16-0075-00-0000

6. Possible architectures Distributed PoS of service exchange information about the load The PoS which observes that a MN is connected to a overloaded PoA initiates the handoff to another network Requires the maintenance of the communication between a PoA with possible handoff candidate PoA The discovery of such candidates in to trivial, but may be done on the basis of MN-initiated handoffs Centralized There is a single entity in the network monitoring the load status of the PoAs and supporting the decision to which PoA switch the MN 21-16-0075-00-0000

7. Relevance to the ITU M2320 ITU M2320 lists as one of the technology enables the dynamic network topology: adjusting network topology including backhaul transmission nodes appropriately in order to accommodate the varying traffic and to adjust the transmission capability Load balancing functions may allow to switch between backhauls in response to load changes Efficient resource scheduling: efficient use of network resources such as frequency, space, power, and time, while maximizing the transmission capability Possible extensions to add information also about power usage 21-16-0075-00-0000